Microcrustaceans defeat dengue fever

Oct 22 2004

Dengue fever causes 50 million infections annually in more than 90 countries; however this may soon become a thing of the past, as QIMR broadens its successful and totally environmentally-friendly mosquito-breeding control programs against dengue fever.

Using tiny micro-crustaceans called copepods, scientists at QIMR have, in a world-first, successfully eliminated the breeding of dengue-carrying mosquitos in 42 Vietnamese communities (of 46 communities trialed). Professor Brian Kay, Laboratory Head of Infectious Diseases and Immunology at QIMR, says that as a result, no cases of dengue fever have been reported in any of these communities since 2001.

The copepods prey on mosquito larvae, particularly the aedes aegyptii mosquito which is the major carrier of dengue fever. QIMR scientists believe this cost-effective model of mosquito control is applicable to other Asian countries, where the major sources of aedes aegyptii are large water storage containers. This method of mosquito control uses natural predators rather than insecticides, thereby reducing the effects of harmful chemicals. The results speak for themselves as the field trials in Vietnam to date have protected more than 400,000 people from dengue fever. The World Health Organisation has acknowledged this program as one of the most successful ever implemented. Reflecting on the program, Professor Kay said, "The major reason for the success of the copepod trial is because it has been embraced by local health personnel and the communities themselves who have been active in the control program."

Each year, there are more than 12,000 deaths related to dengue and in Vietnam it is one of the biggest killers of children under the age of 5. The spread, incidence and severity of dengue fever and dengue haemorrhagic fever are increasing in the Americas, South-East Asia, the Eastern Mediterranean and the Western Pacific. This means that some 2.5 billion to 3 billion people live in areas where dengue viruses can be transmitted

Australia regularly has outbreaks of dengue fever but because most people have piped water, breeding is mainly associated with backyard rubbish, saucers under pot plants etc. However, successful trials have been run at Charters Towers in wells and manholes and in Townsville in underground service manholes. In Cairns where dengue occurs regularly, the underground service manhole system has natural populations of copepods which keep the mossies at bay.