As of 10 March, there were 2,261 dengue infections and 24 deaths reported this year, according to the Health Ministry's epidemiology unit. [ http://www.epid.gov.lk/ ] In 2010 there were more than 9,600 infections and 64 deaths in the first two months of the year alone.
Dengue is a mosquito-borne infection that causes a severe flu-like illness, and in about 6 percent of infections a potentially lethal complication.
This is the first time since early 2009 [ http://www.irinnews.org/Report.aspx?ReportID=82256 ] there has been such a substantial drop, noted Pabha Palihawadena, director of the Health Ministry's epidemiology unit. "There is a very definite slowdown in the spread."
Faced with a mounting epidemic in 2010 [ http://www.irinnews.org/report.aspx?ReportId=89404 ] the Sri Lankan government set up an inter-ministerial dengue-fighting task force last May that included three ministries as well as defence and regional public officials.
Military, police and civil defence forces cleaned public areas suspected of being mosquito breeding grounds; dumping rubbish in unauthorized locations became criminal - violators were arrested and fined as much as US$50; public health inspectors visited homes [ http://www.irinnews.org/Report.aspx?ReportID=90182 ] and offices in search of potential breeding spaces.
Owners of buildings and homes found to be "repeat violators" faced fines of up to $150.
"It was punitive action that really put an end to human induced breeding areas," said the Health Ministry's chief epidemiologist, Sudath Peiris.
Dengue infections are highest in urban areas due to human-made breeding spaces, he explained. "Once we got the people to clean them [breeding spots] continuously, the spread slowed."
World Health Organization (WHO) dengue scientist Raman Velayudhan said aggressive cleaning campaigns do make a difference - as long as they are done correctly and are proven to reduce the mosquito population. "There must be a correlation [between cleaning and vector control]. The government should be monitoring the [mosquito] larvae and pupae population."
He said this can be done by counting breeding spots in and around houses known as "containers".
"It is not just about looking for breeding sites, but also targeting the most productive ones," he advised. "An unused tyre may have hundreds of larvae versus a small coconut shell."
Schools island-wide spread the word about dengue, and private businesses sponsored campaigns in newspapers, radio and TV. [ http://www.irinnews.org/report.aspx?Reportid=90182 ]
"It was a concerted effort," the Health Ministry's Palihawadena said.
By the time the task force was formed, dengue had spread to what officials recognized as "dangerous levels".
In 2009 there was a sudden spike in dengue infections when the country recorded 35,500 infections and 346 deaths, versus the previous year's 6,600 infections and 28 deaths.
Local research has been inconclusive as to the reasons for the outbreaks. [
WHO scientist Velayudhan said spikes and declines in dengue outbreaks are in part due to which of the disease's four different strains may be circulating - and whether it finds a home. "If there are no breeding grounds, transmission is halted. But the threat of new serotypes always exists."
No matter the cause, now that the epidemic is under control, vigilance should not be eased, say doctors. "It is still too early to feel we are in the clear," Palihawadena said.
The next test will come with inter-monsoon rains in late March followed by the monsoon season in mid-June, she added.
The Health Ministry plans additional national awareness projects with village- level environmental officers gearing up to search for breeding areas. A national dengue prevention week is scheduled for the week of 23 March, to be repeated every three months.