A Dutch inventor has come up with a cheap and effective way of combating malaria by placing ventilation grilles doused in insecticide in the walls of houses.

A report, describing a two-year trial run of the grilles, was published in medical journal the Lancet on Thursday. It shows that these ‘lethal lures’ kill potential malaria-carrying mosquitos before they can enter the house, almost halving the number of cases.

A trial carried out by an international team of scientists in Ivory Coast divided villages into two groups, one of which was given mosquito nets to protect them while the other used mosquito nets and the poisoned ventilation grilles. Two years later the instances of malaria among the children in the latter group had fallen by 40%.

Malaria killed over 400,000 people worldwide in 2019, with most cases and deaths occurring in sub-Saharan Africa. However, the WHO regions of South-East Asia, Eastern Mediterranean, Western Pacific, and the Americas also report significant numbers of cases and deaths, according to World Health Organisation data.

Anne Osinga, the Dutch product developer who invented the grilles, said he came up with the idea ‘by thinking like a mosquito’.

The grilles had to be placed at roof height, he said ‘Humans have a temperature of 37 degrees and emit a smell that travels up because it is warmer than the environment. If I were a mosquito I would enter the house by way of the ventilation grille because the smell at night would be irresistible,’ Osinga told the Volkskrant.

Medical entomologist Sander Koenraadt, who was not involved in the trial, said the invention was ‘a breakthrough’. ‘New ways of killing mosquitos are a constant in my field but they all depart from the same principle, and that is finding new insecticides. This approach is different.’

The grille is also killing mosquitos which have become resistant, the trial showed. ‘They are getting a big dose of poison and that finishes them off. But the idea that one simple solution will eradicate malaria is long past. It will always remain a battle between man and mosquito,’ Koenraadt said.