Difference between revisions of "Toxoplasmosis - Sheep"
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==Description== | ==Description== | ||
− | Toxoplasmosis is the disease caused by ''Toxoplasma gondii'', a protozoan parasite. ''T. gondii'' can infect all mammals including man and is a significant cause of abortion in sheep and goats. Toxoplasmosis does not seem to cause disease in cattle. | + | Toxoplasmosis is the disease caused by ''Toxoplasma gondii'', a protozoan parasite. Although the definitive host is the cat, ''T. gondii'' can infect all mammals including man and is a significant cause of abortion in sheep and goats. Toxoplasmosis does not seem to cause disease in cattle. |
==Life Cycle== | ==Life Cycle== |
Revision as of 14:26, 13 August 2010
This article is still under construction. |
Description
Toxoplasmosis is the disease caused by Toxoplasma gondii, a protozoan parasite. Although the definitive host is the cat, T. gondii can infect all mammals including man and is a significant cause of abortion in sheep and goats. Toxoplasmosis does not seem to cause disease in cattle.
Life Cycle
- Sheep
- Mostly asymptomatic
- However, if a non-immune ewe is infected during pregnancy the consequences will be serious
- Infection during the first trimester leads to resorption
- Infection during the second trimester leads to foetal death and mummification
- Infection during the last trimester leads to a weak or stillborn lamb
Signalment
Diagnosis
Clinical Signs
- Clinical outbreaks of toxoplasmosis are sporadic
- Immunity is acquired before tupping
- Significant ill-effects are unlikely if immune ewes are infected during pregnancy
- Not shed from sheep to sheep so predicting outbreaks is difficult
Laboratory Tests
Pathology
Aborted ewes show focal necrotic placentitis with white lesions in the cotyledons and foetal tissue
Treatment
- Toxovax vaccine
- Live, avirulent strain of Toxoplasma
- Does not form bradyzoites or tissue cysts
- Killed by host immune system
- Single dose given 6 weeks before tupping
- Protects for 2 years
- Immunity boosted by natural challenge
- Medicated feed can be given daily during the main risk period
- 14 weeks before lambing
- The best method of protection is to prevent cats from contaminating the pasture, lambing sheds and feed stores
Prognosis
Links
References
- Buxton, D (1990) Ovine toxoplasmosis: a review. Journal of the Royal Society of Medicine, 83, 509-511.
- Innes, E A et al (2009) Ovine toxoplasmosis. Parastiology, 136, 1887–1894.
- Buxton, D et all (2007) Toxoplasma gondii and ovine toxoplasmosis: New aspects of an old story. Veterinary Parasitology, 147, 25-28.
- Dubey, J P (2009) Toxoplasmosis in sheep — The last 20 years. Veterinary Parasitology, 163, 1-14.