[Emergent riboviruses implicated in gastroenteritis]

Abstract

Viral agents are one of the main causes of acute diarrhea, particularly in infants and young children. Astrovirus, coronavirus, torovirus, and picobirnavirus are increasingly being identified as causative agents of gastroenteritis. Astroviruses have been detected in the stools of between 1.2% and 20% of children with diarrhea requiring medical care in a variety of geographical areas. Outbreaks have been described in schools, day care settings and pediatric wards. Children younger than 3 years old are the most frequently affected. In temperate climates incidence is greater in winter whereas in tropical areas infection occurs throughout the year. Transmission is mainly through the fecaloral route. At least seven serotypes of human astroviruses have been recognized and serotype 1 is more common than the other serotypes. Astroviruses are often shed in stools during long periods and can be detected by electron microscopy. An enzymeimmunoassay technique that detects the astrovirus group antigen has been widely used in epidemiological studies. Nucleic acid hybridization and polymerase chain reactionbased techniques have also been used. Enteric coronaviruses have most frequently been associated with gastrointestinal disease in neonates and children younger than 12 years old. The role of toroviruses and picobirnaviruses as causative agents of gastroenteritis is still emerging. Further epidemiological studies to determine the frequency of these viruses in the community and to identify their mechanisms of transmission are needed, as are further studies to elucidate the pathophysiology of diseases due to these agents.