Lacking a dengue vaccine, scientists tinker with skeeter genes

Dengue cases over time

It’s rarely on most Americans’ minds, but worldwide dengue is a big killer. And it’s spreading fast.

The U.S. Centers for Disease Control and Prevention says there are anywhere from 50 to 100 million people infected every year with dengue — including a very small, but increasing number of Americans — and an estimated 50,000 deaths from this mosquito-born disease.

Here’s an interactive look (go to this link) at dengue around the world from HealthMap:

The number of cases of dengue have exploded over the past few decades in tropical and semi-tropical regions. Some believe this may be driven by climate change and an expanded range for the mosquito (Aedes aegypti, which also carries yellow fever).

Dengue cases over time

Others think shipping, cargo transportation, may be the main route of spread. This skeeter tends to like to live in urban and semi-urban areas.

Because of the global surge in dengue, the U.S. military and some pharmaceutical companies have stepped up efforts to develop a vaccine that can protect against the infection. The Bill & Melinda Gates Foundation has donated $60 million to the vaccine efforts as well as some more ‘innovative’ approaches such as modiying the genes of mosquitoes.

Earlier this week, a team of scientists (partly funded by Gates) reported success in a field trial of mosquitoes genetically modified so that their offspring die following reproduction. As the BBC noted, dengue can’t be fought with same tools as malaria, such as bed nets, primarily because these mosquitoes bite during the day time.

The successful field trial — which just tested the genetic tinkering’s effect on reproduction, not dengue transmission — has nevertheless raised concerns about unintended environmental side-effects, the New York Times reports. 

The British biotech company pursuing this approach, Oxitec, had already raised some hackles earlier for too aggressively moving forward with their releasing modified mosquitoes into the wild.

Meanwhile, to much less media attention and fanfare, other scientists (many of them also funded by the Gates Foundation) are working on developing a vaccine against dengue. Here is one recent news brief about an ongoing trial.

For a broader overview of work on developing a vaccine, see the Dengue Vaccine Initiative.

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Tom Paulson

Tom Paulson is founder and lead journalist at Humanosphere. Prior to operating this online news site, he reported on science,  medicine, health policy, aid and development for the Seattle Post-Intelligencer. Contact him at tom[at]humanosphere.org or follow him on Twitter @tompaulson.