What Is Toxoplasma Gondii?

Toxoplasma Gondii is a single-celled parasite that, in order to develop, must penetrate animal cells. The parasite has two separate life cycles: an asexual cycle that can occur in many mammalian cells, and a sexual cycle that can only occur in cat cells. The virus is found in the brain and muscle tissue of many rodents that make up its reservoir, but is only distributed in cat feces. Parasitic oocysts (parasitic eggs, resistant to environmental conditions, up to a period of two years!) Secreted in the infected feces, can contaminate the herd, feed, pasture and substrate of sheep.

Toxoplasmas' typical life cycle in a farm:

• A cat (young, not yet infected and developed immunity) prey on an infected rodent.
• Within 3-4 days the cat secretes millions of oocysts in its feces.
• A sheep is infected by eating food (straw, hay ..) that is contaminated with cat feces.

An infected sheep is unable to infect other sheep, and develops immunity for the rest of its life. Cats also become immune after the first infection.

Infection of sheep during pregnancy

The most difficult infection of sheep is when they are infected for the first time during pregnancy. The parasite infects the placenta and the fetus, and the outcome of the infection depends on the stage of pregnancy in which the infection occurs. If the infection occurred within the first months of pregnancy, it will cause the fetus to die, abort or be absorbed. The sheep will return to being cyclical and may conceive again. Infection in the third or fourth month of pregnancy can cause the fetus to die and mummify (the fetus shrinks, and is covered by the placenta). This will result in either an abortion, or the delivery of these shrunken embryos on time, sometimes it will lead to the birth of a dead fetus a week before the date or at the time of lambing. There may also be a litter of live but small and weak lambs. Many of them will die as a result of starvation, pneumonia or other common diseases. If the infection occurred in the last month of pregnancy, the mother will usually birth normal lambs, and they and their mothers will be immuned against toxoplasma for the rest of their lives.

Prevention and Treatment

As mentioned, after a natural infection with the parasite, the sheep acquires immunity against the parasite for the rest of its life. Therefore the sheep should be infected when they are not pregnant and the lambs before first insemination. This is to develop immunity and prevent abortions or lambing of dead or small and weak lambs. Exposure to the parasite is done by feeding food exposed to cat feces or pasture containing cat feces containing oocysts. If the exposure was not done in time, it is very important to try to prevent cats from reaching the food and pen during pregnancy.

Medicinal treatment

Monensin administration, when given to mothers in the second half of pregnancy, may reduce the number of miscarriages, lambing of dead of weak lambs. The decision to use monensin is made by the veterinarian who treats the herd. Monensin at higher levels than allowed is a very toxic substance (forbidden to use in common European market countries) so adding it to the mixture will be done at a licensed blending institute. There is an argument that giving Decox can be beneficial, however the efficacy of the substance against the parasite has not yet been proven.