lack of immunity to this species in the united states. history one of flewett's original electron micrographs in 1943, jacob light and horace hodes proved that a filterable agent in the faeces of children with infectious diarrhoea also caused scours (livestock diarrhoea) in cattle. three decades later, preserved samples of the agent were shown to be rotavirus. in the intervening years, a virus in mice was shown to be related to the virus causing scours. in 1973, ruth bishop and colleagues described related viruses found in children with gastroenteritis. in 1974, thomas henry flewett suggested the name rotavirus after observing that, when viewed through an electron microscope, a rotavirus particle looks like a wheel (rota in latin); the name was officially recognised by the international committee on taxonomy of viruses four years later. in 1976, related viruses were described in several other species of animals. these viruses, all causing acute gastroenteritis, were recognised as a collective pathogen affecting humans and animals worldwide. rotavirus serotypes were first described in 1980, and in the following year, rotavirus from humans was first grown in cell cultures derived from monkey kidneys, by adding trypsin (an enzyme found in the duodenum of mammals and now known to be essential for rotavirus to replicate) to the culture medium. the ability to grow rotavirus in culture accelerated the pace of research, and by the mid-1980s the first candidate vaccines were being evaluated. in 1998, a rotavirus vaccine was licensed for use in the united states. clinical trials in the united states, finland, and venezuela had found it to be 80 to 100% effective at preventing severe diarrhoea caused by rotavirus a, and researchers had detected no statistically significant serious adverse effects. the manufacturer, however, withdrew it from the market in 1999, after it was discovered that the vaccine may have contributed to an increased risk for intussusception, a type of bowel obstruction, in one of every 12,000 vaccinated infants. the experience provoked intense debate about the relative risks and benefits of a rotavirus vaccine. in 2006, two new vaccines against rotavirus a infection were shown to be safe and effective in children, and in june 2009 the world health organization recommended that rotavirus vaccination be included in all national immunisation programmes to provide protection against this virus. other animals rotaviruses infect the young of many species of animals and they are a major cause of diarrhoea in wild and reared animals worldwide. as a pathogen of livestock, notably in young calves and piglets, rotaviruses cause economic loss to farmers because of costs of treatment associated with high morbidity and mortality rates. these rotaviruses are a potential reservoir for genetic exchange with human rotaviruses. there is evidence that animal rotaviruses can infect humans, either by direct transmission of the virus or by contributing one or several rna segments to reassortants with human strains.