This past December, some 6,000 genetically modified mosquitoes were released in Malaysia, according to a statement just released Wednesday by the government-run Institute for Medical Research (IMR) in Kuala Lumpur.

These GM mosquitoes were developed to fight dengue – a viral infection with severe feverish symptoms transmitted by female mosquitoes. It could also lead to dengue hemorrhagic fever, a potentially lethal complication.

Dengue fever killed 134 people in Malaysia last year. There is no cure or vaccine.

For this field test, the released mosquitoes were ‘genetically sterile’ males of the species Aedes aegypti, and they were developed by Oxitec, a UK biotech firm. The GM males carry a gene so that when they mate with wild females, their offspring will die before reaching sexual maturity. And if dosed with enough of these males, mosquito populations should collapse.

The experiment was carried out in an uninhabited forest near Bentong on Dec. 21. It was designed to test the survival and mobility (or flight range) of the sterile males in the wild. Another 6,000 normal wild-type males were also released for comparison.

“The experiment was successfully concluded on Jan. 5,” says IMR director Shahnaz Murad. “Fogging with insecticide was conducted on Jan. 6 to eliminate all mosquitoes but monitoring will continue for up to two months.”

The news caught the Malaysian media and public by surprise – especially because many recent news stories reported that the study had been postponed after intense protests. Science Insider reports:

Oxitec's chief scientific officer, Luke Alphey, confirms that Malaysian media had it wrong. But Alphey says "nobody should have been terribly surprised" by the release. Once all the regulatory hurdles had been overcome, "it seems predictable that the next step would be the actual release," he says. [Helen Wallace of the advocacy group GeneWatch UK] believes Oxitec is rushing ahead with field trials because it needs to start making money. In a recently posted analysis, GeneWatch UK claimed that the company is losing some £1.7 million ($2.7 million) per year and needs to pay back a £2.25 million ($3.6 million) loan by 2013. But Alphey says that's not the reason. "We are a for-profit company and finance is not irrelevant," he says. "But anyone who realizes that there are 50 to 100 million cases of dengue every year would feel a sense of urgency."

The number of dengue-linked deaths in Malaysia increased 52% last year from 88 in 2009. The total dengue infections rose 11% from 2009 to more than 46,000 cases last year [AP].

Last summer, a larger 3-million-mosquito study was conducted in Grand Cayman. That resulted in an 80% decrease in mosquito numbers.

If these kinds of eradication schemes were to be carried to a logical extreme, the world might be left bereft of mosquitoes… and what would that world be like? I posed this question to several scientists last year.

Image: James Gathany / CDC Public Health Image Library

This post was originally published on Smartplanet.com