Novel control of Dengue fever

August 24, 2011

The spread of Dengue fever in northern Australia may be controlled by a bacterium that infects mosquitoes that harbor the virus, Australian and U.S. researchers report Aug. 25 in two papers published in the journal Nature.

The result grew out of work more than 20 years ago by population biologist Michael Turelli, professor of evolution and ecology at UC Davis, and Ary Hoffmann, now at the University of Melbourne, Australia, who are among the coauthors of one of the new Nature papers.

Turelli and Nick Barton of the Institute of Science and Technology, Austria, also describe the mathematical basis of the elimination project in a paper to be published in the journal in September.

Dengue fever is caused by four spread by the mosquito . The disease causes and has been called "breakbone fever" because of the joint aches and muscle pains it causes. Dengue viruses can also cause a potentially fatal disease, dengue hemorrhagic fever, in people who have previously been infected with a different strain of the virus.

Dengue viruses are found throughout the tropics and and appear annually in . The researchers released infected with the bacterial parasite Wolbachia, which suppresses the virus, and now report that the Wolbachia parasite spreads rapidly through the wild mosquito population.

"The results show we can completely transform local populations in a few months," Turelli said.

Wolbachia is transmitted by to their offspring. A pair of infected mosquitoes produce slightly fewer eggs than an uninfected couple, but when an infected male mosquito mates with an uninfected female, she produces no eggs at all. That provides a big reproductive advantage to the spread of Wolbachia-infected mosquitoes, generation by generation.

"It's natural selection on steroids," Turelli said.

It turns out that Wolbachia also suppresses various other microbes living in the same mosquito – including the dengue virus. As these virus-resistant mosquitoes spread through the wild population, dengue transmission should dry up.

Turelli and Hoffmann first described what turned out to be Wolbachia spreading among Drosophila flies in California's Central Valley in 1991, and Barton developed much of the relevant mathematics in the late 1970s while trying to understand the genetics of grasshoppers in the French Alps. That basic research by Turelli, Hoffman and Barton provides the biological and mathematical basis for the dengue control strategy.

"At the time, none of us expected that this original research might contribute to human health. This is very exciting, once-in-a-lifetime opportunity," Turelli said. "We never thought this would turn into an eradication project."

The mathematics is complicated because when Wolbachia is rare, its spread through an insect population is disadvantaged because infected couples lay fewer eggs than uninfected. However, once the frequency of the infection crosses a certain threshold, there is a strong advantage to its spread.

Originally, Turelli and other researchers lead by Scott O'Neill at the University of Queensland, funded by the Bill & Melinda Gates Foundation, tried to use Wolbachia to shorten the lifespan of Aedes so that the virus would not have the 12 days necessary to develop. However, that approach seems unlikely to work, based on the mathematics of the spread of that type of Wolbachia.

Instead, the team found that Wolbachia itself suppresses certain viruses. The Gates Foundation is providing further funding to support release of infected mosquitoes in Australia, Vietnam and Thailand.

Explore further: Wolbachia bacteria reduce parasite levels and kill the mosquito that spreads malaria

Related Stories

Wolbachia bacteria reduce parasite levels and kill the mosquito that spreads malaria

May 19, 2011
Wolbachia are bacteria that infect many insects, including mosquitoes. However, Wolbachia do not naturally infect Anopheles mosquitoes, which are the type that spreads malaria to humans. Researchers at the Johns Hopkins Bloomberg ...

Recommended for you

Scientists develop infection model for tickborne flaviviruses

August 22, 2017
National Institutes of Health (NIH) scientists have filled a research gap by developing a laboratory model to study ticks that transmit flaviviruses, such as Powassan virus. Powassan virus was implicated in the death of a ...

Zika virus stifles pregnant women's weakened immune system to harm baby, study finds

August 21, 2017
The Zika virus, linked to congenital birth defects and miscarriages, suppresses a pregnant woman's immune system, enabling the virus to spread and increasing the chances an unborn baby will be harmed, a Keck School of Medicine ...

Fatty liver can cause damage to other organs via crosstalk

August 21, 2017
Nonalcoholic fatty liver disease is increasingly common. Approximately every third adult in industrialized countries has a morbidly fatty liver. This not only increases the risk of chronic liver diseases such as liver cirrhosis ...

Novel approach to track HIV infection

August 18, 2017
Northwestern Medicine scientists have developed a novel method of tracking HIV infection, allowing the behavior of individual virions—infectious particles—to be connected to infectivity.

Faulty gene linked to obesity in adults

August 18, 2017
Groundbreaking new research linking obesity and metabolic dysfunction to a problem in the energy generators in cells has been published by researchers from the Harry Perkins Institute of Medical Research and The University ...

Two lung diseases killed 3.6 million in 2015: study

August 17, 2017
The two most common chronic lung diseases claimed 3.6 million lives worldwide in 2015, according to a tally published Thursday in The Lancet Respiratory Medicine.

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.