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United States Department of Agriculture

Agricultural Research Service

Title: Irradiation Killing of Toxoplasma Gondii Oocysts

Authors
item Dubey, Jitender
item Jenkins, Mark
item Thayer, Donald

Submitted to: Journal of Eukaryotic Microbiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: August 27, 1996
Publication Date: N/A
Full Text Available

Interpretive Summary: Infection by the protozoan parasite, Toxoplasma gondii is widely prevalent in man and animals. It causes mental retardation and loss of vision in children and abortion in livestock. Humans become infected with Toxoplasma by ingesting meat infected with tissue cysts or by ingesting food and water contaminated with feces of infected cats containing the resistant form (oocysts) of Toxoplasma. Toxoplasma oocysts are highly resistant to environmental influences and can survive outside the body for months. Scientists at the Beltsville Agricultural Research Center and the Eastern Regional Research Center, ARS, Wyndmoor, PA have determined that oocysts can be killed by low doses (0.25 kGy) of irradiation with cesium 137.

Technical Abstract: Toxoplasma gondii oocysts are highly resistant to environmental influences. To study the effect of gamma-irradiation on the viability of T. gondii oocysts, 1 million sporulated oocysts of the VEG strain were irradiated to absorbed doses of 0.10, 0.15, 0.20, 0.25, 0.30, 0.40 and 0.5 KGy at 5 C with a 137Cs gamma-irradiation source. Treated oocysts were bioassayed for viable T. gondii in mice. Viable T. gondii was not found in brains of mice 2 mo after oral inoculation with oocysts irradiated at levels > 0.25 KGy. Therefore, gamma irradiation is an effective means of killing T. gondii oocysts.

Last Modified: 9/20/2014