Disease Carriers

Viruses: Norwalk and Norwalk-like viruses

These viral agents are a cause of gastroenteritis in all age groups of humans. Infection results in nausea, diarrhea, often vomiting, headache, fever and abdominal cramps. Loss of fluids and electrolytes are particularly serious in the very young and elderly.

The source of infection appears to be contaminated food and water, with person-to-person infection also involved. Food borne infections are, on occasion, associated with raw shellfish. There is no therapy; treatment is to replace fluid loss.

Typical morphology of Norwalk-like viruses seen by transmission electron microscopy. The individual virions have a diameter of only 27nm. (nm=one-millionth of a millimeter)