Submitted to: Journal of Parasitology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: June 15, 2007
Publication Date: February 1, 2008
Citation: Fayer, R., Fair, P.A., Bossart, G.D., Santin, M. 2008. Examination of Naturally-Exposed Bottlenose Dolphins (Tursiops truncatus) for Microsporidia, Cryptosporidium, and Giarda. Journal of Parasitology. 94:143-147. Interpretive Summary: The Dolphin Health and Risk Assessment (HERA) Project was established as a scientific study to evaluate the health of dolphins at two sites - Charleston, South Carolina and the Indian River Lagoon, Florida - under a federal permit issued by the National Marine Fisheries Service. ARS scientists participated as cooperators in this study to determine if pathogens might be found in dolphins contaminated by surface water runoff from animal agriculture sites. Sera and fecal specimens from 98 dolphins were shipped to the Environmental Microbial Safety Laboratory. Serological results indicating a high level of antibodies to Toxoplasma were published in an earlier report. Molecular findings from fecal specimens indicated that 18 dolphins harbored Microsporidia and that none were found infected with Cryptosporidium or Giardia. Genetic analysis of the Microsporidia DNA revealed that 15 isolates were closely related to species reported from fish. These might have been passing through the intestine as the remains from fish that were eaten by the dolphins. The remaining 3 isolates were similar but not identical to a species of Microsporidia found in humans and livestock. Whether they originated from humans or animals on land or whether they represent a new species unique to dolphins is unknown. However, this finding represents the first report of any species of Microsporidia detected in a marine mammal.
Technical Abstract: Bottlenose dolphins (Tursiops truncatus) live-captured in coastal South Carolina and Florida as well as dolphins stranded in coastal South Carolina were examined for the presence of Microsporidia, Cryptosporidium, and Giardia. DNA extracted from feces or rectal swabs was amplified by PCR using parasite specific SSU rRNA gene primers. All positive specimens were subjected to gene sequence analysis. Of 98 dolphins 18 were positive for Microsporidia. None were positive for Cryptosporidium or Giardia. Gene sequence data for each of the positive specimens were compared with data in GenBank. Fifteen specimens were found similar to but not identical to the microsporidian species Kabatana takedai, Tetramicra brevifilum and Microgemma tinca reported from fish, and possibly represent parasites of fish eaten by dolphins. Gene sequence data from three other specimens had ~87% similarity to Enterocytozoon bieneusi, a species known primarily to infect humans and a variety of terrestrial mammals including livestock, companion animals, and wildlife. It is not clear if these specimens represent a species from a terrestrial source or a closely related species unique to dolphins. There were neither clinical signs nor age or gender related patterns apparent with the presence of these organisms.