Indoor and outdoor malaria transmission in two ecological settings in rural Mali: implications for vector control

Abstract Background Implementation and upscale of effective malaria vector control strategies necessitates understanding the multi-factorial aspects of transmission patterns. The primary aims of this study are to determine the vector composition, biting rates, trophic preference, and the overall importance of distinguishing outdoor versus indoor malaria transmission through a study at two communities in rural Mali. Methods Mosquito collection was carried out between July 2012 and June 2016 at two rural Mali communities (Dangassa and Koïla Bamanan) using pyrethrum spray-catch and human landing catch approaches at both indoor and outdoor locations. Species of Anopheles gambiae complex were identified by polymerase chain reaction (PCR). Enzyme-Linked -Immuno-Sorbent Assay (ELISA) were used to determine the origin of mosquito blood meals and presence of Plasmodium falciparum sporozoite infections. Results A total of 11,237 An. gambiae sensu lato (s.l.) were collected during the study period (5239 and 5998 from the Dangassa and Koïla Bamanan sites, respectively). Of the 679 identified by PCR in Dangassa, Anopheles coluzzii was the predominant species with 91.4% of the catch followed by An. gambiae (8.0%) and Anopheles arabiensis (0.6%). At the same time in Koïla Bamanan, of the 623 An. gambiae s.l., An. coluzzii accounted for 99% of the catch, An. arabiensis 0.8% and An. gambiae 0.2%. Human Blood Index (HBI) measures were significantly higher in Dangassa (79.4%; 95% Bayesian credible interval (BCI) [77.4, 81.4]) than in Koïla Bamanan (15.9%; 95% BCI [14.7, 17.1]). The human biting rates were higher during the second half of the night at both sites. In Dangassa, the sporozoite rate was comparable between outdoor and indoor mosquito collections. For outdoor collections, the sporozoite positive rate was 3.6% (95% BCI [2.1–4.3]) and indoor collections were 3.1% (95% BCI [2.4–5.0]). In Koïla Bamanan, the sporozoite rate was higher indoors at 4.3% (95% BCI [2.7–6.3]) compared with outdoors at 2.4% (95% BCI [1.1–4.2]). In Dangassa, corrected entomological inoculation rates (cEIRs) using HBI were 13.74 [95% BCI 9.21–19.14] infective bites/person/month (ib/p/m) at indoor, and 18.66 [95% BCI 12.55–25.81] ib/p/m at outdoor. For Koïla Bamanan, cEIRs were 1.57 [95% BCI 2.34–2.72] ib/p/m and 0.94 [95% BCI 0.43–1.64] ib/p/m for indoor and outdoor, respectively. EIRs were significantly higher at the Dangassa site than the Koïla Bamanan site. Conclusion The findings in this work may indicate the occurrence of active, outdoor residual malaria transmission is comparable to indoor transmission in some geographic settings. The high outdoor transmission patterns observed here highlight the need for additional strategies to combat outdoor malaria transmission to complement traditional indoor preventive approaches such as long-lasting insecticidal nets (LLINs) and indoor residual spraying (IRS) which typically focus on resting mosquitoes.

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Indoor and outdoor malaria transmission in two ecological settings in rural Mali: Implications for vector control

10.21203/rs.3.rs-72314/v2 ◽

2021 ◽

Author(s):

Moussa KEITA ◽

Sidy Doumbia ◽

Ibrahim Sissoko ◽

Mahamoudou Touré ◽

Sory Ibrahim Diawara ◽

...

Keyword(s):

Vector Control ◽

Malaria Transmission ◽

Control Strategies ◽

Indoor Residual Spraying ◽

Credible Interval ◽

Human Landing Catch ◽

Malaria Vector Control ◽

Sporozoite Rate ◽

Mosquito Collection ◽

Indoor And Outdoor

Abstract Background: Implementation and upscale of effective malaria vector control strategies necessitates understanding the multi-factorial aspects of transmission patterns. The primary aims of this study are to determine the vector composition, biting rates, trophic preference, and the overall importance of distinguishing outdoor versus indoor malaria transmission through a study at two communities in rural Mali. Methods: Mosquito collection was carried out between July 2012 and June 2016 at two rural Mali communities (Dangassa and Koïla Bamanan) using pyrethrum spray-catch and human landing catch approaches at both indoor and outdoor locations. Species of Anopheles (An.) gambiae complex were identified by polymerase chain reaction (PCR). Enzyme-Linked -Immuno-Sorbent Assay (ELISA) were used to determine the origin of mosquito blood meals and presence of Plasmodium (P.) falciparum sporozoite infections.Results: A total of 11,237 An. gambiae (s.l.) were collected during the study period (5,239 and 5,998 from the Dangassa and Koïla Bamanan sites, respectively). Of the 679 identified by PCR in Dangassa, An. coluzzii was the predominant species with 91.4% of the catch followed by An. gambiae (8.0%) and An. arabiensis (0.6%). At the same time in Koïla Bamanan, of 623 An. gambiae s.l., An. coluzzii accounted for 99% of the catch, An. arabiensis 0.8% and An. gambiae 0.2%. Human Blood Index (HBI) measures were significantly higher in Dangassa (79.4%; 95% Bayesian credible interval (BCI) [77.4, 81.4]) than in Koïla Bamanan (15.9%; 95% BCI [14.7, 17.1]). The human biting rates were higher during the second half of the night at both sites. In Dangassa, the sporozoite rate was comparable between outdoor and indoor mosquito collections. For outdoor collections, the sporozoite positive rate was 3.6% (95% BCI [2.1-4.3]) and indoor collections were 3.1% (95% BCI [2.4-5.0]). In Koïla Bamanan, the sporozoite rate was higher indoors at 4.3% (95% BCI [2.7-6.3]) compared with outdoors at 2.4% (95% BCI [1.1- 4.2]). In Dangassa, corrected entomological inoculation rates (cEIRs) using HBI were 13.74 [95% BCI: 9.21—19.14] infective bites/person/month (ib/p/m) at indoor, and 18.66 [95% BCI 12.55—25.81] ib/p/m at outdoor. For Koïla Bamanan, cEIRs were 1.57 [95% BCI 2.34 —2.72] ib/p/m and 0.94 [95% BCI 0.43—1.64] ib/p/m for indoor and outdoor, respectively. EIRs were significantly higher at the Dangassa site than the Koïla Bamanan site.Conclusion: The findings in this work may indicate the occurrence of active, outdoor residual malaria transmission is comparable to indoor transmission in some geographic settings. The high outdoor transmission patterns observed here highlight the need for additional strategies to combat outdoor malaria transmission to complement traditional indoor preventive approaches such as long-lasting insecticidal nets (LLINs) and indoor residual spraying (IRS) which typically focus on resting mosquitoes.

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Indoor and outdoor malaria transmission in two ecological settings in rural Mali: Implications for vector control

10.21203/rs.3.rs-72314/v1 ◽

2020 ◽

Author(s):

Moussa Keita ◽

Sidy Doumbia ◽

Ibrahim Sissoko ◽

Mahamoudou Touré ◽

Sory Ibrahim Diawara ◽

...

Keyword(s):

Vector Control ◽

Malaria Transmission ◽

Control Strategies ◽

Indoor Residual Spraying ◽

Credible Interval ◽

Human Landing Catch ◽

Malaria Vector Control ◽

Sporozoite Rate ◽

Mosquito Collection ◽

Indoor And Outdoor

Abstract Background: Implementation and upscale of effective malaria vector control strategies necessitates understanding the multi-factorial aspects of transmission patterns. The primary aims of this study are to determine the vector composition, biting rates, trophic preference, and the overall importance of distinguishing outdoor versus indoor malaria transmission through a study at two communities in rural Mali. Methods: Mosquito collection was carried out between July 2012 and June 2016 at two rural Mali communities (Dangassa and Koïla Bamanan) using pyrethrum spray-catch and human landing catch approaches at both indoor and outdoor locations. Species of Anopheles (An.) gambiae complex were identified by polymerase chain reaction (PCR). Enzyme-Linked -Immuno-Sorbent Assay (ELISA) were used to determine the origin of mosquito blood meals and presence of Plasmodium (P.) falciparum sporozoite infections.Results: A total of 11,237 An. gambiae (s.l.) were collected during the study period (5,239 and 5,998 from the Dangassa and Koïla Bamanan sites, respectively). Of the 679 identified by PCR in Dangassa, An. coluzzii was the predominant species with 91.4% of the catch followed by An. gambiae (8.0%) and An. arabiensis (0.6%). At the same time in Koïla Bamanan, of 623 An. gambiae s.l., An. coluzzii accounted for 99% of the catch, An. arabiensis 0.8% and An. gambiae 0.2%. Human Blood Index (HBI) measures were significantly higher in Dangassa (79.4%; 95% Bayesian credible interval (BCI) [77.4, 81.4]) than in Koïla Bamanan (15.9%; 95% BCI [14.7, 17.1]). The human biting rates were higher during the second half of the night at both sites. In Dangassa, the sporozoite rate was comparable between outdoor and indoor mosquito collections. For outdoor collections, the sporozoite positive rate was 3.6% (95% BCI [2.1-4.3]) and indoor collections were 3.1% (95% BCI [2.4-5.0]). In Koïla Bamanan, the sporozoite rate was higher indoors at 4.3% (95% BCI [2.7-6.3]) compared with outdoors at 2.4% (95% BCI [1.1- 4.2]). In Dangassa, corrected entomological inoculation rates (cEIRs) using HBI were for indoor locations were 13.74 infective bites/person/month (ib/p/m; 95% BCI: 9.21—19.14] and were 18.66 [12.55—25.81] ib/p/m, outdoors locations. For Koïla Bamanan,cEIRs were 1.57 [2.34 —2.72] ib/p/m and 0.94 [0.43—1.64] ib/p/m for indoor and outdoor locations, respectively. EIRs were significantly higher at the Dangassa site than the Koïla Bamanan site. Conclusion: The findings in this work may indicate the occurrence of active, outdoor residual malaria transmission is comparable to indoor transmission in some geographic settings. The high outdoor transmission patterns observed here highlight the need for additional strategies to combat outdoor malaria transmission to complement traditional indoor preventive approaches such as long-lasting insecticidal nets (LLINs) and indoor residual spraying (IRS) which typically focus on resting mosquitoes.

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Long-lasting microbial larvicides for controlling insecticide resistant and outdoor transmitting vectors: a cost-effective supplement for malaria interventions

Infectious Diseases of Poverty ◽

10.1186/s40249-020-00767-3 ◽

2020 ◽

Vol 9 (1) ◽

Author(s):

Guofa Zhou ◽

Eugenia Lo ◽

Andrew K. Githeko ◽

Yaw A. Afrane ◽

Guiyun Yan

Keyword(s):

Cost Effectiveness ◽

Vector Control ◽

Malaria Vector ◽

Indoor Residual Spraying ◽

Cost Effective ◽

Control Measures ◽

Malaria Vector Control ◽

Potential Cost ◽

Outdoor Transmission ◽

Indoor And Outdoor

AbstractThe issues of pyrethroid resistance and outdoor malaria parasite transmission have prompted the WHO to call for the development and adoption of viable alternative vector control methods. Larval source management is one of the core malaria vector interventions recommended by the Ministry of Health in many African countries, but it is rarely implemented due to concerns on its cost-effectiveness. New long-lasting microbial larvicide can be a promising cost-effective supplement to current vector control and elimination methods because microbial larvicide uses killing mechanisms different from pyrethroids and other chemical insecticides. It has been shown to be effective in reducing the overall vector abundance and thus both indoor and outdoor transmission. In our opinion, the long-lasting formulation can potentially reduce the cost of larvicide field application, and should be evaluated for its cost-effectiveness, resistance development, and impact on non-target organisms when integrating with other malaria vector control measures. In this opinion, we highlight that long-lasting microbial larvicide can be a potential cost-effective product that complements current front-line long-lasting insecticidal nets (LLINs) and indoor residual spraying (IRS) programs for malaria control and elimination. Microbial larviciding targets immature mosquitoes, reduces both indoor and outdoor transmission and is not affected by vector resistance to synthetic insecticides. This control method is a shift from the conventional LLINs and IRS programs that mainly target indoor-biting and resting adult mosquitoes.

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Ivermectin as an endectocide may boost control of malaria vectors in India and contribute to elimination

Parasites & Vectors ◽

10.1186/s13071-021-05124-3 ◽

2022 ◽

Vol 15 (1) ◽

Author(s):

Sundus Shafat Ahmad ◽

Manju Rahi ◽

Poonam Saroha ◽

Amit Sharma

Keyword(s):

Vector Control ◽

Malaria Elimination ◽

Control Strategies ◽

Mosquito Species ◽

Indoor Residual Spraying ◽

World Health ◽

Malaria Vectors ◽

Bed Nets ◽

Malaria Vector Control ◽

Indian Government

AbstractMalaria constitutes one of the largest public health burdens faced by humanity. Malaria control has to be an efficient balance between diagnosis, treatment and vector control strategies. The World Health Organization currently recommends indoor residual spraying and impregnated bed nets as two malaria vector control methods that have shown robust and persistent results against endophilic and anthropophilic mosquito species. The Indian government launched the National Framework for Malaria Elimination in 2016 with the aim to achieve the elimination of malaria in a phased and strategic manner and to sustain a nation-wide malaria-free status by 2030. India is currently in a crucial phase of malaria elimination and novel vector control strategies maybe helpful in dealing with various challenges, such as vector behavioural adaptations and increasing insecticide resistance among the Anopheles populations of India. Ivermectin can be one such new tool as it is the first endectocide to be approved in both animals and humans. Trials of ivermectin have been conducted in endemic areas of Africa with promising results. In this review, we assess available data on ivermectin as an endectocide and propose that this endectocide should be explored as a vector control tool for malaria in India. Graphical Abstract

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The effect of cattle-administered ivermectin and fipronil on the mortality and fecundity of Anopheles arabiensis Patton

Parasites & Vectors ◽

10.1186/s13071-021-04846-8 ◽

2021 ◽

Vol 14 (1) ◽

Author(s):

Takalani I. Makhanthisa ◽

Leo Braack ◽

Heike Lutermann

Keyword(s):

Vector Control ◽

Malaria Transmission ◽

Anopheles Arabiensis ◽

Egg Production ◽

Control Strategies ◽

Indoor Residual Spraying ◽

Malaria Vectors ◽

Saline Control ◽

Control Group ◽

Duration Of Action

Abstract Background Malaria control primarily depends on two vector control strategies: indoor residual spraying (IRS) and long-lasting insecticide-treated nets (LLINs). Both IRS and LLIN target indoor-biting mosquitoes. However, some of the most important malaria vectors have developed resistance against the chemical compounds used in IRS and LLINs. Insecticide-induced behavioural changes in vectors, such as increased outdoor feeding on cattle and other animals, also limit the effectiveness of these strategies. Novel vector control strategies must therefore be found to complement IRS and LLINs. A promising tool is the use of cattle-applied endectocides. Endectocides are broad-spectrum systemic drugs that are effective against a range of internal nematodes parasites and blood-feeding arthropods. The aim of this study was to investigate the effect of two endectocide drugs, injectable ivermectin and topical fipronil, on the survival and fecundity of zoophilic Anopheles arabiensis. Methods Laboratory-reared mosquitoes were allowed to feed on cattle treated with either injectable ivermectin (0.2 mg/kg), topical fipronil (1.0 mg/kg) or saline (control) on days 0, 1, 4, 7, 13, 21 and 25 post-treatment, and mortality and egg production were recorded daily. Results Compared to controls, the mortality of An. arabiensis increased by 3.52- and 2.43-fold with injectable ivermectin and topical fipronil, respectively. The overall fecundity of mosquitoes that fed on both ivermectin- and fipronil-treated cattle was significantly reduced by up to 90 and 60%, respectively, compared to the control group. The effects of both drugs attenuated over a period of 3 weeks. Injectable ivermectin was more effective than topical fipronil and increased mosquito mortality by a risk factor of 1.51 higher than fipronil. Similarly, both drugs significantly reduced the fecundity of An. arabiensis. Conclusions This study demonstrates that injectable ivermectin and topical fipronil are able to suppress An. arabiensis density and could help to reduce outdoor malaria transmission. Data from the present study as well as from other similar studies suggest that current-generation endectocides have a limited duration of action and are expensive. However, new-generation, sustained-release formulations of ivermectin have a multi-week, high mortality impact on vector populations, thus holding promise of an effective reduction of outdoor malaria transmission. Graphical abstract

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Effects of indoor residual spraying and outdoor larval control on Anopheles coluzzii from São Tomé and Príncipe, two islands with pre-eliminated malaria

Malaria Journal ◽

10.1186/s12936-019-3037-y ◽

2019 ◽

Vol 18 (1) ◽

Cited By ~ 2

Author(s):

Ying-An Chen ◽

Jih-Ching Lien ◽

Lien-Fen Tseng ◽

Chien-Fu Cheng ◽

Wan-Yu Lin ◽

...

Keyword(s):

Vector Control ◽

Incidence Rate ◽

Malaria Incidence ◽

Control Strategies ◽

Resistance Mutation ◽

Indoor Residual Spraying ◽

Anopheles Coluzzii ◽

Knockdown Resistance ◽

Larval Control ◽

Sao Tome And Principe

Abstract Background Vector control is a key component of malaria prevention. Two major vector control strategies have been implemented in São Tomé and Príncipe (STP), indoor residual spraying (IRS) and outdoor larval control using Bacillus thuringiensis israelensis (Bti). This study evaluated post-intervention effects of control strategies on vector population density, composition, and knockdown resistance mutation, and their implications for malaria epidemiology in STP. Methods Mosquitoes were collected by indoor and outdoor human landing catches and mosquito light traps in seven districts. Mosquito density was calculated by numbers of captured adult mosquitoes/house/working hour. Mitochondrial cytochrome c oxidase subunit I (COI) was PCR amplified and sequenced to understand the spatial–temporal population composition of malaria vector in STP. Knockdown resistance L1014F mutation was detected using allele-specific PCR. To estimate the malaria transmission risks in STP, a negative binomial regression model was constructed. The response variable was monthly incidence, and the explanatory variables were area, rainfall, entomological inoculation rate (EIR), and kdr mutation frequency. Results Malaria vector in STP is exophilic Anopheles coluzzii with significant population differentiation between Príncipe and São Tomé (mean FST = 0.16, p < 0.001). Both vector genetic diversity and knockdown resistance mutation were relatively low in Príncipe (mean of kdr frequency = 15.82%) compared to São Tomé (mean of kdr frequency = 44.77%). Annual malaria incidence rate in STP had been rapidly controlled from 37 to 2.1% by three rounds of country-wide IRS from 2004 to 2007. Long-term application of Bti since 2007 kept the mosquito density under 10 mosquitoes/house/hr/month, and malaria incidence rate under 5% after 2008, except for a rising that occurred in 2012 (incidence rate = 6.9%). Risk factors of area (São Tomé compared to Príncipe), rainfall, outdoor EIR, and kdr mutation frequency could significantly increase malaria incidence by 9.33–11.50, 1.25, 1.07, and 1.06 fold, respectively. Conclusions Indoor residual spraying could rapidly decrease Anopheles density and malaria incidence in STP. Outdoor larval control using Bti is a sustainable approach for controlling local vector with exophilic feature and insecticide resistance problem. Vector control interventions should be intensified especially at the north-eastern part of São Tomé to minimize impacts of outbreaks.

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Impact of seasonality and malaria control interventions on Anopheles density and species composition from three areas of Uganda with differing malaria endemicity

Malaria Journal ◽

10.1186/s12936-021-03675-5 ◽

2021 ◽

Vol 20 (1) ◽

Author(s):

Henry Ddumba Mawejje ◽

Maxwell Kilama ◽

Simon P. Kigozi ◽

Alex K. Musiime ◽

Moses Kamya ◽

...

Keyword(s):

Species Composition ◽

Vector Control ◽

Malaria Control ◽

Mosquito Species ◽

Density Ratio ◽

Indoor Residual Spraying ◽

Sub Saharan Africa ◽

Malaria Vector Control ◽

Vector Density ◽

Llin Distribution

Abstract Background Long-lasting insecticidal nets (LLINs) and indoor residual spraying (IRS) are the malaria control interventions primarily responsible for reductions in transmission intensity across sub-Saharan Africa. These interventions, however, may have differential impact on Anopheles species composition and density. This study examined the changing pattern of Anopheles species in three areas of Uganda with markedly different transmission intensities and different levels of vector control. Methods From October 2011 to June 2016 mosquitoes were collected monthly using CDC light traps from 100 randomly selected households in three areas: Walukuba (low transmission), Kihihi (moderate transmission) and Nagongera (high transmission). LLINs were distributed in November 2013 in Walukuba and Nagongera and in June 2014 in Kihihi. IRS was implemented only in Nagongera, with three rounds of bendiocarb delivered between December 2014 and June 2015. Mosquito species were identified morphologically and by PCR (Polymerase Chain Reaction). Results In Walukuba, LLIN distribution was associated with a decline in Anopheles funestus vector density (0.07 vs 0.02 mosquitoes per house per night, density ratio [DR] 0.34, 95% CI: 0.18–0.65, p = 0.001), but not Anopheles gambiae sensu stricto (s.s.) nor Anopheles arabiensis. In Kihihi, over 98% of mosquitoes were An. gambiae s.s. and LLIN distribution was associated with a decline in An. gambiae s.s. vector density (4.00 vs 2.46, DR 0.68, 95% CI: 0.49–0.94, p = 0.02). In Nagongera, the combination of LLINs and multiple rounds of IRS was associated with almost complete elimination of An. gambiae s.s. (28.0 vs 0.17, DR 0.004, 95% CI: 0.002–0.009, p < 0.001), and An. funestus sensu lato (s.l.) (3.90 vs 0.006, DR 0.001, 95% CI: 0.0005–0.004, p < 0.001), with a less pronounced decline in An. arabiensis (9.18 vs 2.00, DR 0.15 95% CI: 0.07–0.33, p < 0.001). Conclusions LLIN distribution was associated with reductions in An. funestus s.l. in the lowest transmission site and An. gambiae s.s. in the moderate transmission site. In the highest transmission site, a combination of LLINs and multiple rounds of IRS was associated with the near collapse of An. gambiae s.s. and An. funestus s.l. Following IRS, An. arabiensis, a behaviourally resilient vector, became the predominant species, which may have implications for malaria vector control activities. Development of interventions targeted at outdoor biting remains a priority.

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Malaria vector species composition and entomological indices following indoor residual spraying in regions bordering Lake Victoria, Tanzania

Malaria Journal ◽

10.1186/s12936-020-03452-w ◽

2020 ◽

Vol 19 (1) ◽

Author(s):

Charles Kakilla ◽

Alphaxard Manjurano ◽

Karen Nelwin ◽

Jackline Martin ◽

Fabian Mashauri ◽

...

Keyword(s):

Species Composition ◽

Vector Control ◽

Malaria Vector ◽

Lake Victoria ◽

Indoor Residual Spraying ◽

Transmission Risk ◽

Malaria Vectors ◽

Vector Species ◽

Sporozoite Rate ◽

Pirimiphos Methyl

Abstract Background Vector control through long-lasting insecticidal nets (LLINs) and focal indoor residual spraying (IRS) is a major component of the Tanzania national malaria control strategy. In mainland Tanzania, IRS has been conducted annually around Lake Victoria basin since 2007. Due to pyrethroid resistance in malaria vectors, use of pyrethroids for IRS was phased out and from 2014 to 2017 pirimiphos-methyl (Actellic® 300CS) was sprayed in regions of Kagera, Geita, Mwanza, and Mara. Entomological surveillance was conducted in 10 sprayed and 4 unsprayed sites to determine the impact of IRS on entomological indices related to malaria transmission risk. Methods WHO cone bioassays were conducted monthly on interior house walls to determine residual efficacy of pirimiphos-methyl CS. Indoor CDC light traps with or without bottle rotator were hung next to protected sleepers indoors and also set outdoors (unbaited) as a proxy measure for indoor and outdoor biting rate and time of biting. Prokopack aspirators were used indoors to capture resting malaria vectors. A sub-sample of Anopheles was tested by PCR to determine species identity and ELISA for sporozoite rate. Results Annual IRS with Actellic® 300CS from 2015 to 2017 was effective on sprayed walls for a mean of 7 months in cone bioassay. PCR of 2016 and 2017 samples showed vector populations were predominantly Anopheles arabiensis (58.1%, n = 4,403 IRS sites, 58%, n = 2,441 unsprayed sites). There was a greater proportion of Anopheles funestus sensu stricto in unsprayed sites (20.4%, n = 858) than in sprayed sites (7.9%, n = 595) and fewer Anopheles parensis (2%, n = 85 unsprayed, 7.8%, n = 591 sprayed). Biting peaks of Anopheles gambiae sensu lato (s.l.) followed periods of rainfall occurring between October and April, but were generally lower in sprayed sites than unsprayed. In most sprayed sites, An. gambiae s.l. indoor densities increased between January and February, i.e., 10–12 months after IRS. The predominant species An. arabiensis had a sporozoite rate in 2017 of 2.0% (95% CI 1.4–2.9) in unsprayed sites compared to 0.8% (95% CI 0.5–1.3) in sprayed sites (p = 0.003). Sporozoite rates were also lower for An. funestus collected in sprayed sites. Conclusion This study contributes to the understanding of malaria vector species composition, behaviour and transmission risk following IRS around Lake Victoria and can be used to guide malaria vector control strategies in Tanzania.

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New Records of Anopheles benarrochi B (Diptera: Culicidae) in Malaria Hotspots in the Amazon Regions of Ecuador and Peru

Journal of Medical Entomology ◽

10.1093/jme/tjaa293 ◽

2021 ◽

Author(s):

Diego Morales Viteri ◽

Manuela Herrera-Varela ◽

Maribel Albuja ◽

Cristina Quiroga ◽

Gloria Diaz ◽

...

Keyword(s):

Vector Control ◽

Malaria Transmission ◽

New Records ◽

Final Analysis ◽

Human Landing Catch ◽

Light Traps ◽

Control Units ◽

Pcr Rflp ◽

Human Landing ◽

First Time

Abstract The increase in malaria transmission in the Amazon region motivated vector control units of the Ministry of Health of Ecuador and Peru to investigate Anopheles (Diptera: Culicidae) species present in transmission hotspots. Mosquitoes were collected using prokopack aspirators and CDC light traps (Ecuador) and human landing catch in Peru. In Ecuador, 84 Anopheles were captured from Pastaza, Morona Santiago, and Orellana provinces and identified morphologically [An. (An.) apicimacula Dyar and Knab, An. (Nys.) near benarrochi, An. (Nys.) near oswaldoi, An. (Nys.) near strodei, An. (An.) nimbus (Theobald, 1902), and An. (Nyssorhynchus) sp.]. In Peru, 1,150 Anopheles were collected in Andoas District. A subsample of 166 specimens was stored under silica and identified as An. near oswaldoi, An. darlingi, and An. (An.) mattogrossensis Lutz and Neiva. COI barcode region sequences were obtained for 137 adults (107 from Peru, 30 from Ecuador) identified by ITS2 PCR-RFLP as An. benarrochi Gabaldon, Cova Garcia, and Lopez and retained in the final analysis. Haplotypes from the present study plus An. benarrochi B GenBank sequences grouped separately from Brazilian An. benarrochi GenBank sequences by 44 mutation steps, indicating that the present study specimens were An. benarrochi B. Our findings confirm the presence of An. benarrochi B in Ecuador and reported here for the first time from the Amazonian provinces of Orellana and Morona Santiago. Furthermore, we confirm that the species collected in Andoas District in the Datem del Maranon Province, Peru, is An. benarrochi B, and we observed that it is highly anthropophilic. Overall, the known distribution of An. benarrochi B has been extended and includes southern Colombia, much of Peru and eastern Ecuador.

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Residual and Fumigant Effects of Bendiocarb WP80 in a Malarious Areas in Borderline of Iran and Pakistan

10.21203/rs.3.rs-139001/v1 ◽

2021 ◽

Author(s):

Mohammad Reza Abai ◽

Hassan Vatandoost ◽

Hossein Dorzadeh ◽

Mansoreh Shayeghi ◽

Ahmad Ali Hanafi-bojd ◽

...

Keyword(s):

Vector Control ◽

Anopheles Stephensi ◽

Indoor Residual Spraying ◽

Residual Effect ◽

Malaria Vector Control ◽

Biological Assays ◽

The Public ◽

Main Activity ◽

Contact Bioassay ◽

Old Females

Abstract Background: Malaria and leishmaniasis are the public health problems in southern Iran. The main activity of vector control is indoor residual spraying using pyrethrpids. The aim of study was to evaluate the biological assays of bendiocarb WP at different surfaces of wall. Materials and Methods: The residual effect of bendicocarb WP80 at 400 mg/m2 was evauated on various local surfaces of rooms such as mud and plaster as well as thatch roofs and wooden. WHO standard cones using contact bioassays were carried out using laboratory reared sugar-fed, 48-72 h old females of Anopheles stephensi . Contact bioassays were carried out on sprayed surfaces for 150 days.Results: Contact bioassay on surfaces treated with bendicocarb WP80 diffferent surfaces was estimated about 2 months. Fumigant tests of bendicocarb WP80 at 400 mg/m2 revealed 50-93.83% mortality with one month persistency.Discussion: The rsults hsowed that carbamte insecticide could be used as rotation with pyrethroids for malaria vector control .

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