Human toxoplasmosis and the role of veterinary clinicians

133 I In nt te er rn na at ti io on na al l J Jo ou ur rn na al l o of f M Me ed di ic ca al l S Sc ci ie en nc ce es s Human toxoplasmosis is one of the most common parasitic zoonoses worldwide. As for other zoonoses, veterinarians play an important role in the education of the human population regarding the risk of infection. Knowledge of the parasite's biological charateristics, life cycle and trasmission routes is necessary to correctly illustrate real risk factors to those people who have direct contact with animals (farm animals, pets, etc). Toxoplasmosis represents one of the more difficult " educational " challenges for small animal clini-cians. Veterinarians are often faced with the need to explain to their clients that it is not necessary, for example, to give away one's cat during pregnancy and that if they follow a few very simple " rules " , living with their pets need not represent any risk for infection with Toxoplasma gondii. Cats are the definitive host of T. gondii; they are the only animals that pass oocysts in their feces. They become infected by eating infected rodents, birds, or other small animals. Once oocysts are shed, they require 1 to 5 days to sporulate and become infective. Cats pass oocysts for only 2 to 3 weeks following primary infection. Mature cats are less likely to shed Toxoplasma if they have been previously infected. Litter box hygiene is the main precaution in preventing transmission of toxoplasmosis from pet cats [1]. A Toxoplasma-infected cat that is shedding the parasite in its feces (approximately 2% of the cat population at any given time) contaminates the litter box. If the cat is allowed outside, it can contaminate the soil or water in the environment as well. Litter boxes should be cleaned daily and not placed in kitchen or dining areas. Pregnant women should avoid changing cat litter if possible. If no one else can perform the task, they should wear disposable gloves and wash their hands thoroughly with soap and water afterwards. Direct contact with cats is unlikely to result in transmission of toxoplasmosis because most cats do not leave feces on their fur for the 1 to 5 days required for oocyst sporulation. Interestingly, cat ownership has not been associated with an increase in Toxoplasma seroconversion among HIV-infected persons …