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ARS Home » Research » Publications at this Location » Publication #32418



Submitted to: Journal of the American Medical Association
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/1/1994
Publication Date: N/A
Citation: N/A

Interpretive Summary: Infection by the protozoan parasite Toxoplasma gondii can cause abortion and neonatal mortality in livestock and mental retardation and loss of vision in children born with it. Humans become infected by eating undercooked meat of animals infected with this parasite or by ingesting food or water contaminated with the resistant stage of Toxoplasma (oocyst) passed in cat feces. The parasite is also transmitted during pregnancy from the mother to her fetus. Of all the hosts of Toxoplasma, only cats can form the oocyst. Most cats become infected with Toxoplasma after birth by preying on mice and birds. Scientists at the Beltsville Agricultural Research Center and the Colorado State University have found that kittens can become infected with Toxoplasma in utero and they can pass the oocysts in environment after birth. The feces of kittens suspected to have toxoplasmosis should be handled with precautions because they can be infectious to people.

Technical Abstract: Sixteen pregnant queens were inoculated orally with tissue cysts of the ME 49 strain of Toxoplasma gondii, and the products of conception were examined for T gondii infection by bioassay in mice. Queens appeared normal, although all shed T gondii oocysts. Of the 8 queens euthanatized 10, 12, 13, 23, 26, 27, 29, and 31 postinoculation day (PID) T gondii was isolated from tissues of 7 of 33 kittens from 5 litters; 13, 23, 26, 27, and 29 PID. Of the 8 queens that were allowed to partuirate naturally and nurse their kittens, T gondii infection was found in kittens from all 8 litters. A total of 43 kittens were born from these 8 queens. Toxoplasma gondii was isolated from tissues of 26 of 40 kittens bioassayed; tissues of 3 kittens were eaten by their 2 queens and not bioassayed. Toxoplasmosis in kittens was manifested only after birth. Toxoplasmosis was severe in 5 litters born 16, 23, 24, 24, and 31 PID of the queen. In these 5 litters 43 of 44 kittens died or were ill by 24 days of age. Anorexia, lethargy, hypothermia, and sudden death were the most common manifestations and hepatitis was the most likely cause. There was no transplacental transfer of anti-T gondii antibodies in cats. Toxoplasma gondii oocysts were seen in feces of 3 kittens from different litters when kittens were 16, 24 and 63 days old.