Types of Stomach Flu Viruses
Caliciviruses cause infection in people of all ages. This family of viruses is divided into four types, the noroviruses (see Norovirus) being the most common. The noroviruses are usually responsible for epidemics of stomach flu and occur more frequently from October to April. Infected people experience vomiting and diarrhea, fatigue, headache, and sometimes muscle aches. Norovirus symptoms appear within 1 to 3 days of exposure. It is now thought that at least 50 percent of all foodborne outbreaks of gastroenteritis can be attributed to noroviruses. Norwalk virus is a type of norovirus.
Astrovirus infects primarily infants, young children, and the elderly. This type of stomach flu virus is most active during the winter months. Vomiting and diarrhea appear within 1 to 3 days of exposure.