As temperatures drop, outdoor cats may spend more time indoors, which calls for attention to a health threat — Toxoplasma gondii, T. gondii, also known as the “cat parasite.”

This infectious agent infects over 40 million people in the U.S. The parasites reproduce exclusively within cats; however, any warm-blooded animal, including humans, is susceptible to the parasite and can develop an infection called toxoplasmosis.

Susceptible populations

Despite the prevalence of these parasitic agents, their ability to cause critical health issues is low for most people.

“While healthy people may have mild or no symptoms, toxoplasmosis can be dangerous for pregnant women and immunocompromised individuals,” said Elexus Hargis, serology technician at the Texas A&M Veterinary Medical Diagnostic Laboratory, TVMDL.

Women diagnosed with toxoplasmosis during pregnancy experience an increased risk of miscarriage, stillbirth or premature birth. A child born with toxoplasmosis may have physical and intellectual disabilities. People with weakened immune systems may experience damage to major organs and bodily systems.

Toxoplasmosis is one of the most common parasitic infections in humans and is usually asymptomatic, so pregnant women and individuals with weakened immune systems should prioritize prevention and transmission awareness.

Transmission avenues

According to TVMDL, there are three primary routes leading to human infection of toxoplasmosis.

Foodborne transmission.

Animal-to-human transmission.

Mother-to-child or congenital transmission.

Foodborne transmission

Humans may become infected with T. gondii by eating undercooked meat or contaminated, unwashed produce. Recurring sources of toxoplasmosis include undercooked lamb or beef, salami, dried or cured pork or raw sausage.

Additionally, the parasite has been found in some cold-blooded marine animals. Consuming shellfish such as oysters, clams or mussels can pose a risk of infection.

Animal-to-human transmission

T. gondii infects most outdoor cats because they hunt and eat small animals that are intermediate hosts. Millions of parasitic eggs, or oocysts, enter the environment through cat feces.

Humans may become infected by accidentally ingesting contaminated cat feces, which can occur through hand-to-face contact after gardening, cleaning a litter box or touching other surfaces that come in contact with cat feces.

Mother-to-child or congenital transmission

Congenital transmission of toxoplasmosis to a fetus occurs when the mother acquires the infection during pregnancy. In this case,T. gondii travels through the placental connection between the fetus and the infected mother.

“It can cause severe complications like encephalitis or congenital defects in the unborn child,” Hargis said.

How to minimize the risk of a T. gondii infection

Because toxoplasmosis is typically asymptomatic, appropriate prevention and control measures are strongly recommended for susceptible populations.

“Good hygiene is essential, especially for cat owners,” Hargis said. “Pregnant women or immunocompromised individuals should take extra precautions around litter boxes or avoid handling them if possible.”

Hargis made the following recommendations to limit exposure to T. gondii:

Wear disposable gloves to clean litter boxes and when gardening or touching soil or sand contaminated with T. gondii.

Litter boxes should be cleaned daily as it takes three to 10 days for an oocyte to become infective in the environment.

Households with high-risk individuals should restrict their cat’s access to the outdoors and raw meat. Indoor cats pose less of a risk since they are not exposed to sources of T. gondii.

Use a food thermometer to ensure the meat is cooked to an internal temperature high enough to kill the parasite.

Clean areas where food is handled and wash hands with hot, soapy water after preparing each item.

Thoroughly wash fruit and vegetables before eating them.

Animal testing options at TVMDL

TVMDL offers an ELISA test to detect antibodies to T.gondii and a PCR test to detect the presence of the parasitic agent. Specimens from felines, canines, bovines and other species are accepted for these tests. Animal owners interested in diagnostic testing should consult their veterinarian.

Pregnant women and others at risk of toxoplasmosis should discuss additional precautions and testing options with their physicians.