Haemorrhagic septicaemia in cattle and buffaloes€¦ · Haemorrhagic septicaemia in cattle and buffaloes M.C.L. DE ALWIS** Summary : Haemorrhagic septicaemia (HS) is a highly fatal

Rev. sci. tech. Off. int. Epiz., 1984, 3 (4), 707-730.

Haemorrhagic septicaemia in cattle and buffaloes*

M . C . L . D E A L W I S * *

Summary : Haemorrhagic septicaemia (HS) is a highly fatal disease in cattle and buffaloes, caused by specific serotypes of Pasteurella mul to-cida. It is a primary pasteurellosis reproducible in susceptible animals with the specific organism alone. The accepted classification of Pasteu-rella multocida is based on the identification of its somatic and capsular antigens. On this basis two serotypes designated 6:B and 6:E have been found to cause HS.

The disease is prevalent in most countries in Asia, the Near and Middle East, Southern Europe and in the North, Central and East Africa. In Asia, the disease is caused by serotype 6:B and in Africa 6:E, while a few countries have recorded both. In most Asian countries, it is recognised as a disease of utmost economic importance.

In a few countries where epizootiological studies have been done, it has been found that definite patterns of incidence have been established, presumably through the interaction of climatological, immunological and epizootiological factors. The disease is more common in buffaloes than in cattle, and in enzootic areas greater losses occur among young animals. In such areas, a variable proportion of adult animals have acquired natural immunity to the disease. Among these, some are carrier animals, and such animals are believed to be the focal point of fresh outbreaks.

All countries where HS is enzootic adopt vaccination. Broth bacte-rins are most popular, but immunity is of short duration. The oil adjuvant vaccine gives the longest immunity but only a few countries use it as it is thick and difficult to inject. Recent research on vaccines has been directed towards producing thinner emulsions, isolating antigenic fractions and the production of avirulent mutants for use as live vaccines. It is believed that a more effective control of the disease can be achieved with a better understanding of the epizootiology, the production of better vaccines, and by attaining a higher vaccination coverage.

INTRODUCTION

W i t h t h e a d v e n t o f m e t h o d s of s e r o t y p i n g Pasteurella multocida, t h e r e c o g n i t i o n o f h a e m o r r h a g i c s e p t i c a e m i a ( H S ) as a d i s t inc t d i sease en t i ty h a s

* Report presented at the 52nd General Session of the O.I.E., Paris, 21-25 May 1984 (Technical Item II).

** Veterinary Research Institute, Gannoruwa, Peradeniya, Sri Lanka.

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b e c o m e inc reas ing ly c lea r . I t is a n a c u t e , s e p t i c a e m i c d i sease c a u s e d b y t h e specif ic s e r o t y p e s 6:B o r 6 :E ( N a m i o k a - C a r t e r ) , in b u f f a l o e s a n d c a t t l e . U n l i k e m o s t o t h e r p a s t e u r e l l o s e s , H S is a p r i m a r y p a s t e u r e l l o s i s , r e p r o d u c ib le in suscep t ib l e a n i m a l s wi th p u r e c u l t u r e s o f t h e speci f ic o r g a n i s m a l o n e .

OCCURRENCE AND DISTRIBUTION

H a e m o r r h a g i c s e p t i c a e m i a o c c u r s in S o u t h e r n a n d S o u t h e a s t A s i a i nc lu d ing I n d o n e s i a , P h i l i p p i n e s , T h a i l a n d a n d M a l a y s i a , in t h e N e a r a n d M i d d l e E a s t , S o u t h e r n E u r o p e ( i nc lud ing t h e U . S . S . R . ) a n d in N o r t h , C e n t r a l a n d E a s t A f r i c a . I t h a s a l so b e e n r e p o r t e d in t h e R e p u b l i c of S o u t h A f r i c a (15) . I n t h e U . S . A . , t h e d i sease w a s r e p o r t e d a m o n g b i s o n in N a t i o n a l P a r k s in t h e yea r s 1912, 1922 a n d 1967. S ince t h e n , a p a r t f r o m o n e exp los ive o u t b r e a k a m o n g y o u n g d a i r y ca t t l e in N e w Je r s ey in 1969, t h e d i sease h a s n o t b e e n r e p o r t e d a n y w h e r e i n t h e U . S . A . (15) . T h e d i s e a s e d o e s n o t o c c u r in A u s t r a l ia , O c e a n i a , J a p a n , C a n a d a a n d W e s t e r n E u r o p e . T h e r e is r e f e r e n c e t o its o c c u r r e n c e in S o u t h A m e r i c a in t h e F . A . O . - W . H . O . - O . I . E . A n i m a l H e a l t h Y e a r b o o k , b u t n o s u p p o r t i n g l i t e r a t u r e o n s e r o t y p e i d e n t i f i c a t i o n is a v a i l a b l e for c o n f i r m a t i o n . T a b l e I s u m m a r i z e s t h e d i s t r i b u t i o n o f t h e d i s ea se .

D i s t r i b u t i o n o f t h e d i sease b e a r s s o m e r e l a t i o n s h i p t o t h e t y p e o f a n i m a l r e a r e d a n d t h e sys t em of m a n a g e m e n t . T h i s is a m p l y b o r n e o u t in t h e 65 ,000 k m 2 i s l a n d of Sri L a n k a , h a v i n g a va r i e ty o f a g r o c l i m a t i c z o n e s a n d ca t t l e h u s b a n d r y p r a c t i c e s , w h e r e d i s t inc t e n z o o t i c a n d d i sease - f ree a r e a s exis t . I n t h e hil l c o u n t r y w h e r e t h e c l i m a t e is m i l d , a n d t e m p e r a t e b r e e d s of ca t t l e a n d the i r c rosses a r e r e a r e d u n d e r i n t ens ive s y s t e m s , H S is r a r e . I n t h e d r y p l a i n s , o n t h e o t h e r h a n d , w h e r e i n d i g e n o u s ca t t l e a n d b u f f a l o e s r o a m freely, t h e d i sease is e n z o o t i c .

Seasonal inc idence .

T h e d i sease is n o r m a l l y a s s o c i a t e d w i t h w e t , h u m i d w e a t h e r , a n d in m o s t c o u n t r i e s i n c i d e n c e inc reases ea r ly in t h e we t s e a s o n . E x h a u s t i v e e p i d e m i o logica l s tud ies in Sri L a n k a h a v e s h o w n t h a t t h e d i sease o c c u r s a t all t i m e s o f t h e yea r b u t , w h e r e a s d r y s e a s o n o u t b r e a k s a r e c o n t a i n e d , o u t b r e a k s o c c u r r ing d u r i n g t h e we t s e a s o n t e n d t o s p r e a d . T h i s is p r e s u m a b l y d u e t o l o n g e r su rv iva l o f t h e o r g a n i s m u n d e r m o i s t c o n d i t i o n s , a n d t h e m o v e m e n t o f a n i m a l s a s s o c i a t e d w i t h t h e r a i n s .

Distr ibut ion of serotypes .

I n A s i a n c o u n t r i e s , t h e o n l y s e r o t y p e r e c o r d e d s o far is s e r o t y p e 6 :B . T h e r e is o n e r e p o r t o f a s ingle i s o l a t i o n of a t y p e D s t r a i n f r o m w h a t w a s be l ieved t o b e a case o f H S in M a l a y s i a (21) . W h i l e t y p e D in ca t t l e is n o r ma l ly a s s o c i a t e d w i t h a p n e u m o n i c s y n d r o m e , u n d e r c e r t a i n c i r c u m s t a n c e s it m a y p r o d u c e a s e p t i c a e m i a , a n d t h e c o n d i t i o n c o u l d b e m i s t a k e n fo r c lass ica l H S .

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T A B L E I Occurrence of haemorrhagic septicaemia in different countries*

Category A. Countries where the disease is reported to occur, on clinical or bacteriological grounds

* Extracted from F.A.O.-W.H.O.-O.I.E. Animal Health Yearbooks up to 1981, and other available reports. ** It is possible that some countries in this group may be reporting other forms of bovine pasteurellosis, and not specifically haemorrhagic septicaemia.

T h e s e r o t y p e p r e v a l e n t in A f r i c a h a s b e e n iden t i f i ed as 6 . E . A few c o u n t r i es , n o t a b l y E g y p t a n d S u d a n , h a v e r e c o r d e d b o t h . T h e N o r t h A m e r i c a n i so l a t e f r o m b i s o n , w h i c h still exists in t y p e c u l t u r e co l l ec t i ons , b e l o n g s t o 6 . B .

Afghanistan Gambia Nicaragua Angola Ghana Niger Argentina Guatemala Nigeria Bahrain Guinea Pakistan Bangladesh Haiti P a n a m a Belize Honduras Paraguay Bhutan India Philippines Bolivia Indonesia Portugal Brunei Iraq Saudi Arabia Burma Italy Sierra Leone Cameroon Ivory Coast Somalia Central African Republic Kampuchea South Africa Chad Kenya Sri Lanka Colombia Laos Sudan Comoros Lebanon Tanzania Costa Rica Liberia Thailand Djibouti Libya Uganda Dominican Republic Mali Upper Volta East Timor Malawi Venezuela Egypt Malaysia Vietnam El Salvador Mauri tania Zaire Ecuador Mexico Zambia Equatorial Guinea Namibia Ethiopia Nepal

Category B. Countries where HS is reported as an exceptional occurrence, or is suspected to occur but not confirmed

Brazil Jo rdan Spain Denmark Mozambique Syria Fed. Rep. of Germany Poland Togo Finland Qatar Turkey Greece - Romania U .S .A . Guinea-Bissau Rwanda U.S .S .R. Iran Samoa

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ECONOMIC LOSSES

W i t h t h e e r a d i c a t i o n o f r i n d e r p e s t f r o m m o s t A s i a n c o u n t r i e s , H S h a s e m e r g e d as a d i sease of c o n s i d e r a b l e e c o n o m i c i m p o r t a n c e , a n d m o s t c o u n tr ies r a n k H S as t h e m a j o r f a t a l d i sease of t h e w a t e r b u f f a l o . I t s e c o n o m i c i m p o r t a n c e is p a r t i c u l a r l y felt in t h e A s i a n r e g i o n , w h e r e t h e w a t e r b u f f a l o , wh ich is i m p o r t a n t b o t h fo r f o o d a n d d r a u g h t , is p a r t i c u l a r l y s u s c e p t i b l e .

H a e m o r r h a g i c s e p t i c a e m i a o c c u r s m o s t l y in a r e a s w h e r e a n i m a l h u s b a n d r y p rac t i ces a r e p r i m i t i v e , a n d w h e r e V e t e r i n a r y Services ( a n d c o n s e q u e n t l y d isease r e p o r t i n g sys t ems) a r e p o o r l y d e v e l o p e d . R e p o r t e d losses d u e t o H S p r o b a b l y ref lect n o m o r e t h a n t h e g e n e r a l t r e n d , t h e a c t u a l losses be ing c o n s i d e r a b l y h i g h e r . T h i s fac t b e c a m e e v i d e n t in a n e p i d e m i o l o g i c a l s u r v e y in Sri L a n k a , a n d is p r o b a b l y t r u e o f o t h e r c o u n t r i e s w h e r e H S is e n z o o t i c .

SPECIES AFFECTED

U n d e r n a t u r a l c o n d i t i o n s , t h e d i sease o c c u r s p r i n c i p a l l y in b u f f a l o e s a n d ca t t l e . A few r e p o r t s a r e a v a i l a b l e of i ts o c c u r r e n c e in o t h e r spec ies . Seve ra l s p o r a d i c o u t b r e a k s of a c u t e s e p t i c a e m i c p a s t e u r e l l o s i s in p igs a s s o c i a t e d w i t h t h e H S s e r o t y p e 6:B h a v e b e e n r e p o r t e d in Sri L a n k a , a n d o n e of t h e s e w a s a s soc ia t ed wi th t h e feed ing o f p igs w i t h b o v i n e b l o o d f r o m a n a b a t t o i r . T h i s i so la te r e p r o d u c e d t yp i ca l H S in ca t t l e ( D e A l w i s , u n p u b l i s h e d r e p o r t ) . S imi lar r e p o r t s o f s p o r a d i c i n c i d e n c e o f s e p t i c a e m i c pa s t eu re l l o s i s in p igs c a u s e d b y o r g a n i s m s s e r o t y p e d as 6 :B h a v e o r i g i n a t e d f r o m T h a i l a n d (1) a n d M a l a y sia (2). S imi la r r e p o r t s h a v e c o m e f r o m I n d i a , w h e r e t h e o r g a n i s m h a s b e e n ident i f ied as R o b e r t s ' t y p e I o r C a r t e r ' s t y p e B (34 , 46) .

S p o r a d i c o u t b r e a k s of d i sease a s s o c i a t e d w i t h P. multocida h a v e a l so b e e n r e p o r t e d in g o a t s ( 1 , 2 , 3 , 4 , 34) a n d in p o u l t r y (38 , 39) . T h e o r g a n i s m s were ident i f ied as R o b e r t s ' t y p e I , C a r t e r ' s t y p e B o r s e r o t y p e 6:B in d i f f e ren t i n s t a n c e s .

Sep t i caemic pas t eu re l lo s i s c a u s e d b y s e r o t y p e 6:B h a s b e e n r e c o r d e d in e l e p h a n t s in Sri L a n k a , in c o n j u n c t i o n w i t h o u t b r e a k s o f H S in ca t t l e a n d buf fa loes ( 3 1 , 2 4 , 62) .

T h u s , s p o r a d i c o u t b r e a k s o f s e p t i c a e m i c d i sease a s s o c i a t e d w i t h P . multocida a n d t y p e d as R o b e r t s ' t y p e I o r C a r t e r ' s t y p e B (e i ther o f w h i c h c o u l d b e 6:B or 11:B) o r s e r o t y p e 6 :B itself, d e p e n d i n g o n t h e s e r o t y p i n g s y s t e m u s e d , h a v e been r e c o r d e d in species o t h e r t h a n ca t t l e o r b u f f a l o e s . S u c h d i sease h a s been re fe r red t o as « s e p t i c a e m i c pa s t eu re l l o s i s » , t h e t e r m h a e m o r r h a g i c s ep t i c a e m i a be ing usua l ly r e se rved fo r t h e d i s ea se in b u f f a l o e s a n d c a t t l e .

CLINICAL SYNDROME AND PATHOLOGICAL LESIONS

H a e m o r r h a g i c s e p t i c a e m i a o c c u r s m o s t l y in r e g i o n s w h e r e h u s b a n d r y p rac t i ces a r e p r i m i t i v e , a n d w h e r e a n i m a l s a r e r e a r e d u n d e r semi -wi ld c o n d i -

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t i o n s . U n d e r s u c h c o n d i t i o n s , a n i m a l s a r e n o t u n d e r c o n s t a n t o b s e r v a t i o n , a n d t h e o n l y r e p o r t e d s ign m a y b e s u d d e n d e a t h . I l lness u s u a l l y l as t s 1-3 d a y s . I n o r d e r o f o c c u r r e n c e , t h e v is ib le s igns a r e e l e v a t e d t e m p e r a t u r e , s u b m a n d i b u l a r o e d e m a s p r e a d i n g t o t h e b r i s k e t r e g i o n , f o l l o w e d b y p r o g r e s sive r e s p i r a t o r y d i s t r e s s . T h e a n i m a l t h e n b e c o m e s p r o s t r a t e a n d d i e s .

T h e ex t en t o f t h e g ro s s p a t h o l o g i c a l l e s ions d e p e n d s o n t h e c o u r s e of t h e d i sease . I n f e c t i o n e x p e r i m e n t s (28) h a v e s h o w n t h a t a n i m a l s w h i c h d i ed w i t h i n 24-36 h o u r s of i n f e c t i o n h a d o n l y w i d e s p r e a d p e t e c h i a l h a e m o r r h a g e s , m o s t p r o n o u n c e d a t t h e b a s e o f t h e h e a r t , a b o m a s a l wa l l a n d t o a lesser ex t en t o n t h e i n t e s t i n e s . T h e r e w a s a l so g e n e r a l i z e d c o n g e s t i o n o f t h e l u n g s . W h e n t h e c o u r s e o f t h e d i s ea se e x t e n d e d t o 48 h o u r s , t h e h a e m o r r h a g e s w e r e m o r e seve re a n d e c c h y m o t i c , w i t h f i b r i n o u s p e r i c a r d i t i s . W h e n t h e i l lness l a s t e d for ove r 72 h o u r s , t h e r e w a s ex tens ive c o n s o l i d a t i o n o f t h e l u n g s , w i t h l o b u l a t i o n d u e t o m a r k e d t h i c k e n i n g o f t h e i n t e r l o b u l a r s e p t a . T h e r e w a s s e r o f i b r i n o u s p e r i c a r d i t i s a n d p l e u r i s y , w i t h a d h e s i o n s b e t w e e n t h e p e r i c a r d i u m a n d p l e u r a .

I n g e n e r a l , b u f f a l o e s d ie q u i c k e r a n d c o n s e q u e n t l y s h o w fewer l e s ions . C a t t l e m a y l inger o n fo r a few d a y s , r e s u l t i n g in m o r e p r o n o u n c e d p a t h o l o g ical l e s ions . W h i l e m o s t o u t b r e a k s o f H S a r e t y p i c a l , a few n o t e w o r t h y i n s t a n c e s o f a t y p i c a l s y n d r o m e s c a u s e d b y s e r o t y p e 6 :B h a v e b e e n r e c o r d e d . I n Sri L a n k a , a p n e u m o n i c p a s t e u r e l l o s i s s y n d r o m e c a u s e d b y s e r o t y p e 6 :B h a s b e e n r e p o r t e d (28) . A s y n d r o m e a s s o c i a t e d w i t h o e d e m a a n d l a m e n e s s o f t h e f o r e l i m b s h a s b e e n r e p o r t e d in B u r m a . L a m e n e s s i n y o u n g , o t h e r w i s e h e a l t h y b u f f a l o e s in e n z o o t i c a r e a s d u r i n g t h e H S s e a s o n h a s b e e n f r e q u e n t l y r e p o r t ed in Sri L a n k a . T h e s e r e p o r t s h a v e yet t o b e i n v e s t i g a t e d . T h e y m a y b e a n i m a l s w h i c h h a v e r e s p o n d e d t o i n f e c t i o n w i t h subc l in i ca l o r « a r r e s t e d » in fec t i o n s , a n d h a v e b e c o m e i m m u n e (23) .

EPIDEMIOLOGY

1. Morbid i ty and mortal i ty pattern.

I n a r e a s w h e r e H S o c c u r s , e a r ly d e t e c t i o n a n d t r e a t m e n t is n o t f eas ib le , a n d c o n s e q u e n t l y t h e case fa ta l i ty r a t e is n e a r 1 0 0 % . T h u s , m o r b i d i t y a n d m o r t a l i t y a r e n e a r l y t h e s a m e .

2 . Factors inf luencing morbid i ty and morta l i ty .

(a) Species.

W h i l e m o s t c o u n t r i e s , p a r t i c u l a r l y in A s i a , r e c o g n i z e t h a t losses d u e t o H S a r e h i g h e r in b u f f a l o e s t h a n in c a t t l e , few c o u n t r i e s h a v e p r o d u c e d evid e n c e t o s u p p o r t t h i s . I n M a l a y s i a , it is r e p o r t e d t h a t 7 3 % o f al l losses d u e t o H S o c c u r in b u f f a l o e s , d e s p i t e t h e fac t t h a t t he i r b u f f a l o p o p u l a t i o n is o n l y ha l f t h a t of ca t t l e (2) . O n e s u r v e y in Sri L a n k a i n d i c a t e d t h a t t h e h e r d in fec t i o n r a t e w a s m u c h t h e s a m e in ca t t l e a n d b u f f a l o e s , b u t t h e m o r b i d i t y r a t e

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w i t h i n a f fec ted h e r d s w a s c o n s i d e r a b l y h ighe r in b u f f a l o e s . A n o t h e r su rvey p u t b u f f a l o m o r t a l i t y a t t h r e e t i m e s t h a t of ca t t l e (32, 22) . A n o t a b l e e x c e p t i o n is t h e Bal i b r e e d of ca t t l e in I n d o n e s i a , w h i c h is r e p o r t e d t o b e h igh ly suscep t ib l e .

(b) Age.

I t is a l so a g r e e d in m o s t c o u n t r i e s t h a t g r e a t e r losses occu r in y o u n g a n i m a l s t h a n in a d u l t s , b u t q u a n t i t a t i v e e s t ima te s a r e s ca r ce . Surveys in Sri L a n k a h a v e s h o w n t h a t 6 5 % of all losses d u e t o H S in b u f f a l o e s a n d 7 7 % in ca t t l e i nvo lved a n i m a l s u n d e r 2 yea r s o ld (32) . A n o t h e r s t u d y in t h a t c o u n t r y i n d i c a t e d t h a t t h e m o s t v u l n e r a b l e age w a s b e t w e e n 6 m o n t h s a n d 2 y ea r s (29) . F u r t h e r s tud ies h a v e s h o w n t h a t th i s c o r r e l a t i o n b e t w e e n a g e a n d m o r t a lity app l ies t o e n z o o t i c a r e a s o n l y .

I n a r e a s w h e r e r e g u l a r s e a s o n a l o u t b r e a k s o c c u r , m o r t a l i t y in i n d i v i d u a l o u t b r e a k s is l ow a n d is c o n f i n e d t o y o u n g a n i m a l s . W h e n o c c a s i o n a l s p o r a d i c o u t b r e a k s o c c u r o u t s i d e t h e e n z o o t i c a r e a s , m o r t a l i t y is h igh a n d a n i m a l s of all ages d ie (22) . T h i s r e l a t i o n s h i p h a s a n i m m u n o l o g i c a l b a s i s , s ince in e n z o o t i c a r e a s , w h e r e t h e f r e q u e n c y of H S is h i g h , a l a rge p e r c e n t a g e o f a n i m a l s (pa r t i cu l a r ly a d u l t s ) posses s n a t u r a l l y a c q u i r e d i m m u n i t y (32 , 30) .

(c) Enzootic and non-enzootic areas.

M o r b i d i t y a n d m o r t a l i t y d u e t o H S h a v e b e e n s h o w n t o v a r y b e t w e e n e n z o o t i c a n d o t h e r a r e a s in Sri L a n k a . Losses in e n z o o t i c a r e a s o c c u r r e g u lar ly , m o s t l y d u r i n g a c e r t a i n s e a s o n , a n d occu r in sma l l n u m b e r s w h i c h s o m e t i m e s d o n o t a t t r a c t a t t e n t i o n . W h e n , o n t h e o t h e r h a n d , o c c a s i o n a l o u t b r e a k s o c c u r in n o n - e n z o o t i c a r e a s , t h e y c a n r e a c h a l a r m i n g p r o p o r t i o n s .

M a s s i v e ep i zoo t i c s m a y o c c u r w h e n t h e d i sease is first i n t r o d u c e d i n t o a c o u n t r y , o r h a s e s c a p e d f r o m a n e n z o o t i c p o c k e t t o o t h e r a r e a s . R e m a r k a b l y s imi la r e p i d e m i o l o g i c a l p a t t e r n s h a v e b e e n o b s e r v e d in Sri L a n k a a n d in Z a m b i a . I n t h e f o r m e r c o u n t r y , a few cases of H S h a v e b e e n r e p o r t e d a n n u a l l y in c e r t a i n p o c k e t s s ince 1915 . T h e d i sease b r o k e o u t in t he d r y p l a in s for t h e first t i m e in 1955 , a n d t o o k a very h e a v y to l l of ca t t l e a n d b u f f a l o e s o f all ages . S ince t h e n , a p l a t e a u h a s b e e n r e a c h e d in t h e p a t t e r n of i n c i d e n c e . I n t h e s e a r e a s , t h e d i sease h a s b e c o m e e n z o o t i c a n d sma l l n u m b e r s o f y o u n g a n i m a l s c o n t i n u e t o d ie of H S a n n u a l l y . I n Z a m b i a , t h e d i sease h a d b e e n c o n f i n ed t o ce r t a in e n z o o t i c p o c k e t s s ince t h e 1930 ' s , b u t it b r o k e o u t as a v io l en t ep i zoo t i c in 1978. T h e r e a f t e r , t h e t r e n d w a s s imi la r t o t h a t in Sri L a n k a .

(d) System of management.

T h e inc idence of H S a p p e a r s t o b e r e l a t e d t o t h e sys t em of m a n a g e m e n t , s ince it is l owes t in s m a l l s ta l l - fed h e r d s a n d h ighes t in l a rge , n o m a d i c h e r d s . B o t h s i t u a t i o n s h a v e b e e n d e m o n s t r a t e d in t h e s a m e c o u n t r y (32) . F u r t h e r , w i t h i n a n e n z o o t i c a r e a t h e i n c i d e n c e o f H S m a y b e 4-5 t imes g r e a t e r in l a rge h e r d s of over 50 a n i m a l s t h a n in sma l l h e r d s of u n d e r 10 a n i m a l s , a n d th i s is c lear ly r e l a t e d t o d i f fe rences in m a n a g e m e n t p r a c t i c e s .

— 713 —

3 . Natural ly acquired i m m u n i t y .

B a i n (9) f o u n d t h a t s o m e b u f f a l o e s e x a m i n e d in T h a i l a n d w e r e n a t u r a l l y i m m u n e t o H S . T h e i m p o r t a n c e o f th i s f i n d i n g in t h e e p i d e m i o l o g y o f H S w a s n o t r ea l i sed a t t h e t i m e , a n d it w a s c o n c l u d e d t h a t a b o u t 1 0 % of ca t t l e a n d b u f f a l o e s in A s i a m a y b e n a t u r a l l y i m m u n e t o H S . I n v e s t i g a t i o n s m a d e in Sri L a n k a in t h e l a t e 1970 ' s (30 , 23) i n d i c a t e d t h a t t h e p r o p o r t i o n o f n a t u ra l ly i m m u n e a n i m a l s v a r i e d f r o m h e r d t o h e r d , a n d f r o m t i m e t o t i m e in t h e s a m e h e r d . T h i s p h e n o m e n o n w a s r e l a t e d t o r e c e n t o c c u r r e n c e o f H S in t h e h e r d o r loca l i ty . W h i l e a few i n s t a n c e s of c a t t l e n a t u r a l l y i m m u n e t o H S h a v e b e e n f o u n d in A u s t r a l i a (10) , U . S . A . (26) a n d in C h a d ( P e r r e a u , c i ted in 11) w h e r e n a t u r a l e x p o s u r e w a s n o t e v i d e n t , suf f ic ien t e v i d e n c e h a s b e e n a d d u c e d b y D e Alwi s (23) in a s t u d y of t h e i m m u n e s t a t u s o f b u f f a l o e s e x p o s e d t o H S , t h a t subc l in i ca l o r « a r r e s t e d i n f e c t i o n » is t h e chief s o u r c e of n a t u r a l l y a c q u i r e d i m m u n i t y in e n z o o t i c c o u n t r i e s . I n s i t u a t i o n s w h e r e n o v a c c i n a t i o n is p r a c t i s e d , it is c lea r t h a t t h e m o r b i d i t y a n d t h e m o r t a l i t y p a t t e r n s a r e l a r gely g o v e r n e d b y t h e p r o p o r t i o n of n a t u r a l l y i m m u n e t o n o n - i m m u n e a n i m a l s a t t h e t i m e o f t h e o u t b r e a k . T h u s , in e n z o o t i c a r e a s w h e r e f r e q u e n t o u t b r e a k s o c c u r , t h e p r o p o r t i o n of n a t u r a l l y i m m u n e a n i m a l s is h i g h , a n d c o n s e q u e n t l y o n l y a s m a l l n u m b e r o f h i t h e r t o u n e x p o s e d s u s c e p t i b l e a n i m a l s d i e . W h e n t h e d i sease o c c u r s a f te r a l o n g i n t e r v a l , t h e p r o p o r t i o n o f n o n - i m m u n e su scep t i b l e a n i m a l s is h i g h , a n d exp los ive o u t b r e a k s o c c u r .

4 . Carrier an imal s .

I t is wel l k n o w n t h a t a c e r t a i n p r o p o r t i o n o f h e a l t h y ca t t l e a n d b u f f a l o e s h a r b o u r p a t h o g e n i c p a s t e u r e l l a e i n t he i r n a s o p h a r y n x (58 , 63) . I n t h e ea r ly 1960 ' s , G u p t a (37) in I n d i a f o u n d a c o r r e l a t i o n b e t w e e n i n c i d e n c e o f H S a n d t h e ca r r i e r r a t e . D u r i n g a n e p i z o o t i c of H S in a v i l l age , 7 . 5 % of h e a l t h y a n i m a l s w e r e c a r r i e r s , b u t n o n e w a s d e t e c t e d in t h e s a m e v i l lage 4 0 d a y s l a t e r . T h e p r o p o r t i o n of c a r r i e r s v a r i e d w i t h t h e i n c i d e n c e o f H S , r a n g i n g f r o m n o n e in d i sease - f ree a r e a s t o 6 . 1 % in h i g h i n c i d e n c e a r e a s . T h e s e f i n d i n g s w e r e c o r r o b o r a t e d b y M u s t a f a et al. (47) in S u d a n a n d b y H i r a m u n e a n d D e Alwi s (43) in Sri L a n k a . T h e l a t t e r w o r k e r s a l so f o u n d t h a t t h e c a r r i e r r a t e w a s h ighes t a m o n g cl inical ly u n a f f e c t e d a n i m a l s i m m e d i a t e l y a f t e r a n e p i z o o t ic , a n d it dec l ined r a p i d l y in 6-9 w e e k s . T h e p r o p o r t i o n o f c a r r i e r s d e t e c t e d b y severa l w o r k e r s is s h o w n in T a b l e I I . N a t u r a l l y i m m u n e a n i m a l s m a y b e c a r r i e r s , o r a n i m a l s w h i c h h a v e p a s s e d t h r o u g h a c a r r i e r s t a g e , b o t h p h e n o m e n a b e i n g r e l a t e d t o r e c e n t i n c i d e n c e (see T a b l e I I I ) .

I t h a s b e e n s t a t e d t h a t r e g u l a r v a c c i n a t i o n will e l i m i n a t e t h e ca r r i e r s t a t u s . A n e r a d i c a t i o n p r o g r a m m e w i t h i n t ens ive a n n u a l v a c c i n a t i o n w a s a t t e m p t e d o n a n I n d o n e s i a n i s l a n d . A f t e r t h e first y e a r o f v a c c i n a t i o n t h e r e w e r e still 2 . 3 % of c a r r i e r s , b u t n o n e w a s d e t e c t e d a f t e r t h e s e c o n d y e a r . M o r e r e c e n t w o r k in Sri L a n k a ( W i j e w a r d a n a a n d D e A l w i s , u n p u b l i s h e d r e p o r t ) h a s i n d i c a t e d t h a t t h e n a s o p h a r y n g e a l c a r r i e r s t a t e is t r a n s i e n t , a n d t h a t d i f f e ren t a n i m a l s a r e c a r r i e r s a t d i f f e ren t t i m e s in t h e first few w e e k s f o l l o w i n g a n o u t b r e a k . T h e s a m e w o r k e r s h a v e a l s o d e t e c t e d a n i m a l s h a r b o u r i n g v i ru l en t p a s -

— 714 —

T A B L E II Detection of haemorrhagic septicaemia carriers by different workers

Author Country Findings Method of identification

of organism

Singh (1948) India 3 .5% in living animals, 7 .0% in slaughtered animals.

Agglutination with serum prepared against virulent strain.

Wijewantha and Karunaratne (1968)

Sri Lanka 15% carriers. 43/45 isolates were 6:B. Two were 11:B.

Capsular and somatic typing.

Gupta (1962) India 7 .5% in healthy living animals during outbreak. 0 % in same animals, 40 days later.

0 % , 3.84% and 5.55% in Capsular typing, three herds unassociated with H S . 44 .4% among healthy animals in an HS-affected herd.

Hiramune and Sri Lanka 22% in herds one week Somatic and capsular De Alwis (1982) after outbreak diminishing typing.

to 1.9% 6 weeks after.

T A B L E III Carrier status and naturally acquired immunity

in relation to incidence of haemorrhagic septicaemia

Carrier animals Naturally immune animals in India* (%) in Sri Lanka** (%)

Low incidence areas 0 0.47 Moderate incidence areas 1.9 7.2 High incidence areas 5.0-6.0 36.1

* Country Report HS Workshop, December 1979. * De Alwis and Sumanadasa (1982).

t eu re l l ae in the i r r e t r o p h a r y n g e a l l y m p h n o d e s , w i t h o u t the i r b e i n g p r e s e n t in t he n a s o p h a r y n x . W h i l e it is c lear t h a t t h e n a s o p h a r y n g e a l ca r r i e r s t a t u s is on ly t r a n s i e n t , it is n o t k n o w n h o w l o n g t h e o r g a n i s m pers i s t s i n t h e r e t r o p h a r y n g e a l l y m p h n o d e s , a n d w h e t h e r such pe r s i s t ence c o u l d o c c u r in a n y

Mustafa et al. Sudan (1968)

— 715 —

a n i m a l , o r o n l y in c e r t a i n i m m u n o d e f i c i e n t a n i m a l s . T h e d e t e c t i o n o f a n i m a l s w h i c h a r e n a s o p h a r y n g e a l n e g a t i v e b u t l y m p h n o d e p o s i t i v e h a s t o t a l l y c h a n g e d t h e c o n c e p t o f a c a r r i e r . I t s eems r e a s o n a b l e t o d e s i g n a t e t h e n a s o p h a r y n g e a l pos i t ives as « ac t ive ca r r i e r s » o r « s h e d d e r s » a n d t h e n a s o p h a r y n g e a l n e g a t i v e , l y m p h n o d e pos i t i ve s as « l a t e n t c a r r i e r s » . W h e t h e r a l a t e n t ca r r i e r c a n c h a n g e t o a n ac t ive c a r r i e r , a n d t h e c i r c u m s t a n c e s u n d e r w h i c h s u c h c h a n g e c o u l d o c c u r h a s ye t t o b e d e t e r m i n e d .

5. T h e ep idemio log ica l cyc le .

I t m a y b e a c o m m o n o c c u r r e n c e t h a t w h e n a n o u t b r e a k o c c u r s s p o n t a n e o u s l y w i t h i n a c losed h e r d , a l a t e n t c a r r i e r b e c o m e s a c t i v e , a n d t h e a n i m a l beg ins t o s h e d v i ru l en t p a s t e u r e l l a e . A l t e r n a t i v e l y , a n ac t ive ca r r i e r m a y b e i n t r o d u c e d i n t o a h e r d . T h e o u t b r e a k w o u l d c o m m e n c e o n l y w h e n t h e s h e d o r g a n i s m is p i c k e d u p b y a su scep t i b l e a n i m a l in suf f ic ien t n u m b e r s . T h e m a g n i t u d e o f t h e o u t b r e a k wil l d e p e n d o n t h e p r o p o r t i o n of s u s c e p t i b l e a n i m a l s in t h e h e r d o r v i l l age . F i g u r e 1 s h o w s s u c h a cyc le .

F I G . 1 T h e ep idemio log ica l cycle in haemorrhagic sept icaemia

Latent carrier Stress

Active carrier (shedder) Active carrier (shedder)

(6-9 weeks)

Intermittent shedding

Direct fection

Contamination of pasture, water, etc.

Naturally immune animal

Clinical case

Direct infection

Susceptible animal

Sub-clinical infection

— 716 —

DIAGNOSIS

1. Clinical d iagnos is .

A cl inical field d i a g n o s i s is b a s e d o n t h e h i s t o r y , s igns a n d l e s ions . T h e h i s t o r y inc ludes t h e m o r t a l i t y p a t t e r n in r e l a t i o n t o t h e s u r r o u n d i n g c i r c u m s t a n c e s , s u c h as t h e p r e v i o u s o c c u r r e n c e o f H S in t h e h e r d , w h e t h e r it is a n e n z o o t i c a r e a , t h e age g r o u p a n d species a f f ec t ed , a n d v a c c i n a t i o n h i s t o r y . M o r t a l i t y r a t e s c a n v a r y f r o m 5 % in a h e r d of ca t t l e in a n e n z o o t i c a r e a w i t h r e g u l a r a n n u a l e p i z o o t i c s , t o n e a r 1 0 0 % a m o n g b u f f a l o e s in a d isease-f ree a r e a expe r i enc ing a s p o r a d i c o u t b r e a k af ter 10 y e a r s . T h e s igns a n d les ions o b s e r v e d s h o u l d a l so b e v i ewed f r o m t h e a spec t o f t h e s u r r o u n d i n g c i r c u m s t a n c e s .

2 . Laboratory d iagnos i s .

B i o c h e m i c a l l y , s t r a i n s of P. multocida c a u s i n g H S a r e n o d i f fe ren t f r o m o t h e r m e m b e r s o f t h e g r o u p , a n d t h e y c a n b e d i f f e r en t i a t ed on ly b y s e ro l o g y . T h e ear l ies t s e ro log ica l tes ts t o g a i n s o m e a c c e p t a n c e w e r e t h e pass ive m o u s e p r o t e c t i o n tes t , t h e p l a t e a g g l u t i n a t i o n tes t of L i t t l e a n d L y o n (45) , a n d t h e m o u s e p r o t e c t i o n tes t o f R o b e r t s (56) . R o b e r t s d e f i n e d 4 d i f fe ren t se ro log ica l t y p e s , d e s i g n a t e d t ypes I - I V . A l l H S s t r a in s b e l o n g e d t o t y p e I . C a r t e r ( 1 3 , 14) dev i sed a n i nd i r ec t h a e m a g g l u t i n a t i o n tes t a n d iden t i f i ed 4 d i f fe ren t t y p e s , d e s i g n a t e d A , B , D a n d E , b a s e d o n t h e c a p s u l a r a n t i g e n s . T h e l imi ta t i ons o f b o t h t e c h n i q u e s b e c a m e ev iden t w h e n N a m i o k a a n d M u r a t a (50) d e s c r ibed 11 « s o m a t i c » t y p e s . T h e r e w e r e 2 s o m a t i c types w i th in R o b e r t s ' t y p e I o r C a r t e r ' s t y p e B , o n e o f w h i c h c a u s e d H S ( type 6) a n d t h e o t h e r d id n o t ( type 11). N a m i o k a a n d M u r a t a (49) a l so desc r ibed a s impl i f ied c a p s u l a r t y p i n g t e c h n i q u e . H e d d l e s t o n , G a l l a g h e r a n d R e b e r s (42) de sc r ibed a n a g a r gel p r e c i p i t a t i o n tes t ( A G P T ) u s i n g a h e a t - s t a b l e a n t i g e n a n d iden t i f i ed 16 d i f fe ren t t ypes of P. multocida. T h e s e t ypes a r e s o m e t i m e s a l so r e f e r r ed t o as « s o m a t i c » t y p e s , p r e s u m a b l y b e c a u s e t h e H S s e r o t y p e s b e l o n g i n g t o H e d d -l e s t o n ' s t y p e 2 c o r r e s p o n d e d closely t o N a m i o k a ' s s o m a t i c t y p e 6 .

T a b l e IV s h o w s t h e d i f f e ren t s e ro log ica l t e c h n i q u e s t h a t h a v e b e e n d e v e l o p e d a n d t h e p l ace o f H S s e r o t y p e s w i t h i n e a c h s y s t e m . I n e a c h t y p i n g sys t em, a sma l l p r o p o r t i o n of s t r a i n s , b i o c h e m i c a l l y d e s i g n a t e d p a s t e u r e l l a e a n d a s soc i a t ed w i t h d i sease , r e m a i n u n t y p a b l e . B r o g d e n a n d P a c k e r (12) c o m p a r e d P. multocida s e r o t y p i n g sys t ems a n d c o n c l u d e d t h a t s e r o t y p e s d e t e r m i n e d b y o n e sys t em d id n o t c o r r e l a t e w i t h t h o s e d e t e r m i n e d b y a n o t h e r sys t em. T h i s is t o b e e x p e c t e d , as t h e t y p e of a n t i g e n p r e p a r a t i o n u s e d a n d t h e t e c h n i q u e s a d o p t e d dif fer in e a c h c a s e .

(a) A practical serotyping system.

F o r t h e p u r p o s e of d e s i g n a t i n g c u l t u r e s , a s t a n d a r d , p r a c t i c a l s e r o t y p i n g sys t em h a s t o b e a d o p t e d in al l c o u n t r i e s . T h e F . A . O . / A . P . H . C . A . W o r k s h o p o n h a e m o r r h a g i c s e p t i c a e m i a he ld in C o l o m b o in 1979 r e c o m m e n d e d the use of a « s o m a t i c - c a p s u l a r » ( N a m i o k a - C a r t e r ) c o m b i n a t i o n . T h e c a p s u l a r

— 717 —

T A B L E I V Systems adopted for typing Pasteure l la m u l t o c i d a

and the position of haemorrhagic septicaemia serotypes

Authors Technique No . of types Position of

H S types

Little and Lyon (1943) Slide agglutination and passive mouse protection test.

1, 2 and 3 2

Roberts (1947) Passive mouse protection test.

I-V I

Carter (1955) Capsular typing by indirect haemagglutination test using heat-labile (56°C for 30 min) antigen.

A, B, D and E

B and E

Namioka and Mura ta (1961) Simplified capsular typing by slide agglutination test using fresh cultures.

do . B and E

Namioka and Mura ta (1961) « Somatic » typing by agglutination test using HC1-treated cells.

1-11 6

Heddleston et al. (1972) Gel-diffusion test using heat-stable (100°C for 1 hour-supernate) antigen.

1-16 2 and 5

t y p i n g p r o c e d u r e is r e la t ive ly s i m p l e , b u t s o m a t i c t y p i n g neces s i t a t e s t h e p r o d u c t i o n o f type-spec i f i c a n t i s e r a , i n v o l v i n g a c o m p l i c a t e d a b s o r p t i o n s y s t e m (48) s h o w n in T a b l e V . C a p s u l a r t y p i n g is , t h e r e f o r e , p r a c t i s e d in m o s t c o u n tr ies a n d re la t ive ly few r e s o r t t o s o m a t i c t y p i n g . A t t h e V e t e r i n a r y R e s e a r c h I n s t i t u t e in Sri L a n k a , s o m a t i c t y p i n g is d o n e w i t h u n a b s o r b e d r a b b i t a n t i s e r a p r o d u c e d a g a i n s t w h o l e cel ls , u s i n g H C l - t r e a t e d e x t r a c t s of t h e tes t s t r a i n (6 :B — A s i a n H S s e r o t y p e ) in t u b e a g g l u t i n a t i o n tes t s w i t h d i f f e r en t d i l u t i o n s of s e r u m : t h e A f r i c a n H S s t r a i n (6 :E) a n d a n A u s t r a l i a n n o n - H S s t r a i n (11:B) a r e u s e d as c o n t r o l s . S u c h a s impl i f i ed p r o c e d u r e is p o s s i b l e w i t h c a p su la r t y p e B , w h i c h h a s o n l y t w o s o m a t i c t y p e s (6 a n d 11) a n d w i t h t y p e E w h i c h h a s o n l y o n e s o m a t i c t y p e 6, b o t h o f w h i c h a r e H S s e r o t y p e s .

C a r t e r a n d C h e n g a p p a (19) sugges t ed a c o m b i n a t i o n o f t h e H e d d l e s t o n a n d C a r t e r s y s t e m s . H e d d l e s t o n ' s t y p i n g (by A G P T ) , s o m e t i m e s r e f e r r e d t o as s o m a t i c t y p i n g , e m p l o y s a h e a t - s t a b l e ( 1 0 0 ° C fo r 1 h o u r ) s u p e r n a t e a n t i g e n i n s t e a d o f t h e H C l - t r e a t e d r e s i d u a l cells o f t h e N a m i o k a s y s t e m .

T A B L E V Strains and antisera used for preparing factor sera for somatic typing*

« o » Antisera (ml) Strain used No . of Dilution with group Antisera (ml) for absorption Y P C plates saline

1. 3397 (0.3); Kobe 5 (0.5); M 4 (0.2)

P 8 15 1:10

2. P 27 (0.6); Kobe 6 (0.2) Kobe 5 15 1:10 3. P 8 (1.0) M 17 15 1:10 4. M 17 (0.6); M 11 (0.4) M 4 15 1:10 5. TS 8 (0.5); VA 3 (0.5) Kobe 6 10 1:10 6. R 479 (1.0) Kobe 6 10 1:10 7. P M (1.0) TS 8 15 1:10 8. 147 (1.0) Kobe 5 10 1:10 9. Liver P 8 10 1:10

10. TS 9 (1.0) P 27 10 1:10 11. 989 (1.0) R 479 10 1:10

* From Namioka, 1978.

(b) Rapid laboratory diagnostic tests.

M a t e r i a l r e a c h i n g a l a b o r a t o r y is o f t en c o n t a m i n a t e d , a n d d i rec t c u l t u r e usua l ly fails t o i so l a t e P a s t e u r e l l a . M o u s e i n o c u l a t i o n m a y serve as a « b io log ica l sc reen » t o p u r i f y t h e c u l t u r e , whi le s i m u l t a n e o u s l y a s c e r t a i n i n g its m o u s e v i r u l e n c e , w h i c h is of d i a g n o s t i c s ign i f i cance . T h e pu r i f i ed c u l t u r e m a y b e s u b j e c t e d t o s impl i f ied c a p s u l a r t y p i n g b y t h e sl ide a g g l u t i n a t i o n tes t , u s ing t h e f resh c u l t u r e s and h y p e r i m m u n e r a b b i t s e r a . T h e a b o v e p r o c e d u r e s e n a b l e a conc lus ive d i a g n o s i s t o b e m a d e w i t h i n 48 h o u r s of rece iv ing t h e m a t e r i a l . R a p i d d o u b l e d i f fus ion tes ts in a g a r gel u s i n g r a b b i t a n t i s e r a a n d the C a r t e r a n t i g e n ( s u p e r n a t a n t fluid h e a t e d a t 5 6 ° C fo r 30 m i n ) , a n d r a d i a l i m m u n o d i f f u s i o n tes ts u s i n g h y p e r i m m u n e calf a n t i s e r a h a v e a l so b e e n des c r ibed (5 , 64 ) . T h e f o r m e r essent ia l ly ident i f ies w h a t is d e s c r i b e d as t h e « c a p su la r » a n t i g e n a n d h a s , in fac t , b e e n u s e d t o d i s t i ngu i sh e n c a p s u l a t e d f r o m u n e n c a p s u l a t e d s t r a ins (26) .

M o r e r a p i d tes ts for iden t i fy ing H S s e r o t y p e s o f P. multocida h a v e b e e n d e v e l o p e d r ecen t ly . T h e p r o d u c t i o n of h y a l u r o n i d a s e h a s h i t h e r t o b e e n c o n s i d e r e d a p r o p e r t y c o n f i n e d t o c e r t a i n G r a m - p o s i t i v e b a c t e r i a . C a r t e r a n d C h e n g a p p a (17) e x a m i n e d 74 i so la tes of P. multocida of d i f fe ren t s e r o t y p e s , a n d f o u n d t h a t s e r o t y p e 6:B cons i s t en t ly p r o d u c e d h y a l u r o n i d a s e . A l l i so la tes of t h e A f r i c a n H S s e r o t y p e 6 :E a n d t h e A u s t r a l i a n n o n - H S s e r o t y p e 11:B w e r e nega t i ve . T h e s e w o r k e r s u s e d t h e s t r e a k m e t h o d as wel l as t h e r a p i d p l a t e m e t h o d , in w h i c h tes t c u l t u r e s w e r e s p o t t e d o n t o a m e d i u m c o n t a i n i n g s o d i u m h y a l u r o n i d i t e a n d b o v i n e a l b u m i n f r ac t i o n V . T h e u n d e g r a d e d s u b s t r a t e w a s t e s ted b y flooding t h e p l a t e w i t h ace t ic ac id . A w i d e r r a n g e o f

— 719 —

c u l t u r e s n e e d t o b e t e s t e d fo r t h i s p r o p e r t y w h i c h , if ve r i f i ed , will b e c o m e a use fu l r a p i d d i a g n o s t i c tes t for t h i s s e r o t y p e .

C a r t e r a n d C h e n g a p p a (18) d e s c r i b e d t h e u s e o f c o u n t e r -i m m u n o e l e c t r o p h o r e s i s fo r r a p i d i d e n t i f i c a t i o n o f t y p e s B a n d E . T h e I H A a n t i g e n ( 5 6 ° C fo r 30 m i n ) a n d r a b b i t a n t i s e r a w e r e u s e d . D i s t i n c t b a n d s of p r e c i p i t a t i o n w e r e p r o d u c e d b y t y p e s B a n d E w i t h h o m o l o g o u s s e r a w i t h i n 30 m i n u t e s , w i t h n o c ross r e a c t i o n s .

TREATMENT

T r e a t m e n t is r a r e l y a t t e m p t e d , as t h e success r a t e is v e r y p o o r if t r e a t m e n t is c a r r i e d o u t o n c e vis ible s igns h a v e a p p e a r e d . T h u s u n d e r t h e c o n d i t i o n s p r e v a i l i n g in H S - e n z o o t i c a r e a s , case fa ta l i ty is a l m o s t 1 0 0 % .

T r e a t m e n t is ef fect ive o n l y i n t h e ve ry ea r ly s t a g e s . T h e o n l y p r a c t i c a l p r o c e d u r e is t o c h e c k r e g u l a r l y ( twice da i ly ) t h e r ec t a l t e m p e r a t u r e o f al l in -c o n t a c t a n i m a l s a f te r t h e first case h a s b e e n r e p o r t e d , a n d t o c o m m e n c e a n t i b i o t i c t h e r a p y i m m e d i a t e l y . T h e o ld p r a c t i c e o f u s i n g s u l p h o n a m i d e s still c o n t i n u e s in m a n y c o u n t r i e s . I n t e r n a t i o n a l n o n p r o p r i e t a r y n a m e : s u l f a d i m i d i n e s o d i u m 3 3 % s o l u t i o n a d m i n i s t e r e d i n t r a v e n o u s l y a t a d o s a g e o f 1 m l p e r 5 p o u n d s b o d y w e i g h t is e f fec t ive , b u t th i s is c e r t a i n l y n o t t h e b e s t d r u g . T h e p r a c t i c a l d i f f icul t ies o f i n t r a v e n o u s t h e r a p y a n d t h e c o n s e q u e n c e s o f l e a k a g e i n t o s u b c u t a n e o u s t i s sues we igh a g a i n s t th i s t r e a t m e n t . T h e a u t h o r h a s f o u n d i n t r a m u s c u l a r a d m i n i s t r a t i o n o f s t r e p t o m y c i n o r Oxyte t racyc l ine c o n v e n i e n t a n d ef fec t ive . T h e r e a r e few r e p o r t s o f a n t i b i o t i c r e s i s t a n c e in H S s t r a in s o f P. multocida. S t r a i n s f r o m M a l a y s i a , I n d o n e s i a , T h a i l a n d , B u r m a , I n d i a a n d Sri L a n k a , w h e n t e s t e d in Sri L a n k a , w e r e sens i t ive t o all o f 10 c o m m o n a n t i b io t i c s t e s t e d , excep t t h a t t h e T h a i s t r a i n s h o w e d p a r t i a l r e s i s t a n c e t o s t r e p t o m y c i n . T h e a n t i b i o t i c s t e s t e d w e r e pen ic i l l in , a m p i c i l l i n , s t r e p t o m y c i n , t e t r a c y c l i n e , c h l o r a m p h e n i c o l , e r y t h r o m y c i n , n e o m y c i n , s u l p h a d i a z i n e a n d a s u l p h o n a m i d e - t r i m e t h o p r i m c o m b i n a t i o n . T r e a t m e n t w i t h h y p e r i m m u n e s e r u m is h a r d l y a t t e m p t e d . E x p e r i m e n t a l l y , 60-100 m l o f h y p e r i m m u n e s e r u m a d m i n i s t e r e d t o 2 - y e a r - o l d (400 lb w e i g h t ) b u f f a l o e s a t v a r y i n g p e r i o d s r a n g ing f r o m 6 h o u r s b e f o r e t o 18 h o u r s a f te r i n f ec t i on h a d n o t h e r a p e u t i c effect (44) .

CONTROL

I n al l c o u n t r i e s w h e r e H S o c c u r s , v a c c i n a t i o n is a c c e p t e d as t h e m e t h o d o f c o n t r o l . M o s t v a c c i n e s for t h i s p u r p o s e a r e p r o d u c e d in t h e c o u n t r i e s in w h i c h t h e y a r e u s e d .

M o s t c o u n t r i e s u s e b r o t h b a c t e r i n o r a l u m - p r e c i p i t a t e d v a c c i n e ( A P V ) , wh i l e a few u s e oi l a d j u v a n t v a c c i n e ( O A V ) . T h a i l a n d a l o n e uses a n a l u m i n i u m h y d r o x i d e gel v a c c i n e . M o s t o f t h e v a c c i n e s u s e d a r e n o t s t a n d a r d i z e d

— 720 —

p r o d u c t s . Vacc ines p r o d u c e d in d i f fe ren t c o u n t r i e s di f fer in t h e s t r a i n o f o r g a n i s m u s e d , t h e m e t h o d of cu l t i va t i on a n d t h e b a c t e r i a l c o n t e n t p e r d o s e (a cr i t ica l f a c to r in i m m u n i z a t i o n ) .

1. Select ion of vaccine strain.

I n d i a uses a se lected vacc ine s t r a i n « P 52 » w h i c h is be l i eved t o posses s specia l i m m u n o g e n i c p r o p e r t i e s . I n d o n e s i a uses t h e B u r m e s e « K a t h a » s t r a i n for t h e s a m e r e a s o n . M o s t o t h e r c o u n t r i e s use i n d i g e n o u s s t r a i n s . M a l a y s i a uses 5 s t r a ins f r o m 5 d i f fe ren t r eg ions of t h e c o u n t r y .

B a i n (10) c a r r i e d o u t ac t ive i m m u n i t y tes ts in m i c e u s i n g Pasteurella multocida p r o p a g a t e d in b o v i n e cel ls , a n d w i t h l a b o r a t o r y s u b - c u l t u r e s of s a m e . H e f o u n d t h a t c r o s s - p r o t e c t i o n ex is ted b e t w e e n A s i a n H S s t r a in s (6 :B) , Af r i c a n H S s t r a in s (6 :E) a n d t h e n o n - H S A u s t r a l i a n s t r a i n « 989 » (11 :B) , w h e n ce l l - cu l tu red b a c t e r i a w e r e u s e d , b u t t h e c r o s s - p r o t e c t i o n dec l i ned a n d o n l y h o m o l o g o u s p r o t e c t i o n r e m a i n e d w h e n s u b - c u l t u r e s w e r e u s e d . D e A lwi s ( u n p u b l i s h e d d a t a ) c o m p a r i n g t h e i m m u n o g e n i c i t y of s t r a ins f r o m M a l a y s i a , I n d o n e s i a , T h a i l a n d , B u r m a , I n d i a a n d Sri L a n k a f o u n d v a r i a t i o n s b e t w e e n a n d w i th in s t r a ins in t h e d r y we igh t y ie ld of b a c t e r i a w h e n g r o w n u n d e r t h e s a m e c o n d i t i o n s . W h e n ac t ive c r o s s - p r o t e c t i o n tes ts w e r e d o n e us ing d o s e s s t a n d a r d i z e d o n t h e bas i s of d r y w e i g h t , n o c o n s i s t e n t i m m u n o g e n i c d i f f e ren ces w e r e d e m o n s t r a b l e b e t w e e n s t r a in s in ac t ive c r o s s - p r o t e c t i o n tes ts in m i c e .

2 . Preservat ion of seed culture.

I t is wide ly a c c e p t e d t h a t f reshly i so l a t ed cu l tu re s a r e t h e bes t i m m u n i z i n g a g e n t s . V a c c i n e seed cu l tu re s a r e , t h e r e f o r e , pe r iod i ca l l y p a s s a g e d in su scep t i b le ca t t l e or b u f f a l o e s , w h i c h a r e b l ed d u r i n g t h e s ep t i c aemic p h a s e , a n d t h e b l o o d is s t o r e d in t h e f rozen s t a t e . T r y p t o s e a g a r w i t h 0 .3 % yeas t e x t r a c t a n d 5% ox o r b u f f a l o b l o o d is u s e d as a m e d i u m for s u b - c u l t u r e f r o m in fec t ed , f rozen b l o o d . S u b - c u l t u r i n g c a n c o n t i n u e as l o n g as l a rge (2 m m ) e n c a p s u l a t e d co lon ie s a r e f o r m e d w i t h i n 24 h o u r s a t 3 7 ° C . S p o n t a n e o u s d i s s o c i a t i o n m a y o c c u r a t a n y s t age in t h e p r o c e s s of s u b - c u l t u r e , r e su l t i ng in t h e f o r m a t i o n of m i n u t e , p i n p o i n t c o l o n i e s , a n d s u c h c u l t u r e s s h o u l d b e d i s c a r d e d .

3 . Culture of bacteria for vaccine product ion .

(a) Method.

V a r i o u s c u l t u r e m e t h o d s h a v e b e e n a d o p t e d in d i f fe ren t c o u n t r i e s , r a n g ing f r o m s i m p l e s ta t ic b r o t h c u l t u r e s a n d a e r a t e d d e n s e c u l t u r e s t o t h e use of c o m p l e x f e r m e n t o r s . O r d i n a r y b r o t h cu l tu re s m a y b e u s e d for t h e p r o d u c t i o n of s i m p l e b a c t e r i n s , o r fo r t h e a l u m - p r e c i p i t a t e d v acc i n e ( A P V ) . D e n s e cu l tu r e s , a p p r o p r i a t e l y d i lu t ed if n e c e s s a r y , a r e su i t ab l e for p r o d u c i n g A P V a n d p a r t i c u l a r l y t h e oil a d j u v a n t vacc ine ( O A V ) .

T h e m o s t p o p u l a r m e t h o d of p r o d u c i n g d e n s e cu l tu re s is t o u s e a v o r t e x t a n k , b u t th i s h a s t h e d i s a d v a n t a g e o f f r e q u e n t c o n t a m i n a t i o n (6) . I n d i a a n d I r a q h a v e r e p o r t e d t h e use o f a n a g a r w a s h s u s p e n s i o n ( 3 , 7 ) . T h i s is a l a b o -

— 721 —

r i o u s p r o c e s s a n d c o n s e q u e n t l y o n l y 2 . 8 % of I n d i a ' s t o t a l p r o d u c t i o n is r e p o r t ed t o b e of t h e oi l a d j u v a n t t y p e . Sr i L a n k a p r e f e r s t o u s e 10 o r 20 l i t re P y r e x b o t t l e s , o r a s i m p l e c u l t u r e vessel ca l led t h e lift f e r m e n t o r (Bel lco G l a s s I n c . , U . S . A . ) , w i t h s p a r g e r a e r a t i o n . T h e l a t t e r vesse l , f i t t ed w i t h t w o s ide a r m s a n d a n i m p r o v i s e d s i p h o n a r r a n g e m e n t , h a s b e e n u s e d fo r c o n t i n u o u s c u l t u r e t o o .

T A B L E V I Some growth media used in haemorrhagic septicaemia vaccine production

Medium recommended in the F .A.O. haemorrhagic septicaemia monograph (Bain, De Alwis, Carter and Gupta , 1982)

Oxoid t ryptone or Difco casitone 120 g Sucrose 48 g N a 2 H P O 4 . 12 H2O 172 g K H 2 P O 4 . 7 H2O 44 g M g S O 4 . 7 H2O 24 g Yeast extract 100 g Casein hydrolysate from 400 g casein autodigest of pancreas (Seitz filtered) 1 litre Distilled water up to 25 litres

Medium used in Malaysia (Thomas; 1968) Peptone (Oxoid) 150 g Lab Lemco (Oxoid) 150 g Sodium chloride 75 g Sodium bicarbonate 75 g Glucose 30 g Yeast extract 60 g Autodigest of pig pancreas (Seitz filtered) 750 ml Distilled water up to 15 litres

Medium used in Egypt (Geneidy et al., 1967) Casamino acids 500 g Casitone (Difco) or t ryptone (Oxoid) 120 g Yeast extract 100 g Sucrose 45 g M g S 0 4 25 g Phosphate buffer Distilled water 25 litres

Medium used in Sri Lanka (Arawwawela et al., 1981) * Casein hydrolysate (BDH) 0.2 % * Cane sugar 0.6 % * Yeast extract 0.6 %

Sodium chloride 0.5 % Dipotassium hydrogen phosphate (anhydrous) 0.86 % Potassium dihydrogen phosphate (anhydrous) 0.136 %

Peptic digest of blood may be added up to 0 . 5 % * Prepared as a concentrate, filter sterilized and added

— 722 —

(b) Culture media. Basa l m e d i a w i t h v a r i o u s f o r m s of e n r i c h m e n t a r e b e i n g u s e d , a n d s o m e

of t h e m a r e l i s ted in T a b l e V I .

(c) Yields of bacteria.

Yield is i m p o r t a n t b e c a u s e it d e t e r m i n e s t h e p o t e n c y o f t h e v acc i n e a n d t h e e c o n o m y of vacc ine p r o d u c t i o n . It is wide ly a c c e p t e d t h a t a b o u t 2 m g o f d r y b a c t e r i a is r e q u i r e d t o i m m u n i z e a b o v i n e a n d m u s t , t h e r e f o r e , b e t h e m i n i m u m b a c t e r i a l c o n t e n t pe r d o s e .

F e w c o u n t r i e s express vacc ine p o t e n c y in t e r m s of d r y b a c t e r i a l c o n t e n t . T h e M a l a y s i a n b r o t h b a c t e r i n is r e p o r t e d t o c o n t a i n a n a v e r a g e yie ld o f 0 .297 m g / m l a n d t h e O A V a n a v e r a g e of 3.88 m g / d o s e (2) . I n Sri L a n k a , d r y w e i g h t y ie lds o f 1.5-2 m g / m l d e n s e c u l t u r e a r e o b t a i n e d w i t h i n 12-16 h o u r s .

O t h e r p a r a m e t e r s u s e d t o express t h e dens i ty of c u l t u r e a r e t u r b i d i t y a n d t h e t o t a l a n d v i ab l e c o u n t s . A s t h e a m o u n t of c a p s u l a r s u b s t a n c e c a n v a r y b e t w e e n s t r a i n s , t u r b i d i t y a p p e a r s t o b e m o r e m e a n i n g f u l t h a n cell c o u n t s .

(d) Bacterin.

T h i s is t h e m o s t p o p u l a r v a c c i n e u s e d in m o s t c o u n t r i e s , b u t l i t t le h a s b e e n d o n e t o d e t e r m i n e its p o t e n c y . T h e d u r a t i o n of i m m u n i t y c l a i m e d is v a r i a b l e , r a n g i n g f r o m 10-12 w e e k s a f te r 2 i n o c u l a t i o n s 2-3 w e e k s a p a r t ( r e p o r t e d in Z a m b i a ) t o t h e 9 m o n t h s ' i m m u n i t y c l a i m e d in S u d a n .

(e) Alum-precipitated vaccine.

T h i s a p p e a r s t o b e t h e m o s t p o p u l a r vacc i n e u s e d in A s i a n c o u n t r i e s . I m m u n i t y l a s t ing for 5-6 m o n t h s is c l a i m e d . C o n t r o l l e d t r ia l s in Sri L a n k a us ing a s t a n d a r d i z e d vacc ine c o n t a i n i n g 2 .5 m g b a c t e r i a p e r d o s e g a v e 3-4 m o n t h s ' i m m u n i t y t o c h a l l e n g e (33) .

(f) Aluminium hydroxide gel vaccine.

T h i s is u s e d o n l y in T h a i l a n d . I m m u n i t y u p t o 4 m o n t h s is c l a i m e d .

(g) Oil adjuvant vaccine.

T h i s is t h e m o s t p o t e n t of t h e a v a i l a b l e v a c c i n e s , b u t is p r o d u c e d in re la t ively few c o u n t r i e s ( M a l a y s i a , I n d o n e s i a , Sr i L a n k a , E g y p t , I r a q a n d a sma l l p r o p o r t i o n of t h e t o t a l p r o d u c t i o n in I n d i a a n d B a n g l a d e s h ) . I ts p o t e n c y is ve ry v a r i a b l e . C o n t r o l l e d t r ia l s in I n d o n e s i a a n d Sri L a n k a r e p o r t t h e d u r a t i o n of i m m u n i t y as 6-9 m o n t h s a n d in M a l a y s i a as 1 y e a r . B a n g l a d e s h c l a ims 21 m o n t h s a n d I n d i a 28 m o n t h s (4 , 3) . T h e Sri L a n k a t r ia l s w e r e p e r f o r m e d o n ca lves 4-6 m o n t h s o ld , g iven a s ingle d o s e of O A V a n d r e a r e d in a n e n v i r o n m e n t c o m p l e t e l y free o f H S , in c o n t a c t w i t h u n v a c c i n a t e d c o n t r o l s . I n s imi la r t r i a l s m a d e in H S e n z o o t i c a r e a s , a n i m a l s w e r e still i m m u n e 14 m o n t h s a f te r v a c c i n a t i o n , t h e l o n g e s t p e r i o d t e s t ed . S o m e u n v a c c i n a t e d c o n t r o l s a l so a c q u i r e d i m m u n i t y d u r i n g th i s p e r i o d . I n e n z o o t i c a r e a s , t h e i m m u n i t y of v a c c i n a t e d a n i m a l s s e e m e d t o b e p r o l o n g e d b y e x p o s u r e t o i n f ec t i on .

— 723 —

T h e h igh v i scos i ty a n d t h e c o n s e q u e n t d i f f icu l ty in a d m i n i s t r a t i o n we ighs heav i ly a g a i n s t t h e O A V . S o m e r e d u c t i o n in v i scos i ty h a s b e e n ef fec ted in Sri L a n k a b y u s i n g o n l y 4 % l a n o l i n e i n s t e a d o f t h e 8 - 1 2 % u s e d in s o m e f o r m u l a t i o n s .

4 . Eva luat ion of vacc ines .

M o s t c o u n t r i e s a c c e p t a b s e n c e o f d i s ea se f o l l o w i n g v a c c i n a t i o n as a n i n d i c a t i o n o f t h e ef f icacy o f a v a c c i n e . R o u t i n e t e s t ing o f vacc ines in ca t t l e o r b u f f a l o e s , o r in a n y l a b o r a t o r y a n i m a l o t h e r t h a n m i c e , d o e s n o t s e e m feasi b le in m o s t l a b o r a t o r i e s . P o t e n c y t e s t i ng in m i c e h a s b e e n a t t e m p t e d in M a l a y s i a , I n d i a a n d Sri L a n k a (52 , 4 1 , 2 0 , 60 ) . V a r i o u s v a c c i n a t i o n - c h a l l e n g e s chedu l e s h a v e b e e n d e v e l o p e d fo r q u i c k r e s u l t s . A l l t h e s e w o r k e r s h a v e a d a p t e d t h e t e c h n i q u e o f O s e a n d M u e n s t e r (54) . I t m u s t , h o w e v e r , b e n o t e d t h a t t h e l a s t - n a m e d d i d n o t u s e H S s e r o t y p e s of P a s t e u r e l l a . T h e y a r b i t r a r i l y a d o p t e d a p r o t e c t i o n o f 2 log u n i t s i n v a c c i n a t e d m i c e (as c o m p a r e d w i t h u n v a c c i n a t e d c o n t r o l s ) as a n i n d e x o f a d e q u a t e p r o t e c t i o n in c a t t l e , b u t w e r e u n a b l e t o e s t ab l i sh a c o r r e l a t i o n b e t w e e n m o u s e p o t e n c y a n d ca t t l e p o t e n c y . T h u s , wh i l e t h e p r e s e n t tes ts p r o v i d e a r o u g h g u i d e t o t h e ce r t i f i c a t i on o f a v a c c i n e as s u i t a b l e , t h e r e is a n e e d t o d e v e l o p a rea l i s t i c c o r r e l a t i o n b e t w e e n p o t e n c y fo r m i c e a n d p o t e n c y for c a t t l e o r b u f f a l o , w i t h a s t a n d a r d i z e d h a e m o r r h a g i c s e p t i c a e m i a v a c c i n e .

T h e m o u s e p r o t e c t i o n tes t o f O s e a n d M u e n s t e r , w h e n p e r f o r m e d m o s t e c o n o m i c a l l y , r e q u i r e s a b o u t 50 m i c e p e r b a t c h of v a c c i n e . T h i s m a y n o t b e w i t h i n t h e r e a c h o f t h e a v e r a g e l a b o r a t o r y in A s i a o r A f r i c a , excep t for t es t ing o c c a s i o n a l b a t c h e s . F o r r o u t i n e t e s t i ng o f all b a t c h e s o f v a c c i n e , r e l i ance h a s t o b e p l a c e d o n p u r i t y , a g g l u t i n a b i l i t y a n d t h e a n t i g e n c o n t e n t as m e a s u r ed b y r a p i d , t u r b i d i m e t r i c m e t h o d s .

5. Vacc inat ion schedules .

V a r i o u s v a c c i n a t i o n s c h e d u l e s h a v e b e e n a d o p t e d in d i f f e r en t c o u n t r i e s , r a n g i n g f r o m a n n u a l p r o p h y l a c t i c v a c c i n a t i o n a n d v a c c i n a t i o n in t h e face o f a n o u t b r e a k , t o v a c c i n a t i o n j u s t b e f o r e t h e H S s e a s o n . S ince t h e d i sease h a s a s e a s o n a l d i s t r i b u t i o n in m o s t c o u n t r i e s , t h e l a s t - m e n t i o n e d is t h e m o s t p o p u lar s c h e d u l e . T h e d i sease is m o s t p r e v a l e n t i n t h o s e a r e a s o f t h e T h i r d W o r l d w h e r e h u s b a n d r y p r a c t i c e s a r e still p r i m i t i v e , a n d so t h e r e s p o n s e o f f a r m e r s t o v a c c i n a t i o n is v e r y p o o r . M o s t f a r m e r s a r e wi l l ing t o c o o p e r a t e in v a c c i n a t i o n o n l y in t h e face o f a n o u t b r e a k . I n Sri L a n k a , n o n - c o o p e r a t i o n b y fa r m e r s w a s t h e b igges t c o n s t r a i n t t o t h e v a c c i n a t i o n p r o g r a m m e (25) . E x c e p t in spec ia l i n t ens ive v a c c i n a t i o n p r o g r a m m e s in speci f ied a r e a s , v a c c i n a t i o n c o v e r a g e is ve ry l o w a n d r a n g e s f r o m 2 0 - 4 0 % . O n e de t a i l ed s t u d y in Sri L a n k a i n d i c a t e d t h a t t h e t o t a l c o v e r a g e a n n u a l l y w a s a r o u n d 6 0 % of t h e su s cep t ib le s t o c k in e n z o o t i c a r e a s , a n d t h a t a b o u t h a l f of th i s n u m b e r w e r e v a c c i n a t e d o n l y in t h e face o f o u t b r e a k s .

Scient i f ic e v a l u a t i o n s o f t h e eff icacy o f v a c c i n a t i o n p r o g r a m m e s a r e s c a r c e . O n e s u c h e v a l u a t i o n in Sri L a n k a i n d i c a t e d t h a t r o u t i n e v a c c i n a t i o n

— 724 —

w i t h A P V re su l t ed in a s ta t i s t i ca l ly s ign i f ican t d r o p in t h e p e r c e n t a g e o f h e r d s in fec ted , b u t n o t in t h e m o r b i d i t y r a t e o n c e t h e d isease h a d b e c o m e e s t ab l i sh ed in a h e r d (32) . T h i s is a n i n d i c a t o r o f t h e l ow g r a d e a n d s h o r t d u r a t i o n o f i m m u n i t y c o n f e r r e d b y t h e vacc ines in u se , p r o t e c t i o n b e i n g suf f ic ien t t o p r e ven t t h e first case o c c u r r i n g , b u t i n a d e q u a t e a g a i n s t t h e h e a v y b u r d e n o f in fec t ion wi th in a h e r d o n c e c l in ical d i sease h a s b e c o m e e s t a b l i s h e d .

6. E c o n o m i c s o f haemorrhagic sept icaemia control .

T h e r e is l i t t le i n f o r m a t i o n o n e c o n o m i c a spec t s of H S c o n t r o l . O n e i n t e n sive i m m u n i z a t i o n p r o g r a m m e c o v e r i n g t h r e e e n z o o t i c d is t r ic t s in Sri L a n k a cos t on ly U S $0 .66 t o i m m u n i z e a s ingle a n i m a l . T e n pe r cen t o f th i s w a s t h e cos t of t h e O A V p r o d u c e d in a loca l l a b o r a t o r y of m o d e s t m e a n s , a n d w i t h a c a p a c i t y of 2 mi l l ion doses p e r y e a r . T h e r e m a i n i n g 9 0 % w a s t h e cos t of v e t e r i n a r y field se rv ices .

7. Poss ib le improvements t o the present control m e t h o d s .

P r o s p e c t s for i m p r o v i n g t h e p r e s e n t c o n t r o l m e t h o d s d e p e n d u p o n ach iev ing a h ighe r v a c c i n a t i o n c o v e r a g e , a n d p r o d u c i n g a be t t e r v a c c i n e , eas ier t o a d m i n i s t e r a n d p r o v i d i n g l o n g e r i m m u n i t y .

Severa l n e w vacc ines h a v e b e e n t r i ed o u t r ecen t ly b u t n o n e h a s b e c o m e e s t ab l i shed .

(a) Double emulsion vaccine.

T h i s w a s d e v e l o p e d in I n d i a b y G u p t a et al. (40) , in o r d e r t o r e d u c e t h e v iscos i ty o f oil a d j u v a n t v a c c i n e . T h e o r ig ina l vacc ine was r e -emuls i f i ed w i t h a n e q u a l v o l u m e of 0 . 2 % p o l y s o r b a t e 80 ( T w e e n 80) . T h e r e su l t i ng fluid h a d a f ree- f lowing m i l k y c o n s i s t e n c y , b u t t h e p o t e n c y o f t h e v acc i n e w a s less t h a n t h a t of t h e s t a n d a r d O A V .

(b) Purified capsular extract vaccine.

A t t e m p t s t o ident i fy t h e an t igen i c f r ac t ions a n d t o u s e s u c h f r ac t ions t o i m m u n i z e ca t t l e w e r e m a d e d e c a d e s a g o in I n d i a b y D h a n d a (35) , b u t th i s w o r k d id n o t resu l t in a p r a c t i c a l v a c c i n e .

M o r e recen t ly , P e n n a n d N a g y (55) a n d N a g y et al. (53) o b t a i n e d c a p s u l a r ex t r ac t s b y so lven t p r e c i p i t a t i o n f r o m t h e s u p e r n a t a n t fluid o f f e r m e n t o r -g r o w n P. multocida t y p e B . T h e c o m p l e x t e c h n o l o g y i nvo lved in p r o d u c i n g a vacc ine of th i s t y p e m a y b e b e y o n d t h e s c o p e o f m a n y v a c c i n e - p r o d u c i n g l a b o r a t o r i e s in c o u n t r i e s a f fec ted b y H S . F u r t h e r m o r e , t h e v acc i n e w a s of t h e oil a d j u v a n t t y p e a n d th i s w a s a d i s a d v a n t a g e b e c a u s e o f its h i g h v i scos i ty .

(c) Live vaccines.

N u m e r o u s a t t e m p t s h a v e b e e n m a d e f r o m t i m e t o t i m e t o p r o d u c e live vacc ines aga ins t v a r i o u s f o r m s o f p a s t e u r e l l o s i s . T h e m a i n p r o b l e m h a s b e e n t o ach ieve s tab i l i ty of t h e a t t e n u a t e d s t r a i n o r m u t a n t . W h i l e success h a s b e e n ach ieved wi th fowl c h o l e r a , n o s u i t a b l e m u t a n t h a s b e e n f o u n d t o i m m u n i z e

— 725 —

a g a i n s t H S . R e c e n t l y , a v i r u l e n t s t r e p t o m y c i n - d e p e n d e n t m u t a n t s w e r e p r o d u c e d b y c h e m i c a l m u t a g e n e s i s o f 6 :B s t r a i n s ( 6 1 , 2 7 ) . O n e o f t h e s e m u t a n t s was successfu l ly u s e d t o i m m u n i z e ca t t l e a n d b u f f a l o e s (26) . T h e l a r g e n u m b e r s o f th i s m u t a n t ( 1 0 1 0 - 1 0 1 1 ) r e q u i r e d t o p r o d u c e i m m u n i t y d i d n o t p e r m i t t h e d e v e l o p m e n t o f a p r a c t i c a l v a c c i n e . Success fu l i m m u n i z a t i o n w i t h s t r e p t o m y c i n - i n d e p e n d e n t r eve r se m u t a n t s a n d a l so a n a t u r a l l y o c c u r r i n g v a r i a n t s t r a i n (« A T C C 19427 ») h a s b e e n a c h i e v e d w i t h a sma l l e r n u m b e r o f o r g a n i s m s , b u t t h i s w o r k h a s t o b e d e v e l o p e d f u r t h e r b e f o r e a p r a c t i c a l vacc ine is o b t a i n e d ( D e A l w i s , u n p u b l i s h e d r e p o r t ) .

W i t h t h e ava i l ab i l i t y o f f r eeze -d ry ing e q u i p m e n t , t h e o p p o r t u n i t y exis ts fo r d e v e l o p i n g a l ive v a c c i n e in l y o p h i l i z e d f o r m .

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Appendix

5 2 n d G E N E R A L S E S S I O N O F T H E O . I . E .

R E S O L U T I O N N o . I I

H A E M O R R H A G I C S E P T I C A E M I A I N C A T T L E A N D B U F F A L O E S

C O N S I D E R I N G

t h a t t h e r e c o g n i t i o n o f h a e m o r r h a g i c s e p t i c a e m i a as a specif ic d i s ea se e n t i t y is still n o t c lea r in m a n y c o u n t r i e s ;

t h a t m a n y c o u n t r i e s r e p o r t t h e p r e v a l e n c e o f h a e m o r r h a g i c s e p t i c a e m i a w i t h o u t a d e q u a t e s e ro log i ca l i d e n t i f i c a t i o n o f t h e c a u s a l a g e n t ;

t h a t whi l s t it is r e c o g n i s e d t h a t t h e oil a d j u v a n t vacc i n e is t h e bes t p r o p h y lac t i c a g e n t p r e s e n t l y a v a i l a b l e , m a n y c o u n t r i e s c o n t i n u e t o u s e s i m p l e b r o t h b a c t e r i n s o f l o w p o t e n c y ;

t h a t t h e vacc ines p r o d u c e d a n d u s e d in d i f f e ren t c o u n t r i e s a r e n o t s t a n d a r d i s e d i n t e r n a t i o n a l l y ;

t h a t ef fect ive c o n t r o l o f t h e d i sease d e p e n d s o n :

(a) t h e i d e n t i f i c a t i o n o f t h e s e r o t y p e s p r e v a l e n t in e a c h c o u n t r y ; (b) a b e t t e r u n d e r s t a n d i n g o f t h e e p i z o o t i o l o g y o f t h e d i sease in e a c h

c o u n t r y ;

(c) t h e f o r m u l a t i o n a n d e x e c u t i o n o f s t r a t eg ic v a c c i n a t i o n p r o g r a m m e s ; a n d

(d) t h e d e v e l o p m e n t o f h i g h l y p o t e n t v a c c i n e s ,

T H E C O M M I T T E E

R E C O M M E N D S

— 726 —

1. T h a t t h e t e r m « h a e m o r r h a g i c s e p t i c a e m i a » b e d e f i n e d as a specif ic f o r m of p r i m a r y pas t eu re l l o s i s o f ca t t l e a n d b u f f a l o e s w i t h h igh m o r t a l i t y in cl inical cases a n d w h i c h is u n i f o r m l y c a u s e d b y Pasteurella multocida t y p e s 6:B o r 6 :E .

2 . T h a t c o n t i n u e d e f fo r t s b e d i r e c t e d t o w a r d s i m p r o v i n g t h e m e t h o d s fo r r a p i d d i agnos i s a n d c o m p l e t e s e ro log ica l t y p i n g o f Pasteurella multocida.

3 . T h a t s teps b e t a k e n t o iden t i fy a n d s e r o t y p e i so la tes f r o m c o u n t r i e s w h e r e th i s h a s n o t b e e n d o n e a l r e a d y .

4 . T h a t s t a n d a r d s b e la id d o w n for t h e h a e m o r r h a g i c s e p t i c a e m i a oi l a d j u v a n t vacc ine .

5. T h a t s teps b e t a k e n t o e n a b l e al l c o u n t r i e s w h e r e t h e d i sease exists t o p r o d u c e the i r o w n oil a d j u v a n t vacc ine c o n f o r m i n g t o t h e s t a n d a r d s m e n t i o n ed in p a r a g r a p h 4 a b o v e .

6. T h a t a d e q u a t e facil i t ies b e m a d e a v a i l a b l e in n a t i o n a l o r r e g i o n a l l a b o r a to r i e s t o e n a b l e s u c h l a b o r a t o r i e s t o p r o v i d e t h e n e c e s s a r y se rv ices .

7 . T h a t r e s e a r c h b e c a r r i e d o u t o n : (a) t he e p i z o o t i o l o g y o f t h e d i sease in v a r i o u s c o u n t r i e s ; a n d (b) t h e d e v e l o p m e n t o f vacc ines o f h i g h e r p o t e n c y w h i c h a r e eas ier t o

h a n d l e in t h e f ield.

8. T h a t hyg ien ic m e a s u r e s s u c h as t h e c o n t r o l o f m o v e m e n t of a n i m a l s f r o m d i seased a r ea s a n d t h e p r o p e r d i s p o s a l o f ca rcasses a n d o t h e r in fec ted m a t e r i a l , a n d t h e a d o p t i o n o f i m p r o v e d h u s b a n d r y p r a c t i c e s , w h e r e pos s ib l e , b e c a r r i e d o u t in o r d e r t o r e d u c e t h e i n c i d e n c e a n d s p r e a d o f t h e d i s ea se .

(Adopted by the International Committee of the O.I.E. on 23 May 1984.)

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R E F E R E N C E S

1. A N O N . (1979 a). — Country Report , Thailand. F A O / A P H C A Workshop on haemorrhagic septicaemia, Sri Lanka .

2. A N O N . (1979 b). — Country Report , Malaysia. F A O / A P H C A Workshop on haemorrhagic septicaemia, Sri Lanka .

3. A N O N . (1979 c). — Country Report , India. F A O / A P H C A Workshop on haemorrhagic septicaemia, Sri Lanka .

4. A N O N . (1979 d). — Country Report , Bangladesh. F A O / A P H C A Workshop on haemorrhagic septicaemia, Sri Lanka.

5. A N O N . (1981). — Simple serological technique recommended for haemorrhagic septicaemia diagnosis. Asian Liv., 6 (5), 41-42.

— 727 —

6. AHOOJA M.L . , Y A D A V M.S . , MITTAL K . R . and SINHA K . C . (1979). — Improvement of haemorrhagic septicaemia oil adjuvant vaccine through aeration culture technique. Indian J. anim. Sci., 49, 113-117.

7. A L D A B B A S A . H . , M O H A M M E D J . H . , RAZAK A . , KISTO G . , SHARMA G.L. and M O H A M M E D M . M . (1979). — Working paper . Report on F A O / A P H C A Workshop on haemorrhagic septicaemia, Sri Lanka .

8. ARAWWAWELA C . B . , D E A L W I S M . C . L . and VIPULASIRI A . A . (1981). — Formulation of a suitable medium for obtaining dense cultures for haemorrhagic septicaemia vaccine product ion. Ceylon vet. J., 29, 16-19.

9. BAIN R.V.S. (1954). — Studies on haemorrhagic septicaemia in cattle. I. Naturally acquired immunity in Siamese buffaloes. Brit. vet. J., 110, 481-484.

10. BAIN R .V.S. (1979). — Protective antigens of Pasteurella multocida. Working paper. Report on F A O / A P H C A Workshop on haemorrhagic septicaemia, Sri Lanka .

11. BAIN R .V.S . , D E ALWIS M . C . L . , CARTER G . R . and G U P T A B .K . (1982). — Haemorrhagic septicaemia. F A O Animal Product ion and Health Paper N o . 33, F A O , Rome.

12. BROGDEN K.A. and PACKER R .A. (1979). — Comparison of Pasteurella multocida serotyping systems. Amer. J. vet. Res., 40, 1332-1335.

13. CARTER G . R . (1955). — A haemagglutination test for the identification of serological types. Amer. J. vet. Res., 16, 481-484.

14. CARTER G . R . (1961). — A new serological type of P. multocida from Central Africa. Vet. Rec., 73, 1052.

15. CARTER G . R . (1982). — Whatever happened to haemorrhagic septicaemia ? J. Amer. Vet. Med. Ass., 180, 1176-1177.

16. CARTER G . R . and RAPPA Y D .E . (1962). — Formalinised erythrocytes in the haemagglutination test for typing Pasteurella multocida. Brit. vet. J., 118, 289-292.

17. CARTER G . R . and C H E N G A P P A M . M . (1980). — Hyaluronidase product ion by type B Pasteurella multocida from cases of haemorrhagic septicaemia. J. clin. Microbiol., 11, 94-96.

18. CARTER G . R . and C H E N G A P P A M . M . (1981 a). — Identification of type B & E Pasteurella multocida by counterimmunoelectrophoresis . Vet. Rec., 108, 145-146.

19. CARTER G . R . and CHENGAPPA M . M . (1981 b). — Proceedings, 24th Annual Meeting of the American Association of Veterinary Laboratory Diagnosticians, St. Louis, U .S .A.

20. CHANDRASEKERAN S. and Y E A P P . C . (1978). — Safety and potency testing of haemorrhagic septicaemia oil adjuvant vaccine by mouse protection test. Kajian Veterinar, 10, 28-34.

21 . CHANDRASEKERAN S., Y E A P P . C . and CHUINK B .H. (1981). — Biochemical and serological studies on Pasteurella multocida isolated from cattle and buffaloes in Malaysia. Brit. vet. J., 137, 361-367.

— 728 —

22. D E ALWIS M.C .L . (1981). — Mortality among cattle and buffaloes in Sri Lanka due to haemorrhagic septicaemia. Trop. Anim. Hlth. Prod., 13, 195-202.

23. D E ALWIS M.C .L . (1982 a). — The immune status of buffalo calves exposed to natural infection with haemorrhagic septicaemia. Trop. Anim. Hlth. Prod., 14, 29-30.

24. D E ALWIS M . C . L . (1982 b). — Pasteurella multocida serotype 6 :B from an elephant . Sri Lanka vet. J., 30, in press.

25. D E ALWIS M . C . L . (1983). — The economics of haemorrhagic septicaemia control in Sri Lanka. Commonweal th Veterinary Association Seminar on Animal Disease Control and Livestock Development in the Asian Region, Hisser, India.

26. D E ALWIS M.C .L . and CARTER G . R . (1980). — Preliminary field trials with a streptomycin dependent live vaccine against haemorrhagic septicaemia. Vet. Rec., 106, 435-437.

27. D E ALWIS M.C .L . , CARTER G . R . and CHENGAPPA M . M . (1980). — Product ion and characterisation of streptomycin dependent mutants of Pasteurella multocida from bovine haemorrhagic septicaemia. Canad. J. comp. Med., 44, 418-422.

28. D E ALWIS M . C . L . , JAYASEKERA M.U. and BALASUNDERAM P . (1975). — Pneumonic pasteurellosis in buffalo calves associated Pasteurella multocida serotype 6 :B. Ceylon vet. J., 23, 58-60.

29. D E ALWIS M.C .L . , KODITUWAKKU A . O . and KODITUWAKKU S. (1976). — Haemorrhagic septicaemia — an analysis of two outbreaks of disease among buffaloes. Ceylon vet. J., 24, 18-21.

30. D E ALWIS M . C . L . and SUMANADASA M.A. (1982). — Naturally acquired immunity to haemorrhagic septicaemia among cattle and buffaloes in Sri Lanka . Trop. Anim. Hlth. Prod., 14, 27-28.

31 . D E ALWIS M . C . L . and THAMBITHURAI V. (1965). — A case of haemorrhagic septicaemia in a wild elephant in Ceylon. Ceylon vet. J., 13, 17-19.

32. D E ALWIS M . C . L . and VIPULASIRI A . A . (1980). — An epizootiological study of haemorrhagic septicaemia in buffaloes and cattle in Sri Lanka . Ceylon vet. J., 28, 24-35.

33. D E ALWIS M.C .L . , GUNATILEKE A . A . P . and WICKREMASINGHE W . A . T . (1978). — Duration of immunity to haemorrhagic septicaemia in cattle following vaccination with alum precipitated and oil adjuvant vaccines. Ceylon vet. J., 26, 35-41.

34. D H A N D A M.R. (1959 a). — Proceedings of the 1st F A O Meeting on haemorrhagic septicaemia. Manila, Philippines.

35. D H A N D A M.R. (1959 b). — Immunisation of cattle against haemorrhagic septicaemia with purified capsular antigens (a preliminary communicat ion). Indian vet. J., 36, 6-8.

36. GENEIDY A .A. , LOFTY O. and E L AFFENTY A .M. (1967). — Control of haemorrhagic septicaemia with special reference to the new oil adjuvant vaccine. J. Arab. Vet. Med. Ass., 27, 121-126.

37. G U P T A B . K . (1962). — Studies on the carrier problem in haemorrhagic septicaemia. Thesis, Punjab University, Chandigar, India.

— 729 —

38. G U P T A B .K . (1973). — Studies on the pathogenicity of P. multocida in the development of a fowl cholera vaccine. Thesis, Agra University, India.

39. G U P T A B .K . and KUMAR S. (1973). — Serotyping of Indian isolates of Pasteurella multocida from healthy poultry. Indian J. anim. Sci., 48, 301-304.

40. G U P T A B . K . , MITTAL K . R . and JAISWAL T . N . (1979). — Multiemulsion haemorrhagic septicaemia oil adjuvant vaccine. Report on the F A O / A P H C A Workshop on haemorrhagic septicaemia, Sri Lanka , 31 .

41 . G U P T A M.L . and SAREEN R .L . (1976). — Evaluation of the haemorrhagic septicaemia oil adjuvant vaccine by the mouse protection test. Indian vet. J., 53, 489-492.

42. HEDDLESTON K . L . , GALLAGHER J .E . and REBERS P . A . (1972). — Fowl cholera : Gel diffusion precipitin test for serotyping Pasteurella multocida from avian species. Avian Dis., 16, 925-936.

43 . H I R A M U N E T. and D E ALWIS M . C . L . (1982). — Haemorrhagic septicaemia carrier status of cattle and buffaloes in Sri Lanka . Trop. Anim. Hlth. Prod., 14, 91-92.

44. KHENG C.S. and P H A Y C .H . (1963). — Haemorrhagic septicaemia : Sulphame-thazine and immune serum therapy in buffaloes infected by the intranasal spray method. Vet. Rec., 75, 155-159.

45. LITTLE P . A . and L Y O N B.M. (1943). — Demonstrat ion of serological types within the non-haemolytic Pasteurellae. Amer. J. vet. Res., 4, 110-112.

46. M U R T H Y D . K . and KAUSHIK R . K . (1965). — Studies on an outbreak of acute swine pasteurellosis due to P. multocida type B. Vet. Rec., 11, 411-416.

47. M U S T A F A A .A . , GHALIB H . W . and SHIGIDI M.T . (1978). — Carrier rate of Pasteurella multocida in cattle associated with an outbreak of haemorrhagic septicaemia in Sudan. Brit. vet. J., 134, 375-378.

48. NAMIOKA S. (1978). — Pasteurella multocida — Biochemical characteristics and serotypes. In : « Methods in Microbiology », chapter X, 271-292.

49. NAMIOKA S. and M U R A T A M. (1961 a). — Serological studies on Pasteurella multocida. I. A simplified method of capsular typing of the organism. Cornell Vet., 51, 498-507.

50. NAMIOKA S. and M U R A T A M. (1961 b). — Serological studies on Pasteurella multocida. II . Characteristics of somatic (o) antigen of the organism. Cornell Vet., 51, 507-521.

51 . NAMIOKA S. and M U R A T A M. (1964). — Serological studies on Pasteurella multocida. V. Some epizootiological findings resulting from ' O ' antigen analysis. Cornell Vet., 54, 520-534.

52. N A G A R A J A N V., SUNDERAM S. and RAMANI K. (1972). — Evaluation of the potency of haemorrhagic septicaemia alum precipitated vaccine by mouse protection test. Indian vet. J., 49, 1080-1083.

53. N A G Y L . K . , HARTANINGSIH N . and S U D A N A I .G. (1979). — Vaccination experiments with capsular antigen of Pasteurella multocida. Repor t on the F A O / A P H C A Workshop on haemorrhagic septicaemia, Sri Lanka .

— 730 —

5 4 . O S E E . E . and MUENSTER O . A . ( 1 9 6 8 ) . — A method of evaluating vaccines containing Pasteurella multocida. Amer. J. vet. Res., 29, 1 8 6 3 - 1 8 6 6 .

5 5 . P E N N C . W . and N A G Y L . K . ( 1 9 7 6 ) . — Isolation of a protective non toxic capsular antigen from Pasteurella multocida types B and E. Res. vet. Sci., 20, 9 0 - 9 6 .

5 6 . ROBERTS R . S . ( 1 9 4 7 ) . — An immunological study of Pasteurella septica. J. comp. Path., 57, 2 6 1 - 2 7 8 .

5 7 . S U W A D A T. , RIMLER R . B . and RHOADES K . R . ( 1 9 8 2 ) . — Indirect haemagglutina-tion test that uses glutaraldehyde fixed sheep erythrocytes sensitised with extract antigens for detection of Pasteurella antibody. J. clin. Microbiol., 15, 7 5 2 - 7 5 6 .

5 8 . SINGH N . ( 1 9 4 8 ) . — Nasal carriers in bovine pasteurellosis. Indian J. Vet. Sci. Anim. Husb., 18, 7 7 - 8 0 .

5 9 . THOMAS J. ( 1 9 6 8 ) . — Studies of haemorrhagic septicaemia oil adjuvant vaccine. I. Methods of production of vaccine. Kajian Veterinar, 1, 1 5 2 - 1 5 8 .

6 0 . VIPULASIR ; A .A . , WIJEWARDANA, THULA G. and D E A L W I S M . C . L . ( 1 9 8 2 ) . — Effect of storage temperature and time on the potency of haemorrhagic septicaemia oil adjuvant vaccine. Sri Lanka vet. J., 30, in press.

6 1 . W E I B . D . and CARTER G . R . ( 1 9 7 8 ) . — Live streptomycin dependent Pasteurella multocida vaccine for the prevention of haemorrhagic septicaemia. Amer. J. vet. Res., 39, 1 5 3 4 - 1 5 3 7 .

6 2 . WICKREMASURIYA U . G . J . S . and KENDERAGAMA K . M . T . ( 1 9 8 2 ) . — A case report of haemorrhagic septicaemia in a wild elephant. Sri Lanka vet. J., 30, in press.

6 3 . WIJEWANTHA E .A. and KARUNARATNE T . G . ( 1 9 6 8 ) . — Studies on the occurrence of Pasteurella multocida in the nasopharynx of healthy cattle. Cornell Vet., 58, 4 6 2 - 4 6 5 .

6 4 . WIJEWARDANA, T H U L A G., D E ALWIS M.C .L . and VIPULASIRI A . A . ( 1 9 8 2 ) . — An agar gel diffusion test for the rapid identification of Pasteurella multocida type B (Carter). Sri Lanka vet. J., 30, 1 2 - 1 4 .

Documents

Haemorrhagic septicaemia in cattle and buffaloes*€¦ · Haemorrhagic septicaemia in cattle and buffaloes* M.C.L. DE ALWIS** Summary : Haemorrhagic septicaemia (HS) is a highly fatal

Haemorrhagic septicaemia in cattle and buffaloes€¦ · Haemorrhagic septicaemia in cattle and buffaloes M.C.L. DE ALWIS** Summary : Haemorrhagic septicaemia (HS) is a highly fatal