Dengue fever is ranked by the World Health Organization (WHO) as the most critical mosquito-borne viral disease in the world - and the most rapidly spreading - with a 30-fold increase in global incidence over the past 50 years. Dengue - the World Mosquito Program’s primary focus when it first began its research - continues to be a threat to global health.

More than 40 percent of the world’s population, in more than 100 countries are at risk of dengue infection. The most significant dengue epidemics in recent years have occurred in Southeast Asia, the Americas and the Western Pacific. Each year, an estimated 390 million dengue infections occur around the world. Of these, 500,000 cases develop into dengue haemorrhagic fever, a more severe form of the disease, which results in up to 25,000 deaths annually worldwide.

Dengue is a human virus transmitted primarily by the mosquito Aedes aegypti, which is commonly found around homes and workplaces. The transmission cycle for dengue is human - mosquito - human. The World Mosquito Program’s research has shown that when Wolbachia is introduced into the mosquito, it reduces its ability to transmit dengue between people, as well as other Aedes aegypti-borne diseases such as Zika, chikungunya and yellow fever.

Dengue viruses can be grouped into four serotypes, all of which can cause disease in people. Prior infection with one dengue serotype is believed to make people more likely to develop dengue haemorrhagic fever (DHF) in later infections with any of the other serotypes.

There is no specific medical treatment for dengue, although a vaccine is currently being trialled and others are in development. Our research has shown that in areas where high levels of Wolbachia are present, we have not seen any dengue outbreaks.