Brainerd diarrhea is a syndrome of acute onset of watery
diarrhea ( 3 or more loose stools per day) lasting four weeks or
longer, which can occur in outbreaks or as sporadic cases. 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, characterized by urgency and
often by 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.
What causes Brainerd diarrhea?
Despite extensive clinical and laboratory investigations, 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 have been unsuccessful so
far. The possibility remains that Brainerd diarrhea is caused by a
chemical toxin, but no such toxin has yet been found.
How can Brainerd diarrhea be diagnosed?
Because the cause of Brainerd diarrhea is unknown, 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 four weeks, and
for whom stool cultures and examinations for ova and parasites have
been negative. Care should be taken to exclude other causes of
chronic diarrhea, both infectious and noninfectious (e.g.,
lymphocytic colitis, collagenous colitis, tumors, drug reactions).
Brainerd diarrhea is not characterized by any specific laboratory
abnormalities. 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.
How can Brainerd diarrhea be treated?
There is no known curative treatment 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 antinflammatory agents.
Approximately 50% of patients report some relief in symptoms with
high doses of opioid antimotility drugs, such as loperamide,
diphenoxylate, and paregoric.
Are there long-term consequences to Brainerd diarrhea?
Brainerd diarrhea is a self-limited illness. 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
virtually all patients by the end of three years. There have been
no known cases of sequelae or relapse once the illness has
How common is Brainerd diarrhea?
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. Further work needs to be done to
establish the incidence of sporadic cases of Brainerd diarrhea.
How do people get Brainerd diarrhea?
In the original Brainerd outbreak,
was implicated as the vehicle for disease transmission.
Contaminated and inadequately chlorinated or unboiled
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 spread contagiously
from one person to the next.
What can a person do to prevent this illness?
Avoiding 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. Once the cause of
Brainerd diarrhea is identified, more specific prevention measures
can be formulated.
Centers for Disease Control and
Prevention, April 2000
Please be aware that this information is provided to supplement the care
provided by your physician. It is neither intended nor implied to be a
substitute for professional medical advice. CALL YOUR HEALTHCARE PROVIDER
IMMEDIATELY IF YOU THINK YOU MAY HAVE A MEDICAL EMERGENCY. Always seek the
advice of your physician or other qualified health provider prior to
starting any new treatment or with any questions you may have regarding a