Todayโs path rounds are on ๐ญ๐จ๐ฑ๐จ๐ฉ๐ฅ๐๐ฌ๐ฆ๐จ๐ฌ๐ข๐ฌ!
๐๐ก๐๐ญ ๐ข๐ฌ ๐ข๐ญ?
๐๐จ๐ฑ๐จ๐ฉ๐ฅ๐๐ฌ๐ฆ๐ is a protozoan parasite that we most commonly associate with infectious abortion, however it can also cause ๐ฌ๐ฒ๐ฌ๐ญ๐๐ฆ๐ข๐ (whole body) disease with serious consequences!
๐๐ก๐จ ๐ ๐๐ญ๐ฌ ๐ข๐ญ?
We most commonly associate this disease with cats, because they are the ๐๐๐๐ข๐ง๐ข๐ญ๐ข๐ฏ๐ ๐ก๐จ๐ฌ๐ญ, meaning they are the primary species where this protozoa likes to live. However, other species, including humans, can become infected with the parasite, causing disease.
๐๐ก๐๐ญ ๐๐๐ฎ๐ฌ๐๐ฌ ๐ข๐ญ?
As mentioned, cats are the primary source of these protozoans. Cats become infected by ingesting ๐จ๐จ๐๐ฒ๐ฌ๐ญ๐ฌ (egg forms) from the environment, or eating ๐๐ซ๐๐๐ฒ๐ณ๐จ๐ข๐ญ๐๐ฌ, the form found within ๐ข๐ง๐ญ๐๐ซ๐ฆ๐๐๐ข๐๐ญ๐ ๐ก๐จ๐ฌ๐ญ๐ฌ like rodents. These intermediate hosts become infected by eating the oocysts. Regardless of the source, this infection allows the protozoan to develop into adult forms in the gut of the infected cat, which eventually produce oocysts that are shed in the feces and contaminate the environment. Similar to the intermediate hosts, these oocysts can then be ingested by non-target species, like humans, birds, herbivores and carnivores, leading to infection.
๐๐ก๐ฒ ๐ข๐ฌ ๐ญ๐ก๐ข๐ฌ ๐ ๐ฉ๐ซ๐จ๐๐ฅ๐๐ฆ?
Under most circumstances, the immune system will quickly activate to eliminate the protozoan, preventing disease. However, in cases of ๐ข๐ฆ๐ฆ๐ฎ๐ง๐จ๐๐จ๐ฆ๐ฉ๐ซ๐จ๐ฆ๐ข๐ฌ๐ (weak immune system), the protozoan may spread to multiple organs via the bloodstream. The ๐ญ๐๐๐ก๐ฒ๐ณ๐จ๐ข๐ญ๐ stage of the parasite invades the cells, where it forms a big storage vessel for itself and begins to replicate. By living within the cells, the parasite is hidden from the immune system. The parasite can live quite happily in this cyst stage for moths or years. However, as the parasite replicates, eventually the storage vessel becomes too large for the cell, rupturing the cell. This alerts the immune system to the parasiteโs presence, and stimulates an immune response that can cause cell death in the area.
Because this organism can be spread to many different organisms, this cell death can lead to many different outcomes. For example, infection of the brain can cause incoordination, tremors, seizures and even ๐ฉ๐๐ซ๐๐ฌ๐ข๐ฌ (inability to move). If it infects the lungs, it can cause difficulty breathing and pneumonia.
๐๐จ๐ฐ ๐ข๐ฌ ๐ข๐ญ ๐๐ข๐๐ ๐ง๐จ๐ฌ๐๐?
Unfortunately, the clinical signs of this disease arenโt very specific, so additional testing is required to confirm the diagnosis. In live animals, usually the diagnosis is made by ๐ฌ๐๐ซ๐จ๐ฅ๐จ๐ ๐ข๐ ๐ญ๐๐ฌ๐ญ๐ข๐ง๐ , where the blood is tested to see if there are antibodies against the parasite. At necropsy, we can see the cysts formed by the parasites directly, making diagnosis somewhat more simple!
๐๐จ๐ฐ ๐ข๐ฌ ๐ข๐ญ ๐ญ๐ซ๐๐๐ญ๐๐?
Treatment typically involves ๐๐ง๐ญ๐ข-๐๐จ๐๐๐ข๐๐ข๐๐ฅ ๐๐ซ๐ฎ๐ ๐ฌ which target this type of parasite specifically. These drugs can also reduce the number of oocysts produced by cats as a potential preventative measure.
๐๐ก๐๐ญโ๐ฌ ๐ญ๐ก๐ ๐๐๐๐ฅ ๐ฐ๐ข๐ญ๐ก ๐ฉ๐ซ๐๐ ๐ง๐๐ง๐ญ ๐ฐ๐จ๐ฆ๐๐ง?
As mentioned, this parasite can infect humans, and can cause abortion. This is the big concern with pregnant women cleaning litter boxes, as they may become exposed to the oocysts in their catโs feces, leading to abortion. Pregnant women may also be exposed by interacting with soil, raw meat or unwashed vegetables. Thorough cleaning, hand washing and avoiding these circumstances where possible are the best methods of prevention!
๐๐ก๐จ๐ญ๐จ๐ฌ
1-2) Pneumonia in a cat with Toxoplasma.
3) Toxoplasma as seen on ๐๐ฒ๐ญ๐จ๐ฅ๐จ๐ ๐ฒ, where cells are sampled from a live animal.
4) Toxoplasma at ๐ก๐ข๐ฌ๐ญ๐จ๐ฅ๐จ๐ ๐ฒ, where the tissue is examined under the microscope! This cyst happens to be in the brain.
๐๐จ๐ฎ๐ซ๐๐๐ฌ
Maxie, G. Jubb, Kennedy and Palmerโs Pathology of Domestic Animals, Volume 2. Sixth Edition.
Morรฉ GA. Toxoplasmosis in animals. Merck Veterinary Manual 2021.
Photos 1-3 ยฉ Noahโs Arkive contributors King, Jakowski licensed under CC BY-SA 4.0.
Photo 4 from the Agricultural Research Service of the USDA.
