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 🩺
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.
Treatment 💊
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.
Prevention 🛡️
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.