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Published Date: 2012-05-14 09:28:53
Subject: PRO/EAFR> Malaria - East Africa: artemisinin resistance
Archive Number: 20120514.252480

MALARIA - EAST AFRICA: ARTEMISININ RESISTANCE
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Date: Sat 12 May 2012
Source: The East African [edited]
http://www.theeastafrican.co.ke/news/ACTS+resistant+malaria+comes+to+East+Africa/-/2558/1404370/-/vc71yb/-/index.html


ACTs [artemisinin-based combination therapies]-resistant malaria comes 
to East Africa
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A strain of the malaria parasite _Plasmodium falciparum_ that is 
resistant to artemisinin, one of the most powerful anti-malarial drugs, 
has been found in East Africa. The strain tested positive in blood 
samples from foreigners who had travelled in Kenya and Tanzania and 9 
other African countries. This particular strain had been found at the 
border of Thailand and Myanmar and had been predicted to be spreading to 
India and then Africa as resistance to other antimalarial drugs has done 
before.

The results, according to the researchers from St George's, University 
of London, indicate that either the strain has spread to East Africa or 
the other African countries, or the local parasite has developed 
resistance. Although malaria control efforts have been scaled up in the 
region, the researchers say their findings are a further warning that 
the best weapons against malaria could be rendered obsolete.

Sanjeev Krishna, the study lead researcher and professor at St George's, 
University of London, said resistance in parasite samples were taken 
from 11 of the 28 malaria-infected patients from East Africa and the 
other African countries. On average, artemether's effectiveness was 
reduced by half. Each parasite was found to have the same genetic 
mutations, said Dr Krishna.

The artemisinin group of drugs is the most effective and widely used 
treatments for malaria. The drugs in this group are most powerful and 
less likely to be resisted by the malaria parasite when used with other 
drugs as artemisinin-based combination therapies (ACTs).

The patients were infected by malaria parasite-carrying mosquitoes while 
travelling to East Africa and the other 9 sub-Saharan African countries, 
home to 90 percent of the one million people killed worldwide each year 
by malaria.

The researchers then later tested samples from patients infected with 
the _Plasmodium falciparum_ parasite and the parasites were assessed for 
their sensitivity to 4 artemisinins: artemisinin itself, artemether, 
dihydroartemisinin, and artesunate.

The results showed that 11 parasites showing artemether resistance had 
the same genetic mutations in an internal system called the calcium pump 
(this is used to transport calcium, crucial for the parasite to 
function). We already suspected that the calcium pump, which we first 
showed was a target for artemisinins to work on in 2003, had the 
potential to develop artemisinin resistance. But this had been difficult 
to confirm until now, said Dr Krishna.

Artemether and ACTs are still very effective, but this study confirms 
our fears of how the parasite is mutating to develop resistance. Drug 
resistance could eventually become a devastating problem in Africa and 
not just in Southeast Asia where most of the world is watching for 
resistance.

Dr Krishna noted that the effectiveness of the other artemisinins was 
not significantly affected by the mutations. This may be because they 
were able to work on other transport systems in the parasite, 
compensating for the effects of resistance mutations in the calcium pump.

"At the moment, we do not know if the other artemisinins will follow 
suit, but given the shared chemistry they have with artemether it is 
tempting to think that they would, he added. The scientists argued that 
the resistance could be a result of the increasing use of ACTs, 300 
million doses of which were dispensed worldwide in 2011.

Greater use could offer the parasites more opportunities to develop 
genetic mutations that provide resistance. They say this could lead to a 
repeat of how the parasite developed resistance to pre-artemisinin drugs 
such as chloroquine. Incorrect use of anti-malarials, such as not 
completing the treatment course or taking substandard drugs, could aid 
this process.

[Byline: Christabel Ligami]

--
Communicated by:
ProMED-mail from HealthMap alerts
<promed@promedmail.org>

[This report heralds the emergence of artemisinin resistance in East 
Africa and hence the need to enhance antimicrobial resistance 
surveillance for malaria in the region. Such efforts should be 
integrated into the existing malarial control efforts and programs on 
antimalarial use to contain the emergence of resistance in the region.

HealthMap/ProMED-mail interactive maps for the East African countries 
can be seen at http://healthmap.org/r/1wa6 for Uganda; 
http://healthmap.org/r/1zkN for Kenya; http://healthmap.org/r/1KlV 
for Tanzania; http://healthmap.org/r/1f*m for Burundi; and 
http://healthmap.org/r/1jzc for Rwanda. - Mod.JFW]

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