Dengue fever is caused by the dengue virus which is spread by the bite of infected mosquitoes: usually of the species Aedes aegypti. Dengue virus is the commonest mosquito-borne pathogen of humans and its transmission has been recorded in more than 130 countries. It causes an estimated 400 million human infections annually – predominantly in the Asian tropics. Approximately 20,000 people die from the disease each year and its burden on the public health system and on the finances of affected families is substantial ($10 billion USD per annum globally). There are four types of dengue (serotypes 1-4) and although infection with one gives lifelong immunity to that form, subsequent infection with different serotypes can increase the risk of developing severe forms of the disease.
Typically, symptoms occur 3-14 days after a susceptible human is bitten and include fever, headache, vomiting, muscle and joint pains, and a rash. In most people, the virus persists for a few days and a full recovery is made within weeks but a small percentage of cases result in internal haemorrhaging and even death.
There are no cures for dengue. Patients are treated with pain killers to control muscle and joint pain. In severe cases, intravenous drips and transfusions may be required to maintain fluid volumes and replace lost blood or plasma. A vaccine for dengue fever (Dengvaxia®) took 20 years to develop at a cost of more than $1.5 billion USD but it is just 60% effective and can only be administered to individuals who have been previously infected with dengue and that are between 9-45 years of age.
Globally, the management of dengue remains reliant on the control of its vector: Aedes aegypti. This mosquito is remarkably well-adapted to urban landscapes and females rely on human blood for all of their nutritional needs. Aedes aegypti can cause dengue outbreaks even when their numbers are low so contemporary dengue vector control programs have been largely unsuccessful at preventing disease epidemics or slowing the geographic expansion of the mosquito. Moreover, many insecticide-based control programs are threatened by the evolution of resistance.
There is a tremendous need to develop new, more efficient, resistance-proof tools for vector control.