1 Taenia hydatigena : Predilection site: Small intestine Description : Taenia hydatigena is a large tapeworm measuring up to 5 m in length. There are 26-44 hooks on the rostellum, arranged in two rows. The gravid proglottids are about 8-10mm long by 4-7 mm broad. The median uterus has 5-10 lateral branches on each side. The metacestode stage of this species is called Cysticercus tenuicollis, and it is found in the peritoal cavity of sheep, goat, cattle and pig, some wild animals and some rodents, such as hamster. The semi-transparent cysticercus may be up to 5-7 cm in size and contains a watery fluid and invaginated scolex with a long neck. Final hosts : The adult tapeworm is found in dogs and wild carnivores. Intermediate hosts : Sheep, goat, cattle and pig, some wild animals and some rodents, such as hamster Geographical distribution : Worldwide Life cycle : The biology of this species is similar of basic life cycle in tapeworms of taeniidae. The oncospheres, infective to sheep, goat, cattle and pig, are carried in the blood to the liver in which they migrate for about 4 weeks before they emerge on the surface of this organ and attach to the peritoneum. Within a further 4 weeks each develops into the characteristically large metacestode, C. tenuicollis. The complete life cycle T. hydatigena is around 7-8 months. Pathogenesis and clinical signs : Adult tapeworms in dogs are usually asymptomatic. However, in heavy infections there may be gastrointestinal disturbances suc as diarrhoea, abdominal pain and anal pruritis that result from the migration of proglottids from the perianal area. The young metacestode, ( C. tenuicollis - larval stage), may cause serious diseases of livestoks animals, especially sheeps and goats, which are intermediated hosts. They damage and destroy the substance of the liver as they migrate through it, causing haemorrhage. Infrequently, large numbers of developing C. tenuicollis migrate contemporaneously in the liver of the sheep, goat and pig producing “ hepatitis cysticercosa” , a condition whose gross pathology resembles acute fasciolosis and which is often fatal. Severe infection of the liver or tissue may result in liver and carcass condemmation at slaughter. The mature C. tenuicollis in the peritoneal cavity are usually not pathological. Sometimes, infected sheep may be present loss of condition, emaciation and ascites . Diagnosis : Often the first sign of tapeworm infection in dogs in the presence of proglottids in the faeces or more frequently the perianal area as a result of active migration of the segments. The infection in sheep usually confirmed at meat inspection where the large larval cysts are observed on the mentery, omentum and abdominal organs. Epidemiology : If untreated, the final host can harbour tapeworms from several months to ayear or more. 2 Treatment : Praziquantel, nitroscanate, mebendazole and fenbendazole are effective against the adult tapeworms . No practical treatment is avaible fort he intermediated hosts. Taenia ovis : Predilection site: Small intestine Description : The adult tapeworm is large, measuring 0.5-1.5 m in length. The rostellum has 24-36 hooks, and the uterus in the gravid segment has 2-25 lateral branches on each side. The strobila has a scalloped edge and is often coiled into a spiral. The metacestode form of this tapeworm is found in the muscles of a food animals, such as sheep, goat, camel and reindeer, and they are about the size of 10 by 20 mm. Final hosts : The adult tapeworm is found in dogs and wild carnivores. Intermediate hosts : Sheep, goat, camel and reindeer Final hosts : The adult tapeworm is found in dogs and wild carnivores. Intermediate hosts : Sheep, goat, cattle and pig, some wild animals and some rodents, such as hamster Geographical distribution : Worldwide Life cycle : The biology of this species is similar of the biology of T. hydatigena. Dogs and wild canids are infected by consuming the cysticercus in the intermediate hosts. The intermediate host is infected through the ingestetion of cestode eggs that hatch in the intestine. The larval stage, which is called Cysticercus ovis, are mature in about three months, infects the musculature and cysts are usually lpcated in the skeletal muscle, heart, diaphragm and connective tissue. The peratent period in dogs ia around 6-9 months. Pathogenesis and clinical signs : Heavy infections in young dogs can sometimes cause diarrhoea and ill-thrift. Taenia ovis is of less importance because man can not be infected with the adult tapeworm. Epidemiology : Adult tapeworms shed three segments each containing 70000-90000 eggs. Dogs can be infected by more than one adult cestode. The thick-shelled eggs can survive 90- 150 days at 10-15°C but survive for shorter periods at higher temperatures. Ruminants are infected by grazing pasture and forages contaminated with dog or fox faeces harbouring eggs of T. ovis. Diagnosis : Tapeworm infection in dogs is often recognised through the presence of shed proglottids in fresh faeces. Control : Regular treatment of dogs with an effective anthelmintic will reduce contamination of the environment. Dogs should be denied access to raw sheep and goat meat and carcasses. Treatment : As for other taeniid species. Taenia pisiformis : Predilection site: Small intestine 3 Description : The adult tapeworm may be up to 2 m in legth. The rostellum has 34-48 hooks arranged in two rows. Gravid segments are 8-10 mm long and about 4-5 mm broad. The median stem of the uterus has eigth to fourteen lateral branches on each side. The omentum and mezenterium in the intermedited host. Final hosts : Dogs and fox Intermediate host : Rabbit and hare ( wild rabbit) Geographical distribution : Worldwide Life Cycle : The life history of this species resembles that of T.hydatigena and its effects on the final and intermediate hosts are similar. Infection of intermediate host is through ingestion of tapeworm eggs shed by dogs. Ingested eggs hatch in the small intestine of the intermediate hosts and penetrate intestinal wall and pass via the portal system to the liver. The juvenil fo may migrate through tje liver parenchyma and locate in the abdominal cavity after 2-4 weeks, where they develop into cysts ( Cysticercus pisiformis ) attached to the wall of the mesentery and omentum. Cysts can survive the life of the hosts. The final host is infected by ingesting the C. pisiformis. The prepatent period in the dogs is around 6-8 weeks. Pathogenesis and clinical signs : The adult tapeworms in the dogs usually cause little trouble. Cysticercus pisiformis damages the liver of the intermediate hosts, and , if they numerous, they may kill the intermediate hosts quickly. In heavy infections liver damage can occur in the intermediate hosts as a result of migration of juvenile stages through the liver parenchyma. This can lead to hepatitis and cirrhosis. A form of ‘ hepatitis cysticercosa’ is recognised in rabbits, caused during the wanderings of the oncosphere in the liver. Infection is usually asymptomatic. In heavy infection intermediate hosts may show emaciation and jaundice. Epidemiology : there is a high prevalence in hunting dogs. Diagnosis : Infection of the intermediate hosts is detected through the presence of a single cyste or a cluster of several cysts in the abdominal cavity. Control : Hunting dogs should be wormed requlary with an effective anthelmintic and should not be fed carcasses or offal from rabbits and hares. Treatment : As for other taeniid species. Taenia taeniaformis : The adult tapeworm is of medium size, up to 70 cm in length, and is sligthly different from the rest of the genus in groos morphology, for it has no obvious ‘ neck ‘ behind the scolex. The terminal segments are said to be bell-shape, but this is not a reliable differential character. The uterus has five to nine lateral branches. The metacestode , or larval , stage for T. taeniaformis is the strobilocercus, a morphological variation of the ctsticercus, or bladderworm, stage. The name of the metacestode stage of T. taeniaformis is Strobilocercus fasciolaris, which is a small cyst connected with an evaginated scolex by a segmented juvenile strobila. Final hosts : Cat, lynx, stat,fox 4 Intermediate hosts : Mouse, rat, rabbit, squirrel Life cycle : The metacestode, S. fasciolaris, develops in the liver of intermediate hosts and is infective to cats after about 9 weeks. When the cats ingest the metacestode the scolex atacches to the wall of the intestine, and then the neck and its connected bladderr are digested, and the tapeworm begins to grow in the cat’s intestine. For every strobilocercus that is ingested by the cat, one adult tapeworm will develop in the small intestine of that cat. The prepatent period in the cats is around 6 weeks, and cats can remain infected for up to about 2 years. Patogenesis and clinical signs : Adult tapeworms are of minör pathogenic significance and infectiona are usually subclinic. Epidemiology : The rodents are infected by grazing pasture and forages contaminated with cat faeces harbouring eggs of T. taeniaformis. Diagnosis : Diagnosis depends on the demonstration of proglottdis in the cat faeces. Control : Control depends on dietary methods that exclude access to the larval stage in the intermediate host. Where practical, cats should be prevented from eating rodents. Treatment : For adult tapeworms a number of effective drugs are available, including praziquantel, mebendazole and fenbendazole. Taenia multiceps : The adults of T. multiceps are 40-100 cm in length and have a small scolex about 0.8 mm in diameter with four suckers. There is a double ring of 22-32 rostellar hooks. The gravid segments measure 8-12 mm by 3-4 mm and the uterus has 18-26 lateral branches which contain taeniid eggs. The metacestode larval stage ( Coenurus cerebralis ) is readily recognised when mature as a large fluid-filled cyst up to 5.0 cm or more in diamete .