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27 October 2005
Toxoplasmosis Expert Sounds Warning On Cats 
Toxoplasmosis is a very common infection, with figures suggesting that it infects around 25 percent of adult Americans. Most warm-blooded animals can be infected with Toxoplasma gondii but domestic cats and some wild cats are the only animals that can transmit the parasite by shedding the organism in their feces. Humans and other animals can become infected when they indirectly consume the organisms shed by cats. While this method of transmission is called fecal-oral, it doesn't actually mean that feces are directly ingested. The organisms survive in soil long after the feces have decomposed and dust contaminates paws, fingers, feedstuffs and water, ultimately leading to ingestion by animals and people. Toxoplasma infection can cause serious problems in people with suppressed immunity, and experts believe that it could be linked to a growing list of problems in people whose immune systems are not impaired. For healthy individuals, problems might include fever, enlarged lymph nodes, weakness and debilitation, damaged vision, or multi-systemic infections with serious complications such as pneumonia and hepatitis. It is also the third leading cause of food-related deaths in the U.S., behind salmonella and listeria infections, and exposure in the womb is one of the most common causes of birth defects, mental retardation and visual problems. Worryingly, it also appears that toxoplasmosis may be linked to a range of mental disorders. The dangers of toxoplasma infection have prompted one expert to recommend a range of actions to minimize the spread of the pathogen in domestic cats. Milton M. McAllister, a pathobiologist from the University of Illinois at Urbana-Champaign, says that pet cats should be kept inside, people should stop feeding stray cats and meat should not be under-cooked. McAllister's review appears in the journal Veterinary Parasitology. "Our profession needs to come to grip with the accumulating body of evidence about the tremendous burden wrought on society by toxoplasmosis," McAllister says. He also cited other studies that "showed highly significant associations between toxoplasmosis and psychiatric disorders." Recent studies have also linked infections with reduced average intelligence. "Evidence is mounting to link toxoplasmosis with schizophrenia or similar psychiatric disorders (in people)," McAllister said. "Recent studies from three countries found that schizophrenic patients had higher antibody levels to T. gondii than did matched control subjects. Further research is needed to clarify the association between toxoplasmosis and mental health, but until such time that this association may be refuted, it is my opinion that the current evidence is strong enough to warrant an assumption of validity." "Cats usually become infected with toxoplasma by ingesting an infected animal, or raw meat from an infected animal," said McAllister. "So a cat gets infected by catching and eating mice or birds, or by eating meat scraps from such things as poultry, pork, lamb or game. Cats that remain indoors have a low potential to become infected if they don't have access to mice and if they are not fed raw meat or meat products. Owners can safely keep an indoor cat simply by practicing good hygiene with the litter box and washing hands after daily cleanings." McAllister says that domestic cats should not be allowed to roam outdoors. The feeding of stray cats, he added, by cat protectionist groups and some veterinary organizations, unfortunately increases the spread of toxoplasmosis to wildlife, domestic animals and people. "Public lawmakers should consider developing effective solutions that protect the best interests of society," he concluded. Source: University of Illinois at Urbana-Champaign
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