“This rise is mainly due to weather patterns,” Sudath Peries, deputy chief epidemiologist at the Epidemiology Unit of Sri Lanka’s Ministry of Health, told IRIN.
Containers or hollows where stagnant water can accumulate provide breeding grounds for mosquitoes, promoting the spread of dengue. “If there are heavy rains and flooding, dengue breeding grounds will likely be washed away,” said Sumanasiri Gamage, an independent health worker. “However, due to intermittent rains, the breeding continues.”
According to the World Health Organization (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 fever, with an estimated 50 million infections worldwide every year.
The Epidemiology Unit said 9,317 dengue cases and 38 deaths were reported in the first three months of 2012, against 3,103 in the first quarter of 2011.
The highest number occurred in January, when 3,892 cases were reported, followed by 3,004 in February and 2,421 in March.
Local media reported that over 50 percent of dengue cases occurred in the country’s Western Province, where most of the island's 20 million inhabitants live.
Sri Lanka’s meteorological department forecasts that intermittent rains are likely to continue until late April. Heavy rainfall usually occurs during the southwest monsoon (May to September) and during the northeast monsoon (September to January).
Gamage said the public should remain vigilant against the risk of dengue even though there was a downturn in the number of cases in 2011, when 28,473 cases and 185 deaths were reported, compared to 2010 when there were 34,105 recorded cases and 245 deaths.
Health officials agree that removing mosquito breeding sites is the most important step in mitigating risk. In May 2010 the government launched a campaign to curb the spread of the disease.
Fines of US$50-$150 were instituted, and health officials carried out random inspections of homes, offices and public areas, while the armed forces and police were deployed to clean public areas.
Sri Lanka is classified as a “Category A” country by WHO, which means dengue fever is a leading cause of hospitalization and death among children; there are cyclical epidemics in urban areas; and the virus is a major public health concern.
Three other countries in Southeast Asia share this classification: Thailand, Indonesia and Timor-Leste.