Battling the zika virus, one old tyre at a time

Source: BBC

From Canada, the ovillanta is a clever — and highly effective — mosquito trap made from the pests’ favourite breeding spot.

Initial tests show the ovillanta is very effective. During a 10-month study in Guatemala, researchers found that 84 ovillantas placed in seven neighborhoods in the town of Sayaxche destroyed more than 18,000 Aedes larvae per month. That’s nearly seven times better than standard traps. And equally as noteworthy, no new cases of dengue were reported in the area during that period; typically, about two to three dozen cases would occur during that time, Ulibarri says.

The ovillanta, which consists of two roughly 20-inch-long pieces of tyre and a tube drain valve, mimics an Aedes breeding site; three devices can be made from one tyre. Here’s how it works: The bottom half of the device gets filled with about 2 litres of water, topped with so-called “landing strips” – pieces of Pellon or germinating paper, for example – on which the female mosquitoes lay eggs.

Vehicle of Destruction

In Thailand, using the common motorbike to smoke out the common mosquito

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Repurposing old car tyres isn’t the only novel approach being used to kill disease-carrying mosquitoes. ConsiderMotoRepellent, a small mobile device developed in Asia. It dispenses a non-toxic, mosquito-repellent oil from a machine that’s almost as abundant in Asia as mosquitoes: motorcyclus popularus, otherwise known as the common motorcycle.

The brainchild of an advertising agency,BBDO Bangkok, and the Duang Prateep Foundation, a non-profit group dedicated to improving living conditions in Thailand slums,MotoRepellent attaches magnetically to a motorcycle’s exhaust pipe. Heat from the exhaust activates the oil and emits a mosquito-repelling scent. It’s effective up to three meters (nearly 10 feet) from the point of emission.

While the means of dispersal may seem amusingly clever, mosquitoes are no laughing matter in Thailand — or other equatorial countries. In just 2015, Thailand experienced a 270% increase in dengue-virus infections. The World Health Organization (WHO) estimates that the disease afflicts 390m people worldwide and results in 25,000 fatalities. WHO officials say that more than 2.5b people — about one-third of the world’s population — are at risk for dengue infections.

On the other hand, motorcycles are one of the most affordable – and thereby common – forms of transportation worldwide. In 2010, one study estimated there are 455m motorcycles in use globally — almost 80% of them in Asia (primarily China and India). That’s a lot of exhaust pipes. —KW

“Mosquitoes will not lay eggs on a dry surface – they need moisture to hatch,” Ulibarri says. “In a hot climate, you have to add water from time to time because it evaporates very quickly.” The water in the device must be drained about twice a week into a receptacle covered with a filter; something as simple as a piece of white cloth works well because the color makes the larvae clearly visible, he notes.

After that, users destroy the eggs, pour the water back into the ovillanta(topping it off with fresh water) and install two new landing strips. “It’s important to recycle the water because after the eggs hatch, they release a pheromone into the water that tells other mosquitoes it’s a good, safe place to lay eggs,” says Ulibarri, who’s work is funded by Grand Challenges Canada. “Understanding the enemy is the best way to fight it.”


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