Human Rotavirus

	Human rotavirus was discovered in 1973 and is known to cause diarrheal disease in infants and young children. The severity of rotaviruses is seen among babies 11 months old and younger with the highest mortality seen in Africa, Latin America, and Asia.  The mortality rate of rotaviruses in developing countries can be as high as one million which makes up an estimate of 6% overall mortality among children younger than 5 years old (Cook et al, Bull WHO, 1990; 68:171-7.Rotaviruses can be seasonal in temperate climates where the highest rates of incidence is observed in the winter. Frequency: In the US: Reoviruses cause many inapparent infections making it difficult to make accurate estimates. Rotavirus infections account for 3.5 million cases of diarrhea each year and for 20 deaths that occur among children younger than 5 years in 11 states of Western United States. Internationally: In developing countries, 3-5 billion cases of gastroenteritis occur each year. A significant proportion is believed to be caused by rotaviruses. Mortality/Morbidity: Reovirus infection has a benign course with little mortality associated with it. In developing countries, rotavirus leads to 10-20% of gastroenteritis-associated deaths mostly due to hemorrhagic complications. There are reported cases of rare reovirus-induced neurologic disease in humans, including encephalitis and meningitis.

	Rotaviruses are found in the feces of infected individuals but it is not often associated with a symptom. Asymptomatic infections mostly are seen among infants younger than 6 months, during which they are protected by their maternal antibody. It is less likely that the infection will be serious during this period. Transmission The transmission of rotavirus infections is mainly through the fecal-oral route. There has not been enough evidence to show any airborne transmission. A common source of infection is contact with infected children. Some outbreaks have occurred in enclosed spaces among adults, especially in geriatric wards.

	Water treatment and sanitation can be instrumental in controlling fecal-oral transmission. Background on Vaccine Development: Acute diarrhoea is responsible for nearly 1.9 million deaths per year in children under age five. Rotavirus is responsible for as much as one fourth of these casualties, almost all of which occur in developing countries. Status of vaccine development: RotaRix, a vaccine developed by GlaxoSmithKline (GSK), showed an efficacy rate against severe rotavirus diarrhoea of 87% in a clinical study of 1986 infants in Venezuela, Brazil, and Mexico, and is now licensed in Mexico, the Dominican Republic, and Kuwait, although currently used only in the private market. A Phase III trial of over 60 000 infants was carried out in Latin America in 2003-2004, and efficacy results are expected soon. Phase III trials also are under way in South Africa and Bangladesh. RotaTeq, a vaccine developed by Merck, protected more than 95% of recipients from severe rotavirus diarrhoea in a clinical trial of 1946 infants in Finland. A Phase III trial of more than 70 000 infants in the United States and European countries has been carried out to investigate safety, and a subset of that group was followed to determine efficacy. The results of these studies are expected by mid 2005. Trials in Asia and Africa - where different strains of the virus may predominate - are likely to start this year but may not be completed for several years. Rotavirus vaccines in earlier stages of development include two vaccines sponsored by the United States National Institutes of Health; a neonatal vaccine developed by an Indian-US consortium; and an Australian neonatal vaccine. Source: http://www.who.int/entity/mediacentre/factsheets/fs289/en/

Reference:

Gholamreza Rasouli, MD John W King, MD. Reoviruses. July 6, 2005.

http://www.emedicine.com/med/topic2007.htm#section~medication

General Information about Rotavirus

Rotavirus Online
Medscape Article: Emerging Rotavirus Vaccines