Guppy fish could be used to fight dengue fever

Larvae-eating guppy fish could be used as a cheap and effective tool in the fight against dengue, a mosquito-borne disease that causes 20,000 deaths worldwide each year, according to a recent trial study.

The Lao People's Democratic Republic and Cambodia conducted the trial study with the support of the Asian Development Bank and the World Health Organization. The researchers found that there was a sharp decline in mosquito larvae in water storage tanks after the tiny fish were introduced. Guppies eat larvae that grow into mosquitoes and can transmit dengue and other diseases by biting humans.

"This is a low-cost, year-round, safe way of reducing the spread of dengue in which the whole community can participate," Gerard Servais, a health specialist with ADB, said. "It offers a viable alternative to using chemicals and can reduce the scale of costly emergency response activities to contain epidemics."

The study found that guppies do not harm water quality and can survive on microscopic organic material in the absence of mosquito larvae. When the project closed in Cambodia, approximately 88 percent of the storage containers contained guppies. There were guppies in 76 percent of the containers in Lao PDR at the project's close.

"The project was successful in mobilizing communities with widespread grassroots participation, and high levels of acceptance of fish as an effective way of reducing the spread of dengue," Eva Christophel, a vector-borne diseases specialist with the WHO, said. "This project was an important contribution to WHO's efforts to develop a toolkit of different community-based methods to prevent and reduce the magnitude of dengue transmission."

Dengue causes severe joint and muscle pain, headache, high fever and rashes. The disease is fatal in a small number of cases. Approximately 2.5 billion people worldwide are at risk of contracting dengue. Dengue can be spread by mosquitoes that breed easily in standing water, such as found in discarded tires, flower pots and storage containers.