Scientific bulletin n° 344 - March 2010
Combination therapies
against drug resistance in malaria
alaria kills between
one and three million
people each year. The
African continent suffers
90% of these deaths. The
pathogen responsible is
Plasmodium falciparum, a
parasite transmitted to
humans by Anopheles
mosquitoes.
Treatments exist which in
the past have proved to be
effective, such as
chloroquine. However,
confronted by the
emergence in Africa of
resistant parasitic forms in
the 1980s, monotherapies1
failed*. Researchers from
the IRD and the
Organisation de
coordination pour la lutte
contre les endémies en
Afrique centrale, working
in conjunction with the
Cameroon Ministry of
Public Health2, recently
tested the efficacies of
two-drug combination
therapies based on an
artemisinin3 derivative, the
latest development in
antimalarial medicines. The
result was a 96% success
rate. The two-drug
combination helps alleviate
that drug’s rapid
elimination by the human
body and holds back the
emergence of resistance to
this new treatment.
© IRD / Cristelle Duos
M
Awareness-building campaign to promote the use of ACTs (artemisinin-based combination therapy) in
Benin. These treatments, recommended by WHO, limit the development of malaria parasite resistance.
Malaria is the world’s most widespread
parasitic diseases, with about 600 million
people affected. The pathogen responsible
is a microscopic parasite of the genus Plasmodium, the species P. falciparum which
causes the most serious form of this
disease. It is still a major public health
problem in the countries of the South,
especially Africa. Since the 1980s, efforts
to control the disease in Africa have come
up against the parasites’ resistance to
medicines, used up to then in single-drug
based treatment, or monotherapy1. In an
effort to counter this problem, researchers
from the IRD and the Organisation de coordination pour la lutte contre les endémies en
Afrique centrale (OCEAC), in collaboration
with the Cameroon Ministry of Public
Health2, assessed the efficacy of seven twodrug therapeutic combinations.
Treatment failure or new attack ?
In line with the World Health Organization
protocol, the research team conducted a
clinical trial on 1 400 patients infected by
malaria, mostly children under 5 years of
age, in four sites in Cameroon. If treatment
failure occurred 4 , they identified two
possible causes. Either the same strain of the
parasite reappears: in which case, the failure
may be linked to the drug’s insufficient level
of efficacy. Or the strain is different: here a
second malaria attack is responsible, independent of the first. This second case is
therefore considered as a therapeutic
success. A re-infection is commonly
observed in an endemic zone where malaria
transmission to humans, perpetrated by
mosquitoes of the genus Anopheles, is
permanent and intense. In some places,
every person can receive one infectious bite
per night.
Artemisinin: greater efficacy proved
During the trial, the research team tested
different treatment combinations comprising one of the artemisinin derivatives3, the
latest development in in antimalarials.
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You can find IRD photos concerning this bulletin, copyright free for press,
on www.ird.fr/indigo
CONTACTS:
Leonardo BASCO
director of research at the IRD
Tel: 04 91 15 01 49
leonardo.basco@ird.fr
UMR Maladies infectieuses et
tropicales émergentes (IRD /
CNRS/ INSERM/ Université de la
Méditerranée - Aix-Marseille 2)
Address:
Institut de recherche biomédicale
des armées (IRBA)
Allée du médecin colonel
Eugène Jamot
Parc du Pharo - BP60109
13262 Marseille cedex 07, France
Solange Whegang Youdom
PhD student at the IRD
solange.whegang@math-info.univ-paris5.fr
Département de Mathématiques
et Sciences Physiques
Address:
École Nationale Supérieure
Polytechnique
Université de Yaoundé I
Yaoundé, Cameroon
REFERENCES:
whegang s. y., tahar rachida,
foumane v. n.,
soula g., gwet h.,
thalabard j. c., basco leonardo.
Efficacy of non-artemisinin- and
artemisinin-based combination
therapies for uncomplicated
falciparum malaria in Cameroon,
Malaria Journal, 2010, 9 : 56.
doi:10.1186/1475-2875-9-56
KEY WORDS:
These proved highly effective against the
parasite P. falciparum, producing a cure
rate of 96% after three days of treatment
(as against less than 88% for amodiaquine
alone or combined with sulphadoxine-pyrimethamine) and 95% one month later.
These results also show their speed of
action.
In contrast with other antimalarials which
can provoke severe allergies, vomiting or
nausea, the artemisinin derivatives are
almost devoid of serious side-effects.
However, they are eliminated from the
human body very rapidly. This rapid elimination can be the factor behind a resurgence of malaria if another more slowly
eliminated medicine has not been given at
the same time.
Artemisinin: agent against new resistance
Derivatives of artemisinin are the most
recent antimalarial drugs, for which there is
currently no form of resistance in Africa.
Combined use of this compound is a new
therapeutic strategy which improves care
for patients hit by malaria and delays the
emergence of resistant strains of P. falciparum. This method certainly represents a
major advance for malaria control and, in
some endemic areas of South-Est Asia, is
the only effective means of treating against
malaria caused by resistant P. falciparum. It
is generally well tolerated and now strongly
recommended in countries like Cameroon
where the resistance level is high.
Africa currently has quite a good range of
antimalarial medicines at its disposal.
Assessment and comparison of their costeffectiveness and safety-tolerance levels
are essential for rational choices to be
made between them. They are also impe-
rative for devising, as far as possible, a
common policy for using these powerful
malaria-control weapons at the subregional level of Central Africa. One question remains: will these new treatments
maintain-their efficacy against the resistant
parasite much longer? And if this is the
case, can China, the main producer, supply
enough artemisinin to meet the growing
demand for Africa as a whole, or even of
the whole globe, at an affordable price for
all malaria sufferers ?
* See scientific news sheet n° 250 - Malaria:
efficacy of monotherapies in Cameroon
Gaëlle COURCOUX – DIC
Translation – Nicholas FLAY
1. A monotherapy is a treatment involving just one drug.
2. Statistical analysis of data collected by the researchers of the IRD-OCEAC team was conducted in
partnership with mathematicians from the Ecole
Nationale Supérieure Polytechnique of the University of Yaounde I and the Centre National de la
Recherche Scientifique (CNRS) – University of
Paris V.
3. Artemisinin, also called qinghaosu in Chinese, is a
natural substance extracted from a plant, Artemisia annua, used for centuries in the Chinese
pharmacopoeia to treat febrile diseases.
4. Therapeutic failure is defined either as the persistence of fever and the presence of the parasite in
the blood, even of worsening of the clinical signs,
even after 2 to 3 days’ course of treatment, or as
the recurrence of symptoms, fever in particular,
linked to the reappearance of parasites in the
blood after their elimination by the treatment.
Malaria, combination therapy,
resistance, Cameroon
INDIGO,
IRD PHOTO LIBRARY :
Daina Rechner
+33 (0)4 91 99 94 81
indigo@ird.fr
www.ird.fr/indigo
Artemisinin is a natural compound extracted from the
plant Artemisia annua, originating from the Chinese
pharmacopoeia.
© IRD / Céline Ravallec
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© Action Medeor/Brigitte Betzelt
Scientific bulletin n° 344 - March 2010
For further information
Examination of blood samples to detect the possible
presence of the parasite, at the IRD centre in Hann,
Senegal.
Gaëlle Courcoux, coordinatrice
Délégation à l’information et à la communication
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