Washington (CNN) The Agriculture Department announced Tuesday it is discontinuing its practice of infecting kittens with parasites for research purposes.

The department's Agricultural Research Service had been using kittens to conduct research on the Toxoplasma gondii parasite. According to the department, the parasite "causes toxoplasmosis, a disease considered to be a leading cause of death from foodborne illness in the United States, especially for individuals with weak immune systems such as children and HIV patients."

In a statement, USDA said the kittens were used in the research because they were "the only hosts in which (the parasite) can complete its life cycle and produce (eggs)." The department said ARS' research on the disease "has reached its maturity" and that the use of kittens "has been discontinued and will not be reinstated."

The USDA did not respond to CNN's request for comment.

The department, which said it hasn't had any infected kittens in its facilities since September, said it plans to allow USDA employees to adopt more than a dozen kittens that had not been infected with the parasite.

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