Brainerd diarrhea is a syndrome of acute watery diarrhea lasting 4 weeks or longer, which can occur in outbreaks or as sporadic cases. The illness may be foodborne or waterborne and the illness has not been attributed to a specific pathogen. It is named after Brainerd, Minnesota, the town where the first outbreak occurred in 1983. Patients typically experience 10-20 episodes per day of explosive, watery diarrhea. Accompanying symptoms include gas, mild abdominal cramping, and fatigue. Nausea, vomiting, and systemic symptoms such as fever are rare, although many patients experience slight weight loss.
Seven outbreaks of Brainerd diarrhea have been reported since 1983. Six occurred in the United States, five of which were in rural settings. One outbreak occurred on a South American cruise ship based in the Galapagos Islands. The original Brainerd outbreak, which involved 122 persons, was the largest outbreak. An outbreak in Henderson County, Illinois, involved 72 persons; the Galapagos Islands outbreak involved 58. Further work needs to be done to establish the incidence of sporadic cases of Brainerd diarrhea.
In the original Brainerd outbreak, raw (unpasteurized) milk was implicated as the vehicle for disease transmission. Contaminated and inadequately chlorinated or unboiled water has been identified as a source of Brainerd diarrhea in several other outbreaks. For example, illness was strongly associated with drinking untreated well water in the Henderson County outbreak. Persons who drank the same water after it was boiled did not get sick. Contaminated water was also implicated in the Galapagos Island outbreak. The diarrheal illness does not appear spread contagiously from one person to the next.
Richard J. Arsenault, 2011
