INTERNATIONAL A? , Volume 5, October 1998

-.A L 1 LTH NEWSLETTER t k%srno~ Dr. D.E. Goodman, Editor I

IN THIS ISSUE:

THE AUTHOR:

CY S~CERCQSIS: HImRY AND REVIEW OF LIFE CYCLE

CLINICAL DISEASE IN ANIMALS

CLMICAL DISEA~E IN HUMANS

This issue of the International Animal Health News continues the series on major animal diseases that have implications for human health. A few of the rnajor food-born parasitic m n o t i c diseases will be discussod. Cysticercosis, onc of the r n o ~ common and serious diseases of this category is addressed in detail.

Dr. k i t h Flanagan of Texhoma. Oklahoma. USA, Dr. Flanagan is cumntly hs Director of Training for Chrisd~n Veterinary Mission. He has served 9 as a CVM fieldworker in Haiti.

Cysticercosis is caused by the ingestion af eggs of the T ~ m i a tapeworm. This is more common in developing countries because sanitation facilities are lacking and mimals are allowed to roam freely, having accas to h u m feces. It is also seen more frequently in areas where beef and pork are eaten raw or insufficien~ly cooked. Prevalence is bighest in parts or L a t h America. Africa, Southeast Asia and Eastern Europe.

The definitive host (host that harbors the adult parasite) for both bovine cyst imsis (Trrenk saginutu) md swine cyscicerwsis (Tuenia solirrm) is man. The adult tapeworm in h u m s occurs after the ingestion of the encysted lame from insuficiendy wok& beef or pork, The infection of an adult tapeworm is called taeniasis. Pmple infected with an adult tapeworm may expel several segments of the tapeworm daily. Each segment con- taitrs over e thowand eggs, which can survive for a month in water and up to six months in the g m s or soil, These eggs are immediately infective and can then be ingested by cattle or swine resulting in clinical cysticercosis. Toenia s o h m is considmd a much grater public health threat than T. saginata. This is because T. solilurs eggs, when in- gested by humans, can deceelop and encyst in the brain often causing serious health problems (neurorystirenc~sis).

Cyaicercosis is generally more common in rural areas, however a tapeworm carrier in a highly o v m w d e d lrrban area may represent an e m more dangerous source of cases than in a rural area, especially if that person works as a food handler.

Cysticercosis in beef ca~le (beef measCes) and swine (pork measles) rarely cause any clinical s i p and usually gow undetmted until siwghter. Severe infections may cause muscle swelling and pain, cspciaIly in the neck and tongue. Paralysis of the tongue may occru: On rare mxasions, the larvae of 'l: solium may encyst in the brain of a pig, causing seizures or ather nturological signs. Cystkercosis cause a great economic lass due ra condemnation or reduced value of mar at slaughtex.

Adult tapeworm infections in humans may often go undiagnosed with fcw ciiaical signs. Thme signs m y include abdominal discomfon, nervousna loss of appetite, insomnia, weight loss and diarrhea. Scchons of the tape worm (proglottides) may k observed in the f ~ . These appear as shott, flat, white segments that, when ~IY, look much like a grain of rice.

I B ~ ~ ~ N A L * W N - ~ ~ ~ ~ * ~ ~ ~ * I ~ ~ h W + ~ B f k ~ ~ I ~ P M m ~ ~ * ~ ~ ~ @ ~ ~ . ~

Serological testing can also be done in animals, but is usually too expwsive to be fea- sible. Cysticcmsis is wually discovered during daughter. Hawevw, abwt 80% of the infected pigs will have visible cysts on the venm1 surface of the tongue. These cysts will appear as .5- 1 crn, shiny, h i d filled nodules. This visual mamination may tK useful for field weening and suwey work. In the caress, cysts are most often found in the muscles of the jaw. neck, tongue, diaphragm, hem, shoulder. and thigh.

Aduh tapeworm mfection can be diagnosed by identification of the segments or tbe eggs in the f w under a mimscope. Obtaining the swlw (head) of the upeworm following treatmerit confirms the diagnosis and a s m s the elimination of the worn. Usually, only one worm is present. Specific serologic tests should support the clinical dignosis of cysticercosis. These tests arr: cxpcnsive and usually not available in developing counhiw. Subcutaneous cysts may be vis j ble or can be palpated as -5- 1 cm nodules just under the skin. Microscopic examination of an excised cyst wnfirrns the diagnosis. Intern! cystiwmsis can be diagnosed by an MRI or CAT scan.

cysdcercosis should be a y to break, and the disease easily conmllod. Howveer, due to lack of education abwr the discase, poor sanitation pmctices, and long standing animal hushdry practices. control and eradication may bt a long time in comimg.

As with any disease, education of the population is essential prior to any other control m u t e s being implemented. Thc population must be aware of the dangers of the d i m e as well as the life cycle of cysticcr~osis, Personal hygiene must be stressed in both the public schools as well as in adult edumtion classes. Improved personal hygiene would dehcase the risk of hman-to-human tmnmission of egs. Incmsd acws to improved sanitation facilities is essential, in preventing animals from having access to human feces. Then is a direct cotretalion between the incidence of cysticescosis and the lack of latrine facilities. RAW sewage should not be used for fwti lizing or irrigating fields. Coinposting human waste for six month lo a yerrr kills the egp and renders it safe w fertilizer.

Improvd animal husbandry practices are essential. If animals ate not allowed access to human feces, the life cycle can be cffectivc~y broken. Even with education, these changes wiII be slow in coming. Pens are expensive to build and free ranging animals are easier and chcapcr to take care of.

Proper handling of infected meat is also a critical step. Inspection and condemuation af infecbd meat is effective in deeming the incident of dim but often the infrastructure is not in place to carry this out, Freezing infected meat at -10 degrees C for four days will kill the cyst. This is mmly ~ i M e in developing countries. Cooking the meal at tcm-

Mass treatment of the human population in an m a endemic for cystiwwis would also be beneficial toward control and eradication. This would bc expensive a d would only be effective if other control measures were implemented at the same Bme. S e v d isolated caw of human myst icercosis have been recently identified in developed countries. Most of ihtse cases have occurrod because of pmr sanitary hygiene practices of Taenia positive food handlers. Most of these food haridkrs haw been wnigmnts Fnrrn Tasnia endemic areas. An adult worm may remain in the intestine and miifiut shedding t g p for up to 30 years. The eggs can remain viable in the ewimnment for months. Testing and tmtment of selected individuals, especially those preparing f d . should be consid- ered for control ling human cysticercosis.

Until recently, treatment of animals for cysticercosis has not been ewnomically feasible. Praziquaniel given to pigs at a dose of 5On@cg daily for I 5 days was effective, but cwld cost up to US $200'. Albendazal~ givcn at 30 m&g daily for 3 days was also effectim. The cost is almost US $20 per trearment. A recent study using a single dose of oxfamle at 30 mgkg s h o d great promise at a cast of about US $1.20. Further studies need to be documented to confirm &ese findings.

Both praziqumtd and a lhdamte are k i n g used for the treatment of both tamiasis and cystiwrcosis in h u m . lfeilber ciisease. is suspected, one should contact their physician for proper diagnosis a d ma.

WfllRm CEUQPCS

&add wmanlr bnok off and pauwlfnfrdn.

.ool.whiJlhDlcLatdBrvrlop iRm-.

Life Cyde of Taenia Solium, the park tapeworm

JAHN NEWS- VOI.. 5 - 1W8 PAGE 4

OTHER FOOD-BORN PARASITIC ZOONOTIC DISEASES

This Iist is in no way complete, but includes a brief summary of two more common disusses of this category.

f l o b o ~ ( B m a d or Fish Tapeworm infection) This is a human intestinal infection cat& by the aduk tapeworm, Di/phyIlloborhrirun laam or D. pncflinrm. Symptoms arc usually mvial or absent. In long standing cases, vitamin 01 2 deficiency anemia may devtlop. Massive infections may be asscdated with diacrhes and obstructian of the bile duct or intestine.

Thb disease is most common in subarctic, temperate end tropical zones where eating at' raw or pmly cooked freshwtcr fish is common. Through this pmctice, hu~nans are infected by the infective larval stage of the tapcwom. It then develops into an adult within the intesPne and attaches to !he jejunum. where it matures and starts laying eggs. These eggs arc con- tained in segments of the tapeworm a d art passed in thc focc;s where they can eontarninate fresh bodies of water. Thew eggs hatch and infect copepoda which arc the intermediate host, The infected copepde are thm eaten by freshwaier fish. It is the infective stage in the fish that is infective for humans. It takes 3 to 6 wxks sfter ingestion of the i n k t c d larvae until there is a passage ofthe eggs in the stool.

Education abDul the diseaseand its lifecycle is important. Cooking fish at 56 degrees C for five minute or W i n g for 24 hours at - 18 degrees C insures prowion. Dogs, bears and other fishating mammals are also reservoirs, so b r & q the life cycle in nature, woJd be almost imp9ssibIe.

Consult your physician for proper diagnosis and treatment if Diphy llobmhriasis is suspected

. . -(Trichinosis) is a disease caused by the intarind round worm (nematode) Trichiwlla spiralis whose Cwat migrate to and k o m erlcapsulased in the muscle, It is normally a d i e of swine, dogs, cats, rats, and many wild animals; including fox. wolf, b, plar bcar, wild b a r and marine mammats in the Arctic. The hyena, jackal, lim, and 1- may be infccted in IIR tropics. It is transmitted by eating raw or insufficiently m k e d flesh or animals containing viable encysted lanrac. Contarninatd pork producb are the mod common source of inkhon for man. The larvae develop into adults in the withe I ium of the small intestine. The marure fcmak w o r n then produce lmae. which travel hughout tht body and form cysts in the muscle tissue.

Clinical s i p often appear 8 - I$ &ys after ingestion of infected meat and start with h e s u d h appearance of muscle s ~ e n e s s and f in. Edema of the uppet eyelids and somas are mmmon and characteristic signs. Hmarrhage and pttin of the eyes o h follows. Thirst, sweating, chills and weakness folIow tht mutar signs. Remittent fever up to 40 degrees C is commoa. Cardiac and neurological complications may appear during [he third to the sixth week. Death due to h e m failure may occur either very early on, or between the fwh to the c@ we&. SmlagicaJ twits a d m increase in eosimphilas may be helpful with the diagnosis.

Human trichinellosis occurs world wide, but iu incidence varfes depending on the practices of cating and preparing insuficiently m k e d pork or wild animal meat. Thoroughly m k - ing the meat so that all parts reach a! leas 77 &gees C or until the meat changes Barn pink to gray wi I1 i nme safety. Freczing m a t at - 1 5 degrees C for 20 days will also effectively kill the cyst.

----' a , '

~ , l 3 4 i U b * v a m ~ m 3 1 ~ m m & r c a p * * - - h w :-' . . 14 -A

MHN N E W S ~ R VOL 5 - 1 W 8 P A ~ F $

BASIC ~ ~ M ~ ~ ~ :

If trichim~i~ is suspected, me should consult heir physician for proper diaposis and treatment. AIIergic ractions lo the dying larvae may cause compiic~rions during the treatment.

- . - * # I L f NEwKI= W I M W l N U M U ~

W U mtll la MVAE ~riwfl~~n Y ~ S U ~ I W A lME3fML MU- W g l L I I O R Y SYSTEM

1 h m arm fmd from ~k mwe WWI and dwdw &in& diqmdlm. Y in- ~t - ,

HQBT * K I B S S I U T mwllBIW- YR- U V A N

Life Cycle of the Trichinella spiralis, the cmsahve agent of Trichinosis in man

The parasitic diseases discussed in this paper 8s well as many others affecting both animals and man, cause untold suffering md economic hss in much of the world. Though poorly understood in ths past, animal disease and parasite problems with human implications have long been with us. They have been much studied in this century and are now well under- stood. Many of these problem could be greatly lewmed and even eliminated. There arc several basic steps chat we welt within he reach of most individuals. In other cases, ~ommunify effort% are necessary. Successful control and prevention programs have been carried out in many areas of the world.

Prevent humans from coming into contact with the fece of other humans. Prevent animals, especially dogs and pigs, from contact with human feces. Measures that prevmt human usually take care of this problem. Reventative plans arc avaiWe in most countries, h n l international agencies such as the United Nations and many other organizalions. In tempomy situations, such as campsites where buildrbg materials are castly or not available. treoches or mad holes can be dug and cawred. They must be deep enough to prevent mimal access and some distance from the drinking water source.

2 . L . 1 , In order to kill organisms in meat it must be oookcd to 55 degrees C and until at least gray in color with no Feddish arcas remaining or h u g h I y boiled for at least thirty minutes. This will help in !he prevention of other diseases such as Tuberculosis.

. -7-2- A

WfRd N E W $ I . ~ R VOL. 5 - 10198 PAGE 6

C o ~ s u L ~ N G BY MAL:

a ~ ~ ~ ~ * l ~ ~ * J ~ ~ m ~ w 5 4 & ~ . ~ ~ ~ ~ - ~ ' . , * W L 7 , . :*

3. D o n ' t f e e d s~W!Uu!iNlMk&S Any soum of meat scraps, firom slaughter houses, restaurmis, hospitals and ahports as well as household waste should be thoroughly cooked to kill the causative organisms of parasitic and disease problems. Bonw protect the organisms and are a problem which requires a prolonged procedure.

4.0- 0f This i snwemy toenswethatoher animals do not have contact with ihecarcasses and spread the disease.

ECT MEAT PRT)DUCTTS AT SI-AI IG- PJ *AM'S Though not possible in many a m this is one of the most important measura.

The M X U X R E . C ' T I C E S that can be carried out THE GREATER THE CHANCE OF IMPROVlNG HEALTH AND LIVMG CONDITIONS.

This dmwing is that of an outdoor sanitary facility in the Middle k t . Ofnote is the covering over the pit that contains feces and the screened door to keep flies out. There are many variations of this very successful design used worldwide.

We appreciate your excellent response to our request for sugptiorts to make this publication more kIpful to you. We welcome further corn- spondenm and would q i a l l y like information on successful practices that are practical and have witnessed improved animal h d t h and produc- lion.

In the developmental stages of this publication we had hoped that it would w e as an information exchange as we1 l as to provide indepth coverage of selected subjects.

'

The author of this edition as well as those on our Board of Advisors will be glad to provide rnm information on subjects in this edition and ohm topics as well. Please address any correspondence to:

Dr. A.L. Dorrniny Christian Veterinary Mission

1 9303 Fremont Ave N Seattle WA98 I33 USA

email: missionvet @I ,corn

h53mmu-m-