Pregnant women are often warned to stay away from kitty’s litter box because of toxoplasmosis, a parasitic disease of cats. Toxoplasmosis is spread to humans through cat feces and can lead to severe health issues for unborn babies.
Species Name: Toxoplasma gondii
Type of Microbe: Protozoa
How Toxoplasma Causes Disease: Interestingly, cats are a necessary host for the toxoplasma life cycle. After a cat ingests an infected small animal, such as a rodent or bird, the protozoa invade cells of the cat's intestine. The parasite next undergoes several developmental changes to become the infective form, or “oocyst,” and is released into the environment in cat feces. The parasite can then invade the body of another animal or human, burying itself into skeletal muscles, heart muscles, and the brain. It forms cysts, and can remain there throughout one's entire life.
How it Spreads: Toxoplasmosis is spread through food (undercooked meats, especially pork, lamb, and venison), from cat feces, and from mother-to-child (congenital infections). The parasite is not infectious until 1 to 5 days after being excreted by an infected cat, but it can survive in the environment (or litter box) for over a year.
Who’s at Risk? Toxoplasma can infect anybody, but the consequences are more severe in people whose immune systems are weakened, such as pregnant women.
Symptoms/Risks: For most healthy people, toxoplasmosis usually has little or no symptoms. Approximately 10 to 20% of patients will develop mild flu-like symptoms that last for several weeks or more, but resolve without any treatment.
If a pregnant woman gets infected, the infection can be passed to the fetus, leading to possible miscarriage, stillbirth, or birth abnormalities, including enlargement or smallness of head. In many instances, babies born with toxoplasmosis do not show any symptoms at birth, but can later develop loss of vision, mental disability, and seizures. Ocular toxoplasmosis can cause a disease known as retinochoroiditis, which usually does not occur until the patient is in his twenties or thirties.
For people with significant immunosuppression, such as those with advanced AIDS or who are receiving high-dose chemotherapy, there is the risk of reactivating the toxoplasma that was previously controlled, which can have serious consequences, such as brain lesions.
Diagnosis: Blood samples are drawn for detection of antibodies against Toxoplasma. The specific antibody type can help clinicians to estimate when the infection occurred. Less commonly used methods of diagnosis include microscope examination of tissues or body fluids for presence of the parasite. Detection of Toxoplasma DNA in amniotic fluid can also be used to determine if a fetus is infected.
Prognosis: For healthy people, the prognosis is generally good, with no long-term side effects. For pregnant women, infection of the fetus has more severe consequences, including eye or brain damage at birth, or blindness or mental disability later in life.
Treatment: Most healthy people recover without any treatment. Pregnant women and infants can be treated with drugs, usually a combination of pyrimethamine, sulfadiazine, and folinic acid, but the parasite cannot be completely eliminated. There are alternative regimens for people with certain drug allergies.
Prevention: Wear gloves when gardening (to avoid contact with cat feces in the soil), and keep outdoor sandboxes covered (to keep out infected cats). Follow safe kitchen practices, especially when cooking meats (70 degrees Celsius for 10 minutes to kill the parasite). To keep your cats Toxoplasma-free, don’t let them eat raw or undercooked meats, and keep them indoors. For pregnant women, avoid changing the kitty litter (and make sure whoever does the kitty litter changes it daily to keep it clean), and stay away from stray cats or kittens.
Sources Toxoplasmosis. Department of Health and Human Services. Centers for Disease Control and Prevention. Accessed: February 10, 2009. http://www.cdc.gov/toxoplasmosis/
Toxoplasmosis. Parasites and Health. Laboratory Identification of Parasites of Public Health Concern. Centers for Disease Control and Prevention. Accessed: February 10, 2009. http://www.dpd.cdc.gov/dpdx/HTML/Toxoplasmosis.htm
