scholarly journals Are Dawn Collections of Anopheles stephensi a Better Method To Estimate the Resting Vector Density? A Study from Chennai, India

2021 ◽  
Author(s):  
Sangamithra Ravishankaran ◽  
Aswin Asokan ◽  
N. Johnson Amala Justin ◽  
Shalu Thomas ◽  
Manu Thomas Mathai ◽  
...  
Keyword(s):  
Longitudinal Study ◽  
Vector Control ◽  
Malaria Transmission ◽  
Anopheles Stephensi ◽  
Urban Setting ◽  
Larval Source Management ◽  
Vector Density ◽  
Management Measures ◽  
Close Proximity ◽  
Source Management

The study was an attempt to capture Anopheles stephensi from cattle sheds during dawn to understand the realistic density of the resting mosquitoes. A 2-year longitudinal study was carried out in cattle sheds in close proximity to the human dwellings to collect the resting vector mosquitoes. The man-hour density of A. stephensi ranged from 24.7 to 206.5. The vector incrimination results indicated 0.15% of A. stephensi infected with Pv210 in 2015 and 0.09% in 2016. The current study has revealed that cattle sheds are the preferred resting place of A. stephensi and that dawn is the perfect time to collect and estimate its densities. Hence, adult vector control may also be given due importance in addition to the routine larval source management measures to curb malaria transmission in an urban setting.

scholarly journals Defining the larval habitat: abiotic and biotic parameters associated with Anopheles farauti productivity

2019 ◽  
Vol 18 (1) ◽  
Author(s):  
Kimberley McLaughlin ◽  
Thomas R. Burkot ◽  
Jance Oscar ◽  
Nigel W. Beebe ◽  
Tanya L. Russell
Keyword(s):  
Vector Control ◽  
Control Strategy ◽  
World Health ◽  
Effective Control ◽  
Biological Parameters ◽  
Insecticide Treated Nets ◽  
Larval Habitats ◽  
Anopheles Farauti ◽  
Larval Source Management ◽  
Source Management

Abstract Background In the Solomon Island, the dominant malaria vector, Anopheles farauti, is highly anthropophagic and increasingly exophilic and early biting. While long-lasting insecticide-treated nets remain effective against An. farauti, supplemental vector control strategies will be needed to achieve malaria elimination. Presently, the only World Health Organization recommended supplemental vector control strategy is larval source management (LSM). Effective targeted larval source management requires understanding the associations between abiotic, chemical and biological parameters of larval habitats with the presence or density of vector larvae. Methods Potential and actual An. farauti larval habitats were characterized for presence and density of larvae and associated abiotic, chemical and biological parameters. Results A third of all sampled potential habitats harboured An. farauti larvae with 80% of An. farauti positive habitats being in three habitat classifications (swamps/lagoons, transient pools and man-made holes). Large swamps were the most abundant positive habitats surveyed (43% of all An. farauti positive habitats). Habitats with An. farauti larvae were significantly associated with abiotic (pH, nitrate, ammonia and phosphate concentrations and elevated temperature) and biotic (predators) parameters. Conclusion Large swamps and lagoons are the largest and most abundant An. farauti habitats in the Solomon Islands. Positive habitats were more frequently associated with the presence of predators (vertebrates and invertebrates) and higher water temperatures. Cohabitation with predators is indicative of a complex habitat ecosystem and raises questions about the potential of biological control as an effective control strategy. Increased presence of An. farauti with higher water temperature suggests a potential explanation for the coastal distribution of this species which is not found inland at elevated altitudes where temperatures would be cooler.

scholarly journals Cost of Community-Led Larval Source Management and House Improvement for Malaria Control: A Cost Analysis Within A Cluster-Randomised Trial in A Rural District in Malawi

2020 ◽  
Author(s):  
Mphatso Dennis Phiri ◽  
Robert Sean McCann ◽  
Alinune Nathanael Kabaghe ◽  
Henk van den Berg ◽  
Tumaini Malenga ◽  
...  
Keyword(s):  
Cost Analysis ◽  
Vector Control ◽  
Malaria Control ◽  
Randomised Trial ◽  
Wire Mesh ◽  
Sensitivity Analyses ◽  
Larval Source Management ◽  
House Improvement ◽  
Implementation Costs ◽  
Source Management

Abstract Background: House improvement (HI) to prevent mosquito house entry, and larval source management (LSM) targeting aquatic mosquito stages to prevent development into adult forms, are promising complementary interventions to current malaria vector control strategies. Lack of evidence on costs and cost-effectiveness of community-led implementation of HI and LSM has hindered wide scale adoption. This study presents an incremental cost analysis of community-led implementation of HI and LSM, in a factorial design trial, in addition to standard national malaria control interventions in Chikwawa district, southern Malawi.Methods: In the trial, LSM comprised draining, filling, and Bacillus thuringiensis israelensis larvicide application, while HI involved closing of eaves and gaps on walls, and screening windows and ventilation spaces with wire mesh. Communities implemented all interventions. Costs were estimated retrospectively using the ‘ingredients approach’, combining both ‘bottom-up’ and ‘top-down approaches’, from the societal perspective. To estimate the cost of independently implementing each intervention arm, resources shared between trial arms (e.g. overheads) were allocated to each consuming arm using proxies developed based on share of resource input quantities consumed. Incremental implementation costs (in 2017 US$) are presented for HI only, LSM only and HI+LSM arms. In sensitivity analyses, the effect of varying costs of important inputs on estimated costs was explored. Results: The total economic program costs of community-led HI and LSM implementation was $626,152. Economic implementation costs of HI, LSM and HI+LSM were estimated as $27.04, $25.06 and $33.44, per person per year, respectively. Staff, transport and labour costs, but not larvicide or screening material, were the major cost drivers across all interventions. Estimated costs were sensitive to changes in staff costs and population covered. Conclusions: In the context of the trial, the economic costs of community-led HI and LSM implementation were high compared to conventional vector control interventions. Several factors, including the year-round implementation of LSM and low human population density could explain the high costs. The factorial trial design necessitated use of proxies to allocate costs shared between trial arms, which may limit generalisability of estimated costs where different designs are used. Nevertheless, costs may inform planners of future similar intervention packages. Trial registration: Not applicable. The original trial was registered with The Pan African Clinical Trials Registry on 3 March 2016, trial number PACTR201604001501493.

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

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.

scholarly journals Addressing key gaps in implementation of mosquito larviciding to accelerate malaria vector control in southern Tanzania: results of a stakeholder engagement process in local district councils

2021 ◽  
Vol 20 (1) ◽  
Author(s):  
Salum A. Mapua ◽  
Marceline F. Finda ◽  
Ismail H. Nambunga ◽  
Betwel J. Msugupakulya ◽  
Kusirye Ukio ◽  
...  
Keyword(s):  
Malaria Control ◽  
Public Engagement ◽  
Indoor Residual Spraying ◽  
Malaria Vectors ◽  
Malaria Vector Control ◽  
Production Plant ◽  
Community Members ◽  
Key Informants ◽  
Larval Source Management ◽  
Source Management

Abstract Background Larval source management was historically one of the most effective malaria control methods but is now widely deprioritized in Africa, where insecticide-treated nets (ITNs) and indoor residual spraying (IRS) are preferred. However, in Tanzania, following initial successes in urban Dar-es-Salaam starting early-2000s, the government now encourages larviciding in both rural and urban councils nationwide to complement other efforts; and a biolarvicide production-plant has been established outside the commercial capital. This study investigated key obstacles and opportunities relevant to effective rollout of larviciding for malaria control, with a focus on the meso-endemic region of Morogoro, southern Tanzania. Methods Key-informants were interviewed to assess awareness and perceptions regarding larviciding among designated health officials (malaria focal persons, vector surveillance officers and ward health officers) in nine administrative councils (n = 27). Interviewer-administered questionnaires were used to assess awareness and perceptions of community members in selected areas regarding larviciding (n = 490). Thematic content analysis was done and descriptive statistics used to summarize the findings. Results A majority of malaria control officials had participated in larviciding at least once over the previous three years. A majority of community members had neutral perceptions towards positive aspects of larviciding, but overall support for larviciding was high, although several challenges were expressed, notably: (i) insufficient knowledge for identifying relevant aquatic habitats of malaria vectors and applying larvicides, (ii) inadequate monitoring of programme effectiveness, (iii) limited financing, and (iv) lack of personal protective equipment. Although the key-informants reported sensitizing local communities, most community members were still unaware of larviciding and its potential. Conclusions The larviciding programme was widely supported by both communities and malaria control officials, but there were gaps in technical knowledge, implementation and public engagement. To improve overall impact, it is important to: (i) intensify training efforts, particularly for identifying habitats of important vectors, (ii) adopt standard technical principles for applying larvicides or larval source management, (iii) improve financing for local implementation and (iv) improve public engagement to boost community awareness and participation. These lessons could also be valuable for other malaria endemic areas wishing to deploy larviciding for malaria control or elimination.

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

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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