Submitted to: Journal of Eukaryotic Microbiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/17/2003
Publication Date: 11/18/2003
Citation: Lindsay, D., Collins, M., Mitchell, S., Cole, R., Flick, G., Wetch, C., Lindquist, A., Dubey, J.P. 2003. Sporulation and survival of Toxoplasma gondii oocysts in sea water. Journal of Eukaryotic Microbiology. 50:S687-S688. Interpretive Summary: Infections by the single-celled parasite Toxoplasma gondii causes mortalities in humans and animals. Recently, Toxoplasma has been found to kill marine mammals. Scientists at the Beltsville Agricultural Research Center and Virginia Tech, Blacksburg have found that Toxoplasma oocysts can survive in sea water for six months. These findings will be of interest to biologists, parasitologists and public health workers.
Technical Abstract: Since 1992, we have been collaborating in studies on southern sea otters (Enhdyra lutris nereis) as part of a program to define factors which may be responsible for limiting the growth of the southern sea otter population. We previously demonstrated Toxoplasma gondii in sea otters. We postulated that cat feces containing oocysts could be entering the marine environment through storm run-off or through municipal sewage since cat feces are often disposed down toilets by cat owners. The present study addressed the sporulation of T. gondii oocysts in sea water and the survival of sporulated oocysts in sea water. Unsporulated oocysts were placed in 15 ppt artificial sea water, 32 ppt artificial sea water or 2% sulfuric acid (positive control) at 24 C in an incubator. Samples were examined daily for 3 days and development monitored by counting 100 oocysts from each sample. From 75 to 80% of the oocysts were sporulated by 3 days postinoculation in all treatments. Groups of 2 mice were fed 10,000 oocysts each from each of the 3 treatments. All inoculated mice developed toxoplasmosis indicating that oocysts were capable of sporulating in sea water. Survival of sporulated oocysts was examined by placing sporulated T. gondii oocysts in 15 ppt sea water at room temperature 22-24 C (RT) or in a refrigerator kept at 4 C. Mice fed oocysts that had been stored at 4C or RT for 6 months became infected. These results indicate that T. gondii oocysts can sporulate in and remain viable in sea water for several months.