SYMPTOMS and SIGNS
This virus causes watery diarrhea, abdominal cramps, nausea and vomiting. Fever headache and muscle aches are other common complaints. Examination of the stool reveals no inflammatory cells and culture is negative for bacteria known to cause infectious diarrhea. The disease is self-limiting usually lasting 2-6 days.
Treatment consists of supportive care. Some individuals require intravenous fluids; however most individuals are able to prevent dehydration by drinking fluids. No vaccine is presently available for this virus.
CAUSES and RELEVANCE to FLORIDA
The Norwalk virus is shed in the stool for 24-48 hours after the onset of illness. Infection is spread by contaminated water, foods and from person to person. The virus is relatively resistant to chlorine and can contaminate swimming pools. The virus is also relatively resistant to heat and cooking of shellfish may not completely eliminate the risk of infection. Outbreaks are common in closed environments such a cruise ships and nursing homes. Florida is the provides and ideal environment for the spread of Norwalk virus. Swimming pools are very common in our state and shellfish are popular among Floridians. Finally our ports are the home to many cruise lines and major outbreaks of Norwalk virus have become a major problem for our cruise passengers.
Careful and extensive cleaning of closed environments such as ships is required. Food handlers with diarrhea should stay home from work and always wash their hands. Shellfish need to be thoroughly cooked. Children with diapers should not be allowed in swimming pools and pools should be periodically hyperchlorinated.
Prepared by Frederick Southwick, M.D.
Professor of Medicine and Chief of Infectious Diseases
University of Florida College of Medicine
For more information see Infectious Diseases in 30 Days, McGraw-Hill, 2003, pg 250-252.