Rotavirus is the primary causative agent of pediatric gastroenteritis and diarrhea worldwide.The improvement of food, water,and hygiene has done nothing to decrease the incidence of rotavirus disease. Almost every child on the planet may get infected by age 5. Scientists say that families of the 900,000 young children around the world who die each year from rotaviruses. Many of them get it between December and April in the temperate climates of the northern hemisphere.Most of these deaths occur in developing countries.The infection usually begins with a fever.Soon the little one begins to vomit and has a nasty tummyache. The vomiting goes away, by watery diarrhea that lasts from 3to 9 days.Most of the time,kids recover with little difficulty.Sometimes, severe dehydration results.The extreme dehydration that can be caused by rotaviruses is second only to the dehydration caused by cholera.The infection starts suddenly and lasts for an average of four to six days. Rotaviruses are extremely contagious.Only a very few particles are needed to transmit infection.They originate in the stool, but are found throughout the environment wherever young children spend much time,especially during the winter months.They are resistant to disinfectants used to clean surfaces and to anti-bacterial hand-washing agents. Rotavirus particles remain active on human hands for at least 4 hours, on hard dry surfaces for 10 days,and on wet areas for weeks.Untreated, rotavirus infection may result in severe illness with dehydration and disturbances of the body's normal electrolyte balance,especially in babies and preschool children. Rotavirus is the cause of up to 50% of the hospitalized cases of diarrheal illness in infants and young children. Rotavirus induced dehydration is a major cause of infant morbidity in both developed and underdeveloped countries,and a major cause of infant mortality in the developing countries. The highest prevalence of the disease is experienced in temperate climates during the cooler months of the year. In tropical climates, rotavirus infection can occur all year round. The age groups most susceptible to the disease are that of infants and children. Adenovirus is the second most common cause of viral gastro-enteritis in Children(10-15%).This virus may also cause respiratory diseases and, depending on the serotype,also diarrhea,conjunctivitis, cystitis,etc.At lease 47 serotypes of adenovirus have been described,all sharing a common hexon antigen. Serotypes 40 and 41 are the ones associated with gastro-enteritis.The main syndrome is diarrhea that may last between 9 and 12 days associated with fever and vomits.