Health officials expressed concern on Tuesday that abnormally high numbers of dry season dengue fever cases may indicate an imminent wet season outbreak.
The National Dengue Control Program recorded 1,644 cases of dengue and 27 deaths between January and April 2003, the first 18 weeks of Cambodia’s dry season. More than 60 percent of the cases were recorded in densely populated Phnom Penh and Kandal and Kompong Cham provinces. In 2002, 762 cases were recorded in the same period.
“This could be the precursor to a rainy season outbreak,” said Dr Chang Moh Seng, vector control scientist for the Ministry of Health and the World Health Organization.
This is the second dry season dengue outbreak in Cambodia’s recorded history, Chang Moh Seng said. The last dry season dengue epidemic occurred in 1998, when 1,933 cases were recorded between January and April. The National Dengue Control Program recorded a total of 16,216 cases and 475 deaths over the course of the year.
This year’s high numbers are noteworthy, as the mosquito-borne disease normally reaches its peak during the wet season, Chang Moh Seng said. Dengue outbreaks also generally occur in two- to three-year cycles, and health officials determined 2002 to be Cambodia’s normally scheduled outbreak, with 12,441 cases and 153 deaths, he said.
No concrete data exists to explain why more dengue cases erupted in this year’s dry season than in previous years, but Chang Moh Seng said intermittent rainfall and a change in the dengue virus may be contributing factors. Increased numbers of cases may also reflect increased surveillance, he said.
Dengue outbreaks could occur more often, Chang Moh Seng said, unless preventive measures are taken to stop mosquitoes before they start biting.
Twice a year, the Ministry of Health and the WHO conduct mass distributions of a non-toxic pesticide to be used in the water jars of densely populated areas with high dengue rates. This year’s first round of distributions will begin May 19 in 15 provinces, covering more than 700,000 households and 3.8 million people, Chang Moh Seng said.
“We can prevent against a massive outbreak but we’re worried about a rural area outbreak,” he said.
Households without pesticide protection should clean their water jars each week to prevent mosquitoes from breeding, Chang Moh Seng said.