It’s not only the flu striking hard this year. A new strain of norovirus is the cause of over 50 percent of outbreaks that began last fall. It is one of the most common causes of food borne diarrheal disease outbreaks.
Norovirus outbreaks originate with contaminated food, and usually occur in daycare centers, schools, prisons, and on cruise ships. It is spread by water, person-to-person contact, or by touching an infected surface. Introduction of the virus into the community leads to sporadic or widespread epidemics, much like influenza virus.
Humans appear to be the only species that harbor norovirus and as a result, humans not only spread disease, but serve as the reservoir for the virus. Unlike many infectious diseases, ingestion of a very small number of infectious particles can cause disease. The virus is hardy and can live on countertops, doorknobs and other surfaces for extended periods of time.
In Philadelphia, the city’s health department issued a norovirus advisory earlier this month based on an increase in cases of vomiting and diarrhea at its health clinics and increased pharmacy sales of over the counter drugs that treat diarrheal disease. The Centers of Disease Control and Prevention reported on the new strain from Australia in the Jan. 25 issue of the Morbidity and Mortality Weekly Report.
Within 10 to 50 hours after ingestion of the tainted food, patients experience the explosive onset of vomiting and diarrhea. The disease is short-lived with symptoms resolving within three days.
Young children, adults over 65 years of age, and individuals with altered immune systems from cancer or HIV infection may experience prolonged illness. In developing countries, a significant number of young children and elderly people die from norovirus infection annually.
No vaccine is currently available to prevent norovirus infections. Treatment is designed to prevent dehydration. Pedialyte for infants and young children, and sport drinks for older children and adults can be used at home to maintain hydration. Because vomiting is a prominent symptom, these fluids are best administered in small volumes (3-5 oz) frequently (every 20-30 minutes) while awake. Close attention should be paid to urine output during the course of the illness. Individuals who cannot tolerate oral fluids, maintain urine output, or become lethargic or poorly arousable should be seen by a healthcare provider.
To try to prevent infection, here are some tips from the CDC:
- Handwash with soap and running water for at least 20 seconds.
- Minimize contact with infected persons if possible. Someone is the most contagious when symptoms first begin and the period following recovery while the virus is still being shed.
- Use chemical disinfectants, especially in bathrooms and high-touch surfaces such as door knobs and hand rails.