Submitted to: Applied and Environmental Microbiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: April 21, 1998
Publication Date: N/A
Interpretive Summary: It has not been entirely clear how the protozoan parasites of livestock and humans, Cryptosporidium parvum and Giardia spp. become spread so widely through the environment and contaminate so much of our surface waters. In an earlier study we demonstrated. that C. parvum could pass through the digestive tract of ducks and geese and remain infections for mammals. The present study has shown that migratory waterfowl actually do serve as mechanical vectors of both these parasites in nature, that flocks deposit large numbers of parasites in fields, and that the C. parvum parasites are infectious for mammals. These findings present a new complexity in our understanding of how these parasites are spread and indicate that treatment of point source pollution alone will be insufficient to control these organisms.
Feces freshly deposited by flocks of migratory Canada geese were collected from 9 field sites in Maryland near the Chesapeake Bay. From 0.83 to 1.82 kg of goose feces were collected at each site. Oocysts of Crypto sporidium and cysts of Giardia were identified by immun.- fluorescence microscopy at 7 and 9 sites, respectively. Oocysts recovered at one site and cleaned of fecal debris were infectious for mice indicating they were C. parvum. They were further characteri- zed as genotype 2 by polymerase chain reaction for the TRAP-C2 gene.