The American Journal of Tropical Medicine and Hygiene
ABSTRACT. Zambia’s National Malaria Elimination Program transitioned to Fludora Fusion in 2019 fo... more ABSTRACT. Zambia’s National Malaria Elimination Program transitioned to Fludora Fusion in 2019 for annual indoor residual spraying (IRS) in Nchelenge District, an area with holoendemic malaria transmission. Previously, IRS was associated with reductions in parasite prevalence during the rainy season only, presumably because of insufficient residual insecticide longevity. This study assessed the impact of transitioning from Actellic 300CS to long-acting Fludora Fusion using active surveillance data from 2014 through 2021. A difference-in-differences analysis estimated changes in rainy season parasite prevalence associated with living in a sprayed house, comparing insecticides. The change in the 2020 to 2021 dry season parasite prevalence associated with living in a house sprayed with Fludora Fusion was also estimated. Indoor residual spraying with Fludora Fusion was not associated with decreased rainy season parasite prevalence compared with IRS with Actellic 300CS (ratio of prevalen...
Background Over a decade of vector control by indoor residual spraying (IRS) and long-lasting ins... more Background Over a decade of vector control by indoor residual spraying (IRS) and long-lasting insecticidal nets (LLINs) distribution on mainland and only LLINs on islands, has had minimal impact on disease burden in Nchelenge district, northern Zambia. Anopheles funestus and An. gambiae are vectors known only from the mainland. Understanding vector bionomics in the district is necessary for planning and targeting effective vector control. This study aimed to provide information on malaria vectors’ abundance, seasonality and Plasmodium falciparum sporozoite infectivity in Nchelenge including islands.Methods Mosquitoes were collected in 192 CDC indoor light traps set in 56 households between January 2015 and January 2016. Morphological and molecular species identifications, and P. falciparum circumsporoites by ELISA were performed. Mosquito counts and relative abundances from the islands and mainland were compared and household factors associated with vector counts determined.Results ...
The American Journal of Tropical Medicine and Hygiene
ABSTRACT. For a decade, the Southern and Central Africa International Center of Excellence for Ma... more ABSTRACT. For a decade, the Southern and Central Africa International Center of Excellence for Malaria Research has operated with local partners across study sites in Zambia and Zimbabwe that range from hypo- to holoendemic and vary ecologically and entomologically. The burden of malaria and the impact of control measures were assessed in longitudinal cohorts, cross-sectional surveys, passive and reactive case detection, and other observational designs that incorporated multidisciplinary scientific approaches: classical epidemiology, geospatial science, serosurveillance, parasite and mosquito genetics, and vector bionomics. Findings to date have helped elaborate the patterns and possible causes of sustained low-to-moderate transmission in southern Zambia and eastern Zimbabwe and recalcitrant high transmission and fatality in northern Zambia. Cryptic and novel mosquito vectors, asymptomatic parasite reservoirs in older children, residual parasitemia and gametocytemia after treatment,...
The American Journal of Tropical Medicine and Hygiene
ABSTRACT. The International Centers of Excellence for Malaria Research (ICEMR) were established b... more ABSTRACT. The International Centers of Excellence for Malaria Research (ICEMR) were established by the National Institute of Allergy and Infectious Diseases more than a decade ago to provide multidisciplinary research support to malaria control programs worldwide, operating in endemic areas and contributing technology, expertise, and ultimately policy guidance for malaria control and elimination. The Southern and Central Africa ICEMR has conducted research across three main sites in Zambia and Zimbabwe that differ in ecology, entomology, transmission intensity, and control strategies. Scientific findings led to new policies and action by the national malaria control programs and their partners in the selection of methods, materials, timing, and locations of case management and vector control. Malaria risk maps and predictive models of case detection furnished by the ICEMR informed malaria elimination programming in southern Zambia, and time series analyses of entomological and paras...
Background Nchelenge District in northern Zambia suffers from holoendemic malaria transmission de... more Background Nchelenge District in northern Zambia suffers from holoendemic malaria transmission despite a decade of yearly indoor residual spraying (IRS) and insecticide-treated net (ITN) distributions. One hypothesis for this lack of impact is that some vectors in the area may forage in the early evening or outdoors. Anopheles gibbinsi specimens were identified in early evening mosquito collections performed in this study area, and further insight was gleaned into this taxon, including characterizing its genetic identity, feeding preferences, and potential role as a malaria vector. Methods Mosquitoes were collected in July and August 2019 by CDC light traps in Nchelenge District in indoor sitting rooms, outdoor gathering spaces, and animal pens from 16:00–22:00. Host detection by PCR, COI and ITS2 PCR, and circumsporozoite (CSP) ELISA were performed on all samples morphologically identified as An. gibbinsi, and a subset of specimens were selected for COI and ITS2 sequencing. To dete...
Williams mean (Mw) catch (95Â % C.I.) of An. funestus (s.l.) and An. gambiae (s.l.) by season and... more Williams mean (Mw) catch (95Â % C.I.) of An. funestus (s.l.) and An. gambiae (s.l.) by season and locality. Collections were made from CDC miniature light traps from May 2012 to April 2014 in Nchelenge district, Zambia and are presented by season (Dry: May to September, Rainy: November to April) and by locality (within 3Â km of the lake; inland). Data represent catches from cross-sectional study households and first visit to longitudinal households. (DOCX 12Â kb)
Additional file 2: Figure S1. Structure clusters by population in each of the countries, Malawi, ... more Additional file 2: Figure S1. Structure clusters by population in each of the countries, Malawi, Mozambique, Uganda, Zambia and Zimbabwe with eight microsatellites. The X-axis corresponds to the population codes. The Y-axis presents the probability of assignment of a population to each cluster.
Additional file 1: Table S1. Population comparisons, HW proportions and independence of loci (sig... more Additional file 1: Table S1. Population comparisons, HW proportions and independence of loci (significant values recorded in bold).
IntroductionMosquitoes transmit various mosquito-borne diseases such as malaria, filariasis and a... more IntroductionMosquitoes transmit various mosquito-borne diseases such as malaria, filariasis and arthropod-borne viruses (arboviruses) including, dengue virus, yellow fever virus, West Nile virus and Zika virus (1-8). Zambia is prone to mosquito-borne diseases because it has suitable ecological and climatic conditions for mosquito vector survival throughout the year during the rainy and hot season (November-May) and cool dry season (June-September) (9,10).A yellow fever risk assessment survey (11) necessitated a similar entomological survey to obtain a greater understanding on the vector-larval distribution in relation to human settlements. Information on mosquito spatial distribution patterns in Zambia is limited and yet, its use could optimize resource utilization and hopefully contribute towards evidence-based vector control to reduce mosquito-borne diseases (12).Mosquito breeding sites, areas where immature forms of mosquitoes transform and grow into the adult stage, are an impor...
Residual vector populations that do not come in contact with the most frequently utilized indoor-... more Residual vector populations that do not come in contact with the most frequently utilized indoor-directed interventions present major challenges to global malaria eradication. Many of these residual populations are mosquito species about which little is known. As part of a study to assess the threat of outdoor exposure to malaria mosquitoes within the Southern and Central Africa International Centers of Excellence for Malaria Research, foraging female anophelines were collected outside households in Nchelenge District, northern Zambia. These anophelines proved to be more diverse than had previously been reported in the area. In order to further characterize the anopheline species, sequencing and phylogenetic approaches were utilized. Anopheline mosquitoes were collected from outdoor light traps, morphologically identified, and sent to Johns Hopkins Bloomberg School of Public Health for sequencing. Sanger sequencing from 115 field-derived samples yielded mitochondrial COI sequences, ...
The American Journal of Tropical Medicine and Hygiene, 2021
ABSTRACTThe global malaria burden has decreased substantially, but gains have been uneven both wi... more ABSTRACTThe global malaria burden has decreased substantially, but gains have been uneven both within and between countries. In Zambia, the malaria burden remains high in northern and eastern regions of the country. To effectively reduce malaria transmission in these areas, evidence-based intervention strategies are needed. Zambia’s National Malaria Control Centre conducted targeted indoor residual spraying (IRS) in 40 high-burden districts from 2014 to 2016 using the novel organophosphate insecticide pirimiphos-methyl. The Southern and Central Africa International Centers of Excellence for Malaria Research conducted an evaluation of the impact of the IRS campaign on household vector abundance in Nchelenge District, Luapula Province. From April 2012 to July 2017, field teams conducted indoor overnight vector collections from 25 to 30 households per month using Centers for Disease Control light traps. Changes in indoor anopheline counts before versus after IRS were assessed by specie...
Despite ongoing malaria control efforts implemented throughout sub-Saharan Africa, malaria remain... more Despite ongoing malaria control efforts implemented throughout sub-Saharan Africa, malaria remains an enormous public health concern. Current interventions such as indoor residual spraying with insecticides and use of insecticide-treated bed nets are aimed at targeting the key malaria vectors that are primarily endophagic and endophilic. While these control measures have resulted in a substantial decline in malaria cases and continue to impact indoor transmission, the importance of alternative vectors for malaria transmission has been largely neglected. Anopheles coustani, an understudied vector of malaria, is a species previously thought to exhibit mostly zoophilic behavior. However, recent studies from across Africa bring to light the contribution of this and ecologically similar anopheline species to human malaria transmission. Like many of these understudied species, An. coustani has greater anthropophilic tendencies than previously appreciated, is often both endophagic and exop...
Despite ongoing malaria control efforts implemented throughout sub-Saharan Africa, malaria remain... more Despite ongoing malaria control efforts implemented throughout sub-Saharan Africa, malaria remains an enormous public health concern. Current interventions such as indoor residual spraying with insecticides and use of insecticide-treated bed nets are aimed at targeting the key malaria vectors that are primarily endophagic and endophilic. Anopheles coustani s.l., an understudied vector of malaria, is a species previously thought to exhibit mostly zoophilic behavior. Like many of these understudied species, An. coustani has greater anthropophilic tendencies than previously appreciated, is often both endophagic and exophagic, and carries Plasmodium falciparum sporozoites. The aim of this study was to explore genetic variation of An. coustani mosquitoes and the potential of this species to contribute to malaria parasite transmission in high transmission settings in Zambia and the Democratic Republic of the Congo (DRC). Morphologically identified An. coustani specimens that were trapped ...
The mosquito Anopheles gambiae s.s. is distributed across most of sub-Saharan Africa and is of ma... more The mosquito Anopheles gambiae s.s. is distributed across most of sub-Saharan Africa and is of major scientific and public health interest for being an African malaria vector. Here we present population genomic analyses of 111 specimens sampled from west to east Africa, including the first whole genome sequences from oceanic islands, the Comoros. Genetic distances between populations of A. gambiae are discordant with geographic distances but are consistent with a stepwise migration scenario in which the species increases its range from west to east Africa through consecutive founder events over the last ~200,000 years. Geological barriers like the Congo River basin and the East African rift seem to play an important role in shaping this process. Moreover, we find a high degree of genetic isolation of populations on the Comoros, confirming the potential of these islands as candidate sites for potential field trials of genetically engineered mosquitoes for malaria control.
The American Journal of Tropical Medicine and Hygiene
ABSTRACT. Zambia’s National Malaria Elimination Program transitioned to Fludora Fusion in 2019 fo... more ABSTRACT. Zambia’s National Malaria Elimination Program transitioned to Fludora Fusion in 2019 for annual indoor residual spraying (IRS) in Nchelenge District, an area with holoendemic malaria transmission. Previously, IRS was associated with reductions in parasite prevalence during the rainy season only, presumably because of insufficient residual insecticide longevity. This study assessed the impact of transitioning from Actellic 300CS to long-acting Fludora Fusion using active surveillance data from 2014 through 2021. A difference-in-differences analysis estimated changes in rainy season parasite prevalence associated with living in a sprayed house, comparing insecticides. The change in the 2020 to 2021 dry season parasite prevalence associated with living in a house sprayed with Fludora Fusion was also estimated. Indoor residual spraying with Fludora Fusion was not associated with decreased rainy season parasite prevalence compared with IRS with Actellic 300CS (ratio of prevalen...
Background Over a decade of vector control by indoor residual spraying (IRS) and long-lasting ins... more Background Over a decade of vector control by indoor residual spraying (IRS) and long-lasting insecticidal nets (LLINs) distribution on mainland and only LLINs on islands, has had minimal impact on disease burden in Nchelenge district, northern Zambia. Anopheles funestus and An. gambiae are vectors known only from the mainland. Understanding vector bionomics in the district is necessary for planning and targeting effective vector control. This study aimed to provide information on malaria vectors’ abundance, seasonality and Plasmodium falciparum sporozoite infectivity in Nchelenge including islands.Methods Mosquitoes were collected in 192 CDC indoor light traps set in 56 households between January 2015 and January 2016. Morphological and molecular species identifications, and P. falciparum circumsporoites by ELISA were performed. Mosquito counts and relative abundances from the islands and mainland were compared and household factors associated with vector counts determined.Results ...
The American Journal of Tropical Medicine and Hygiene
ABSTRACT. For a decade, the Southern and Central Africa International Center of Excellence for Ma... more ABSTRACT. For a decade, the Southern and Central Africa International Center of Excellence for Malaria Research has operated with local partners across study sites in Zambia and Zimbabwe that range from hypo- to holoendemic and vary ecologically and entomologically. The burden of malaria and the impact of control measures were assessed in longitudinal cohorts, cross-sectional surveys, passive and reactive case detection, and other observational designs that incorporated multidisciplinary scientific approaches: classical epidemiology, geospatial science, serosurveillance, parasite and mosquito genetics, and vector bionomics. Findings to date have helped elaborate the patterns and possible causes of sustained low-to-moderate transmission in southern Zambia and eastern Zimbabwe and recalcitrant high transmission and fatality in northern Zambia. Cryptic and novel mosquito vectors, asymptomatic parasite reservoirs in older children, residual parasitemia and gametocytemia after treatment,...
The American Journal of Tropical Medicine and Hygiene
ABSTRACT. The International Centers of Excellence for Malaria Research (ICEMR) were established b... more ABSTRACT. The International Centers of Excellence for Malaria Research (ICEMR) were established by the National Institute of Allergy and Infectious Diseases more than a decade ago to provide multidisciplinary research support to malaria control programs worldwide, operating in endemic areas and contributing technology, expertise, and ultimately policy guidance for malaria control and elimination. The Southern and Central Africa ICEMR has conducted research across three main sites in Zambia and Zimbabwe that differ in ecology, entomology, transmission intensity, and control strategies. Scientific findings led to new policies and action by the national malaria control programs and their partners in the selection of methods, materials, timing, and locations of case management and vector control. Malaria risk maps and predictive models of case detection furnished by the ICEMR informed malaria elimination programming in southern Zambia, and time series analyses of entomological and paras...
Background Nchelenge District in northern Zambia suffers from holoendemic malaria transmission de... more Background Nchelenge District in northern Zambia suffers from holoendemic malaria transmission despite a decade of yearly indoor residual spraying (IRS) and insecticide-treated net (ITN) distributions. One hypothesis for this lack of impact is that some vectors in the area may forage in the early evening or outdoors. Anopheles gibbinsi specimens were identified in early evening mosquito collections performed in this study area, and further insight was gleaned into this taxon, including characterizing its genetic identity, feeding preferences, and potential role as a malaria vector. Methods Mosquitoes were collected in July and August 2019 by CDC light traps in Nchelenge District in indoor sitting rooms, outdoor gathering spaces, and animal pens from 16:00–22:00. Host detection by PCR, COI and ITS2 PCR, and circumsporozoite (CSP) ELISA were performed on all samples morphologically identified as An. gibbinsi, and a subset of specimens were selected for COI and ITS2 sequencing. To dete...
Williams mean (Mw) catch (95Â % C.I.) of An. funestus (s.l.) and An. gambiae (s.l.) by season and... more Williams mean (Mw) catch (95Â % C.I.) of An. funestus (s.l.) and An. gambiae (s.l.) by season and locality. Collections were made from CDC miniature light traps from May 2012 to April 2014 in Nchelenge district, Zambia and are presented by season (Dry: May to September, Rainy: November to April) and by locality (within 3Â km of the lake; inland). Data represent catches from cross-sectional study households and first visit to longitudinal households. (DOCX 12Â kb)
Additional file 2: Figure S1. Structure clusters by population in each of the countries, Malawi, ... more Additional file 2: Figure S1. Structure clusters by population in each of the countries, Malawi, Mozambique, Uganda, Zambia and Zimbabwe with eight microsatellites. The X-axis corresponds to the population codes. The Y-axis presents the probability of assignment of a population to each cluster.
Additional file 1: Table S1. Population comparisons, HW proportions and independence of loci (sig... more Additional file 1: Table S1. Population comparisons, HW proportions and independence of loci (significant values recorded in bold).
IntroductionMosquitoes transmit various mosquito-borne diseases such as malaria, filariasis and a... more IntroductionMosquitoes transmit various mosquito-borne diseases such as malaria, filariasis and arthropod-borne viruses (arboviruses) including, dengue virus, yellow fever virus, West Nile virus and Zika virus (1-8). Zambia is prone to mosquito-borne diseases because it has suitable ecological and climatic conditions for mosquito vector survival throughout the year during the rainy and hot season (November-May) and cool dry season (June-September) (9,10).A yellow fever risk assessment survey (11) necessitated a similar entomological survey to obtain a greater understanding on the vector-larval distribution in relation to human settlements. Information on mosquito spatial distribution patterns in Zambia is limited and yet, its use could optimize resource utilization and hopefully contribute towards evidence-based vector control to reduce mosquito-borne diseases (12).Mosquito breeding sites, areas where immature forms of mosquitoes transform and grow into the adult stage, are an impor...
Residual vector populations that do not come in contact with the most frequently utilized indoor-... more Residual vector populations that do not come in contact with the most frequently utilized indoor-directed interventions present major challenges to global malaria eradication. Many of these residual populations are mosquito species about which little is known. As part of a study to assess the threat of outdoor exposure to malaria mosquitoes within the Southern and Central Africa International Centers of Excellence for Malaria Research, foraging female anophelines were collected outside households in Nchelenge District, northern Zambia. These anophelines proved to be more diverse than had previously been reported in the area. In order to further characterize the anopheline species, sequencing and phylogenetic approaches were utilized. Anopheline mosquitoes were collected from outdoor light traps, morphologically identified, and sent to Johns Hopkins Bloomberg School of Public Health for sequencing. Sanger sequencing from 115 field-derived samples yielded mitochondrial COI sequences, ...
The American Journal of Tropical Medicine and Hygiene, 2021
ABSTRACTThe global malaria burden has decreased substantially, but gains have been uneven both wi... more ABSTRACTThe global malaria burden has decreased substantially, but gains have been uneven both within and between countries. In Zambia, the malaria burden remains high in northern and eastern regions of the country. To effectively reduce malaria transmission in these areas, evidence-based intervention strategies are needed. Zambia’s National Malaria Control Centre conducted targeted indoor residual spraying (IRS) in 40 high-burden districts from 2014 to 2016 using the novel organophosphate insecticide pirimiphos-methyl. The Southern and Central Africa International Centers of Excellence for Malaria Research conducted an evaluation of the impact of the IRS campaign on household vector abundance in Nchelenge District, Luapula Province. From April 2012 to July 2017, field teams conducted indoor overnight vector collections from 25 to 30 households per month using Centers for Disease Control light traps. Changes in indoor anopheline counts before versus after IRS were assessed by specie...
Despite ongoing malaria control efforts implemented throughout sub-Saharan Africa, malaria remain... more Despite ongoing malaria control efforts implemented throughout sub-Saharan Africa, malaria remains an enormous public health concern. Current interventions such as indoor residual spraying with insecticides and use of insecticide-treated bed nets are aimed at targeting the key malaria vectors that are primarily endophagic and endophilic. While these control measures have resulted in a substantial decline in malaria cases and continue to impact indoor transmission, the importance of alternative vectors for malaria transmission has been largely neglected. Anopheles coustani, an understudied vector of malaria, is a species previously thought to exhibit mostly zoophilic behavior. However, recent studies from across Africa bring to light the contribution of this and ecologically similar anopheline species to human malaria transmission. Like many of these understudied species, An. coustani has greater anthropophilic tendencies than previously appreciated, is often both endophagic and exop...
Despite ongoing malaria control efforts implemented throughout sub-Saharan Africa, malaria remain... more Despite ongoing malaria control efforts implemented throughout sub-Saharan Africa, malaria remains an enormous public health concern. Current interventions such as indoor residual spraying with insecticides and use of insecticide-treated bed nets are aimed at targeting the key malaria vectors that are primarily endophagic and endophilic. Anopheles coustani s.l., an understudied vector of malaria, is a species previously thought to exhibit mostly zoophilic behavior. Like many of these understudied species, An. coustani has greater anthropophilic tendencies than previously appreciated, is often both endophagic and exophagic, and carries Plasmodium falciparum sporozoites. The aim of this study was to explore genetic variation of An. coustani mosquitoes and the potential of this species to contribute to malaria parasite transmission in high transmission settings in Zambia and the Democratic Republic of the Congo (DRC). Morphologically identified An. coustani specimens that were trapped ...
The mosquito Anopheles gambiae s.s. is distributed across most of sub-Saharan Africa and is of ma... more The mosquito Anopheles gambiae s.s. is distributed across most of sub-Saharan Africa and is of major scientific and public health interest for being an African malaria vector. Here we present population genomic analyses of 111 specimens sampled from west to east Africa, including the first whole genome sequences from oceanic islands, the Comoros. Genetic distances between populations of A. gambiae are discordant with geographic distances but are consistent with a stepwise migration scenario in which the species increases its range from west to east Africa through consecutive founder events over the last ~200,000 years. Geological barriers like the Congo River basin and the East African rift seem to play an important role in shaping this process. Moreover, we find a high degree of genetic isolation of populations on the Comoros, confirming the potential of these islands as candidate sites for potential field trials of genetically engineered mosquitoes for malaria control.
Uploads
Papers by Mbanga Muleba