ENZYME-LINKED IMMUNOELECTROTRANSFER BLOT ANALYSIS OF A CRYPTOSPORIDIOSIS OUTBREAK ON A UNITED-STATES COAST-GUARD CUTTER

Symptoms consistent with an outbreak of cryptosporidiosis (diarrhea, v omiting, nausea, and abdominal cramps) occurred on a U.S. Coast Guard cutter within 0-18 days after the cutter filled its tanks with Milwauk ee, Wisconsin city water in March 1993. At three-weeks postdocking (PD ) the suspected water was removed, and serum samples and stool specime ns were collected from 47 of the 58 crew members, as well as questionn aire data on their water consumption and symptoms aboard the cutter. A t 10-weeks PD and/or at 28-weeks PD, additional serum specimens were c ollected. Intensitometric data from enzyme-linked immunoelectrotransfe r blot (EITB) were obtained on IgA responses to a 17-kD antigen group, IgM responses to a 27-kD antigen group, and IgG responses to 27-, 17- , and 15-kD antigen groups extracted from oocysts. In addition, IgG re sponses to crude oocyst antigens were obtained by ELISA. Based on repo rted symptoms, EITB results, and stool examination, the crew members w ere classified as confirmed (10), probable (10), suspected (22), and n oncases (16). Of the 10 confirmed cases (all symptomatic) and the 10 p robable cases (eight symptomatic) whose stools were positive and negat ive, respectively, for Cryptosporidium oocysts by microscopy, all show ed changes in EITB intensities to the antigen groups and were consider ed EITB positive. The remaining 38 crew members, 22 suspected cases (a ll symptomatic), and 16 noncases (all asymptomatic), if tested, had ne gative stool examinations and were considered EITB negative. Of the 10 confirmed cases, only four showed a significant change in IgG respons es (P < 0.05) between three-weeks PD and follow-up serum specimens by ELISA. Crew members considered confirmed cases consumed significantly more water (P less than or equal to 0.005) aboard the cutter than nonc ases. Crew members considered EITB positive consumed more water (P les s than or equal to 0.04) than crew members considered EITB negative wh ile there was no significant difference in water consumption (P greate r than or equal to 0.19) between crew members considered ELISA positiv e and ELISA negative. Using the EITB, the observation of changes in in tensity of IgA responses to the 17-kD antigen group, IgM responses to the 27-kD antigen group, and IgG responses to the 27-17-, and 15-kD an tigen groups from C. parvum oocysts between acute and convalescent ser um specimens appears useful for immunodiagnosis of Cryptosporidium inf ection and for prospective epidemiologic studies designed to monitor i nfection risk.