USDA ends toxoplasmosis research that used cats

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U.S. Department of Agriculture officials halted toxoplasmosis research that relied on the use of cats, announcing this spring that others will need to take up remaining work.

Scientists with the USDA Agricultural Research Service will no longer use cats in any research, the April 2 announcement states.

Toxoplasmosis is the most common fatal foodborne illness in the U.S., and the agency's research into Toxoplasma gondii had helped reduce national prevalence of the parasite by as much as half, according to the agency announcement.

"ARS toxoplasmosis research has reached its maturity and ARS considers the project's objectives for agriculture achieved," the announcement states. "While there is still additional research needed in this area regarding human health, this research area is outside of USDA's stated mission."

Agency spokeswoman Kim Kaplan said in a message that ARS scientists started research on toxoplasmosis in 1982. Some investigators focused their work on finding in vitro and in vivo alternatives to the use of cats.

Toxoplasmosis studies used cats, and kittens in particular, because they are the only animals known to shed T gondii oocytes, USDA information states. In May 2018, U.S. Rep. Michael D. Bishop of Michigan wrote to Agriculture Secretary Sonny Perdue to object to the practice of euthanizing cats after parasite eggs are harvested, calling instead for antimicrobial treatment and adoption.

The ARS announcement indicates the agency commissioned reviews of the research and the potential for sending those cats out for adoption in May 2018 and halted infestation and euthanasia of cats by September of that year. In November, an external panel found that adoption of once-infested cats was too dangerous for people, but USDA employees adopted 14 cats that had never been exposed to the parasite.

When the agency commissioned the review in May 2018, ARS research on T gondii involved refining assays to investigate human exposure to oocysts, developing mitigation strategies for oocyst contamination on produce, understanding the molecular epidemiology and genetics of environmental oocyst contamination, defining virulence and persistence of T gondii genotypes in food animals, evaluating genetic subsets of T gondii in swine and deer, evaluating whether the oocysts that cause most infections come from particular populations, and finding ways to improve inactivation of T gondii in meat and surveillance of exposure, Kaplan said.

Asked whether other USDA entities are performing similar research on toxoplasmosis, Kaplan said the USDA National Institute of Food and Agriculture has funded food safety–related research at outside institutions.

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Congressman wants cats adopted after research (July 1, 2018)