Toxoplasmosis in Goats
Protect your goats and yourself from infection
Reading Time: 4 minutes
Toxoplasmosis in goats isn’t a disease that will cause severe production losses. However, its zoonotic risk makes it an important disease.
Most people are instructed not to change the cat litter box while pregnant. However, the same parasite that can be transmitted to humans from cats can also be transmitted from goats to humans. Toxoplasma gondii is a protozoa found throughout the world. While infection with this parasite is often asymptomatic, it can cause serious disease in immunocompromised or pregnant individuals.
Felids, or cats, are the definitive host of the protozoa. Cats obtain the parasite through ingestion of infected, uncooked meat. The parasite replicates within the cat, which then sheds large quantities of oocytes within their feces for several weeks. These oocytes can live for up to 18 months in the environment. After the initial shedding of the oocytes, most cats won’t shed them again, though immunocompromised animals may do so.
Other mammals become intermediate hosts, or hosts in which the parasite doesn’t reach the fecal shedding phase. In these animals, the parasite can replicate in the intestines, spread throughout the body, transfer through the placenta, or form cysts within muscle tissue. The parasite replication in intermediate hosts can result in clinical disease, particularly in young, pregnant, or immunocompromised individuals
Infection in Goats
Goats become infected with the protozoa by ingesting feeds containing contaminated feline feces. Healthy adult animals often show no signs of disease, though the protozoa can encyst in muscle tissue.
The protozoa can transfer through the placenta if the goat is infected during pregnancy, resulting in abortion, stillbirth, or weak kids. After initial infection with the parasite, goats generally won’t show signs of infection again. A study performed in Switzerland found that 81.1% of farms had Toxoplasma gondii present in their goats, and 50.5% of the goats tested had been infected with Toxoplasma gondii.
Toxoplasmosis should be considered as a cause for abortion in goats, particularly in younger animals that are less likely to have been exposed. Because of the nature of the parasite, it doesn’t cause widespread abortion within a herd. However, because of its zoonotic nature, it can easily spread to other mammals, including humans. Care should be taken when handling aborted goat fetal tissues, as contact with infected tissues can result in infection. This is true with many abortive agents in goats. For pregnant women, contact with aborting goats should be avoided.
Care should be taken when handling aborted goat fetal tissues, as contact with infected tissues can result in infection.
In addition to causing abortion, Toxoplasma gondii can also encyst in the muscles of infected goats. Humans can become infected with the parasite by consuming unpasteurized milk or undercooked meat. The Centers for Disease Control and Prevention (CDC) recommends cooking all meat to a temperature of 145 degrees Fahrenheit for roasts and chops and 160 degrees F for ground meats and sausages. Because of the severe disease that the parasite can cause in infected people, the CDC considers Toxoplasma the leading cause of death from foodborne illness in humans. Goats infected with T. gondii can also shed the parasite in their milk. Studies have shown that 100% of animals with T. gondii PCR-positive blood also have the parasitic DNA within their milk. Testing has shown that there can be irregular and sporadic shedding of the parasite within milk, making it difficult to isolate animals with the risk of shedding the protozoa.
Prevention, Diagnosis, and Safety
Complete prevention of infection of goats with T. gondii is nearly impossible, especially in animals raised outside. However, measures can be taken to reduce risk. Whenever possible, feed should be covered and protected from fecal contamination, particularly grain and minerals. Feed bunks should be frequently cleaned to prevent further contamination. Abortive materials should be cleaned and removed from contact with other animals.
Diagnosing toxoplasmosis in goats can be difficult, requiring blood and tissue samples. In aborting animals, testing of the fetus, placenta, and blood of the dam can help to isolate the cause of infection. In live animals, paired serum samples taken several weeks apart can be necessary to distinguish chronic infections from active infections.
Toxoplasmosis isn’t a disease that will cause severe production losses in goats. However, its zoonotic risk makes it an important disease. Infection in humans can result in severe disease and even death, especially in those with compromised immune systems.
While toxoplasmosis won’t cause major losses in goats, infection in humans can result in severe disease and even death.
The prevalence of Toxoplasma gondii in the environment makes it difficult to prevent infection. There is a vaccine available for small ruminants; however, it isn’t available in the United States. Without means of preventing infection in goats, the best way to prevent the transmission of the protozoa from goats to humans is by properly handling products from goats.
Depending upon the type, meat should be cooked thoroughly, from 145 to 160 degrees F, and milk should be pasteurized. Consumption of cheese from unpasteurized milk can also result in infection. For pregnant and immunocompromised individuals, it’s even more important to be aware of the risk of toxoplasmosis.
DR. KATIE ESTILL DVM is a veterinarian consultant for Goat Journal and Countryside & Small Stock Journal. She works with goats and other large livestock at Desert Trails Veterinary Services in Winnemucca, Nevada.
Originally published in the 2024 Winter issue of Goat Journal and regularly vetted for accuracy.
