Urban areas in dengue risk

Saturday, 4 June 2011 00:41 -     - {{hitsCtrl.values.hits}}

IRIN: Last year’s drive to raise awareness of dengue fever in Sri Lanka and reduce the number of places where the mosquito that causes the disease breeds has had some positive impacts but urban areas are still at risk, health experts say.

“In an urban area there are many more places, and number of containers where this particular mosquito can breed compared to less populated rural areas of the country,” Kumari Navaratne, a public health specialist at the World Bank, told IRIN.

Since the beginning of 2009, Sri Lanka has seen high levels of dengue with infections rising to 35,500 from 6,600 in 2008, the Health Ministry’s Epidemiology Unit reported.

In 2009, 346 deaths were reported, an alarming increase from the 28 recorded in 2008. In 2010, 34,105 infections were reported but deaths fell to 241.

Western Province

The Western Province, the island’s most populous region, saw 11,711 infections and 107 deaths in 2010, according to the Health Ministry. Of the 6,225 infections reported by the third week of May this year, about half, according to Government data, were in the Western Province.

Other urbanised regions recorded high infection rates, including the Kandy, Jaffna and Ratnapura Districts; a trend which has continued in 2011.

Urban areas have an abundance of places where mosquitoes breed, including gutters, vases, the water collection units of air conditioners, old tyres, bottles and uneven concrete surfaces.

“In the densely populated areas, there are enough and more of these [places] around,” said Pabha Palihawadana, head of the Epidemiology Unit, adding: “Unfortunately, where there are more mosquito breeding places in urban areas, there are also more people.”

In May 2010 the Government launched a campaign to curb the virus’s spread. With fines of US$ 50-150, health officials visited homes, offices and public areas for random inspections, and the armed forces and police were deployed to clean public areas. When infections began to fall earlier this year, experts at the Epidemiology Unit attributed the slowdown in part to these efforts, but warned that the real test would be once the rains arrived.

Fewer cases this year

During the first three months of this year only 3,078 infections were reported compared to over 12,000 the year before. However, since the monsoon, which began in mid-April, infections have risen to over 3,000.

Though the number of cases in the last two months is about 2,000 fewer than in the same period in 2010, the drop is not as big as that seen in the first three months of the year.

“It is the fines that made people clean up their home or office environment, but they soon forget and the mosquito returns,” said Sudath Peiris, Chief Epidemiologist at the Epidemiology Unit.

The World Bank’s Navaratne attributed the fall in dengue cases in part to guidelines introduced in 2009 on the handling of suspected and confirmed dengue cases in government hospitals.

According to the World Health Organisation (WHO), dengue is the most common mosquito-borne viral disease in humans. Some 2.5 billion people — two fifths of the world’s population — are at risk from dengue, with an estimated 50 million dengue infections worldwide every year.

Sri Lanka is classified as a “Category A” country, which means there are cyclical epidemics in urban areas and dengue is a major public health concern.