HONG KONG, Dec. 21 (Xinhua) -- The Center for Health Protection(CHP) of the Health Department of the Hong Kong government said Friday that seven institutional outbreaks of noroviral gastroenteritis had been detected so far this month and asked people to be vigilant.

    The CHP reminded members of the public and management of institutions to maintain strict personal and environmental hygiene to avoid contracting the disease.

    A CHP spokesman said six out of the seven cases occurred in elderly homes affecting a total of 30 people. There were five and one norovirus gastroenteritis outbreaks in November and October, respectively.

    "Although CHP's surveillance system did not detect any recent sign of an upsurge of acute diarrhea at institutions, strict hygiene measures should be maintained to prevent infection as gastroenteritis caused by norovirus was more active in the winter months," the spokesman said.

    The spokesman said norovirus infection could be transmitted viafood or water contaminated with the virus, contact with vomitus or faeces or any objects contaminated by the virus.

    "Proper management and adequate disinfection of vomitus and faeces matter is of crucial importance in preventing and controlling the spread of the disease," he said.

    According to the CHP, 93 noroviral gastroenteritis outbreaks in institutions, including child care centers and schools had been reported so far this year.

    In 2006, there were 269 norovirus outbreaks in institutions, affecting 3,250 people.