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<0.05) with higher slide positivity rates (42-53%) among children aged >5 years old and adults than in young children aged <5 years old in both 2009 and 2010. In Hodh Elgharbi, high slide positivity rates (60.9-86.2%) were observed in all age groups in 2010, and there was no significant trend (P>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.