Passing the Parasite: Transmission from Painted Turtles to Snapping Turtles

            Siddall et al. (2001) conducted this experiment of transferring Haemogregarina balli from painted turtles, Chrysemys picta marginata, to snapping turtles, Chelydra serpentina, via the leech Placobdella ornata. Eleven painted turtles were collected from the Algonquin Park in Ontario, and six of them were determined to have hemogregarine in their peripheral circulation. Siddall et al. (2001) had hatchling leeches feed on the most heavily infected painted turtle and later had the leeches feed on two snapping turtles. The snapping turtles were uninfected before the leeches fed on them, and consequent blood films were taken periodically to determine when the hemogregarine would appear in the blood smears. The first hemogregarine merozoites were in the peripheral blood of the snapping turtles four months after they were infected by the leeches (Siddall et al., 2001).

            The ability of Haemogregarina to infect multiple vertebrates had never been tested before this experiment, although it has been known for a long time that hemogregarines can cross-infect a wide range of hosts (Siddall et al., 2001).  The authors determined that both parasite isolates from each separate species are likely to be H. balli as they are morphologically indistinguishable, not to mention that they personally passed the same H. balli amongst the turtles. However, that often isn’t the case and scientists may make the assumption that a speices of parasite is completely new because it is in a host that it has never been found in before. Many parasites have several species that they can utilize as intermediate or primary hosts, and that hasn’t always been discovered. The authors also mention that if there are no morphological differences between species of hemogregarines of turtle then they should be simply grouped under the oldest name that they are known by.

            Siddall et al. (2001) touch upon a very interesting point that has been mentioned before. Sometimes scientists make mistakes, or they categorize something inaccurately and it is important to keep that in consideration as taxonomic knowledge and species classification grows and develops. If two species of hemogregarine are essentially the same then they should be condensed under a single classification for greater simplicity and accureacy. However, I would want a genetic comparison between found parasites rather than basing species on morphological characteristics. Tkach et al. (2012) mentioned in their article about a new species of Trematode in the gall bladder of turtles. There was a species that was recorded to have the same unique morphological characteristic (the posteriorly extending cirrus sac beyond the ventral sucker). It was described so poorly that Tkach et al. (2012) had to base their decision on small morphological clues that identified their species as a newly discovered species. In both cases, it is important to recognize the significance of an analytical mind when discovering and identifying species of parasites.

Works Cited:

Siddall, M.E., and S.S. Desser. 2001. Transmission of Haemogregarina balli From Painted Turtles to Snapping Turtles Through the Leech Placobdella ornata. The Journal of Parasitology 87(5): 1217 – 1218.

Tkach, V.V., T.R., Platt and S.E. Greiman. 2012. A New Species of Opisthioglyphe (Trematoda: Telorchiidae) from Gall Bladder of Turtles in Malaysia. The Journal of Parasitology 98 (4): 863 – 868.