Submitted to: Journal of Parasitology
Publication Type: Peer reviewed journal
Publication Acceptance Date: 6/10/2002
Publication Date: 7/12/2002
Citation: Kniel, K.E., Lindsay, D.S., Sumner, S.S., Hackney, C.R., Pierson, M.D., Dubey, J.P. 2002. Examination of attachment and survival of toxoplasma gondii oocysts on raspberries and blueberries. Journal of Parasitology 88:790-793. Interpretive Summary: Toxoplasma gondii is a single-celled parasite of worldwide distribution. It causes loss of vision and mental retardation in congenitally infected children and abortion in livestock. Cats are the only definitive host for T. gondii because they are the only hosts that can excrete the environmentally resistant Toxoplasma (oocyst) in their feces. The consumption of produce contaminated with T. gondii oocysts may be a means of transmission to humans. Scientists at the Beltsville Agricultural Research Center an the Virginia Tech studied survival and recovery of oocysts on raspberries and blueberries. The results will be of interest to biologists, parasitologists, and public health workers.
Technical Abstract: The consumption of Toxoplasma gondii oocysts on fresh produce may be a means of its transmission to humans. Cats can shed T. gondii oocysts that contaminate produce directly or contaminate water sources for agricultural irrigation, pesticide and fertilizer application. Cyclospora cayetanesis is a related coccidial parasite and outbreaks of diarrhea due to T. cayetanensis have been associated with ingestion of contaminated raspberries. The oocysts of these coccidians are similar in size and shape indicating that they may attach to and be retained on produce in a similar manner. In the present study, the attachment and survival of T. gondii oocysts on 2 structurally different types of berries was examined. Raspberries and blueberries were inoculated individually with 1.0 x 10 to 2.0 x 10 sporulated oocysts of T. gondii. Berries inoculated with 2.0 x 10 oocysts were stored at 4 C for up to 8 wk. Oocysts viability and recovery were analyzed by feeding processed material to mice. Mice fed T. gondii inoculated berries stored at 4 C for 8 wk developed acute infections. In other experiments, mice fed raspberries inoculated with >1.0 x 10 oocysts became infected; while only mice fed blueberries inoculated with >1.0 x 10 oocysts became infected. This study demonstrates that T. gondii oocysts can adhere to berries and be recovered by bioassays in mice and that raspberries retain more inoculated oocysts than do blueberries. Results suggest that T. gondii may serve as a model for C. cayetanensis in food safety studies.