Toxoplasmosis
Toxoplasmosis is a disease caused by the protozoan parasite <em>Toxoplasma gondii</em>. This parasite can infect a wide range of warm-blooded animals, including sheep and humans. In sheep, it is one of the most common causes of infectious abortion, accounting for about a quarter of cases. The disease is primarily spread through the ingestion of oocysts from contaminated environments.
Symptoms and diagnosis of Toxoplasmosis
Symptoms
The symptoms of toxoplasmosis in sheep can vary depending on the stage of pregnancy when the ewe is infected:
- Early Pregnancy: Infection can lead to foetal reabsorption, making the ewe appear barren.
- Mid Pregnancy (Days 50-120): Infection can result in abortion, stillbirth, or the birth of weak lambs. Mummified foetuses may also be observed.
- Late Pregnancy: Ewes may give birth to stillborn or weak lambs, often accompanied by a mummified foetus.
The placenta of an infected ewe often has a characteristic "frosted strawberry" appearance, with white spots on the cotyledons.
Diagnosis
To diagnose toxoplasmosis, submit dead lambs along with their placenta to a veterinary laboratory. The presence of white spots on the cotyledons is a key indicator. Laboratory tests can confirm the presence of the parasite.
How to treat Toxoplasmosis in sheep
Treatment options for toxoplasmosis in sheep include:
- Chemoprophylaxis: Feeding decoquinate during pregnancy can significantly reduce perinatal lamb mortality. It should be added to the feed to provide 2 mg/kg body weight/day from mid-pregnancy.
- Medication: A combination of pyrimethamine and sulfadimidine has been shown to be effective in treating infected sheep.
How to prevent Toxoplasmosis in sheep
Preventing toxoplasmosis involves several strategies:
- Vaccination: Vaccination is the most effective method of preventing T. gondii infection. A single injection provides long-lasting protection. Vaccination should be done at least three weeks before tupping and never during pregnancy.
- Environmental Management: Store sheep feed in vermin-proof facilities to prevent contamination by cats. Maintain a healthy adult cat population to control vermin without increasing the risk of toxoplasmosis.
- Hygiene: Dispose of dead lambs and infected placentas responsibly. Disinfect contaminated pens and equipment.
Important Note
Toxoplasmosis is a zoonotic disease, meaning it can be transmitted to humans. Pregnant women and immunocompromised individuals should take extra precautions to avoid exposure.