Dengue is the most common mosquito-borne viral disease and in recent years has become a major international public health concern, according to the WHO.
Dengue viruses infect around 390 million people a year. Most of those affected live in Asia, Africa and Latin America. However, the disease is now also spreading to non-tropical countries. The number of people living in the over 150 countries at high risk from dengue fever has been estimated at 3.9 billion – around half the world’s population.
In addition, millions of travellers to those areas are also at risk of being bitten by the disease carrying mosquitos.
Symptoms include fever, headache, pain behind the eyes, muscle and joint pain, and rash. People affected by the disease often experience long-term fatigue. Dengue is a major cause of hospitalisation in countries where it is endemic.
Most people recover well but infection can occasionally develop into a life-threatening form known as severe dengue which causes abdominal pain and vomiting, along with breathing difficulty and internal bleeding.
Dengue fever was first identified in the 1950s during epidemics in the Philippines and Thailand with nine countries reporting outbreaks by 1970. The number of cases has increased more than fourfold since then and continue to grow.
Transmitted mainly by the Aedes aegypti mosquito, there are four distinct, but closely related, viruses that cause dengue. Recovery from infection by one provides lifelong immunity against that serotype but confers only partial and transient protection against subsequent infection by the other three. There is good evidence that sequential infection increases the risk of more serious disease resulting in DHF.
Vector control i.e. killing the infested mosquitos, has been the primary method of disease control. The first vaccine against dengue is now approved in Mexico, Brazil and The Philippines.