Health Experts Look for Ways to Fight Spread of Dengue Fever
New York Times, September 1, 2009
KUALA LUMPUR — When Muhammad Fariz Irfan Noordin’s father took him to the University Malaya Medical Center, his blood platelet count was so low that doctors admitted him immediately. The 15-year-old boy had been ill for several days with a fever, headache and vomiting, and he had a rash on his hands and face.
Muhammad was hooked up to an intravenous drip, and nurses constantly monitored his vital signs to ensure that he would not suffer internal bleeding and become another victim of the disease that has already claimed 67 lives in Malaysia this year.
With 28,710 cases reported through Aug. 15, compared with 27,900 for the same period last year, Malaysia is losing ground in its campaign to contain the spread of dengue fever. The government recently announced its “Dengue Strategic Plan, 2009-2013,” an effort aimed at reducing cases 10 percent each year.
But Malaysia, which has continued to record new dengue cases after the end of its peak season, is not alone in its struggle. Sri Lanka has experienced one of its worst outbreaks in recent years, and health officials are waiting to see what will happen once India enters its peak transmission season in September.
“We anticipate this is the beginning of the transmission season for many countries in the region,” said Chusak Prasittisuk, the World Health Organization’s communicable diseases control coordinator for Southeast Asia.
While emerging diseases like influenza A(H1N1), also known as swine flu, continue to dominate the headlines, experts say dengue is not only thriving in many endemic areas, it is also spreading to countries previously unaffected by the disease. Data compiled by the W.H.O. show the number of cases in Southeast Asia surged from 152,448 in 2004 to 242,241 last year. In the Western Pacific region, 213,248 cases were reported in 2008, up from 160,823 in 2004.
The spread of dengue has been facilitated by greater population mobility, combined with urbanization. Both factors have helped the Aedes mosquito carry the virus further afield and infect greater numbers of people. Some also point the finger at global warming, arguing that higher temperatures have increased the number of potential breeding areas for mosquitoes.
“This has been going on now for the better part of 30 years, this global spread of dengue,” said Duane Gubler, director of the Emerging Infectious Diseases program at the Duke-National University of Singapore Graduate Medical School. “You can see it’s a dramatic increase every decade. It can be correlated perfectly with urbanization and modern air travel.”
But health officials are cautiously optimistic that, from a regional perspective, 2009 may not be as severe as previous years.
“From the information we see now,” Dr. Prasittisuk said, “it’s subject to India,” which the W.H.O. includes in Southeast Asia.
He said the decline in cases since 2007 was “a good sign, but we won’t stop. It may not be sustained because of the nature of dengue.” Outbreaks usually fluctuate in two- to three-year cycles, he added.
Historically, dengue has been found in tropical areas, which provide ideal breeding conditions for mosquitoes. But the disease has spread in recent years to countries like Nepal, which reported its first case in 2006. Bhutan recorded its first cases in 2004, and the disease can now be found in seven districts, Dr. Prasittisuk said.
Australia recorded its second death from dengue in a century this year, prompting the authorities in the northeastern state of Queensland to distribute mosquito repellant to schools. Sri Lanka recorded 190 deaths and 18,500 cases since January, more than double the number of cases from last year, according to figures from the Ministry of Healthcare and Nutrition.
There is still no vaccine for the illness, which has earned the nickname “breakbone fever” for the severe headaches and joint and abdominal pain that can accompany it. Although skillful management of the illness — ensuring the patient is well hydrated and monitored for internal hemorrhaging — has markedly brought down the death rate to less than 1 percent of cases in the region, the relentless spread of the disease has raised concerns.
Exposure to one strain of dengue does not confer immunity to the three other main strains, and, in fact, can leave the patient more susceptible to later, more severe, infection.
The urban sprawl found in Asian cities like Bangkok, Jakarta and Manila, where many residents live in substandard housing with poor sewage and water management, provides ample breeding sites for mosquitoes. The increase in air travel in the region has also made it more likely that a person bitten by an infected mosquito can carry the virus to another country.