Ultraviolet 'zappers' can be used to kill mosquitoes

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UN Peacekeepers who were plagued by malaria in West Africa reduced their infection rate to zero with a new approach.

The Chinese peacekeeping unit was posted to Zwedru, a city in southeast Liberia. Malaria is widespread there, with year-round transmission.

Previous units deployed to the Chinese hospital in the city contracted malaria despite the usual precautions of bednets, indoor spraying and antimalarial drugs. After more than three quarters of the 43 members of one unit contracted the disease, the next unit to arrive decided to implement the extra measure.

Unit members erected electric housefly killers, designed for indoor use, under the eaves of their houses, which were positioned in a circle around a courtyard. They switched the machines on an hour before dusk and they remained live until morning.

The machines lure flying insects with ultraviolet light and then kill them on contact with a high-voltage burst. The four machines, arranged around the 2,000 square-metre area, killed "a huge number of insects, most of them ants and unknown flies and lots of mosquitoes, each day," scientists reported.

Health for the unit was transformed — not one of its members fell victim to malaria in the eight-month posting. Two months after leaving Liberia they were still malaria free, according to Lihua Song, a researcher at the Beijing Institute of Microbiology and Epidemiology.

"Even though it is specifically noted in the instruction booklets of these apparatuses that they are not suitable for outdoor use, our eight months of practice demonstrated that they can also attract and kill mosquitoes in the outdoors," the scientists wrote in the journal, Clinical Infectious Diseases.

The approach appeared to be environmentally friendly as well as cheap and easy to use, the authors say, though they caution that "...countless ants and unknown flies were also killed each day, but how the local ecology will be affected cannot be known in a short time".

Song questioned, however, whether the devices would work in more open areas.

"I think [the device] could work just outside a mud hut. But if a person lives in a mud hut, can he afford to buy the device and enough electric power?" For now, Song recommends the use of 'mini electric mosquito-killing devices', which cost just US$1.50 rather than the original machines, which cost about US$12 each.