Investigators said on Wednesday they had made important lab discoveries in mosquitoes and the parasite which causes malaria, opening up new paths for attacking a disease that claims nearly a million lives per year.
In one of two studies published in the British journal Nature, Yale University researchers said they had found more than two dozen smell receptors in the mosquito Anopheles gambiae that enables the insect to home in on human sweat.
Some of the receptors "could be excellent targets" for chemicals to snare mosquitoes or repel them, said the study's senior author, John Carlson, a professor of molecular biology.
"We're now screening for compounds that interact with these receptors," Carlson said in a press release.
"Compounds that jam these receptors could impair the ability of mosquitoes to find us. Compounds that excite some of these receptors could help lure mosquitoes into traps or repel them. The best lures or repellents may be cocktails of multiple compounds."
Malaria is transmitted when a female Anopheles mosquito takes a blood meal from a person infected with the disease and then hands on a parasite in its saliva when it bites someone else.
The parasites hole up in the liver for a number of weeks and then break out, escaping into the bloodstream, where they infect red blood cells and mature and multiply. They erupt from the blood cells in waves, causing bouts of fever that can lead to coma or death.
In the second study, scientists in Australia identified a mechanism that helps Plasmodium falciparum, the most lethal of the five malarial parasites, to infiltrate blood cells and evade the body's defenses.
The parasite dispatches hundreds of so-called "effector" proteins into the blood cell's cytoplasm, modifying the cell and masking the invader from the immune system.
One of the primers for this is an enzyme called Plasmepsin V.
"Plasmepsin V is responsible for determining that all the hundreds of effector proteins are exported. If we could find drugs to block Plasmepsin V, the malaria parasite would die," said Alan Cowman of the Walter and Liza Hall Institute in Melbourne.
There were 247 million cases of malaria in 2006, causing nearly one million deaths, according to the World Health Organisation (WHO) website. Most of the fatalities were African children.
Countries that have widespread incidence of malaria are also hit economically, losing as much as 1.3 percent of their gross domestic product (GDP), says the WHO.