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Epidemiologic Notes and Reports Toxigenic Vibrio cholerae O1 Infection Acquired in Colorado

On August 17, 1988, a 42-year-old man was treated for profuse watery diarrhea, vomiting, and dehydration at an emergency room in Rifle, Colorado. On August 15, he had eaten approximately 12 raw oysters from a new oyster-processing plant in Rifle. Approximately 36 hours after eating the oysters, he had sudden onset of symptoms and passed 20 stools during the day before seeking medical attention. Stool culture subsequently yielded toxigenic Vibrio cholerae O1, biotype El Tor, serotype Inaba. The patient had no underlying illness, was not taking medications, and had not traveled outside the region during the month before onset.

The oysters had been harvested on August 8, 1988, in a bay off the coast of Louisiana. Approximately 1000 bushels (200,000 oysters) arrived by refrigerator truck at the plant in Rifle on August 11. The patient purchased three dozen of these oysters on August 15.

During a 6-day period, eight other persons shared the oysters purchased by the patient. None became ill. Although one of seven tested had a vibriocidal antibody titer of 1:640, none had elevated antitoxic antibody titers, and none had V. cholerae O1 isolated from stool. Physicians and local health departments were asked to notify the Colorado Department of Health about similar cases, but none were reported.

The oyster-processing plant in Rifle began operation in May 1988 and functioned as a wet-storage unit. The Gulf oysters were reportedly harvested from approved waters, trucked to Colorado, and placed in recirculating disinfected artificial seawater baths for a variable number of days before packaging for market. These oysters were probably the vehicle of infection for the case of cholera. Reported by: M Doran, P Shillam, RE Hoffman, MD, State Epidemiologist, Colorado Dept of Health. LM McFarland, DrPH, Louisiana Dept of Health and Hospitals. Div of Field Svcs, Epidemiology Program Office; Enteric Diseases Br, Div of Bacterial Diseases, Center for Infectious Diseases, CDC.

Editorial Note

Editorial Note: VcA-3 phage typing showed that the organism is identical to all others associated with an endemic focus known to have been present in the Gulf of Mexico since 1973 (1-3). This is the third reported case of toxigenic V. cholerae O1 apparently acquired from oysters shipped interstate in the United States (4) and is the first case known to have been acquired in Colorado during this century.

This report suggests that V. cholerae O1 may persist in oysters for many days after harvest. Several different Vibrio species previously have been associated with infections related to consumption of raw oysters (5). Since this case occurred, five additional oyster-related cases of cholera have been reported by five other states from August to October 1988. Thorough cooking remains he best method to prevent acquisition of infectious diseases from raw shellfish.


  1. Blake PA, Allegra DT, Snyder JD, et al. Cholera--a possible endemic focus in the United States. N Engl J Med 1980;302:305-9. 2.CDC. Toxigenic Vibrio cholerae O1 infections--Louisiana and Florida. MMWR 1986;35:606-7. 3.CDC. Cholera in Louisiana--update. MMWR 1986;35:687-8. 4.Pavia AT, Campbell JF, Blake PA, Smith JDL, McKinley TW, Martin DL. Cholera from raw oysters shipped interstate (Letter). JAMA 1987;258:2374. 5.Blake PA. Vibrios on the half shell: what the walrus and the carpenter didn't know. Ann Intern Med 1983;99:558-9.

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