mosquito

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Irrigation leads to better crops and more malaria | 

An irrigation canal in the northwestern Indian state of Gujarat.

Andres Baeza

An irrigation canal in the northwestern Indian state of Gujarat.

Mosquitoes and plants thrive where there is water. Farmers in arid regions who use irrigation systems to collect water also construct a mosquito breeding ground.

New research shows that irrigation systems malaria prone areas can cause an increase in local malaria risk that lasts for more than a decade. Even when health authorities mount a response to kill off mosquitoes using insecticides, the problem of malaria is still worse than before the open water.

“In these dry, fragile ecosystems, where increase in water availability from rainfall is the limiting factor for malaria transmission, irrigation infrastructure can drastically alter mosquito population abundance to levels above the threshold needed to maintain malaria transmission,” said lead author and University of Michigan graduate student Andres Baeza.

Baeza and her team studied cases of malaria in northwest India. Infrequent and inconsistent rain makes for more challenging farming and is why farmers employ various irrigation methods to ensure crop health. The study looked at the effects of a large irrigation project that will provide enough water to cover more than 47 million acres.
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Taking a closer look at whether anti-malaria programs really work | 

Malaria and the mosquitoes that carry it met a formidable foe in the form of nets laced with deadly pesticides a decade ago. Hanging a net above the bed so that it drapes around the people inside provided protection from mosquito bites while not making it hotter in tropical locations nor harming the people that use them.

Programs flourished that distributed and/or sold the bed nets. People used them and progress towards ending malaria seemed on track.

Ten years later malaria is still around and the mosquitoes are showing signs of resistance to the insecticide used in the bed nets. Journalist Amy Costello, host of the podcast Tiny Spark, recently traveled to Malawi to see what was actually happening in the fight against malaria. She sees mosquitoes that are surviving the only pesticide used in bed nets to kill them and families using bed nets with giant holes.

The story was carried by Public Radio International’s The World earlier this week. It’s the first in a series of stories called Tracking Charity. Like she does with the malaria piece, Amy will travel around the world to see if aid projects are delivering on their promises.

“To my mind, the most important barometer of aid effectiveness is how it impacts the people it is trying to help. That is why I will put the recipients of aid at the forefront of every story I report,” explains Costello in introducing the series.

“I am interested in knowing if programs work for them. I want to find out what happens to people who live at the end of dirt roads when charitable projects don’t pan out as promised.”

In this week’s podcast, I spoke with with Amy about the project (our producer re-recorded my questions to improve audio quality). We discuss her previous investigations into TOMS shoes and medical volunteers following the Haitian earthquake. Costello explains why she is driven to take a tougher look at the business of doing good and the resistance she receives from people in and out of the charity sector.

And don’t miss a podcast! Subscribe on iTunes.

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UW and British scientists explore how to spread genetically modified mosquitoes to fight malaria | 

Flickr, Gustavo

Over the last few years, scientists have explored a number of different approaches to genetically modify mosquitoes in order to make them unable to pass on the malaria parasite, or other causes of human illness.

The Bill & Melinda Gates Foundation is a big supporter of this strategy, having donated nearly $40 million in research funding to various scientific endeavors. One of the primary challenges, besides accomplishing the genetic modification in the lab, is in getting the protective changes to spread in the wild when the bugs breed.

In this week’s scientific journal Nature, a team of researchers at Imperial College London and the University of Washington report the first-ever successful “proof-of-principle” demonstration in which such genetic modifications get passed on by modifying a few individuals who then breed them into the population at large.

Reuters quotes the lead scientist at Imperial College:

“This is an exciting technological development, one which I hope will pave the way for solutions to many global health problems,” said Andrea Crisanti of Imperial’s life sciences department, who led the study.

The UW scientists involved in the study included Summer B. Thyme, Hui Li, Umut Y. Ulge, Blake T. Hovde, David Baker and Raymond J. Monnat Jr.

New skeeter bugs malaria control campaign | 

CDC

Anopheles gambiae

One of the big news stories in the malaria world recently is the discovery, announced last week in the journal Science, of a previously unknown type of mosquito that some reports said could threaten malaria control efforts in Africa.

Here’s the problem: Most malaria control efforts in Africa — bednets, spraying — are aimed at preventing mosquitoes from biting humans indoors at night. This newly discovered mosquito, dubbed “Goundry” (after the community in Burkina Faso where it was identified), appears to operate outdoors. The news reports:

After reading a number of these stories that cited the scientists who made this discovery warning that this new skeeter could undermine the massive — and apparently fairly successful — ongoing effort to reduce malaria deaths and disease in Africa, I decided to get a second opinion.

I asked Stefan Kappe, a malaria expert at Seattle Biomed, for his thoughts on this. Kappe and his colleagues are working on a number of fronts to combat malaria, including testing a genetically engineered malaria parasite for use as a vaccine.

Seattle Biomed

Stefan Kappe

“If it turns out that this mosquito is a significant vector for human malaria, the whole malaria control strategy will fail,” said Kappe. But that, he says, remains a big “if” because it’s quite possible this particular sub-type is one of those that doesn’t bite humans.

The species Anopheles gambiae, of which the Goundry bug is a subtype, does transmit malaria and Goundry has been shown to carry the malaria parasite.

But it’s worth considering that, in the mosquito world, there are some 3,500 known species of mosquito — most which don’t carry malaria and most of which aren’t attracted to biting humans for their blood meal.

“What they did not show is that this mosquito will actually bite and transmit malaria to humans,” said Kappe. “It might seem like a trivial question but it’s not really.”