The Centre for Health Protection is investigating a domestic cluster of typhoid fever following the confirmation of two cases, involving a 10-year-old boy and his nine-year-old sister living in Yuen Long.

The boy and his sister developed fever on December 6 and November 24 and were admitted to Tuen Mun Hospital on December 8 and 9 respectively. They are now in stable a condition.

Clinical and environmental samples have been taken to help ascertain the source of infection. Preliminary investigations have failed to find suspicious food source. At present, the evidence suggests a domestic cluster of infection possibly with intra-familial spread.

The patients' two brothers, aged 10 and 13, also had fever, abdominal pain and vomiting, starting on November 25 and 27. They were admitted to Tuen Mun Hospital on December 4 and 5 respectively. Bacteriological culture is being grown to confirm if they also have typhoid fever.

The children's parents have no symptoms and are under medical surveillance. There was no abnormal illness in the children's school, and a health talk is being arranged for the school.