Pet Cats & Toxoplasmosis – Risk For Pregnancy and the Immunocompromised
• Concerns about toxoplasmosis revolve mainly around 2 groups: pregnant women and immunocompromised individuals. In other humans, Toxoplasma exposure typically results in seroconversion (the development of detectable antibodies in the blood that are directed against an infectious agent), with no disease.
• Fetal infections can be devastating, resulting in fetal loss or stillbirth.
• In immunocompromised individuals, toxoplasmosis concerns largely emerged during the HIV/AIDS epidemic. Cerebral toxoplasmosis became a serious problem in HIV-infected individuals before highly active anti-retroviral therapy (HAART) was available.
• Even in highly immunocompromised individuals, the incidence of cerebral toxoplasmosis was relatively low in individuals.
• This highlights the fact that disease predominantly developed as a result of recurrence of latent infection, not acute infection. They typically cause no clinical signs and exist in a viable but dormant stage.
• The life cycle continues when felines ingest tissue cysts from prey, although cats can also be infected transplacentally and through milk.
• The most likely source is ingestion of tissue cysts, while hunting rodents.
• Because cats are the definitive host, it is logical to assume that cat contact would be an important risk factor; however, ingestion of raw or undercooked meat is the most commonly identified risk factor, and there is limited information implicating contact with pet cats as an important cause of exposure or disease.
• However, other factors (diet, low socioeconomic level, poor hygiene status, degree of soil exposure) are more common or typically have stronger associations.
• Many studies have been unable to identify an association between cat ownership and toxoplasmosis.
• Veterinary students and veterinarians (who presumably have much more cat exposure) do not have significantly higher rates of occurrence.
• The lack of an association of cat ownership with cerebral toxoplasmosis in individuals with AIDS also highlights the fact that the main risks do not include cat ownership or routine cat contact.
• Although the risks associated with toxoplasmosis must not be dismissed, they must be approached in a balanced manner.
• While the risks are low, the severity of disease dictates a need to be proactive. The low risk of exposure from a pet cat can be decreased further using some practical infection-control practices.
• Avoiding raw or undercooked meat, washing hands after contact with meat or soil, washing fruits and vegetables, and either having someone else change their cat’s litterbox or washing their hands thoroughly after litterbox cleaning if they must do it themselves.
• Guidelines also recommend that HIV-infected individuals do not adopt or handle stray cats and do not feed them. The overall incidence of zoonotic infections associated with pet cat contact is low, risks can be reduced with practical measures, and pets can offer many health and emotional benefits.
• Guidelines for pregnancy take a similar approach and do not recommend removal of cats from the household.
• Rarely, if ever, is removal of a low-risk cat from a household a justifiable response.
• PREVENTIVE MEASURES IN HIGH-RISK HOUSEHOLDS
o Keep cats indoors and do not feed raw meat.
o Control pets in the house so the cat cannot hunt.
o Remove feces from the litterbox daily.
o Keep high-risk individuals away from the litterbox.
o Do not clean litterboxes in sinks that may be used by high-risk individuals.
o Wash litterbox periodically in hot (>60 ̊C) water.
o Dispose of cat litter in sealed bags and carefully clean any spills.
o If a new cat is to be obtained, avoid kittens, strays, or animals from shelters.
o Fecal staining of the haircoat should be removed, ideally not by the immunocompromised individual.
o If fecal staining is a common occurrence, measures to reduce it should be discussed (clipping perianal hair in longhair cats).
o Dispose of cat litter as municipal waste. Do not compost or spread used litter outside.