Malaria: why the drugs don't always work

Drug-resistant strains of malaria are more common than previously thought and they can pass on their resistance far quicker than anyone realised, a study has found. Scientists who analysed the genetic makeup of the malaria parasites taken from 87 patients from around the world have found that the genetic mutations which confer drug resistance are widespread.

Drug-resistant strains of malaria are more common than previously thought and they can pass on their resistance far quicker than anyone realised, a study has found. Scientists who analysed the genetic makeup of the malaria parasites taken from 87 patients from around the world have found that the genetic mutations which confer drug resistance are widespread.

Many of the Plasmodium falciparum parasites – the deadliest form of malaria which kills two million people a year worldwide – carried the gene which made them resistant to chloroquine, a common anti-malarial treatment. Analysis of the parasite's DNA suggested that the resistance gene against chloroquine had spread across continents with alarming speed and had evolved in response to the drug's widespread introduction. John Wootton, of the US National Institutes of Health and lead author of the study published in Nature, said research indicates that chloroquine resistance evolved at least four times independently, once in south-east Asia in the 1950s, which then spread through Asia and Africa, at least twice in South America and once in Papua New Guinea. Xin-zhuan Su, the leader of the team, said that the findings change the way scientists will think about how the Plasmodium falciparum form of malaria became so quickly untreatable with chloroquine. It took only 10 to 15 years for the resistant strain to spread across Africa. "This means that when a drug or vaccine-resistant parasite arises, it will not take long for this resistance to spread to other continents, reflecting human travel, particularly by air, and the high transmission rate via mosquitoes in Africa," Dr Su said.

Specks of dust found in the crevices of mobile phones could soon be used to detect drug dealers. Scientists at Mass Spec Analytical in Bristol have shown that cellphones used by dealers harbour traces of drugs between the most frequently used keys. They believe that patterns of contamination can indicate whether the phone was used by someone routinely handling cocaine, heroin or ecstasy or whether it is the result of a more innocent, chance contamination. Tests on 150 old handsets showed that those which were innocently contaminated tended to have deposits at one point, whereas those used by people who handle drugs have deposits all over them.

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