Genetic diversity of Plasmodium falciparum isolates from concurrent malaria and arbovirus co-infections in Kedougou, southeastern Senegal

Niang, Makhtar; Loucoubar, Cheikh; Sow, Abdourahmane; Diagne, Moussa Moïse; Faye, Oumar; Diallo, Mawlouth; Touré-Baldé, Aïssatou; Sall, Amadou Alpha

doi:10.1186/s12936-016-1208-7

Cited by 20 publications

(25 citation statements)

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“…Such observations are supported by previous studies in Senegal [5, 13] and Nigeria [25] but contrast with data from Benin and Gabon [26, 27], emphasizing the need for multicentric studies using P. falciparum isolates from both asymptomatic and symptomatic individuals to comprehensively establish the potential relationship between specific allele carriage and disease outcome. High to moderate mean MOI was observed among P. falciparum isolates across all the studied villages with the highest mean MOI being observed in Kedougou village.…”

Section: Discussionsupporting

confidence: 55%

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Spatio-temporal analysis of the genetic diversity and complexity of Plasmodium falciparum infections in Kedougou, southeastern Senegal

et al. 2017

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BackgroundGenetic analyses of the malaria parasite population and its temporal and spatial dynamics could provide an assessment of the effectiveness of disease control strategies. The genetic diversity of Plasmodium falciparum has been poorly documented in Senegal, and limited data are available from the Kedougou Region. This study examines the spatial and temporal variation of the genetic diversity and complexity of P. falciparum infections in acute febrile patients in Kedougou, southeastern Senegal. A total of 263 sera from patients presenting with acute febrile illness and attending Kedougou health facilities between July 2009 and July 2013 were obtained from a collection established as part of arbovirus surveillance in Kedougou. Samples identified as P. falciparum by nested PCR were characterized for their genetic diversity and complexity using msp-1 and msp-2 polymorphic markers.ResultsSamples containing only P. falciparum accounted for 60.83% (160/263) of the examined samples. All three msp-1 allelic families (K1, MAD20 and RO33) and two msp-2 allelic families (FC27 and 3D7) were detected in all villages investigated over the 5-year collection period. The average genotype per allelic family was comparable between villages. Frequencies of msp-1 and msp-2 allelic types showed no correlation with age (Fisher’s exact test, P = 0.59) or gender (Fisher’s exact test, P = 0.973), and were similarly distributed throughout the 5-year sampling period (Fisher’s exact test, P = 0.412) and across villages (Fisher’s exact test, P = 0.866). Mean multiplicity of infection (MOI) for both msp-1 and msp-2 was highest in Kedougou village (2.25 and 2.21, respectively) and among younger patients aged ≤ 15 years (2.12 and 2.00, respectively). The mean MOI was highest in 2009 and decreased progressively onward.ConclusionCharacterization of the genetic diversity and complexity of P. falciparum infections in Kedougou revealed no spatio-temporal variation in the genetic diversity of P. falciparum isolates. However, mean MOI varied with time of sera collection and decreased over the course of the study (July 2009 to July 2013). This suggests a slow progressive decrease of malaria transmission intensity in Kedougou Region despite the limited impact of preventive and control measures implemented by the National Malaria Control Programme on malaria morbidity and mortality.

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Section: Discussionsupporting

confidence: 55%

“…1), southeastern Senegal. A detailed description of the study area (climate, rainfall, landscape, fauna, population) has been provided elsewhere [3, 13, 14]. The Kedougou Region borders Guinea, Mali and Gambia between isohyets 1200 and 1300 mm.…”

Section: Methodsmentioning

confidence: 99%

Spatio-temporal analysis of the genetic diversity and complexity of Plasmodium falciparum infections in Kedougou, southeastern Senegal

et al. 2017

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“…Asymptomatic carriage (presence of circulating blood stages detected by microscopy in healthy subjects) was detected by examining Giemsa-stained blood smears by microscopy, the microscopic detection level being in our hands 2 parasites/uLblood[48] and in 2013 by nested PCR [50]. …”

Section: Methodsmentioning

confidence: 99%

Serological signatures of declining exposure following intensification of integrated malaria control in two rural Senegalese communities

et al. 2017

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Recent control scale-up has reduced malaria in many areas but new tools are needed to monitor further progress, including indicators of decreasing exposure to parasite infection. Although serology is considered a promising approach in this regard, the serological impact of control interventions has been so far studied using indirect quantification of exposure. Cohort surveys concomitantly recording entomological and malariometric indices have been conducted in two Senegalese settings where supervised control intensification implemented in 2006 shifted malaria from historically holoendemic in Dielmo and mesoendemic in Ndiop to hypoendemic in both settings by 2013. We analyse here serological signatures of declining transmission using archived blood samples. Responses against ten pre-erythrocytic and erythrocytic antigens from Plasmodium falciparum and P. malariae alongside an Anopheles gambiae salivary gland antigen were analysed. Cross-sectional surveys conducted before (2002) and after (2013) control intensification showed a major impact of control intensification in both settings. The age-associated prevalence, magnitude and breadth of the IgG responses to all antigens were village-specific in 2002. In 2013, remarkably similar patterns were observed in both villages, with marginal responses against all parasite antigens in the 0-5y children and reduced responses in all previously seropositive age groups. Waning of humoral responses of individuals who were immune at the time of control intensification was studied from 2006 to 2013 using yearly samplings. Longitudinal data were analysed using the Cochran-Armittage trend test and an age-related reversible catalytic conversion model. This showed that the antigen-specific antibody declines were more rapid in older children than adults. There was a strong association of antibody decline with the declining entomological inoculation rate. We thus identified serological markers of declining exposure to malaria parasites that should help future monitoring of progress towards malaria elimination.

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“…Our results also demonstrate that children living in the northern part of GND and NDI were highly exposed to both Aedes and Anopheles bites and, thus, exposed to the risk of both malaria and arbovirus transmission. Concurrent infections with malaria parasites and arboviruses were previously reported in patients infected with arboviruses in southeastern Senegal [15,49]. Also, it has been shown that dengue virus and malaria parasite coinfection is more severe than monoinfection with either pathogen [50].…”

Section: Discussionmentioning

confidence: 84%

Spatial Assessment of Contact Between Humans and Anopheles and Aedes Mosquitoes in a Medium-Sized African Urban Setting, Using Salivary Antibody–Based Biomarkers

Sagna

Kassié

Couvray

et al. 2019

The Journal of Infectious Diseases

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Background Anarchic and poorly controlled urbanization led to an increased risk of mosquito-borne diseases (MBD) in many African cities. Here, we evaluate the spatial heterogeneity of human exposure to malaria and arboviral disease vectors in an urban area of northern Senegal, using antibody-based biomarkers of exposure to Anopheles and Aedes mosquito bites. Methods A cross-sectional study was undertaken during the rainy season of 2014 in 4 neighborhoods of Saint-Louis, a city in northern Senegal. Among children aged 6–59 months in each neighborhood, the dried blood spot technique was used to evaluate immunoglobulin G (IgG) responses to both gSG6-P1 (Anopheles) and Nterm–34-kDa (Aedes) salivary peptides as validated biomarkers of respective mosquito bite exposure. Results IgG response levels to gSG6-P1 and Nterm–34-kDa salivary peptides varied significantly between the 4 neighborhoods (P < .0001). The level of exposure to Aedes bites also varied according to household access to sanitation services (P = .027), whereas that of exposure to Anopheles bites varied according to insecticide-treated bed net use (P = .006). In addition, spatial clusters of high contact between humans and mosquitoes were identified inside 3 neighborhoods. Conclusions Antibody-based biomarkers of exposure to Anopheles and Aedes mosquito bites could be helpful tools for evaluating the heterogeneity of exposure to malaria and arboviral disease vectors by national control programs.

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Genetic diversity of Plasmodium falciparum isolates from concurrent malaria and arbovirus co-infections in Kedougou, southeastern Senegal

Cited by 20 publications

References 44 publications

Spatio-temporal analysis of the genetic diversity and complexity of Plasmodium falciparum infections in Kedougou, southeastern Senegal

Spatio-temporal analysis of the genetic diversity and complexity of Plasmodium falciparum infections in Kedougou, southeastern Senegal

Serological signatures of declining exposure following intensification of integrated malaria control in two rural Senegalese communities

Spatial Assessment of Contact Between Humans and Anopheles and Aedes Mosquitoes in a Medium-Sized African Urban Setting, Using Salivary Antibody–Based Biomarkers

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