Dengue is a tropical disease (caused by a virus with four separate serotypes) which is transmitted by the bite of an infected mosquito. It is a growing epidemic. The vast majority of cases are found in the Asia Pacific region, but Aedes mosquitoes, which transmit dengue, have expanded into areas including Australia, the United States, southern Europe and Africa.
Dengue starts with a fever that lasts for about seven days, and is accompanied by headaches and muscle or bone pain. Symptoms of moderate dengue include nausea, vomiting, pain in the eyes and rashes on the upper and lower limbs. Of the 390 million cases of dengue annually, a small proportion develop into severe dengue, which can lead to death.
Dengue is the most common arboviral disease (a group which includes chikungunya and Zika), with 40 percent of the world’s population living in areas with dengue virus transmission.
Treatment and prevention
There is no specific treatment available, so timely interventions are crucial for saving lives. Severe forms of dengue include dengue haemorrhagic fever, characterised by low blood counts and bleeding, and dengue shock syndrome, characterised by low blood pressure, which can lead to death. For these cases, intravenous fluids and blood transfusions are the required courses of treatment.
Severe dengue is most commonly found in Asian and Latin American countries, although it is beginning to spread to new areas. With quick and effective treatment fatality rates are below one percent of cases; but the rapid growth of dengue, particularly in urban and semi-urban areas, means that the disease has become a major international public health concern.
Due to similarities in symptoms between dengue and malaria, there is often confusion when diagnosing and effectively treating dengue. The most rational and effective approach is to prevent the transmission. This is complicated as the mosquitos carrying the dengue virus bite mainly during the day so the use of mosquito nets at night does not provide adequate protection. Killing the mosquito or preventing it from breeding are the most effective approaches to control. Working with communities to develop and sustain dengue vector control measures is an area that we have been focusing on in our work in Asia.
Increased surveillance and management of outbreaks of dengue will help to reduce mortality rates and so community seminars promoting training and early treatment are also effective tools. Research into better control and treatment options is also underway, including the development of improved diagnostics and antiviral medications. There is a vaccine available but it is not suitable for children below the age of nine or adults above 45 years. Other vaccines are in development.
We have been working in Cambodia, Myanmar and Thailand, implementing these preventive strategies as well as using innovative vector control programmes to combat the rise of dengue fever. We produced an advocacy brief on dengue in 2016 highlighting this growing health concern.
For more on dengue, visit the WHO page here.