Research

Preliminary study of malaria incidence in Nouakchott, Mauritania

Khadijetou Mint Lekweiry¹ , Mohamed Ould Abdallahi² , Hâmpaté Ba² , Céline Arnathau³ , Patrick Durand³ , Jean-François Trape⁴ and Ali Ould Mohamed Salem¹

¹  Laboratoire de Biotechnologie, Faculté des Sciences et Techniques, Université de Nouakchott, BP 5026, Mauritanie

²  Service de Mycologie et de Parasitologie, Institut National de Recherches en Santé Publique, BP 695, Nouakchott, Mauritanie

³  Génétique et Evolution des Maladies Infectieuses, UMR 2724 IRD-CNRS-UMI, Centre IRD, 911 avenue Agropolis, BP 64501, 34394 Montpellier Cedex 5, France

⁴  Laboratoire de Paludologie et Zoologie tropicale, UMR 198, Institut de Recherche pour le Développement, BP 1386, CP 18524 Dakar, Sénégal

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Malaria Journal 2009, 8:92doi:10.1186/1475-2875-8-92

Published:	5 May 2009

Abstract

Background

Malaria is one of the main motives for outpatient consultation and hospitalization in Mauritania. However, its incidence remains unclear because of diagnostic problems and insufficient epidemiological data.

Methods

Between April and August 2007, a study on malaria incidence was carried out in Nouakchott city. A total of 237 febrile outpatients, from all Nouakchott districts, attending the two main hospitals of the city were investigated. Finger prick and blood dried filter paper samples were performed to prepare thick and thin films and nested-PCR for malaria parasite species identification and density. The accuracy of diagnosis of 'presumptive malaria', assigned by clinicians and based on fever and other malaria suggestive symptoms, was assessed. Entomological investigations based on morphological and molecular characterization of Anopheline species were conducted in Dar Naïm district.

Results

Malaria prevalence rate was 25.7% (61/237), the majority of positive blood slides as well as nested-PCR products were due to Plasmodium vivax 70.5% (43/61) and Plasmodium ovale 24.6% (15/61). Two malaria patients, both with P. vivax, have never travelled out of Nouakchott and seem likely to have been autochthonous (3.3%). Of the 237 individuals included in the survey, 231(97.5%) were clinically diagnosed and treated as malaria cases. 26.4% of clinically diagnosed cases were positive for Plasmodium using microscopic examination and PCR. Thus, false positive cases constituted 73.6% (170/231) of the clinically diagnosed malaria cases. The search for mosquito vectors in Dar Naïm district allowed morphological and molecular identification of Anopheles arabiensis and Anopheles pharoensis.

Conclusion

This study demonstrates that, during the hot and dry season, Plasmodium species responsible of recurrent malaria (P. vivax and P. ovale) are the dominant species in Nouakchott city and autochthonous malaria cases exist but are rare. Clinical diagnosis of malaria has a very low positive predicted value. The systematic use of microscopy-based diagnosis and/or rapid diagnostic tests should be considered to appropriately manage malaria and non-malaria cases.