L'oasis d'Atar (à gauche, séparée de la ville par une digue) abrite le parasite P. vivax, responsable du paludisme.

© Dr Khadijetou M. Lekweiry-GEMI-JEAI 2017

Malaria: P. vivax detected in the oasis of Atar


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Updated 21.10.2019

For the first time, the presence of the Plasmodium vivax parasite has been confirmed in Atar, northern Mauritania: it is responsible for most cases of malaria. It is therefore crucial to take every step to avoid an epidemic, not just in Mauritania but also in North Africa, or even beyond, notably in Europe.

The Plasmodium vivax parasite has been found in Atar, as attested by a study 1 led by Ali Ould Mohamed Salem Boukhary, in charge of JEAI RI3M 2 . Due to a parasite of the genus Plasmodium spread by the bite of anopheles mosquitoes and causing acute fevers, malaria kills nearly 500,000 people worldwide every year, 90% of whom live in Africa. Originating in Nouakchott, in the late 1990s, this scourge is a major health issue in Mauritania. And yet, up until recently, there was limited data on its possible presence in the north of the country, notably in Atar, 440 km north-east of the capital, in the vast wilayah of Mauritania’s Adrar region. “A few suspected cases were reported in this oasis in the early 2010s. But they were not confirmed by any well-conducted study”, points out the molecular biologist.

P.vivax, responsible for 74% of malaria cases

To address this gap, from March 2015 to December 2016 researchers recruited 453 patients from the Atar hospital with a fever or a history of fever. They were all given a rapid on-site diagnosis and appropriate treatment. The subsequent use of PCR?Polymerase chain reaction. This technique consists of the mass duplication of the genetic material of the parasites found in blood to accurately identify the species. in a laboratory confirmed the diagnosis of malaria. “This is the only technique capable of rigorously distinguishing and detecting P. vivax amongst the five species of Plasmodium. The most common being P. falciparum and P. vivax”, stresses Ali Ould Mohamed Salem Boukhary. In the end, 162 patients were found to be infected: 120 (74.1%) were infected with P.vivax, 4 (2.5%) with P. falciparum and 38 (23.4%) with both species.

However, the antimalarial treatment currently recommended in Mauritania is artesunate-amodiaquine or artemether-lumefantrine. Unfortunately, while they are effective against P.falciparum, “these therapies are unable to kill a particular form of P. vivax, known as hypnozoite, which can lay dormant in the liver for years”, explains Leonardo Basco, parasitologist and IRD correspondent of the JEAI, who participated in the study. Consequently, this “latent” form can revive the disease at any time even if the patient has not been bitten by a mosquito again.

Les bassins d'irrigation des palmiers d'Atar servent de gîtes aux anophèles, vecteurs potentiels de Plasmodium.

© Dr Khadijetou M. Lekweiry-GEMI-JEAI 2017

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Atar, potential source of an epidemic

The situation is all the more worrying as population movements into Atar, which are likely to promote the dissemination of P. vivax, have become more frequent lately: foreign tourists, notably from Europe, have joined the thousands of Mauritanians who visit the oases of the Adrar region every year. In addition, the oases are a transit zone for thousands of illegal migrants from Sub-Saharan Africa on their way to Northern African countries and Europe. Hence the fear of an epidemic outbreak in Atar. “There is an urgent need to develop prevention and control strategies adapted to P. vivax”, insists Leonardo Basco.

And yet, effective treatment – the only one – against the latent hepatic form of P. vivax is available: primaquine. This drug is not being used at the moment as it is contraindicated in deficiency of the enzyme glucose-6-phosphate dehydrogenase (G6PD). And this disorder affects up to 30% of all Africans! “Researchers are stressing the need to validate the effectiveness of rapid tests making it possible to diagnose this disorder. This will finally pave the way for the safe administration of primaquine”. Ali Ould Mohamed Salem Boukhary’s team are conducting research in this area right now.

Notes :

1.   Jemila Mint Deida, Rachida Tahar, Yacoub Khalaf, Khadijetou Mint Lekweiry, Abdoullah Hmeyade, Mohamed Lemine Ould Khairy, Frédéric Simard, Hervé Bogreau, Leonardo Basco, Ali Ould Mohamed Salem Boukhary. Oasis malaria, northern Mauritania , Emerging Infectious Diseases , 17 décembre 2018

2. Jeune équipe associée à l’IRD « Recherches intégrées sur les moustiques et les maladies infectieuses en Mauritanie »

Contacts : ali.boukhary@ird.fr / leonardo.basco@ird.fr