The malarial mosquito up close

Most nights, several of the 16 researchers here lie down with their own mosquitoes and wait for the biting to begin. The prize is to find new solutions — perhaps the ultimate solution — to one of the world’s most lethal, widespread and rapidly growing diseases.

Forty years ago, a generation of medical crusaders believed they were on the verge of eradicating malaria for ever. With a blitz of drugs to kill the parasite and a rain of DDT to wipe out its principal carrier, the Anopheles mosquitoes, they thought malaria was well on the way to the dustbin of medical history. But it wasn’t to be. The mosquito began to develop resistance to DDT. And the parasite responsible for most deaths, Plasmodium falciparum, became resistant to most of the drugs.

Today, the malarial mosquito’s kingdom is growing again. More than 40 per cent of the world’s population live in areas where they are at risk from the disease. Deforestation and irrigation projects are creating new habitats where mosquito larvae can flourish. And global warming is taking the disease into regions that were once too cold. Half a billion people suffer periodic bouts of malaria fever and the disease kills an estimated 2 million people every year.

Ecologists such as Knols, whose research station is an outpost of the Nairobi-based International Centre of Insect Physiology and Ecology, say the long-term solution lies in probing the lifestyle of the malarial mosquito itself. “Why does it bite humans? Why does it prefer some humans to others? What, besides human blood, does it eat? What repels it? What triggers swarming and mating? And, crucially, how can we intervene to disrupt its ability to infect humans? These are the kinds of questions we urgently need answers to if we are to outsmart the disease,” says Knols.

Excerpted from `Malariasphere’, by Fred Pearce; `New Scientist’, July 15