dengue

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November 3, 2011 | 11:22 AM | By

Lacking a dengue vaccine, scientists tinker with skeeter genes

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:

HealthMap, CDC

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).

WHO

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.

FILED UNDER: Science, dengue, genetically modified organisms, vaccine
August 25, 2011 | 11:48 AM | By

Altered skeeter update: Infecting mosquitoes to fight dengue

Flickr, Gustavo

The idea of altering mosquitoes to fight disease appears to be quite contagious.

It’s almost become a news category unto itself, with at least a story every month or so involving something like:

Bacteria.

Scientists in Australia want to expand upon successful field tests indicating that infecting mosquitoes with a particular bacteria, known as Wolbachia, prevents the bugs from transmitting the dengue virus.

WHO

Dengue cases over time

Dengue, also known as dengue fever or “break-bone” fever, is exploding worldwide and so there are a number of efforts underway to stave off the epidemic, including finding a vaccine and, well, messing with mosquitoes.

Here are a number of good stories on the latest strategy aimed at fighting disease by messing with mosquitoes:

NPR:  Better you than me: Scientists sicken mosquitoes to stop dengue

WashPost: Field tests show bacterial oddball may be a dengue destroyer

Nature News: Bacterium offers way to control dengue fever

Guardian: Injecting mosquitoes with bacteria could stop dengue fever

Few of the news reports go into much detail scrutinizing the potential adverse side-effects, whether to humans, the environment or the skeeters, but that’s routine for news stories based on early stage scientific studies.

The bacterium, Wolbachia, is a common insect infector and is widely regarded as fairly benign if not downright beneficial. Still, you never know when you fool with Mother Nature — which is why we do phased scientific testing.

Another problem with any intervention is evolution, aka resistance. Bugs have a way of finding ways around things that get in their way. Still, the scientists say, if this approach can work for a decade or so we will do much to hold the dengue explosion at bay.

I’ll be writing more later about the dengue vaccine research, which is perhaps less exciting than manipulating skeeters but perhaps more feasible.

 

FILED UNDER: Science, dengue, mosquitoes, science
July 28, 2010 | 10:00 AM | By

Dengue Fever in Florida, On the Rise Globally

Aedes aegypti mosquito

CDC

Dengue is spreading globally

Dengue fever, also known as “breakbone fever,” used to be confined to a small part of the tropics. As a recent outbreak in Florida illustrates, it is no longer so confined.

In fact, dengue is now the most common and the fastest-growing mosquito-borne disease in the world, currently threatening a third of the world’s population.

In the worst cases, the infection can cause a potentially deadly form of the disease known as dengue hemorrhagic fever (DHF). Epidemics of both dengue and DHF are now routine in many parts of Latin America only several generations after the mosquito-borne virus was first identified there.

Dengue cases over time

WHO

Dengue cases over time

Due to the combination of human travel, cargo transportation and perhaps the changing climate, the mosquito that carries the dengue virus (Aedes aegypti, which also carries yellow fever) has been spreading to nearly all tropical and semi-tropical regions worldwide. 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 these efforts as well.

FILED UNDER: Health, Science, CDC, dengue