As concerns mount in Hong Kong about a dengue fever outbreak, a monthly index measuring the extent of the distribution of Aedes albopictus, which is the main infectious vector of the acute mosquito-borne disease, suggests that warning signs were actually detected last month.
However, the ovitrap index for Aedes albopictus for July was not released until Tuesday this week, suggesting that it has become a lagging indicator to help the government and the public to take precautionary measures, the Hong Kong Economic Journal reports.
In order to strengthen dengue vector surveillance, the Food and Environmental Hygiene Department (FEHD) increased the number of survey areas from 52 to 57 last month, and the survey period has also been extended from one week to two weeks every month.
According to the department, the index rose to 15.7 percent in July from 11.3 percent in June across Hong Kong, meeting the definition of Level 2 by the four-level of infestation of Aedes albopictus and indicating that mosquito infestation was slightly more extensive in the areas surveyed.
A point worth noting is that 13 areas hit the third level of the system with a reading of the Area Ovitrap Index (AOI) of 20 percent to 40 percent below, meaning that infestation of the mosquito exceeds one-fifth of the area surveyed.
They included Tseung Kwan O North (33.3 percent), Tsuen Wan West (29.8 percent), Tuen Mun West (28.7 percent), Kowloon Bay (28.7 percent), among others.
Two areas, Yau Tong in Kowloon East and Wo Che in Sha Tin, even saw their AOI rise above 40 percent, which is defined as Level 4, suggesting that almost half of the surveyed area was infested with the mosquito.
The AOI in Yau Tong was 45.1 percent and the reading in Wo Che was at 42.6 percent, data unveiled by the FEHD showed.
Lui Tung-hai, a member of Kwun Tong District Council, said he has asked the FEHD to step up anti-mosquito works in the district.
Acting Secretary for Food and Health Dr. Chui Tak-yi said on Tuesday, after an inter-departmental Pest Control Steering Committee held a meeting, that his bureau is looking at ways to enhance the efficiency of releasing monthly ovitrap index figures.
Chui added that so far the major sources of dengue fever infection are Lion Rock Park and Cheung Chau.
The FEHD will coordinate with property management companies of private estates near the park to carry out anti-mosquito measures, the official said.
Meanwhile, a campaign will be launched in Cheung Chau to enhance public awareness on the issue of domestic mosquito prevention.
The campaign will kick off in collaboration with the Islands District Council, the Cheung Chau Rural Committee, the Civil Aid Service and the Home Affairs Department, according to Chui.
In related news, the Department of Health’s Centre for Health Protection confirmed on Tuesday that two more people have contracted dengue fever, bringing the total number of local cases to 18 so far this year.
The two new cases were of a 59-year-old man living in Cheung Chau and a 43-year-old woman living in Chuk Yuen (South) Estate in Wong Tai Sin who had visited Lion Rock Park.
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