Lawmaker claims workers may have been bullied into fiddling with figures Police are questioning Food and Environmental Hygiene Department staff about allegations that they ordered subcontractors to tamper with mosquito ovitraps. They will also examine equipment removed by the department. One in 10 of Hong Kong's 2,000 ovitraps have been tampered with and police are investigating whether criminal intimidation was involved. The ovitraps are used to measure the prevalence of mosquito species that can spread dengue fever and Japanese encephalitis. The monthly ovitrap index fell to zero in several districts at the height of the mosquito-breeding season this summer. Department staff are alleged to have ordered subcontractors to clear the traps to get zero readings. Superintendent Yip Sheung-fung, of the New Territories South regional crime unit, said his officers had interviewed 10 people so far. 'I was told by the hygiene department that the ovitraps had been recovered by them and we are contacting the department to get hold of them to see if there are signs of tampering.' He said it was premature to speculate about when or if arrests would be made. The investigation is centred on Kwai Tsing district, which includes Kwai Chung and Tsing Yi, although areas on Hong Kong Island had also registered zero. On Thursday the legislator for the medical sector, Kwok Ka-ki, said the tampering had dealt a huge blow to public confidence in the government and the department. But last night the permanent secretary for health, welfare and food, Carrie Yau Tsang Ka-lai, hit back and said anti-mosquito operations were carried out all year round regardless of low ovitrap figures in some districts. 'Apart from the ovitrap index, we also look at a basket of factors to monitor the extent of the mosquito problem,' she said. These included information from health authorities of nearby cities or countries and the World Health Organisation; the number of imported and local mosquito-borne disease cases; the number of mosquito complaints; and feedback from district councils. Legislator Fred Li Wah-ming, chairman of the Legislative Council's panel on food safety and environmental hygiene, said pressure from their bosses may have led staff to order subcontractors to tamper with mosquito ovitraps. 'This incident is quite damaging. This is really shocking. I am sure frontline staff are pretty much involved with this one, especially in Kwai Tsing district,' he said. 'My guess is the higher the figure, the more pressure from seniors who question why they're not doing more to keep the figures lower.' Tsing Yi recorded one of the highest ovitrap index levels in May, when it reached 36.5 out of a possible 100. In the next two months that figure dropped to zero; in August it was 1.9. At Kwai Chung, the index was 17.8 in June, 4 in July and zero in August. In nearby Ma Wan, the index was 29.2 in June and zero in July and August; in Lai King the reading was 9.4 in June, 3.6 in July and zero in August. Mr Li said the acceptable threshold was 20 to 25, so when the Tsing Yi figure rose to 36.5 in May, steps were taken to reduce the figure. 'But it was stupid to make it zero. If it was zero in January or February, that could be possible, not in July and August,' he said. The department's website says an index above 20 triggers special mosquito-eradication measures.