Gastroenteritis

Acute gastroenteritis causes almost 3 million deaths each year worldwide, mostly among children under 5 years of age in developing countries. The known causes of viral gastroenteritis include the RNA viruses rotavirus, astrovirus, sapovirus and norovirus and the DNA adenoviruses.
Enteroviruses do not usually, despite their name, cause gastroenteritis, but replicate in the intestine and can be isolated from faeces in patients with meningitis, myocarditis and symptoms from many other organs. Electron microscopy has been valuable for the discovery and diagnosis of viruses in diarrhoea and the names of rotavirus (‘wheel’) and astrovirus (‘star’) refer to the electron microscopy images. Agglutination tests provide rapid diagnosis of rotavirus and adenovirus gastroenteritis.
However, reverse PCR tests are increasingly coming into use for the rapid diagnosis of viral gastroenteritis. The incubation time of norovirus gastroenteritis may be less than 1 day and noroviruses commonly cause outbreaks of gastroenteritis in hospitals and in other situations where groups of people live closely together. By means of reverse PCR and DNA sequencing, the hundreds of strains of noroviruses (also known as caliciviruses/Norwalk agents) have been identified and classified into genogroups and genetic clusters. Reverse PCR tests using nucleic acids extracted from diarrhoeal faecal specimens have come into broad use to diagnose norovirus infection.The genetic variability of viruses causing gastroenteritis represents a great challenge to molecular diagnosis and new protocols take advantage of new chemistry and computer analysis to design multiplex PCR protocols directed at different strains of each virus and to cover several different viruses in one reaction.