Mosquito blitz as dengue cases rise

PUBLISHED : Friday, 14 August, 1998, 12:00am
UPDATED : Friday, 14 August, 1998, 12:00am

A battle against mosquitoes is being stepped up after a sharp rise in the number of cases of dengue fever spread by the insects.

Five cases were notified in 1996 and 10 last year, but by the end of July this year, eight had already been identified.

An annual campaign against the insects is starting three months early in an attempt to stop the disease spreading.

A survey has pinpointed Tsuen Wan as a high-risk zone with large numbers of mosquitoes in the area.

Health Department pest control officer Yuen Ming-chi said all the dengue fever cases had been imported, with East Asia the main source. Most cases detected this year had been imported from Indonesia.

'Hong Kong is likely to face a mosquito menace if we don't keep a clean environment. East Asia is already being infested by the pest and I won't rule out the possibility of passengers bringing mosquitoes to Hong Kong,' he said.

Dengue fever can lead to severe headache and nausea and can progress to the potentially fatal dengue haemorrhagic fever.

Hong Kong's two municipal councils plan to start their annual anti-mosquito drive this month instead of November and run it for three months instead of one.

To monitor the mosquito population, the Health Department set up 800 mosquito ovitraps throughout the SAR. The ovitrap is a plastic cup, sprayed with oil with a white stick inside, which is filled with water.

Mosquitoes, especially those carrying dengue fever are attracted by the colour and lay eggs in the water.

Six hundred traps were installed at the airport to see if mosquitoes carrying dengue fever were being imported.

Department staff collect the traps after two weeks and then conduct laboratory tests.

Of districts tested from April to June, Tsuen Wan was the most severely infested with 35.7 per cent of the ovitraps there laden with mosquito eggs, while in Ho Man Tin, only 6.5 per cent of the traps contained eggs.