Current clinical concerns on HISTOMONOSIS

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Current clinical concerns on HISTOMONOSISand authorised medicines to treat and prevent the disease

Stephen Lister

Crowshall Veterinary Services, UK

salister@crowshall.co.uk

…. of a major catastrophe”

“A minor risk ….

Easy to diagnose

Difficult to manage

The problem

• An animal health catastrophe

• An animal welfare catastrophe

• An economic catastrophe

The problem

• Turkey meat flocks – up to 100% mortality

• Turkey breeder flocks – up to 100% loss of birds & hatching

eggs

• Broiler breeders – variable mortality, ~10% morbidity,

egg drops

• Layers – 1% mortality/week, egg drop

The problem

• Turkey meat flocks– up to 100% mortality

• Turkey breeder flocks– up to 100% loss of birds & hatching

eggs

• Broiler breeders– variable mortality, ~10% morbidity,

egg drops

• Layers – 1% mortality/week, egg drop

The problem

• Turkey meat flocks – up to 100% mortality

• Turkey breeder flocks – up to 100% loss of birds & hatching

eggs

• Broiler breeders – variable mortality, ~10% morbidity,

egg drops

• Layers – 1% mortality/week, egg drop

HISTOMONOSIS – Meat turkey examples

Tried oregano product in drinking water

and Flubenvet in feed - no response!

BLACKHEAD MORTALITY

OCTOBER 2012 - Numbers per day

0

100

200

300

400

500

600

700

800

1 3 5 7 9 11 13 15 17 19 21 23 25 27 29 31 33 35 37 39

Turkey meat birds – 2 houses, 7,500 birds placed in each house

>50% mortality - rest of flock destroyed on site - very high morbidity

PM

MEAT BIRDS MORTALITYSITE 1 – daily mortality

0

50

100

150

200

250

300

350

5,350 birds/house – 2 houses,cumulative mortality 18%, 22%

Mortality settled but poor condition

Mortality from 7 weeks

MEAT BIRDS MORTALITYSITE 1 – daily mortality

0

50

100

150

200

250

300

350

5,350 birds/house - cumulative mortality 18%, 22%

Mortality settled but poor condition

MEAT BIRDS MORTALITYSITE 2 – daily mortality

0

100

200

300

400

500

600

700

800

900

4,400 birds/house - cumulative mortality 99%, 83%, 83%

Mortality from 7 weeks, 3 houses

Culls

MEAT BIRDS MORTALITYSITE 2 – daily mortality

0

100

200

300

400

500

600

700

800

900

4,400 birds/house - cumulative mortality 99%, 83%, 83%

Mortality from 7 weeks, 3 houses

Culls

Meat flock outbreak

3 sites affected

total cost ~ £300,000

The problem

• Turkey meat flocks – up to 100% mortality

• Turkey breeder flocks – up to 100% loss of birds & hatching

eggs

• Broiler breeders – variable mortality, ~10% morbidity,

egg drops

• Layers – 1% mortality/week, egg drop

Blackhead in 17 week old turkey breeders in rear

• March 2009

• 4 houses on site

• 4 rearing flocks – each 5200 hens + 450 stags

• Uneventful rear to 17 weeks

• House 1 hens went very dull & quiet, stopped feeding. Stags OK

• Very little mortality

SGrain store

Stag shed

A140

S = shower block

MORTALITYNumbers per day

0

1

2

3

4

5

6

7

8

9

10

21 22 23 24 25 26 27

Turkey breeders in rear at 17 weeks – 5200 hens, 450 stags

Flock

went

quiet

MORTALITYNumbers per day

0

1

2

3

4

5

6

7

8

9

10

21 22 23 24 25 26 27

Turkey breeders in rear at 17 weeks – 5200 hens, 450 stags

Flock

went

quiet

50%

Sitting,

Not eating

Post mortem lesions

Advanced lesions within 24 hours

of onset of morbidity

MORTALITYNumbers per day

0

1

2

3

4

5

6

7

8

9

10

21 22 23 24 25 26 27

Turkey breeders in rear at 17 weeks – 5200 hens, 450 stags

Flock

went

quiet

50%

Sitting,

Not eating

MORTALITYNumbers per day

0

1

2

3

4

5

6

7

8

9

10

21 22 23 24 25 26 27

Turkey breeders in rear at 17 weeks – 5200 hens, 450 stags

Flock

went

quiet

Whole flock depressed

Decision

to

slaughter

50%

Sitting,

Not eating

0

1

2

3

4

5

6

7

8

9

10

21 22 23 24 25 26 27

Turkey breeders in rear at 17 weeks – 5200 hens, 450 stags

Flock

went

quiet

Flock

killed

Slaughterhouse warned that there

may be viscera lesions and bad colour

0

1

2

3

4

5

6

7

8

9

10

21 22 23 24 25 26 27

Turkey breeders in rear at 17 weeks – 5200 hens, 450 stags

Flock

went

quiet

Flock

killed

Of 5,200 hens sent for slaughter

54% (2,800) were condemned

Bad colour, bad livers and intestines

Blackhead in 17 week old turkey breeders in rear

• Loss of >5,000 breeders

• Rapid morbidity, poor welfare

• 54% of birds sent for slaughter condemned

• Loss of >500,000 hatching eggs

• Even after prompt diagnosis no treatment options available

BLACKHEAD MORTALITY

SEPTEMBER 2012 - Numbers per day

0

2

4

6

8

10

12

14

16

18

20

7 8 9 10 11 12 13 14 15 16

Turkey breeders in rear at 15 weeks – 5000 hens

PM

Severe dehydration

Severe caecal lesions

No macroscopic liver lesions

Histopathology

confirmed Histomonas

in liver and caecal sections

Turkey Breeders

15 weeks in rear

4 houses on site

Only 1 house affected

BLACKHEAD MORTALITY

SEPTEMBER 2012 - Numbers per day

0

2

4

6

8

10

12

14

16

18

20

7 8 9 10 11 12 13 14 15 16

Turkey breeders in rear at 15 weeks – 5000 hens

Flock

killed

PM

No specific risk

factors identified

Highly biosecure site

Very wet weather

?Movement of soil

onto concrete, walked

into house?

Breeder flock outbreak

Loss of 5000 hens

Loss of >550,000 hatching eggs

Total direct cost ~ £350,000

or ~ 420,000 Euros

These turkeys need our help !

Therapeutic Options

• No authorised medicines for treatment

• No authorised medicines for prevention

• Medicines previously licenced lost licences due to issues relating to mutagenicity and carcinogenicity

Therapeutic Options

• Previous options were:

–Dimetridazole (DMZ, Emtryl)

–Nifursol (Salfuride)

• Both were effective as preventive

in feed additives and DMZ as

water treatment

Dimetridazole - DMZ

• DMZ placed in Annex IV of Regulation 2377/90 (ban of use as VMP in food animals) in September 1995 as no agreed MRL could be set due to concerns on mutagenicity in rodents

• DMZ was still available for in feed use under Feed Additive Regulation 70/524 for prevention of Histomoniasis in turkeys and guinea fowl

Dimetridazole - DMZ

• Scientific Committee on Animal Nutrition (SCAN) concluded no consumer health risk from DMZ in September 2000, …… BUT

• EU Commission made a formal decision to withdraw DMZ from all use in turkeys – banned as medicinal feed additive in May 2002

Nifursol (Salfuride)

• In 2003 SCAN concluded that the safety for consumers could not be ensured on the basis of the data made available for the evaluation

• “As both the acceptable daily intake (ADI) and the human exposure to nifursol residues (including metabolites) cannot be established, the safety of nifursol for the human consumer cannot be ensured”

What other options are available ????

Therapeutic Options ??

• Use of DMZ to treat an

affected breeder flock, if

prevented from entering the

food chain at end of lay (as for

horse passport system)?

Use of DMZ in breeders ??

• Most breeder flocks are members of

Government controlled health

schemes – specific veterinary control

• Veterinary Health Plan could cover

requirements for strict control and

identification of treated flocks to

ensure no human consumption

Use of DMZ in breeders ??

• Not possible under current

legislation unless new data

presented to enable DMZ to

be removed from “Annex IV”

–Currently lack of sufficient data on

human safety

Personal communication with Dr Isaura de Conceicao Duarte,

Head of Animal and Public Health,

European Medicines Agency (EMA), January 2013

Therapeutic Options ??

• Variety of antimicrobials, herbal remedies tried with variable but limited success–Doxycycline, chlortetracycline,

oxytetracycline, tiamulin, amoxycillin, oregano etc etc etc

• Other options ???????????

Enhanced biosecurity ?

BUT outbreaks in high health

status breeding farms

Can we do better ?

Yes, but not the whole answer

Other Options – “wish list”!

• Histomonostat– preventive, in feed, safe

• Therapeutic options– effective and cost effective – under

MUMS legislation – minor use, minor species (reduced dossier requirements)

• Vaccination– effective and commercially available

…. of a major catastrophe”

“A minor risk ….

…. of a major catastrophe”

“A minor risk ….

An animal health,

animal welfare and

economic catastrophe

Solutions are needed-a cooperative approach

to veterinary control and food safety

Stephen ListerCrowshall Veterinary Services

www.crowshall.co.uk

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