14 June 2012

Ways to track malaria parasite evolution found

An international research team says it has found a way to identify hotspots of malaria parasite evolution and track the rise of resistance to malaria drugs faster.


An international research team says it has found a way to identify hotspots of malaria parasite evolution and track the rise of resistance to malaria drugs faster and more efficiently than before.

The success of the technique, which involves analysing the genetic maps of malaria parasites straight from patients' blood samples, suggests scientists should be able to track changes in the parasite population and follow the disease's evolution.

Malaria infects more than 200 million people worldwide every year and kills around 600,000 of them – primarily children under age five in sub-Saharan Africa.

Monitor genetic diversity

Experts say one of the most challenging features of the parasite plasmodium falciparum is its ability to evolve and overcome anti-malarial drugs, which is undermining global work toward eradicating the killer disease.

"If we want to control resistance, we first need to be able to monitor the genetic diversity of P. falciparum and identify hotspots of potential resistance as they occur," said Dominic Kwiatkowski, of Britain's Wellcome Trust Sanger Institute and Oxford University, who led the research team.

"Rapid sequencing of parasite genomes from the blood of infected people is a powerful way of detecting changes in the parasite population and potentially an important new surveillance tool ... for controlling malaria."

Kwiatkowski's team developed a new technique to extract the parasite's DNA directly from blood removing as much human DNA from the sample as possible.

Geography affects parasite evolution

The new method means there is no need to grow the parasite in a blood culture in a laboratory dish before deciphering its genetic code, speeding up the process and minimising the potential for mistakes, the researchers explained in a report of the study published in the journal Nature.

The team used the technique to analyse samples from Burkina Faso, Cambodia, Kenya, Mali, Papua New Guinea and Thailand.

The researchers found that one infected person could harbour several genetically different malaria parasites, which allowed the parasite populations to swap DNA and create new forms.

This showed how the pace of parasite evolution is drastically affected by human factors as well as geography, the researchers said.

Identify hotspots around the world

"The emergence and spread of anti-malarial drug resistance is a major threat to current global initiatives to control and eliminate malaria," said Nick White of Oxford University and Mahidol University in Thailand, who also worked on the study.

He said new insights like those revealed by this study are essential if scientists are to be able to identify, map and then contain spreading resistance.

"We can now build on this technique to identify hotspots of anti-malarial drug resistance around the world and contain them effectively," he said.

(Reuters Health, June 2012) 

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