28th ANNUAL EASTERN FISH HEALTH WORKSHOP April 21-25, 2003 United States East And Gulf Coast Study Of Cryptosporidium In Shellfish – The Rest Of The Story Earl J. Lewis1, Ronald Fayer2, James M. Trout2, Lihua Xiao3, Dorothy W. Howard1, Robert Palmer2, Kristie Ludwig2, and Suzanne S. Tyler1 1NOAA, NOS, Coastal Center for Environmental Health and Biomolecular Research, Oxford, MD 21654; 2USDA, Agriculture Research Station, ANRI, Animal Waste Pathogen Laboratory, Beltsville, MD 20705; 3Centers for Disease Control and Prevention, Chamblee, GA 30341 Results of a 1997 study conducted by the National Oceanic and Atmospheric Administration (MNOAA), the United States Department of Agriculture (USDA),Johns Hopkins University School of Public Health, and the Center for Disease Control showed a high prevalence of Cryptosporidium parvum in tissues of oysters Crassostrea virginica at 13 Maryland sites in Chesapeake Bay, 9 of which were open to shellfish harvest.  In several instances, oocysts recovered from oysters were infectious in laboratory mice.  Oocysts of C. parvum were also found in hard clams and hooked mussels.  The presence of these organisms in shellfish growing waters indicates contamination by human or animal feces.  These findings were viewed as an environmental and potential public health issue that required further investigation. To better understand the distribution of Cryptosporidium on a multi-state basis, a 2001 and 2002 study by NOAA, USDA, and CDC scientists investigated Cryptosporidium spp. in oysters and hard clams obtained from retail markets along the East and Gulf coasts of the U.S.Forty-nine shellfish samples, 33 oyster and 16 clam, were examined from 17 coastal states from Maine to Texas and 1 from New Brunswick, Canada.  Cryptosporidium oocysts were detected in at least 1 sample of shellfish from New Brunswick, Canada and 13 of 17 states.  In all, 4% of 1225 oysters and clams examined by immunofluorescent antibody (IFA) methodology were found to harbor Cryptosporidium.  Cryptosporidium DNA was also detected by polymerase chain reaction (PCR) in 13% of 245 pools of shellfish examined.  Multiple species of Cryptosporidium, some potentially infectious for humans, were found in commercial shellfish from 59% (29/49) of sites examined along the Atlantic and Gulf coasts by either microscopy or molecular assays As a one-time sample acquired during a time of drought, these results may or may not be indicative of the long-term prevalence of Cryptosporidium in coastal shellfish.  In addition, there have been no reports of cryptosporidiosis linked to eating raw shellfish. Return to 28th Annual Eastern Fish Health Workshop Return to Leetown Science Center Home Page