Phnom Penh Uses Sprays To Combat Rising Tide of Mosquitoes

Phnom Penh health officials on Tuesday completed a month-long mosquito abatement program after observing a rise in the early dry season mosquito population in the capital, the director of the Municipal Health De­partment said Wednesday.

Dr Veng Thai said a $30,000 in­sec­ticide-spraying program focus­ed on eradicating mosquitoes in 30 communes in four of Phnom Penh’s districts. The spraying had successfully reduced the city’s mosquito population, he said.

Though an increase in the mosquito population prompted the program, the increase was more significant among mosquitoes that do not carry dengue fever than among those that do, Veng Thai said.

However, in a notice dated Feb 14, Phnom Penh Governor Kep Chuk­­tema warned city residents to be­­ware of the dengue-carrying Ti­ger mosquito. He said the city had “ob­served an un­usual increase in the num­ber of mosquitoes that can cause dengue fever” and would spray for the insects in districts where they were prevalent.

Though the spraying has been halted, officials are determining whether it needs to continue, according to Veng Thai.

In his Feb 14 notice, Kep Chuk­tema also asked authorities to provide security for mosquito abatement workers and advised Phnom Penh residents to clear bushes grow­­ing outside their houses.

Kep Chuktema also called on the Ministry of Public Works to un­block the Phnom Penh sewer system to deprive mosquitoes of breed­­ing grounds.

The abatement program in­volved diesel fuel being mixed with con­centrated Mostyn-brand insecticide and the solution being spray­ed through hand-held de­vices, Veng Thai said.

According to one insecticide manufacturer’s Web site, such ap­plications are best in “dense foliage, closely stacked ware­houses, narrow alleys and crowded housing, tents or market stalls.”

Before spraying, workers play­ed a recorded announcement tell­ing residents to open their windows but cover food, Veng Thai said.

Last year, there were 9,040 re­ported cases of dengue fever in Cam­­bodia, of which 155 were fatal, said Dr Ngan Chan Tha, vice-director of the Health Ministry’s Nation­al Malaria Center and director of the dengue control program.

Compared to figures in 2004, he said, the 2005 statistics represented an overall drop of 947 cases of dengue fever but a rise in the mortality rate from 0.9 percent to 1.7 per­cent. But only a small percentage of dengue fever cases are be­lieved to be reported to medical authorities.

The fatality rate among dengue fever suffers, in most countries where the disease is present, is five percent, according to the US Cen­ters for Disease Control and Pre­ven­tion. Symptoms after a first in­fection can include body and head­aches, fever at temperatures up to 41 degrees Celsius, abdominal pains, vomiting and skin rash, Ngan Chan Tha said.

A “secondary infection” can cause hemorrhagic fever, which can be lethal, he said.

Hemorrhagic symptoms include bruising easily and other forms of skin hemorrhage, bleeding in the nose and mouth and sometimes internal bleeding, according to the CDC. Permeable capillaries allow blood fluids to leak out of the body, and this can lead to a state of shock as well as the failure of the circulatory system.

“In Cambodia, we observe that [people of ages] from zero to 15 years are most affected,” Ngan Chan Tha said.

No medication to treat the disease has been discovered.

 

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