First cases of resistance to the main antimalarial in Africa
For the first time in Africa, a Franco-Rwandan team of scientists, led by Didier Ménard from the Institut Pasteur in Paris and Aline Uwimana from the Rwanda Biomedical Center in Kigali, highlighted what field doctors and the WHO feared for a long time: the appearance of parasites Plasmodium resistant to the drug most used since the 2000s, artemisinin, in patients with malaria (1).
Strictly speaking, the latter is not alone, but combined with another molecule, a bit like the combinations of drugs implemented against bacteria (antibiotics) or AIDS (antiretrovirals). Artemisinin acts very quickly (it kills most parasites within a few hours) while a partner molecule acts over a long time. Artemisinin itself is a molecule extracted from the leaves of the annual mugwort (Artemisia annua or Chinese wormwood), a plant growing naturally in Africa and cultivated in particular in Madagascar.
« This resistance, which shortens the period of elimination of parasites from treated subjects, currently represents a serious threat that can hamper disease control efforts., warns Didier Ménard, research director who has worked for a long time in Cambodia and head of the Genetics and resistance of malaria unit at the Institut Pasteur. In particular, the major fear of seeing these resistant parasites spread to sub-Saharan Africa, the continent most affected by malaria (more than 90% of cases), as was the case with previous generations of antimalarial drugs such as chloroquine in particular “, he continues.
Ants work on the ground led by Rwandan biologists
In the field, Rwandan biologists and doctors detected in more than 500 people with malaria based on their clinical signs, treated and followed them for 42 days, while sending blood samples to the Institut Pasteur in Paris (2 ). Result: the identification, for the first time in Africa, of parasites resistant to artemisinin and presenting mutations within the K13 gene. With different infection rates from city to city, proving that the resistant strain is spreading throughout Rwanda.
However, from an epidemiological point of view, the complete sequencing of these parasites indicates that the mutations were selected from the populations of Rwandan parasites and that they did not result from a diffusion of Asian parasites. ” Unexpectedly, these results differ from previous scenarios in which the emergence of parasites resistant to chloroquine and pyrimethamine in Africa was due to the spread of resistant parasites from South East Asia. », Explains Didier Ménard,
Improve clinical monitoring of patients
In terms of public health, it is feared that, in the absence of effective measures to contain the spread of resistant strains in Rwanda and in the Great Lakes countries (Uganda, DRC, Burundi, Kenya, Zambia, Tanzania), these parasites acquire over time the ability to resist the combination of molecules including artemisinin. ” As a result, the only available treatments would become ineffective, as happened in Southeast Asia. », Explains Didier Ménard.
To counter this development, “ the clinical tools allowing the follow-up of the persons treated should be improved, such as the implementation of a new clinical examination from the 2nde day rather than the 3e or the 4e after starting drug treatment », Offers Didier Ménard.
Indeed, a modeling of this scenario by a team from Imperial College in London, in which no action would be taken, recently predicted that the ineffectiveness of artemisinin-based drugs in Africa could be responsible for 78 million cases and 116,000 additional deaths over a five-year period.