Dengue is a serious disease in the tropics and subtropics which is caused by viruses transmitted by mosquitoes. The Centers for Disease Control and Prevention writes that with greater than one-third of the world’s population living in areas at risk for transmission, dengue infection is a leading cause of illness and death in the tropics and subtropics. The Asian Development Bank reported in a news release on Sept. 12, 2013, "Guppy Fish Proven to Be Cheap, Effective Tool in Fight against Dengue."
According to a trial study done by the Governments of Cambodia and the Lao People’s Democratic Republic with support from the Asian Development Bank (ADB) and the World Health Organization (WHO), larvae-eating guppy fish can help combat the spread of dengue. This is significant in view of the fact that there hundreds of thousands of severe cases including 20,000 deaths worldwide every year.
In this study conducted in two districts in Cambodia and the Lao PDR from 2009 to 2011, there was a sharp decline in mosquito larvae in water storage tanks after the tiny fish were introduced. Guppies have been found to eat larvae which grow into mosquitoes, and which in turn bite humans and transmit dengue. ADB health specialist Gerard Servais has said, “This is a low-cost, year-round, safe way of reducing the spread of dengue in which the whole community can participate.”
At the present time there is no vaccine or any specific medicine to treat this viral disease. There are about 2.5 billion people worldwide at risk of contracting dengue, with more than 70% living in Asia and the Pacific. The threat of exposure to dengue carrying mosquitoes has been rising with uncontrolled urbanization coupled with a surge in the use of non-biodegradable packaging, which often acts as a water reservoir for dengue mosquito breeding.
A specific mosquito that breeds readily in standing water spreads dengue. Storage containers, flower pots and discarded tires offer such reserviors for the growth of mosquitoes, and guppies have been found to be particularly effective in these settings. Widespread grassroots participation was seen with this project with high levels of acceptance of guppy fish seen as an effective way of reducing the spread of dengue.