Malaria in Mauritania : retrospective and prospective overview

Malaria has become a major public health problem in Mauritania since the 1990s, with an average of 181,000 cases per year and 2,233,066 persons at risk during 1995-2012. This paper provides the first publicly available overview of malaria incidence and distribution in Mauritania. Information on the burden and malaria species distribution is critical for guiding national efforts in malaria control. As the incidence of malaria changes over time, regular updates of epidemiological data are necessary

Malaria epidemiology in Kobeni department, southeastern Mauritania from 2015 to 2017

Background Plasmodium falciparum malaria is endemic in the southern sahelian zone of Mauritania where intense internal and trans-border human and livestock movement occurs. The risk of importation and spread of drug-resistant parasites need to be regularly assessed in this region. The objective of the study was to assess the recent malaria situation near the Mauritania-Mali border. Methods Between February 2015 and December 2017, patients with fever or history of fever during the previous 48 h, presenting at the health centre of Kobeni city, were screened for malaria using a rapid diagnostic test (RDT) and microscopic examination of blood smears. The diagnosis was later confirmed by PCR. Cohen's kappa statistics was used to estimate the degree of agreement between diagnostic methods. Fisher's exact test was used to compare proportions. The odds ratio was calculated to measure the association between the use of bed nets and malaria infection. Results A total of 2326 febrile patients (mean age, 20.2 years) were screened for malaria. The presence of malaria parasites was detected by RDT and microscopy in 53.0% and 49.3% of febrile patients, respectively, and was confirmed by PCR in 59.7% (45 missing data). Of 1361 PCR-positive samples, 1205 (88.5%) were P. falciparum, 47 (3.5%) P. vivax, and 99 (7.3%) P. falciparum-P. vivax mixed infection. Malaria transmission occurred mostly during and shortly after the rainy season. The annual rainfall was relatively low in 2016 (267 mm) and 2017 (274 mm), compared to 2015 (448 mm), and coincided with a decline in malaria prevalence in 2016-2017. Although 71.8% of febrile patients reported to possess at least one bed net in the household in our questionnaire, its reported use was not protective against malaria infection (odds ratio: 1.1, 95% CI: 0.91-1.32). Conclusions Our study confirmed that P. falciparum is the dominant species in the sahelian zone and that malaria transmission is seasonal and associated with rainfall in this zone. The application of the current national policy based on rapid and reliable malaria diagnosis, case management with artemisinin-based combination therapy, intermittent preventive treatment for pregnant women, distribution and use of long-lasting insecticide impregnated bed nets, and the planned introduction of seasonal malaria chemoprevention for all children under 6 years old is expected to sustainably reduce malaria transmission in this zone

Malaria-associated morbidity during the rainy season in Saharan and Sahelian zones in Mauritania

Reliable epidemiological data based on laboratory-confirmed cases are scarce in Mauritania. A large majority of reported malaria cases are based on presumptive clinical diagnosis. The present study was conducted to establish a reliable database on malaria morbidity among febrile paediatric and adult patients consulting spontaneously at public health facilities in Nouakchott, situated in the Saharan zone, and in Hodh Elgharbi region in the Sahelian zone in south-east Mauritania during the peak transmission periods. Giemsa-stained thin and thick films were examined under the microscope, and the parasite density was determined according to the procedures recommended by the World Health Organization. Microscopy results were confirmed by rapid diagnostic test for malaria. A total of 1161 febrile patients (498 in Nouakchott and 663 in Hodh Elgharbi region) were enrolled during two successive peak transmission periods in 2009 and 2010. In Nouakchott, 253 (50.8%) febrile patients had positive smears (83% Plasmodium vivax monoinfections and 17% Plasmodium falciparum monoinfections). In Hodh Elgharbi, 378 of 663 patients (57.0%) were smear-positive, mostly due to P. falciparum monoinfections (96.6%). Unlike in Nouakchott, mixed P. falciparum-P. vivax infections, as well as P. vivax, P. ovale, and P. malariae monoinfections, were also observed at a very low prevalence in southern Mauritania. In Nouakchott, malaria occurred more frequently (P 5 years old and adults than in young children aged 0.05) in relation with age groups. The present study confirmed the predominance of P. falciparum in southern Mauritania reported in previous studies. The presence of P. vivax in Nouakchott is a new epidemiological reality that requires an urgent adoption of novel strategies for parasitological and vector control to combat urban malaria. Moreover, the present study provides evidence-based data on malaria burden in two regions in Mauritania that may serve as a springboard to establish and develop a national surveillance system of malaria epidemiology

Aedes aegypti (Diptera : Culicidae) in Mauritania : first report on the presence of the arbovirus mosquito vector in Nouakchott

Aedes aegypti L. (Diptera: Culicidae) is a major vector of yellow fever, dengue, and chikungunya viruses throughout tropical and subtropical areas of the world. Although the southernmost part of Mauritania along the Senegal river has long been recognized at risk of yellow fever transmission, Aedes spp. mosquitoes had never been reported northwards in Mauritania. Here, we report the first observation of Aedes aegypti aegypti (L.) and Aedes (Ochlerotatus) caspius (Pallas, 1771) in the capital city, Nouakchott. We describe the development sites in which larvae of the two species were found, drawing attention to the risk for emergence of arbovirus transmission in the city

Increasing prevalence of Plasmodium vivax among febrile patients in Nouakchott, Mauritania

The occurrence of Plasmodium vivax malaria was reported in Nouakchott, Mauritania in the 1990s. Several studies have suggested the frequent occurrence of P. vivax malaria among Nouakchott residents, including those without recent travel history to the southern part of the country where malaria is known to be endemic. To further consolidate the evidence for P. vivax endemicity and the extent of malaria burden in one district in the city of Nouakchott, febrile illnesses were monitored in 2012-2013 in the Teyarett health center. The number of laboratory-confirmed P. vivax cases has attained more than 2,000 cases in 2013. Malaria transmission occurs locally, and P. vivax is diagnosed throughout the year. Plasmodium vivax malaria is endemic in Nouakchott and largely predominates over Plasmodium falciparum

Comparative post-rainy season surveys of malaria-associated morbidity among febrile pediatric patients in Nouakchott, Mauritania

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Assessment of drug resistance associated genetic diversity in Mauritanian isolates of Plasmodium vivax reveals limited polymorphism

BackgroundPlasmodium vivax is the predominant malaria species in northern Mauritania. Molecular data on P. vivax isolates circulating in West Africa are scarce. The present study analysed molecular markers associated with resistance to antifolates (Pvdhfr and Pvdhps), chloroquine (Pvmdr1), and artemisinin (Pvk12) in P. vivax isolates collected in two cities located in the Saharan zone of Mauritania.MethodsBlood samples were obtained from P. vivax-infected patients recruited for chloroquine therapeutic efficacy study in 2013 and febrile patients spontaneously consulting health facilities in Nouakchott and Atar in 2015-2016. Fragments of Pvdhfr (codons 13, 33, 57, 58, 61, 117, and 174), Pvdhps (codons 382, 383, 512, 553, and 585), Pvmdr1 (codons 976 and 1076) and Pvk12 (codon 552) genes were amplified by PCR and sequenced.ResultsMost of the isolates in Nouakchott (126/154, 81.8%) and Atar (44/45, 97.8%) carried the wild-type Pvdhfr allelic variant (IPFSTSI). In Nouakchott, all mutants (28/154; 18.2%) had double Pvdhfr mutations in positions 58 and 61 (allelic variant IPFRMSI), whereas in Atar only 1 isolate was mutant (S117N, allelic variant IPFSTNI). The wild-type Pvdhps allelic variant (SAKAV) was found in all tested isolates (Nouakchott, n=93; Atar, n=37). Few isolates in Nouakchott (5/115, 4.3%) and Atar (3/79, 3.8%) had the mutant Pvmdr1 allele 976F or 1076L, but not both, including in pre-treatment isolates obtained from patients treated successfully with chloroquine. All isolates (59 in Nouakchott and 48 in Atar) carried the wild-type V552 allele in Pvk12.ConclusionsPolymorphisms in Pvdhfr, Pvdhps, Pvmdr1, and Pvk12 were limited in P. vivax isolates collected recently in Nouakchott and Atar. Compared to the isolates collected in Nouakchott in 2007-2009, there was no evidence for selection of mutants. The presence of one, but not both, of the two potential markers of chloroquine resistance in Pvmdr1 in pre-treatment isolates did not influence the clinical outcome, putting into question the role of Pvmdr1 mutant alleles 976F and 1076L in treatment failure. Molecular surveillance is an important component of P. vivax malaria control programme in the Saharan zone of Mauritania to predict possible emergence of drug-resistant parasites