Modern afflictions like DVT, CJD and heart disease grab the medical headlines, but they are fleabites in the global disease league compared with the tropical pestilence, malaria. This scourge of the Indian subcontinent and Africa, caused by a microscopic parasite in the blood and spread by mosquitoes, was first described in Indian texts of 1600BC and has seen off as many as half of all humans.
Medical science held the disease in check in the 20th century, yet still there is neither vaccine nor a fully effective treatment, and it kills about a million a year, including a few business travellers. And because of global warming, carrier mosquitoes are moving into Europe. Thankfully, international researchers led by the Institute of Genomic Research in Maryland, US, have just completed the six-year task of mapping the genomes of both parasite and carrier, a breakthrough that could bring a range of potent new treatments.
THE CHALLENGE: Four species of parasite cause malaria, the most deadly of them Plasmodium falciparum, and 10 or more species of Anopheles mosquito spread the plasmodium by biting humans. Parasites are pumped into the human bloodstream with the mosquito's saliva. Once there, they move to the liver to recuperate and multiply before migrating to the vital oxygen-transporting red blood cells (see picture). These become so full of propagating plasmodium that they burst, causing fever and maybe death. A patient surviving the first crisis can suffer recurrent debilitating attacks for years.