In Cambodia, dengue is endemic and a big cause of hospitalisation and death among children. It also causes illness in adolescents and adults.
The World Health Organization estimates there are 50 million cases of dengue infection each year. About 250,000 individuals a year manifest the severe forms, which have a mortality rate of about 10 per cent.
Given the dramatic geographic expansion of epidemic dengue fever and dengue haemorrhagic fever, the WHO has classified dengue as a serious international public health concern.
Dengue, a viral disease, is transmitted to humans by daytime-biting female Aedes mosquitoes. Most common of the Aedes mosquito species is Aedes aegypti, which rests indoors and can breed in small collections of water.
The local name for dengue is “krun chheam”, which translates as “haemorrhagic fever” in English.
The incidence of dengue rises at the beginning of the rainy season, because of the increase in the mosquito larva population.
Cambodian mothers are well aware of the risks during the dengue season. They also know very well the devastating effects on their poor households brought about by dengue.
Dengue fever affects not only the sick child but also household members who provide care to the patient.
In addition, a dengue episode with an average duration of less than a week results in twice as many days of paid employment lost by household members while they stay full-time with the patient while he or she is hospitalised, and look after the patient at home during the rest of the illness.
Many poor households will be burdened by large out-of-pocket spending on medical and non-medical items and income lost from days when they did not work.
To cope with these financial challenges, it will come as no surprise that the majority of these households have to borrow money or sell some of their assets.
In most countries, including Cambodia, top-down and pesticide-dependent approaches have failed to curb the spread of dengue.
During dengue outbreaks, public demand for action often leads to pesticide spraying. But this is unlikely to be effective, as pesticide released in the streets is unlikely to reach the adult mosquitoes resting and feeding inside homes.
There is no specific medication for dengue, but the best intervention would be the availability of a vaccine.
Unfortunately, vaccine development, although in the research pipeline, is complicated because the vaccine needs to be effective against all four types of the dengue virus.
In the absence of a vaccine and specific treatment, prevention is the key.
Prevention strategies require community involvement supported by local infrastructure, and must lead to sustainable practices that motivate community members to participate in dengue-control measures.
Because of the domestic habitat and behaviour of Aedes mosquitoes, most preventive measures in which community members are urged to be involved are relatively straightforward: maintaining safe water storage indoors and outdoors to prevent breeding; ensuring there are no pools of stagnant water; and careful disposal of hard waste.
Large domestic water-storage containers constitute more than 80 per cent of Aedes aegypti larval habitats.
One low-cost, community-based intervention for dengue control is the distribution of mosquito larvae-eating guppy fish to households for release in these jars.
This is being done successfully in Kampong Speu province, using a community-based model with village meetings, education and recruitment of unpaid volunteers for guppy breeding and distribution.
Because of this success, the National Dengue Control Program plans to scale up this model to other provinces.
Although the larvicide Abate has been used since 2001, reducing the number of dengue cases, it is viewed as an interim measure because of its high cost, dependency on donor support, the low level of community participation and the prospect of mosquitoes developing a resistance to insecticide.
Within ASEAN, there is an urgent need to harmonise dengue surveillance systems. Nearly every country has suspected dengue cases, but in Cambodia dengue surveillance is conducted only among children younger than 15.
Dengue is not only a public-health emergency but a heavy socio-economic burden on the poor.
But it is preventable, and the war against dengue is a people’s war that can be won if we pledge to fight this disease in a united, co-ordinated manner and involve communities all the way.
Dr Pieter JM Van Maaren is a representative of the WHO in Cambodia.