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Background: In Senegal, a significant decrease of malaria transmission intensity has been noted the last years. Parasitaemia has become lower and, therefore, more difficult to detect by microscopy. In the context of submicroscopic parasitaemia, it has become relevant to rely on relevant malaria surveillance tools to better document malaria epidemiology in such settings. Serological markers have been proposed as an essential tool for malaria surveillance. This study aimed to evaluate the sero-epidemiological situation of Plasmodium falciparum malaria in two sentinel sites in Senegal., Methods: Cross-sectional surveys were carried out in Velingara (south Senegal) and Keur Soce (central Senegal) between September and October 2010. Children under 10 years old, living in these areas, were enrolled using two-level, random sampling methods. P. falciparum infection was diagnosed using microscopy. P. falciparum antibodies against circumsporozoite protein (CSP), apical membrane protein (AMA1) and merozoite surface protein 1_42 (MSP1_42) were measured by ELISA method. A stepwise logistic regression analysis was done to assess factors associated with P. falciparum antibodies carriage., Results: A total of 1,865 children under 10 years old were enrolled. The overall falciparum malaria prevalence was 4.99% with high prevalence in Velingara of 10.03% compared to Keur Soce of 0.3%. Symptomatic malaria cases (fever associated with parasitaemia) represented 17.37%. Seroprevalence of anti-AMA1, anti-MSP1_42 and anti-CSP antibody was 38.12, 41.55 and 40.38%, respectively. The seroprevalence was more important in Velingara and increased with age, active malaria infection and area of residence., Conclusion: The use of serological markers can contribute to improved malaria surveillance in areas with declining malaria transmission. This study provided useful baseline information about the sero-epidemiological situation of malaria in Senegal and can contribute to the identification of malaria hot spots in order to concentrate intervention efforts., Trial Registration Number: PACTR201305000551876 ( http://www.pactr.org ).

Our study investigated the possible impact of SP-IPT given to infants and children on the prevalence of SP-resistant haplotypes in the Plasmodium falciparum genes Pfdhfr and Pfdhps, comparing sites with and without IPTi/c. P. falciparum positive samples (N = 352) collected from children < 5 years were analyzed to determine the prevalence of SP resistance-related haplotypes by nested PCR followed by sequence-specific oligonucleotide probe-enzyme-linked immunosorbent assay. The prevalence of the Pfdhfr triple mutant haplotype (CIRN) increased in both groups, but only significantly in the IPTi/c group from 41% to 65% in 2011 (P = 0.005). Conversely, the Pfdhps 437G mutation decreased in both groups from 44.6% to 28.6% (P = 0.07) and from 66.7% to 47.5% (P = 0.02) between 2010 and 2011 in the control and the IPTi/c groups, respectively. A weak trend for decreasing prevalence of quadruple mutants (triple Pfdhfr + Pfdhps 437G) was noted in both groups (P = 0.15 and P = 0.34). During the two cross-sectional surveys some significant changes were observed in the SP resistance-related genes.

Senegal has since 2003 used sulphadoxine-pyrimethamine (SP) for Intermittent Preventive Treatment (IPT) of malaria in risk groups. However, the large-scale IPT strategy may result in increasing drug resistance. Our study investigated the possible impact of SP-IPT given to infants and children on the prevalence of SP-resistant haplotypes in the Plasmodium falciparum genes Pfdhfr and Pfdhps, comparing sites with and without IPTi/c. P. falciparum positives samples (n=352) were collected from children under 5years of age during two cross-sectional surveys in 2010 and 2011 in three health districts (two on IPTi/c and one without IPTi/c intervention) located in the southern part of Senegal. The prevalence of SP-resistance-related haplotypes in Pfdhfr and Pfdhps was determined by nested PCR followed by sequence-specific oligonucleotide probe (SSOP)-ELISA. The prevalence of the Pfdhfr double mutant haplotypes (CNRN and CICN) was stable between years at<10% in the control group (P=0.69), while it rose significantly in the IPTi/c group from 2% in 2010 to 20% in 2011 (P=0.008). The prevalence of the Pfdhfr triple mutant haplotype (CIRN) increased in both groups, but only significantly in the IPTi/c group from 41% to 65% in 2011 (P=0.005). Conversely, the Pfdhps 437G mutation decreased in both groups from 44.6% to 28.6% (P=0.07) and from 66.7% to 47.5% (P=0.02) between 2010 and 2011 in the control and the IPTi/c groups, respectively. Combined with Pfdhfr, there was a weak trend for decreasing prevalence of quadruple mutants (triple Pfdhfr+Pfdhps 437G) in both groups (P=0.15 and P=0.34). During the two cross-sectional surveys, some significant changes were observed in the SP-resistance-related genes. However, since these changes were observed in the two groups, the IPTi/c strategy does only seem to have limited impact on resistance development and other factors as well. However, continuous monitoring will be needed, due to the up-scaling of the IPTi/c strategy in Senegal according to WHO recommendations., (Copyright © 2013 Académie des sciences. Published by Elsevier SAS. All rights reserved.)

Background: In sub-Saharan Africa, malaria is the leading cause of morbidity and mortality especially in children. In Senegal, seasonal malaria chemoprevention (SMC) previously referred to as intermittent preventive treatment in children (IPTc) is a new strategy for malaria control in areas of high seasonal transmission. An effectiveness study of SMC, using sulphadoxine-pyrimethamine (SP) plus amodiaquine (AQ), was conducted in central Senegal from 2008 to 2010 to obtain information about safety, feasibility of delivery, and cost effectiveness of SMC. Here are report the effect of SMC delivery on the prevalence of markers of resistance to SP and AQ., Methods: This study was conducted in three health districts in Senegal with 54 health posts with a gradual introduction of SMC. Three administrations of the combination AQ + SP were made during the months of September, October and November of each year in children aged less than 10 years living in the area. Children were surveyed in December of each year and samples (filter paper and thick films) were made in 2008, 2009 and 2010. The prevalence of mutations in the pfdhfr, pfdhps, pfmdr1 and pfcrt genes was investigated by sequencing and RTPCR in samples positive by microscopy for Plasmodium falciparum., Results: Mutations at codon 540 of pfdhps and codon 164 of pfdhfr were not detected in the study. Among children with parasitaemia at the end of the transmission seasons, the CVIET haplotypes of pfcrt and the 86Y polymorphism of pfmdr1 were more common among those that had received SMC, but the number of infections detected was very low and confidence intervals were wide. The overall prevalence of these mutations was lower in SMC areas than in control areas, reflecting the lower prevalence of parasitaemia in areas where SMC was delivered., Conclusion: The sensitivity of P. falciparum to SMC drugs should be regularly monitored in areas deploying this intervention. Overall the prevalence of genotypes associated with resistance to either SP or AQ was lower in SMC areas due to the reduced number of parasitaemia individuals.

As a result of widespread antimalarial drug resistance, all African countries with endemic malaria have, in recent years, changed their malaria treatment policy. In Senegal, the health authorities changed from chloroquine (CQ) to a combination of sulfadoxine-pyrimethamine (SP) plus amodiaquine (AQ) in 2003. Since 2006, the artemisinin combination therapies (ACTs) artemether-lumefantrine (AL) and artesunate plus amodiaquine (AS/AQ) were adopted for uncomplicated malaria treatment. After several years of CQ withdrawal, the current study wished to determine the level of CQ resistance at the molecular level in selected sites in Senegal, because the scientific community is interested in using CQ again. Finger prick blood samples were collected from Plasmodium falciparum-positive children below the age of 10 years (N = 474) during cross-sectional surveys conducted in two study sites in Senegal with different malaria transmission levels. One site is in central Senegal, and the other site is in the southern part of the country. All samples were analyzed for single nucleotide polymorphisms (SNPs) in the P. falciparum CQ resistance transporter gene (Pfcrt; codons 72-76) using polymerase chain reaction (PCR) sequence-specific oligonucleotide probe (SSOP) enzyme-linked immunosorbent assay (ELISA) and real-time PCR methods. In total, the 72- to 76-codon region of Pfcrt was amplified in 449 blood samples (94.7%; 285 and 164 samples from the central and southern sites of Senegal, respectively). In both study areas, the prevalence of the Pfcrt wild-type single CVMNK haplotype was very high; in central Senegal, the prevalence was 70.5% in 2009 and 74.8% in 2010, and in southern Senegal, the prevalence was 65.4% in 2010 and 71.0% in 2011. Comparing data with older studies in Senegal, a sharp decline in the mutant type Pfcrt prevalence is evident: from 65%, 64%, and 59.5% in samples collected from various sites in 2000, 2001, and 2004 to approximately 30% in our study. A similar decrease in mutant type prevalence is noted in other neighboring countries. With the continued development of increased CQ susceptibility in many African countries, it may be possible to reintroduce CQ in the near future in a drug combination; it could possibly be given to non-vulnerable groups, but it demands close monitoring of possible reemergence of CQ resistance development.

Background: In view of the high level of chloroquine resistance in many countries, WHO has recommended the use of combination therapy with artemisinin derivatives in the treatment of uncomplicated malaria due to Plasmodium falciparum. Four antimalarial drug combinations, artesunate plus amodiaquine (Arsucam), artesunate plus mefloquine (Artequin), artemether plus lumefantrine (Coartem; four doses and six doses), and amodiaquine plus sulphadoxine-pyrimethamine, were studied in five health districts in Senegal., Methods: This is a descriptive, analytical, open, randomized study to evaluate the efficacy and tolerability of these four antimalarial combinations in the treatment of uncomplicated falciparum malaria using the 2002 WHO protocol., Results: All drug combinations demonstrated good efficacy. On day 28, all combinations resulted in an excellent clinical and parasitological response rate of 100% after correction for PCR results, except for the four-dose artemether-lumefantrine regimen (96.4%). Follow-up of approximately 10% of each treatment group on day 42 demonstrated an efficacy of 100%.The combinations were well tolerated clinically and biologically. No unexpected side-effect was observed and all side-effects disappeared at the end of treatment. No serious side-effect requiring premature termination of treatment was observed., Conclusion: The four combinations are effective and well-tolerated.

We previously investigated malaria in the southern health district of the city of Dakar, which includes the oldest neighborhoods. In this study, we investigated malaria in the central health district, corresponding to the central area of the conurbation. The study was carried out at 12 sites, from March 1996 to February 1997. The sites were selected such that the entire district was covered and included 2 sites in the shanty town and three in an old village that has been absorbed into the city. We carried out prospective monthly entomological analyses with a view to identifying the vectors and the mode of transmission of malaria. We also carried out clinical and parasitological follow up to determine the incidence of parasitemia and of bouts of malaria. Insects were collected overnight from humans and the insects remaining the next morning in 10 bedrooms in the health district were collected. For clinical and parasitological follow up, families were visited at home once per week and their clinical state was assessed. Blood smears were taken to facilitate the detection of bouts of malaria. Body temperature was measured and we checked for the presence of organisms in the blood systematically during the last weekly visit of each month. For a total of 308 collections at night from human volunteers and 1,395 bedroom collections of residual fauna, we obtained 12,879 Culicidae females, 199 (1.5%) of which were anopheles mosquitoes, with Culex quinquefasciatus accounting for 98% of the remaining mosquitoes. As in the southern district, A. arabiensis was the only species of the A. gambiae complex collected. Anopheles mosquitoes accounted for only 0.3 bites per man per night and 0.07 females per room. They were therefore poorly represented in this district and were not detected at all at five sites. They were found in large numbers only during the rainy season, especially in September, when they accounted for 2.25 bites per man per night and 0.3 females per room at 3 sites in an undeveloped zone in which 81.4% of all the anopheles mosquitoes were collected. The parturition frequency of the biting females was 32.6% and that of the females collected in houses was 50.0%. None of the A. arabiensis females dissected (98.5% of those collected) carried Plasmodium sporozoites. The clinical and parasitological follow up concerned 2,583 individuals, aged from 1 month to 80 years, from 285 families resident in Dakar who volunteered for the study; 41.9% of these individuals were less than 15 years old and 92.2% had been living in Dakar for more than 2 years. Thick and thin blood smears taken monthly showed the frequency of the parasite to be 1.0% and that of gametocytes to be 0.1%. P. falciparum was the only parasite detected in the subjects. Plasmodium infections were observed in all age groups, with a frequency of 0.4% (adults over the age of 20 years) to 1.6% (children under two years of age). Parasitized subjects were detected in every month of the study, with a frequency of 0.4% (in January) to 1.9% (in December). The largest number of cases detected in a three-month period (38.8% of all cases) was that for October to December, the three-month period immediately after the rainy season (July to September). Parasite frequency, which was no higher than 1. 2% at 10 sites, was clearly higher at two sites in the shanty town (3.8 and 6.8%), mostly inhabited by immigrants from rural areas. At the end of the study year, satisfactory weekly follow up was considered to have been achieved for 1,067 of the participants. The annual incidence of parasitemia in this cohort was 5.1% and that of malaria was 2.4%. Incidence did not vary significantly with age and was between 1.8% and 7.6% for parasitemia and between 0.8% and 3.5% for malaria. However, significant differences in incidence were observed between areas. Incidence was higher at the two sites in the shanty town, with rates of 12.1% and 36.5% for parasitemia and 6.1% and 15.9% for malaria. (ABSTRACT TR