The Centre for Health Protection is reviewing nine reports of typhoid fever in the past three weeks - seven in Yuen Long, one in Sham Shui Po and an imported case.

The seven cases in Yuen Long included four children aged nine to 13 in one family, a 51-year-old man, and two girls aged eight and 17.

The Sham Shui Po case involved a seven-year-old boy.

They developed symptoms including fever, stomach pain and vomiting between November 18 and December 6. 

All the Yuen Long patients were admitted to Tuen Mun Hospital. The four children from the same family and the 17-year-old girl are in stable condition while the eight-year-old girl and the 51-year-old man have been discharged.

The seven-year-old boy in Sham Shui Po was admitted to Caritas Medical Centre and is now in stable condition.

Community Medicine Consultant Dr Thomas Tsang said initial investigations did not reveal a single common food shop or hawker all the patients had patronised.

The centre is conducting detailed tests to find out if the cases originated from a common source. More definitive laboratory results are expected in about two weeks.

Typhoid fever is endemic in Hong Kong, Dr Tsang said, adding there were from zero to 11 cases reported monthly in the past two years.

A total of 33 cases have been reported so far this year There were 53 cases in 2004, 49 in 2003, 67 in 2002 and 67 in 2001. 

Yuen Long district had from one to nine cases each year from 2001 to 2004, Dr Tsang said.

Typhoid fever is caused by the bacteria salmonella typhi, with an incubation period of seven to 21 days.

It is usually transmitted by consuming food and water contaminated by faeces or urine of patients or carriers. Onset of the illness is usually marked by fever, tiredness, chills, headache and generalised muscle and joint aches. Diarrhea, constipation, or abdominal discomfort may occur, Dr Tsang said.

To prevent infection, people should heed the following:

* wash their hands properly before eating or handling food, and after using the toilet or changing diapers;

* clean, wash and cook food thoroughly;

* wash fruits and vegetables before eating;

* do not handle cooked food with bare hands;

* handle and store raw and cooked food separately to avoid cross contamination; and