Diarrhea, Brainerd

Diarrhea, Brainerd: A syndrome characterized by the acute onset of watery nonbloody diarrhea (3 or more loose stools per day), lasting 4 weeks or more, and resolving spontaneously. The disease is of unknown causation and appears in outbreaks or as sporadic cases. It is named after Brainerd, Minnesota, USA the town where the first outbreak was recognized in 1983.

People with Brainerd diarrhea typically have 10-20 episodes per day of explosive, watery nonbloody diarrhea with urgency and, often, fecal incontinence. 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.

Despite much research, the cause of Brainerd diarrhea has not yet been identified. Although it is thought to be an infectious agent, intensive searches for bacterial, parasitic, and viral pathogens (agents of disease) have been unsuccessful. The remote possibility remains that Brainerd diarrhea is caused by a chemical toxin.

There is no laboratory test that can confirm the diagnosis. Brainerd diarrhea should be suspected in any patient who presents with the acute onset of nonbloody diarrhea lasting for more than 4 weeks, and for whom stool cultures and examinations for O&P (ova and parasites) have been negative. On colonoscopy, petechiae, aphthous ulcers and erythema may be observed. Microscopic examination of colonic tissue biopsy specimens often reveals mild inflammation, with an increased number of lymphocytes, particularly in the ascending and transverse colon. The stomach and small intestine generally appear normal.

There is no known cure for Brainerd diarrhea. A variety of antimicrobial agents have been tried without success, including trimethoprim-sulfamethoxazole, ciprofloxacin, doxycycline, ampicillin, metronidazole, and paromomycin. Neither has there been any response to steroids or antiinflammatory agents. Approximately 50% of patients report some relief in symptoms with high doses of opioid antimotility drugs, such as loperamide, diphenoxylate, and paregoric.

Brainerd diarrhea is a self-limited disease. Symptoms may last a year or more, and typically have a waxing and waning course. Long-term follow-up studies have shown complete resolution in essentially all patients by the end of 3 years. There have been no known cases of sequelae or relapse once the illness has completely resolved.

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.

A survey of gastroenterologists suggested that many patients who are not associated with a recognized outbreak seek treatment for illness compatible with Brainerd diarrhea. The incidence of sporadic cases of Brainerd diarrhea is not known but may be appreciable.

Raw (unpasteurized) milk was implicated (but not proven) as the vehicle for the original 1983 Brainerd outbreak. Contaminated and inadequately chlorinated or unboiled water has been suspected 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.

Brainerd diarrhea does not spread contagiously from one person to the next. It is thought that not drinking raw (unpasteurized) milk and water that has not been properly chlorinated or boiled will help reduce the risk for Brainerd diarrhea (and many other diseases).