Gwynne Dyer: Malaria and chickens

Gwynne Dyer

I HAD malaria once, and it was extremely unpleasant. I had been working in Yemen, but I contracted it while flying home on a Dutch airline that must remain nameless. The flight made a stop in Jeddah in Saudi Arabia, and the plane was parked out on the runway while waiting to pick up passengers -- right on the edge of a mangrove swamp on the Red Sea coast.

The pilot turned the engines off to save fuel and opened the door to give us fresh air. It was night, so a million mosquitoes swarmed in. In five minutes everybody had been bitten multiple times. The passengers then revolted and the pilot shut the door and turned the air con back on, but it was too late.

I fell ill and collapsed a couple of weeks later, when I was at my wife's family's house in southern France, but I was lucky. My wife, who grew up in Africa, thought it was malaria, and the village doctor (who had served with the French army in Africa) confirmed it, so he gave me a huge dose of antimalarial drugs.

By the time they got me to the hospital in Bayonne, they couldn't even find any of the Plasmodium parasites in my bloodstream. They kept me in hospital for a couple of days anyway, but it wasn't that bad, because in French hospitals they give you wine with your meals.

But the story's point is none of this would have happened to me (and presumably to other passengers too) if only there had been chickens on the plane.

Statistics can sometimes lead to significant breakthroughs. In this case a team of Ethopian and Swedish scientists did a statistical study in three villages in western Ethiopia about the feeding habits of nocturnal, malaria-carrying Anopheles arabiensis mosquitoes. The results were instructive.

Outdoors, the mosquitoes preferred to feed on cattle (63 per cent of bites), with human beings coming next (20 per cent), and goats and sheep bringing up the rear (5 per cent and 2.6 per cent). Indoors, people provided 69 per cent of the mosquitoes' meals, compared with cattle at 18 per cent and sheep and goats last again. (In this region people sometimes bring their animals indoors at night.)

There were also plenty of chickens around, both indoors and out. But in one outdoor sample, only one female mosquito out of 1200 had chicken blood in her. In the indoor sample, none did. Mosquitoes don't bite chickens.

We can't disguise ourselves as chickens, but we could try smelling like them, or have something that smells chickeny nearby. In one experiment, the scientists hung cages of live chickens over people's beds at night, and lo! They had very few mosquito bites -- fewer even than people sleeping under insecticide-treated bed nets.

Admittedly, something more compact and less noisy is better. So the scientists tried putting chicken feathers near people's beds, and it still worked. Then they tried distilled essence of chicken odour (isobutyl butyrate, naphthalene, hexadecane and trans-limonene, if you must know), and that worked too.

Almost half the world's population (3.2 billion people) lives in areas where malaria-bearing mosquitoes are present. About one in 15 falls ill with malaria each year, and almost half a million of them die of it. Many tens of millions more spend a long, agonising time being very sick indeed.

Anything that cuts into those numbers would be welcome, and prevention is better than cure. CHEAP prevention is even better, and compared with insecticide-treated bed nets and various experimental vaccines, just sprinkling some chicken fragrance around before going to bed has got to be cheaper.

That probably won't be on the market for a while yet, but hats off to Professor Habte Tekie, of the University of Addis Ababa, and Professor Rickard Ignell, of the Swedish University of Agricultural Sciences, who led the Ethiopian-Swedish team that did the study. (Their full report is available online in the July 21 issue of Malaria Journal).

� Gwynne Dyer is an independent journalist whose articles are published in 45 countries.