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SPORULATION AND SURVIVAL OF TOXOPLASMA GONDII OOCYSTS IN SEA WATER
Lindsay, D. S., M. V. Collins, S. M. Mitchell, R. Cole, G. J. Flick, C. N. Wetch, H.D A. Lindquist, AND J. P. Dubey. SPORULATION AND SURVIVAL OF TOXOPLASMA GONDII OOCYSTS IN SEA WATER. JOURNAL OF EUKARYOTIC MICROBIOLOGY 50(S1):687-688, (2003).
1) Refine new, practical methods for the detection of CCL-related and emerging waterborne human protozoa.
2) Perform field tests of devices or methods that have been developed under this task.
3) Evaluate these methods or devices in a variety of water matrices and parasite concentrations.
This work in this task supports CCL2 and 3 and is expected to be completed by 9/07.
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.
Toxoplasma gondii is acquired by the ingestion of tissue cysts in raw or under cooked meat, by ingestion of oocysts, or by transplacental infection in mammalian species [6,9]. Clinical and subclinial toxoplasmosis has been reported in marine mammals [1-4,10-12,14-16,18,19]. Cole et al.  suggested that marine mammals acquired T. gondii infection by ingesting invertebrates which were acting as phoretic agents for T. gondii oocysts. They believed that cat feces containing T. gondii oocysts could be entering the marine environment through storm run-off and were picked up by invertebrate food items of Southern sea otters. Miller et al.  have shown a positive correlation between the presence of costal storm run off water and the presence of antibodies to T. gondii in sea otters. The present study was done to determine if nonsporulated T. gondii oocysts would sporulated in sea water and to determine if sporulated oocysts would survive in sea water.