HEALTH: WHO Raises Alarm Over Dengue Fever Outbreak

By Marwaan Macan-Markar Reprint | | Print |

Marwaan Macan-Markar

BANGKOK, Sep 30 2001 (IPS) - The monsoon rains lashing through south- east Asia and the Pacific have raised fears among public health authorities that the region may witness a rapid increase in dengue fever cases this year.

The concerns have been fuelled by two factors: the reported deaths due to dengue since May and a lack of a continuous mosquito control programme in most of the affected countries.

Cambodia is among the countries worrying authorities at the World Health Organisation (WHO). By the end of July, it had 4,136 dengue cases reported and 90 deaths due to dengue fever. The disease had infected many in rural areas this year unlike before, where most cases were detected in Phnom Penh, the capital.

Other countries singled out by the WHO’s Western Pacific regional office include Singapore, Malaysia, the Philippines, and the Pacific- island nations French Polynesia and Samoa. In Singapore, for instance, there were 1,334 cases of dengue fever reported by the end of July, as opposed to 673 cases reported for all of 2000.

In Malaysia, there were “a total of 4,464 serologically confirmed cases and 26 deaths,” states a WHO note, and in the Philippines there were 7,697 cases, including 67 deaths, reported by end July.

In the Pacific, French Polynesia has experienced a major epidemic that started in January and has already resulted in an estimated 28,600 cases with four deaths reported, reveals the WHO.

“This year, the dengue problem is worse than in 1999 or 2000 but not as severe as 1998, which was an unusually bad year,” says Dr. Kevin Palmer, the regional adviser in vector-borne and parasitic diseases at the WHO’s Western Pacific office.

“Distribution of the disease is similar to that seen in previous years but some areas, especially French Polynesia, are experiencing particularly severe outbreaks this year,” he said.

According to the WHO note, some 356,544 cases were reported in 1998, 64,066 cases in 1999 and 45,603 in 2000.

A lack of regular mosquito control programmes has contributed to this year’s rapid spread of dengue, adds Dr. Palmer. “Most countries do nothing to control the Aedes mosquitoes until an outbreak hits and then it is too late.”

And even those who have a continuous mosquito control policy are not immune to outbreaks. “Singapore is one of the best examples where vector control is an ongoing activity, but they still have outbreaks, demonstrating that even the best preventive measures we have cannot totally prevent the dengue outbreaks,” he affirms.

In Cambodia, on the other hand, ‘Operation Mosquito Blitz’ is credited for protecting Cambodians living in high-risk areas, states Dr. Stefan Hoyer, a WHO project officer for malaria and dengue control in Phnom Penh.

If governments are serious about mosquito control efforts, combined strategies have to be initiated, says Basil Rodriques, regional immunisation officer at the United Nations Children’s Fund (UNICEF) East Asia and Pacific office. “This requires the full participation of communities to remove water sites which act as a breeding ground for the mosquito.”

“This must also be coupled with intensified awareness efforts to ensure individual responsibilities for the control programmes to work,” he adds.

What largely prevails currently is “space spraying of insecticide to kill the flying mosquito,” says. Dr. Palmer. “Unless it is done properly, this type of control measure is not effective and turns out to be a waste of money.”

He is more in favour of mosquito control efforts that “focus on the identification of containers where the vectors breed and then eliminating those containers rather than spraying insecticide in a random way.”

The WHO is also urging affected countries and those vulnerable to a dengue fever epidemic to intensify laboratory testing “in order to detect potential outbreak areas quickly and to implement epidemic control measures”.

What worries UNICEF is the impact the dengue outbreak will have on children, since the dengue mosquito is often present during the day, from early mornings to late afternoons, which are the hours children play outside.

“Children are especially vulnerable,” says Rodriques. “This is different for example from the Malaria mosquito that tends to bite when it is dark. During those times, the use of bednets is effective.”

The WHO wants mothers to be roped into child-care efforts, which require early detection and immediate treatment to prevent deaths from the disease. “Mothers should be alert to the dangers of dengue and be encouraged to take any child with fever for treatment.”