Acute gastroenteritis ( AGE ) is the second eading cause of morbidity and mortalitv woridwide. Screening efforts must focus particularly on enteric viruses as they are extremely contagious. Rotavirus, Adenovirus and Norovirus are most common and major causes of severe gastroenteriis in infants and young children. Pat ter n also observed in adults. They are transmited by faecal-oral contact.
Rotavirus is considered the first cause of serious acute gastroenteritis in babies and children worldwide and main causal agent of severe dehydration in children between 6 months and 2 years, both in developing countries, where it shows a high mortality, as well as in developed countries. At the age of 5 years, the majority of children (>95%) have suffered at least one episode of gastroenteritis caused by Rotavirus. Rotavirus is transmitted by oral-fecal route , less frequently, through contaminated water and food with an incubation period of 1-3 days. Rotaviral gastroenteritis may result in mortality for populations at risk such as infants, the elderly and immunocompromised patients. Rotavirus is the cause of up to 50% of the hospitalized cases of diarrheal illness in infants and young children. The highest prevalence of the disease is experienced in temperate climates during the cooler months of the year. In tropical climates rotavirus infection occur year round.
Adenoviruses have been implicated in a wide range of clinical diseases affecting mainly the respiratory, ocular and the gastrointestinal systems of the human. Some adenovirus serotypes ( primarily Ad40 and Ad41 ) are enteric and have emerged as a major source of pediatric gastroenteritis. E nteric Adenovirus is the third leading cause of viral gastroenteritis in children (10-15%) , also observed in adults . These viral pathogens have been isolated throughout the world, and can cause diarrhea in children year round. Infections are most frequently seen in children less than two years of age, but have been found in patients of all ages. Adenovirus is transmitted by fecal-oral contact. The main symptoms of viral gastroenteritis are watery diarrhea and vomiting. The affected person may also have headache, fever, and abdominal cramps ("stomach ache"). In general, the symptoms begin 1 to 2 days following infection with Adenovirus that causes gastroenteritis and may last for 5-8 days. Rapid and accurate diagnosis of gastroenteritis due to adenovirus is helpful in establishing the etiology of gastroenteritis and related patient management.
Norovirus is considered the leading cause of nonbacterial AGE worldwide. lt is responsible for almost 50% of the gastrointestinal outbreaks at any age and 73% in the elderly. Transmission is predominantly faecal-oral but may be airborne due to aerosolisation of vomitus, which typically contains abundant infectious virus particles. And also contaminated food/water can be a possible source of infection. The virus usually causes large epidemics in closed communities (hospitals, homes for the elderly, schools, nurseries, restaurants, cruise ships, etc.), where once it has been introduced, infection propagates very rapidly. Norovirus are grouped in five genogroups (GI to GV) and within each genogroup this virus is classified into genotypes. The majority of clinical cases are as a result of strains of the genogroups I and II being the genotypes GI.1 and GII.4 the most common ones. In general, GI infections are less frequent than GII infections. The symptoms of Norovirus related diseases are those typical of gastroenteritis, that is, vomiting, watery diarrhea and abdominal cramps . The illness is acute, usually mild, although it has caused fatalities among the frail elderly, and self-limiting with symptoms lasting for about 1 or 2 days . The incubation penod of the disease is generay between 12 and 48 hours, while infection lasts between 12 and 60 hours. lnfection may also be asymptomaic, and thus contnibute to the spread of the virus in the community .
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