The Centre for Health Protection has confirmed Japanese encephalitis in a five-year-old Yuen Long boy, the year's fourth case.

He developed fever, runny nose, sore throat, vomiting and diarrhoea on October 16 and was admitted to Tuen Mun Hospital on October 19. He is now in stable condition.

Consultant Dr Thomas Tsang said: "Investigations so far have not shown epidemiological linkage with the previous three local cases confirmed earlier this year, and at present there are no other suspected cases known."

Residents in the Sha Kong Tsuen vicinity where the boy lived can call 2575 1848 for health information. The centre is organising a health talk for residents on November 3 and blood tests will be offered.

Anti-mosquito work to be stepped up

The Food & Environmental Hygiene Department's Pest Control Officer-in-charge Yuen Ming-chi said the major vector for Japanese encephalitis in Hong Kong, Culex tritaeniorhynchus, has been collected in the area.

"The department has been conducting anti-mosquito operations around piggeries on a regular basis and larvicides have been applied to control mosquito breeding," he said, adding anti-mosquito work in that area will be stepped up.

Noting concern about whether the area's mangroves are a breeding ground for the vector, Mr Yuen said salt water is not the natural habitat for Culex tritaeniorhynchus.

On reports of mosquitoes breeding in the septic tanks, Mr Yuen said anyone found accumulating water containing larvae or pupae of mosquitoes on their premises faces a $25,000 fine.

Agriculture, Fisheries & Conservation Department staff have inspected several pig farms in the area and found hygienic conditions satisfactory. Farmers have been reminded to conduct anti-mosquito measures. The department will continue to intensify inspections of Lau Fau Shan farms.