Closer to eradicate Dengue

[Tonka]

http://www.abc.es/salud/noticias/cerca-erradicacion-dengue-9985.html
Spanish to English translation

Closer to eradicate Dengue

A new way to control dengue, a disease according to World Health Organization (WHO) would affect more than 50 million people each year, seems to be yielding positive results, according to two studies published in Nature . The two new studies show the success of biological control tests with wild populations of Aedes aegypti , the mosquito that transmits dengue virus. The work involves a new approach to reduce infection in the world.


The computer program for the eradication of dengue ( dengue Eliminate Project ) managed to enter the Wolbachia , a bacterium that reduces sensitivity of the mosquito to dengue virus in wild populations of the insect. "This is the first deliberate release of mosquitoes infected with the bacterium Wolbachia in nature to replace existing insect populations, "say the authors, who claim that these results are repeatable," there is the possibility that reductions occur drastic in the incidence of dengue virus. "

These results are the work program for dengue eradication, led by Scott O'Neill, University of Monash (Australia), with the collaboration of research institutes in Australia, Vietnam, Thailand, USA and Brazil.

For Michael Turelli, University of California UC Davis (USA), and Ary Hoffmann, University of Melbourne (Australia), the results show that "could transform the mosquito population in the coming months."

Mathematical model

Turelli and Hoffmann first described what happened with the spread of Wolbachia in the fruit fly Drosophila in 1991. Subsequently, we designed a mathematical model that laid the foundation for designing a strategy for dengue control. "At that time none of us thought that this research could contribute to improving human health. And, of course, did not think of project such as the eradication of dengue, "says Turreli.


Current control methods based on the use of insecticides, they fail to stop this global health problem. However, "methods that use Wolbachia are easy to use and could be the key to a new sustainable approach to control dengue, which should be adapted to the big cities of the developed world, where conventional control measures have been ineffective and costly. The method should also be compatible with the vaccines when they start using, "says O'Neill.

Fieldwork

So far, experiments have shown for years that could enter the Wolbachia in the mosquito in the laboratory, however, the articles also describe the successful introduction of the same strain of Wolbachia in wild populations of mosquitoes in Australia.


In January this year, researchers released Wolbachia-carrying mosquitoes in Yorkeys Knob and Gordonvale, two areas on the outskirts of Cairns in Queensland (Australia). In three months, the Wolbachia had completely invaded the local populations of mosquitoes.


"The field trial involves releasing mosquito Wolbachia each week for over two months. Five weeks after the mosquitoes released, it was estimated that 100% of mosquitoes Yorkeys Knob and 90% of the Gordonvale carrying the Wolbachia . It was a great day, "says O'Neill.


The authors provide further testing when the weather is more humid, to analyze whether the Wolbachia spreads to areas less controlled the first in which the test was conducted. Upon success, is trying to get legal approval for testing in Thailand, Vietnam, Brazil and Indonesia to determine directly the effectiveness of the method in reducing the incidence of dengue in human populations.

 

[Tonka]

Re: Closer to eradicate Dengue

http://www.publico.pt/Ciências/bacteria-torna-mosquito-do-dengue-imune-ao-virus_1509213
Portuguese to English translation

Technique could curb the epidemic in natural populations
Bacteria become immune to mosquito of dengue virus
25.08.2011 - 20:38 By AFP


Dengue mosquitoes before being released in Australia (Eliminate Dengue Program)
Bacteria can be a barrier to stop dengue, a disease that affects between 50 and 100 million people in tropical and subtropical, show two studies published in Thursday's journal Nature .

"The results show that we can completely transform the local population [mosquito] in a few months," said Michael Turelli, a biologist at the University of California, USA. "It's natural selection fueled by steroids." Dengue is caused by four strains of a virus that infects people through mosquito bites of Aedes aegypti . The virus causes fever, muscle aches and can be fatal in cases of hemorrhagic fever. About 20 000 people die annually of this disease. There is no vaccine and a way to combat the disease is to control the mosquito population. In 2009, the team Turelli, which involves researchers from several universities in Australia, decided to use the Wolbachia bacteria that exists naturally in mosquitoes to shorten the time life of the insect and prevent the development of the virus. The first attempt proved a failure, because the bacteria was very strong and rapidly kill the mosquitoes. The investigators returned to the laboratory and remembered to use a less violent strain of Wolbachia. Eventually obtained another result was unexpected: the bacteria prevented the insect from getting infected by the dengue virus without killing the mosquito. Scientists do not yet know how the bacteria protects the mosquito virus. It may be a molecular process, an increased immune response or both. bacterium passing from generation to generation, from mother to child, which facilitates their spread. Moreover, only the eggs survive to mothers infected with the bacterium Wolbachia. The female insect eggs that are fertilized by healthy males with the bacteria will die. After testing this system in the biology lab team gave thousands of mosquitoes infected with the bacteria in Queensland, Australia. Before that, however, have come a long process in which consulted with local governments, regulators, and spoke to people to explain what would follow. After releasing the mosquitoes, the bacteria thrived. A location, 100 percent of mosquitoes captured had the bacteria in another location, Wolbachia was present in 80 percent of individuals. The team also found elements of the new population spread in places where there is no insect was released. Experience "opens the beginning of a new era of control of mosquito-borne diseases," said Jason Rasgon, an expert from the Institute of Malaria Research at Johns Hopkins in Maryland, a commentary on the discovery also published in the journal Nature . "The advantage of this replacement method is that once people are established, spreads by itself. And because the mosquito population is changed rather than eliminated, the effects on ecosystems will be minimal. " The researchers now want to implement the technique in other parts of the world, as in Brazil.