Research

Ex vivo susceptibility of Plasmodium falciparum isolates from Dakar, Senegal, to seven standard anti-malarial drugs

Bécaye Fall¹, Silmane Diawara¹, Kowry Sow¹, Eric Baret², Bakary Diatta³, Khadidiatou B Fall⁴, Pape S Mbaye⁵, Fatou Fall⁶, Yaya Diémé¹, Christophe Rogier², Boubacar Wade⁷, Raymond Bercion¹ and Bruno Pradines^2,8*

• * Corresponding author: Bruno Pradines bruno.pradines@free.fr

Author Affiliations

¹ Laboratoire d'étude de la chimiosensibilité du paludisme, Fédération des laboratoires, Hôpital Principal de Dakar, Dakar, Sénégal

² Unité de parasitologie - Unité de recherche sur les maladies infectieuses et transmissibles émergentes - UMR 6236, Institut de recherche biomédicale des armées, Allée du Médecin-colonel Jamot, Parc le Pharo, BP 60109, 13262 Marseille Cedex 7, France

³ Service de réanimation médicale, Hôpital Principal de Dakar, Dakar, Sénégal

⁴ Service de pathologie infectieuse, Hôpital Principal de Dakar, Dakar, Sénégal

⁵ Département de médecine interne et spécialités médicales de pathologie tropicale, Hôpital Principal de Dakar, Dakar, Sénégal

⁶ Service interne d'hépato-gastroentérologie, Hôpital Principal de Dakar, Dakar, Sénégal

⁷ Chefferie, Hôpital Principal de Dakar, Dakar, Sénégal

⁸ Centre National de référence du Paludisme, Marseille, France

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Malaria Journal 2011, 10:310 doi:10.1186/1475-2875-10-310

Published: 20 October 2011

Abstract

Background

As a result of widespread chloroquine and sulphadoxine-pyrimethamine resistance, artemisinin-based combination therapy (ACT) (which includes artemether-lumefantrine and artesunate-amodiaquine) has been recommended as a first-line anti-malarial regimen in Senegal since 2006. Since then, there have been very few reports on the ex vivo susceptibility of Plasmodium falciparum to anti-malarial drugs. To examine whether parasite susceptibility has been affected by the widespread use of ACT, the ex vivo susceptibility of local isolates was assessed at the military hospital of Dakar.

Methods

The ex vivo susceptibility of 93 P. falciparum isolates from Dakar was successfully determined using the Plasmodium lactate dehydrogenase (pLDH) ELISA for the following drugs: chloroquine (CQ), quinine (QN), mefloquine (MQ), monodesethylamodiaquine (MDAQ), lumefantrine (LMF), dihydroartemisinin (DHA) and doxycycline (DOX).

Results

After transformation of the isolate IC₅₀ in ratio of IC₅₀ according to the susceptibility of the 3D7 reference strain (isolate IC₅₀/3D7 IC₅₀), the prevalence of the in vitro resistant isolates with reduced susceptibility was 50% for MQ, 22% for CQ, 12% for DOX, 6% for both QN and MDAQ and 1% for the drugs LMF and DHA. The highest significant positive correlations were shown between responses to CQ and MDAQ (r = 0.569; P < 0.0001), LMF and QN (r = 0.511; P < 0.0001), LMF and DHA (r = 0.428; P = 0.0001), LMF and MQ (r = 0.413; P = 0.0002), QN and DHA (r = 0.402; P = 0.0003) and QN and MQ (r = 0.421; P = 0.0001).

Conclusions

The introduction of ACT in 2002 has not induced a decrease in P. falciparum susceptibility to the drugs DHA, MDAQ and LMF, which are common ACT components. However, the prevalence of P. falciparum isolates with reduced susceptibility has increased for both MQ and DOX. Taken together, these data suggest that intensive surveillance of the P. falciparum in vitro susceptibility to anti-malarial drugs in Senegal is required.