Canadian team set to turn tires against Zika virus

Friday, April 8, 2016, 9:41 AM -

A Canadian-led team has designed a $5.00 weapon that could turn the tide in the global fight against mosquito-borne diseases.

The team, lead by Laurentian University professor Gerardo Ulibarri, released findings from a preliminary study of their "ovillanta" this week, and the results are encouraging thus far.

Old tires have become a main breeding ground worldwide for Aedes aegypti, the Zika-spreading mosquito that is also a carrier of dengue, chikungunya, and yellow fever. Ulibarri's team aims to turn the mosquito's breeding behaviour against them by making the artificial ponds that form in discarded tires into traps.

"That's the beauty of the project; we are using recycled tires, which is the main source of these mosquitoes," Ulibarri told the Toronto Star. "I think this exemplifies very nicely that we can reduce the amount of mosquitoes that bite through an ecological and cheap, efficient method."

The design is deceptively simple; easy enough that the team has released a do-it-yourself video along with their findings. The trap is built using two 50 cm long sections of rubber tire fitted together, with a fluid release valve at the bottom.

The ovillanta design. Photo courtesy Daniel Pinelo.

The lower portion of the trap holds the water, along with a milk-based attractant Ulibarri invented, although he adds the water itself can be recycled once the mosquitoes have started laying their eggs there. "All mosquitoes, when they lay their eggs, within the egg there is a microgram of a pheromone," Ulibarri told CBC Radio. "When the larva hatches, it liberates the pheromone into the water, which helps indicate to other female mosquitoes that that's a good place for their babies to be born."

The final component of the ovillanta is a wooden or paper strip in the water on which the female mosquitoes deposit their eggs. The strip is removed twice a week for study and disposal.

The study, funded by a grant from Grand Challenges Canada, was conducted over 10 months in Sayaxche, Guatemala, where the team was able to collect and destroy more than 18,100 eggs per month, deploying 84 ovillantas throughout the town. In contrast, 84 standard traps in the same areas collected only about 2,700 eggs per month.

A view inside the ovillanta shows the water reservoir and paper strips. Photo courtesy Daniel Pinelo.

An exciting, but thus far only anecdotal, side note to the study was that there were no new cases of dengue in the Sayaxche area during the test period. Normally, health officials would expect between 24 and 36 new cases over the course of 10 months. Ulibarri cautions that this result wasn't the focus of the study; a lack of disease surveillance in the area means there could be other reasons for the occurrence.

Sources: EurekAlert! | CBC Radio | Toronto Star | Grand Challenges Canada | 

Watch: Another Canadian approach to mosquito control