scholarly journals High Plasmodium falciparum genetic diversity and temporal stability despite control efforts in high transmission settings along the international border between Zambia and the Democratic Republic of the Congo

2019 ◽  
Vol 18 (1) ◽  
Author(s):  
Julia C. Pringle ◽  
Amy Wesolowski ◽  
Sophie Berube ◽  
Tamaki Kobayashi ◽  
Mary E. Gebhardt ◽  
...  
Keyword(s):  
Genetic Diversity ◽  
Plasmodium Falciparum ◽  
Malaria Elimination ◽  
Democratic Republic ◽  
Small Sample ◽  
Suitable Alternative ◽  
High Transmission ◽  
Republic Of The Congo ◽  
Genetic Signatures ◽  
International Border

Abstract Background While the utility of parasite genotyping for malaria elimination has been extensively documented in low to moderate transmission settings, it has been less well-characterized in holoendemic regions. High malaria burden settings have received renewed attention acknowledging their critical role in malaria elimination. Defining the role for parasite genomics in driving these high burden settings towards elimination will enhance future control programme planning. Methods Amplicon deep sequencing was used to characterize parasite population genetic diversity at polymorphic Plasmodium falciparum loci, Pfama1 and Pfcsp, at two timepoints in June–July 2016 and January–March 2017 in a high transmission region along the international border between Luapula Province, Zambia and Haut-Katanga Province, the Democratic Republic of the Congo (DRC). Results High genetic diversity was observed across both seasons and in both countries. No evidence of population structure was observed between parasite populations on either side of the border, suggesting that this region may be one contiguous transmission zone. Despite a decline in parasite prevalence at the sampling locations in Haut-Katanga Province, no genetic signatures of a population bottleneck were detected, suggesting that larger declines in transmission may be required to reduce parasite genetic diversity. Analysing rare variants may be a suitable alternative approach for detecting epidemiologically important genetic signatures in highly diverse populations; however, the challenge is distinguishing true signals from potential artifacts introduced by small sample sizes. Conclusions Continuing to explore and document the utility of various parasite genotyping approaches for understanding malaria transmission in holoendemic settings will be valuable to future control and elimination programmes, empowering evidence-based selection of tools and methods to address pertinent questions, thus enabling more efficient resource allocation.

scholarly journals Identification of main malaria vectors and their insecticide resistance profile in internally displaced and indigenous communities in Eastern Democratic Republic of the Congo (DRC)

2020 ◽  
Vol 19 (1) ◽  
Author(s):  
Jeanine A. C. M. Loonen ◽  
Dominic B. Dery ◽  
Bertin Z. Musaka ◽  
Janvier B. Bandibabone ◽  
Teun Bousema ◽  
...  
Keyword(s):  
Plasmodium Falciparum ◽  
Insecticide Resistance ◽  
Democratic Republic ◽  
Anopheles Funestus ◽  
Indigenous Communities ◽  
Health Concern ◽  
Malaria Vectors ◽  
Species Determination ◽  
Insecticide Susceptibility ◽  
Republic Of The Congo

Abstract Background Malaria remains a major public health concern in the Democratic Republic of the Congo (DRC) and its control is affected by recurrent conflicts. Médecins Sans Frontières (MSF) initiated several studies to better understand the unprecedented incidence of malaria to effectively target and implement interventions in emergency settings. The current study evaluated the main vector species involved in malaria transmission and their resistance to insecticides, with the aim to propose the most effective tools and strategies for control of local malaria vectors. Methods This study was performed in 52 households in Shamwana (Katanga, 2014), 168 households in Baraka (South Kivu, 2015) and 269 households in Kashuga (North Kivu, 2017). Anopheles vectors were collected and subjected to standardized Word Health Organization (WHO) and Center for Disease Control (CDC) insecticide susceptibility bioassays. Mosquito species determination was done using PCR and Plasmodium falciparum infection in mosquitoes was assessed by ELISA targeting circumsporozoite protein. Results Of 3517 Anopheles spp. mosquitoes collected, Anopheles gambiae sensu lato (s.l.) (29.6%) and Anopheles funestus (69.1%) were the main malaria vectors. Plasmodium falciparum infection rates for An. gambiae s.l. were 1.0, 2.1 and 13.9% for Shamwana, Baraka and Kashuga, respectively. Anopheles funestus showed positivity rates of 1.6% in Shamwana and 4.4% in Baraka. No An. funestus were collected in Kashuga. Insecticide susceptibility tests showed resistance development towards pyrethroids in all locations. Exposure to bendiocarb, malathion and pirimiphos-methyl still resulted in high mosquito mortality. Conclusions This is one of only few studies from these conflict areas in DRC to report insecticide resistance in local malaria vectors. The data suggest that current malaria prevention methods in these populations are only partially effective, and require additional tools and strategies. Importantly, the results triggered MSF to consider the selection of a new insecticide for indoor residual spraying (IRS) and a new long-lasting insecticide-treated net (LLIN). The reinforcement of correct usage of LLINs and the introduction of targeted larviciding were also included as additional vector control tools as a result of the studies.

scholarly journals Modeling impact and cost‐effectiveness of driving‐Y gene drives for malaria elimination in the Democratic Republic of the Congo

2021 ◽  
Author(s):  
Nawaphan Metchanun ◽  
Christian Borgemeister ◽  
Gaston Amzati ◽  
Joachim von Braun ◽  
Milen Nikolov ◽  
...  
Keyword(s):  
Cost Effectiveness ◽  
Malaria Elimination ◽  
Democratic Republic ◽  
Republic Of The Congo ◽  
Gene Drives

scholarly journals Evolution of Plasmodium vivax populations in border areas of the Greater Mekong Subregion during malaria elimination

2020 ◽  
Author(s):  
Yuling Li ◽  
Yubing Hu ◽  
Yan Zhao ◽  
Qinghui Wang ◽  
Huguette Gaelle Ngassa Mbenda ◽  
...  
Keyword(s):  
Genetic Diversity ◽  
Plasmodium Vivax ◽  
Malaria Elimination ◽  
Scale Up ◽  
Transmission Dynamics ◽  
Clinical Samples ◽  
Effective Population ◽  
Border Areas ◽  
Greater Mekong Subregion ◽  
International Border

Abstract Background: Countries within the Greater Mekong Subregion (GMS) of Southeast Asia have committed to eliminating malaria by 2030. Although malaria situation has greatly improved, Plasmodium vivax remains at international border regions. Therefore, to gain a better understanding of transmission dynamics, knowledge on the evolution of P. vivax populations after the scale-up of control interventions will guide more effective targeted control efforts. Methods: We investigated genetic diversity and population structures in 206 longitudinally collected P. vivax clinical samples in two international border areas at the China-Myanmar border (CMB, n=50 in 2004 and n=52 in 2016) and western Thailand border (n=50 in 2012 and n=54 in 2015). Parasites were genotyped using 10 microsatellite markers. Results: Despite intensified control efforts, genetic diversity in the four populations remained high (HE = 0.66-0.86). The proportions of polyclonal infections showed substantial decreases to 23.7 and 30.7% in the CMB and western Thailand, respectively, with corresponding decreases in the multiplicity of infection. Consistent with the shrinking map of malaria transmission in the GMS over time, there were also increases in multilocus linkage disequilibrium, suggesting of more fragmented and increasingly inbred parasite populations. There were considerable genetic differentiation and subdivision with the four tested populations. Various degrees of clustering were evident between the older parasite samples collected in 2004 at the CMB with the 2016 CMB and 2012 Thailand populations, suggesting some of these parasites had shared ancestry. In contrast, the 2015 Thailand population was genetically distinctive, which may reflect a process of population replacement. The moderately large effective population sizes and proportions of polyclonal infections highlight the necessity of further coordinated and integrated control efforts on both sides of the borders in the pursuit of malaria elimination. Conclusions: With enhanced control efforts on malaria elimination, P. vivax population in the GMS has fragmented into a limited number of clustered foci, but the presence of large P. vivax reservoirs still sustains genetic diversity and transmission. These findings provide new insights into P. vivax transmission dynamics and population structure in this area.

scholarly journals The changing landscape of Plasmodium falciparum drug resistance in the Democratic Republic of Congo

2019 ◽  
Author(s):  
Molly N/A Deutsch-Feldman ◽  
Ozkan Aydemir ◽  
Margaret Carrel ◽  
Nicholas F. Brazeau ◽  
Samir Bhatt ◽  
...  
Keyword(s):  
Plasmodium Falciparum ◽  
Democratic Republic ◽  
Democratic Republic Of Congo ◽  
Chloroquine Resistance ◽  
Molecular Surveillance ◽  
Mixed Effects Modeling ◽  
Republic Of The Congo ◽  
Temporal Model ◽  
Wide Population ◽  
Representative Samples

Abstract Background: Drug resistant malaria is a growing concern in the Democratic Republic of the Congo (DRC), where previous studies indicate that parasites resistant to sulfadoxine/pyrimethamine or chloroquine are spatially clustered. This study explores longitudinal changes in spatial patterns to understand how resistant malaria may be spreading within the DRC, using samples from nation-wide population-representative surveys. Methods: We selected 552 children with PCR-detectable Plasmodium falciparum infection and identified known variants in the pfdhps and pfcrt genes associated with resistance. We compared the proportion of mutant parasites in 2013 to those previously reported from adults in 2007, and identified risk factors for carrying a resistant allele using multivariate mixed-effects modeling. Finally, we fit a spatial-temporal model to the observed data, providing smooth allele frequency estimates over space and time. Results: The proportion of co-occurring pfdhps K540E/A581G mutations increased by 16% between 2007 and 2013. The spatial-temporal model suggests that the spatial range of the pfdhps double mutants expanded over time, while the prevalence and range of pfcrt mutations remained steady. Conclusions: This study uses population-representative samples to describe the changing landscape of SP resistance within the DRC, and the persistence of chloroquine resistance. Vigilant molecular surveillance is critical for controlling the spread of resistance.

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