AFRO-NETS> New test readily identifies drug-resistant malaria

[Dieter Neuvians MD <neuvians@harare.iafrica.com>]

New test readily identifies drug-resistant malaria
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NEW YORK, Jan 24 (Reuters Health)
Malaria, a deadly mosquito-borne infectious disease especially common 
in Africa, has recently become more difficult to treat in certain re-
gions because of resistance to chloroquine, the most commonly used 
anti-malarial drug.

Now, according to researchers, a new test has been developed that can 
readily identify a genetic mutation within a certain type of malaria 
parasite that indicates they will be resistant to treatment with 
chloroquine.

"The assay can be performed quickly on filter paper blood samples 
collected by finger stick at the same time that a drop of blood is 
taken for microscopic diagnosis of malaria," Dr. Christopher V. Plowe 
from University of Maryland School of Medicine in Baltimore, Mary-
land, told Reuters Health.

"It has already been used in an outbreak of (malaria) in northern 
Mali, where there were no facilities for (microscopic analysis)," 
Plowe said.

Identifying drug-resistant malaria parasites early is important, ac-
cording to Plowe and associates, particularly in sub-Saharan Africa, 
where increasing resistance to chloroquine is the source of rising 
medical complications and death rates from malaria.

The investigators studied mutations in two genes--pfcrt and pfmdr 1--
within the malaria parasite that contributed to their ability to re-
sist treatment with chloroquine, according to their report in the 
January 25th issue of The New England Journal of Medicine.

Among 60 patients in Mali with drug-resistant malaria, all had para-
sites with pfcrt mutations, the report indicates, whereas 30% of 
these patients had parasites with at least one normal pfmdr 1 gene.

Additional experiments indicate that treatment with chloroquine con-
tributed to the emergence of parasites with the pfcrt mutations, fur-
ther evidence of their role in causing drug resistance.

The effect of pfcrt mutations also depended on the age of the pa-
tient, the researchers note. Older patients with mutated parasites 
were more likely to fight off the infection than were younger pa-
tients whose parasites carried the mutation.

The authors conclude that pfcrt mutations will be the most predictive 
marker of drug resistance in malaria infection.

"We now have a quick and robust tool for monitoring chloroquine re-
sistance on a broad scale," Plowe said, "something that has not been 
possible before due to the high cost in time, money, and manpower to 
conduct standard clinical studies of chloroquine resistance."

--
For more information see the NEJM abstract and full editorial:

A Molecular Marker for Chloroquine-Resistant Falciparum Malaria
Abdoulaye Djimde, Ogobara K. Doumbo, Joseph F. Cortese, Kassoum
Kayentao, Safi Doumbo, Yacouba Diourte, Alassane Dicko, Xin-zhuan Su, 
Takashi Nomura, David A. Fidock, Thomas E. Wellems, Christopher V. 
Plowe, Drissa Coulibaly

The New England Journal of Medicine 2001: Volume 344: 257-263
http://www.nejm.org/content/2001/0344/0004/0257.asp

EDITORIAL

A Molecular Marker for Chloroquine-Resistant Falciparum Malaria
D. C. Warhurst
http://www.nejm.org/content/2001/0344/0004/0299.asp

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