Norovirus Infection

Abstract

Norovirus (NoV) is the most common cause of sporadic or epidemic acute gastroenteritis in school- age children, teenagers and adults. In infants and young children, is the most frequent second after rotavirus. The diversity between the NoV is very large. Distinguished 5 genotypes (G) and 29 genotypes; the human strains are grouped into three genotypes (GI, GII and GIV), the genotypes I and II being the most frequent cause of disease. The NoV of genogroup II, genotype 4 (GII.4) are the most prevalent and responsible for the majority of outbreaks of gastroenteritis worldwide. Genotype GII.4 undergoes a process of evolution sequence,similar to what happens with influenza viruses, allowing the NoV to escape recognition by antibodies and originating variants of the virus that hinder the creation of a vaccine against this agent. NoV outbreaks involving all age groups being most prevalent in children, and can occur in a variety of settings such as hospitals, day care, restaurants, cruises, schools, hotels and others. The virus spreads from vomiting, contact from person to person and environmental pollution. The fecal-oral spread is the primary mode of transmission. On NoV explains lots of outbreaks both in the developed and the developing countries. In the United States, is the most common cause of outbreaks of gastroenteritis and food-borne disease. Studies of gastroenteritis in Peru, made in pediatric population, found a frequency of infection NoV ranging from 16% to 35%. NoV infection is characterized by short period of incubation, a symptomatic period which is resolved quickly and a secondary attack rate very high. The disease often starts abruptly usually first with vomiting and hours after diarrhea. NoV diagnosis is based on detection of the virus in fecal specimens by any of the following three methods: 1) transmission electron microscopy; (2) ELISA, preferably with monoclonal antibodies to increase specificity; or (3) PCR polymerase with reverse transcription (RT-PCR), preferably in real time to shorten the time of delivery of results. As in all gastroenteritis, the main and unavoidable element of the treatment is the replacement of losses to avoid dehydration. But the intensity and persistence of vomiting in NoV infection do try to replacement of losses by a serum administered orally and resort to intravenous hydration only if a good attempt of oral hydration has been done and it did not work. Control of an outbreak of NoV is a challenge by the rapid spread of the infection. Transmission is facilitated by the large amount of viral particles excreted by patients and because the excretion of virus may persist for several weeks after the disappearance of symptoms. To decrease the spread, the standard measures for the control of diarrhea, implementation of a proper hygiene of hands, training of caregivers of children and the elderly should be used which handled food, proper cleaning of the areas where prepared foods, proper disposal of excreta and use appropriate disinfectants approved for this purpose. The washing of hands with solutions that contain alcohol can be of utility.