Ultrastructure of Sphaeidiotrema Globulus found in Waterbirds on the Upper Mississippi River

Over 30,000 migrating waterbirds (especially lesser scaup and American coot) have died as a result of trematode parasitism in Minnesota and Wisconsin since 2004. The leading cause of these deaths has been 2 parasites, Sphaeridiotrema globulus and Cyathocotyle bushiensis. A study done by Gagnon (1990) found that C. bushiensis caused damage to the bird’s cecae. However, S. globulus only showed damage to the mucosa of the small intestine and displayed no distortion of the cecae. In birds infected with both S. globulus and C. bushiensis, the cecum appeared to be infected and distorted. Gagnon’s (1990) work relied upon histological examination using stereomicroscopy. I used scanning electron microscopy (SEM) to determine the external features of S. globulus and overall development of the parasite through intestinal segment of birds in Minnesota. Tissue samples were collected from waterbirds that died as a result of infection. These tissues were prepared for scanning electron microscopy (SEM) and examined at a variety of levels of magnification to view the ultrastructure characteristics of these worms. Particular attention was paid to examining the presence or absence of structures the worms may use when attaching to host tissues. With the availability of worms from different regions of the intestines of these birds, we also measured the size of worms and various ultrastructural features to see if there were differences between worms from regions of the intestine. These findings help us to better understand the interaction that occurs between the waterbird host and the parasitic worm