Gastroenteritis, or winter vomiting disease, has for the first time peaked during the summer months in England and Wales, writes Natasha Gilbert.
UK researchers Mark Reacher and his team from the Communicable Disease Surveillance Centre and the Central Public Health Laboratory at the Health Protection Agency, observed 430 cases of norovirus infection, which causes mild gastroenteritis, in July 2002. This was the only summertime occurrence observed from January 1995 to October 2002.
Scientists were aware that transmission of the virus could occur year-round, but outbreaks were thought to exhibit a cold-weather peak. The researchers state in a study published in the online journal BMC Public Health: "This observation is in contrast with a ubiquitous collection of reports that noroviruses are principally an infection associated with the winter months."
Dr Reacher thinks this sudden summer episode could have been caused by the emergence of a more virulent strain of the virus, the multiplicity of pressures in healthcare settings or a combination of both. He told The THES: "The exact mechanism for the virus's seasonality has not been worked out."
Noroviruses are the leading cause of gastroenteritis in communities and are the most common cause of outbreaks in semi-closed environments such as schools, cruise ships, hospitals and residential homes. Infection is disruptive but not hugely damaging to patients. However, Dr Reacher said, more effective controls were urgently needed because the agents were highly infectious and outbreaks difficult to manage due to the high frequency of vomiting and widespread contaminations. He said protection via a vaccine would be short-lived because there were multiple strains of the virus. He suggested the most effective measures would be to take it seriously when people vomit and try to be scrupulously clean.