[Australia] Mozzies put bite on malaria

from the Sydney Morning Herald

MANY mosquitoes seem to kill naturally the malaria parasites they ingest, so it may be possible to exploit that genetic trait to fight malaria, a study says.

Researchers have long dreamed of inserting an anti-malaria gene into mosquitoes, but this study suggests for the first time that this may be unnecessary because "most mosquitoes are malaria-resistant, and the susceptible ones are the oddballs", said Kenneth Vernick, a microbiologist at the University of Minnesota and the lead author.

The study, published in the journal Science yesterday, was a "major step forward" in understanding mosquito genetics, said Allan Schapira, a co-ordinator of the World Health Organisation's malaria program.

The discovery changes the terrain in the war on malaria, which kills more than 1 million people a year, most of them children and pregnant women. On this shifting battlefield, mutating parasites and mosquitoes eventually outwit each ingenious new drug or pesticide created to destroy them.

Natural resistance in mosquitoes to the Plasmodium falciparum parasite is good news for malaria researchers because it is theoretically easier to bolster an existing gene than to implant one from another species.

However, even if a better mosquito could be bred in a laboratory, the idea of releasing manipulated bugs into the wild to hunt human blood would be fraught with political perils.

After lobbying by environmental groups, some African countries now refuse food aid containing genetically modified corn and are sceptical of genetically modified seeds that may confer drought resistance.

As an alternative, Dr Vernick suggested that a soil fungus that devoured insects, whose mosquito-killing powers were described by British scientists last year, could be used to hunt down the most malaria-susceptible bugs in any swarm and knock them out of the gene pool.

Dr Schapira said the idea was "interesting" but cautioned that years of testing would be needed to see if it was practical and safe.

The fungus, Beauveria bassiana, is harmless to humans and approved for use on aphids. It grows in insects that land on surfaces on which it has been sprayed.