Submitted to: Journal of Parasitology
Publication Type: Peer reviewed journal
Publication Acceptance Date: 10/31/2007
Publication Date: 6/30/2008
Citation: Lindsay, D.S., Holliman, D., Flick, G.J., Goodwin, D.G., Mitchell, S.M., Dubey, J.P. 2008. Effects of high pressure processing on toxoplasma gondii oocysts on raspberries. Journal of Parasitology. 94:761-763. Interpretive Summary: Toxoplasma gondii is a single-celled parasite of all warm-blooded hosts worldwide. It causes mental retardation and loss of vision in children, and abortion in livestock. Cats are the main reservoir of T. gondii because they are the only hosts that can excrete the resistant stage (oocyst) of the parasite in the feces. Humans become infected by eating undercooked meat from infected animals and food and water contaminated with oocysts. Toxoplasmosis causes mortality in many species of animals in the zoos, especially wallabies. Scientists at the Beltsville Agricultural Research Center and Virginia Tech report the effect of high pressure processing on raspberries contaminated with T. gondii oocysts. The results will be of interest to biologists, parasitologists, and veterinarians
Technical Abstract: Oocysts of Toxoplasma gondii are environmentally resistant stages. Humans can become infected by accidentally ingesting the oocysts in water or on contaminated produce. Severe disease can occur in immunocompromised individuals and non-immune pregnant women can infect their offspring. Chronic infection is associated with decreased mental functions, vision and hearing problems and some mental disorders such as schizophrenia. High pressure processing (HPP) is a commercial method used to treat food to eliminate pathogens. Treatment of produce to eliminate viable T. gondii oocysts would provide a means to protect consumers. The present study was done to better define the effects of HPP on oocysts placed on raspberries. Raspberries were chosen because they are a known source of a related human intestinal parasite, Cyclospora cayetanensis. Raspberries were inoculated with 5 x 104 oocysts of the VEG strain of T. gondii for 20 hr prior to HPP. Individual raspberries were exposed to 500 MPa, 400 MPa, 340 MPa, 300 MPa, 270 MPa, 250 MPa, 200 MPA, 100 MPa, or no MPa treatment for 60 sec in a commercial HPP unit (1 MPa = 10 atm = 147 psi). Treatment of raspberries with 340 MPa for 60 sec was needed to render oocysts spot inoculated on the raspberries noninfectious for mice. Treatment of raspberries with 200 MPa or less for 60 sec was not effective in rendering oocysts noninfectious for mice.