The monthly ovitrap index has risen from the 0% in March to 3.4% in April, the Food & Environmental Hygiene Department says, adding 18 of the 38 areas surveyed have recorded positive Area Ovitrap Index.

The department's consultant Dr Ho Yuk-yin today said in Pok Fu Lam, an area ovitrap index of 22.6% was recorded, the first time this year an area index reading fell under the alert zone, that is, between 20% and 40%.

Other areas with higher readings were Tai Wai (19.2%), Fanling (11.3%), Yuen Long Town (10%), Tai Po North (9.8%), Tin Shui Wai (8.9%) and Wong Tai Sin Central (8.1%).

"As for the port areas, the ovitrap index has also risen slightly from 0% to 0.2%," Dr Ho said.

Mosquito alert

"The situation in these areas clearly reflects the volatility of mosquito problems. Any lapse in mosquito control could contribute to a rise in the ovitrap index."

Concerning the department's year-long Japanese encephalitis vectors survey, Dr Ho said specimens of adult Culex tritaeniorhynchus, a known JE vector commonly found in Hong Kong, were recently collected in Yuen Long, Tuen Mun, Sai Kung and North District.

"However, no JE virus was detected in the specimens examined. Nevertheless, we have strengthened mosquito control action in the areas concerned and provided technical support to other departments and organisations involved in operations against mosquito breeding," he said.

Preventive measures

Dr Ho reminded the community to take prompt measures to remove potential mosquito breeding grounds. They include:

*scrubbing vases and pot plant saucers at least once a week;

*properly disposing of containers such as soft drink cans and lunch boxes;

*clearing drains and surface channels to prevent blockage;

*removing stagnant water;

*filling up all defective ground surfaces; and

*drilling large holes in unused tyres.

For detailed ovitrap indices and information on anti-mosquito measures, visit the department's website or call 2868 0000.