HYPEREMESIS HIEMISS - A SICK HAZARD

Epidemic non-bacterial gastroenteritis or winter vomiting disease is a well recognized clinical syndrome causing significant morbidity in th e general population and in semi-closed communities. The Norwalk group of viruses has become established as the aetiological agents responsi ble for this important clinical syndrome. As a result of their histori cally poorly-defined taxonomic status they have been alternatively des cribed as small round structured viruses (SRSVs) which allow their dif ferentiation from other morphologically distinct small round viruses, e.g. astroviruses, and classical human enteric caliciviruses. The Norw alk viruses are highly infectious, give rise to high secondary attack rates through person-to-person transmission and are common causes of o utbreaks in hospitals leading to either ward or hospital closures. Tra nsmission occurs via the faecal/oral route but also, and probably more importantly, from projectile vomiters, through environmental contamin ation. Inhalation of aerosolized virus arising from projectile vomiter s is a possibility which requires further study. Laboratory diagnosis is currently achieved by electron microscopy but the recent molecular characterization of this group of viruses will allow the development o f sensitive and specific assays. The future control of hospital outbre aks will rely heavily on effective control of infection procedures.