A doctor in Canada has devised a mosquito trap that might dramatically reduce mosquito populations as a part of the ongoing fight against mosquito-borne diseases like Zika, dengue and chikungunya.

Ironically, the method only costs around Can$3.50 and an old tyre.

Dr Gerardo Ulibarri of Laurentian University in Canada calls his trap ‘ovillanta’, combining the words oviposition (when insects lay eggs) and llanta (Spanish for ‘tyre’). Research has shown that this innovative trap captures almost seven times more eggs of the Zika-spreading Aedes aegypti mosquitoes when compared to standard mosquito traps.

Dr Ulibarri started modifying the standard traps for the West Nile virus in Canada, and then began focusing on the mosquitoes that spread dengue fever in Guatemala. However, as he was unable to bring the standard traps from Canada to Guatemala, he conceived of constructing the mosquito traps from discarded tyres. His team then trained local health workers and engaged a town of 15,000 Guatemalans in using the constructed devices to kill mosquito eggs.

Details of Dr Ulibarri’s work were released recently on ‘ F100Research‘, an online platform that exists for the rapid dissemination of research findings that are awaiting peer review and publication. The World Health Organization has encouraged such widespread and rapid dissemination of information during public health emergencies.

HOW DOES IT WORK?

Although the work was focussed on the Aedes aegypti mosquito and the transmission of dengue, the researchers are now pivoting their project towards the Zika public health emergency. During a 10-month study of their efforts in Guatemala, more than 180,000 Aedes mosquito eggs were captured by the conceived mosquito trap, compared to 27,000 eggs using the same number of standard mosquito traps.

During that period, no new cases of dengue were reported in the testing area, compared to two to three dozen cases that would normally have been reported in the particular community during that period. The work is being done through Grand Challenges Canada, an organisation that is supporting the project with funding from the Canadian Government.

The method makes use of mosquito hormones. The insects are attracted by pheromones that are placed in the traps as the mosquitoes look for a breeding site to lay their eggs. A paper in the trap then collects the eggs that are floating in water inside the device. The paper is then destroyed by being placed in alcohol or being burnt, and is replaced twice per week while a drain allows the water to be safely emptied, filtered and re-used, thus potentially concentrating the hormones released by the mosquitoes along the way.

So, in areas where clean water is difficult to find, the specially devised traps uses less water and recycles it. It also helps ecologically by putting old tyres to good use, as they otherwise could become sites for mosquito breeding, and they do not require toxic pesticides that can harm other beneficial insects or natural mosquito predators in the environment.

MINISTRY OF HEALTH IMPRESSED

The Guatemalan Ministry of Health was reported to be particularly impressed by the results, and are planning to expand the use of the specially devised traps to other cities.

The Aedes aegypti mosquito is very difficult to combat or control, and spraying doesn’t work very well for two reasons. Spraying most times do not get to the mosquitoes as they are safely nestled inside our houses whilst spraying is being done on the outside, in our streets and across our communities. For such spraying to be at least partially effective, we would have to tolerate the smell of the ‘smoke’ and open up our doors and windows widely to let the ‘fumes’ in. To complicate the matter further, many mosquitoes have now become resistant to the chemicals that are used in the spraying.

As a country with very limited resources to spend on health-related matters, our approach to the containment of the Aedes aegypti mosquito must be very cost-beneficial. Whilst the concept of using genetically modified mosquitoes in the Zika outbreak may be very appealing to some, the cost of that venture is likely to be very prohibitive. The use of old tyres to serve as mosquito traps in resource-poor countries present a much more attractive venture, and so ministries of health should begin exploring this method as another possible armamentarium in the fight against mosquito-borne diseases.

We should note however that following the use of this recent innovation, further studies will be needed to evaluate it effects on Zika disease outcomes and other mosquito-borne diseases. Health care workers will need to be trained in using these innovative mosquito traps in their communities, and public education about the process will be crucial.

However, based on the work in Guatemala, the results are very encouraging and the cost minimal.

Derrick Aarons MD, PhD is a consultant bioethicist/family physician, a specialist in ethical issues in medicine, the life sciences and research, and is the ethicist at the Caribbean Public Health Agency – CARPHA. (The views expressed here are not written on behalf of CARPHA)