Hygiene warning for sushi lovers as norovirus spreads

PUBLISHED : Wednesday, 27 December, 2006, 12:00am
UPDATED : Wednesday, 27 December, 2006, 12:00am

Hong Kong records a peak in cases with 25-year high in Japan

The Centre for Health Protection is appealing to lovers of raw seafood to observe good personal hygiene amid a spreading norovirus outbreak in Japan and a rising number of cases in Hong Kong.

In Osaka, the Chinese consulate warned travellers on Monday to avoid consuming raw seafood in Japan, where the number of patients has hit a 25-year high.

Hong Kong is now experiencing its winter peak for norovirus infections, according to the centre's controller, Leung Pak-yin. It has recorded an increase in such infections over the past two months, many occurring in homes for the elderly.

'Homes for the elderly are high-risk areas where people stay close together. Schools are also high-risk places,' Dr Leung said.

Norovirus is a common cause of sporadic acute gastroenteritis cases, and outbreaks of food poisoning and acute gastroenteritis. Symptoms include nausea, vomiting, diarrhoea, abdominal pain, low-grade fever and malaise. The symptoms usually last for 12 to 60 hours.

Oysters and other bivalves often cause norovirus infections as they concentrate the virus after taking it in along with plankton in the water.

Dr Leung alerted travellers to Japan to be careful eating sashimi and raw oysters. 'We are closely monitoring the situation in the whole region,' he said.

In the two weeks from late November to early this month, the centre saw nine confirmed institutional norovirus outbreaks in Hong Kong affecting 102 people. Most of the outbreaks were in homes for the elderly. The average between September and November was one or two institutional outbreaks a week.

The centre's sentinel surveillance system showed that for the week ending December 16, 33.8 of every 1,000 consultations at private clinics were for acute diarrhoeal diseases. This compared with 25.8 in the previous week.

In Japan, the norovirus infected more than 300 people at a Tokyo hotel early this month. According to the Kyodo news agency, 3,000 medical institutions across Japan reported they treated 65,638 patients between November 27 and December 3, a record average of 21.8 per institution, compared with 19.8 in the preceding week, also a record.

Lo Wing-lok, a specialist in infectious diseases, said the norovirus mutated late last year, leading to the emergence of two variants.

'Most people have no immunity to the new variants and it results in a global outbreak. The virus hit many places in Europe and America. There were outbreaks on cruises that forced a shortening of their voyages.'

Dr Lo said it was important to carefully handle vomitus and patients should stay home to avoid spreading the virus to others.

Wing On Travel general manager Lanny Leung Kwong-lan said tourists to Japan had been advised to steer clear of raw seafood and restaurants that do not meet recognised health standards. Tourists have also been told to regularly use wipes to help sterilise their hands and surroundings.

The news has not scared off diehard sashimi fans. Lam Pui-yin, 30, who eats in sushi shops about once a week, said: 'It's really hard for me to refuse the temptation of sushi. What I will probably do is to eat less of it and choose the reputable restaurants offering quality-guaranteed food.'

Andrew Choo, who works in an IT company, said there was too much negative coverage about food safety in Hong Kong. 'If we believe in all of them, what can we eat?' the 30-year-old complained.

norovirus infections

Symptoms: nausea, vomiting, diarrhoea, abdominal pain, low fever and malaise. They usually last for 12 to 60 hours.

Infection by:

contaminated food or water

contact with vomit or faeces from infected persons;

contact with contaminated objects;

contaminated droplets spread through the air when vomiting.

Incubation period: 24 to 48 hours.

Source: Centre for Health Protection