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Preferred resting surfaces of dominant malaria vectors inside different house types in rural south-eastern Tanzania.

ABSTRACT: BACKGROUND:Malaria control in Africa relies extensively on indoor residual spraying (IRS) and insecticide-treated nets (ITNs). IRS typically targets mosquitoes resting on walls, and in few cases, roofs and ceilings, using contact insecticides. Unfortunately, little attention is paid to where malaria vectors actually rest indoors, and how such knowledge could be used to improve IRS. This study investigated preferred resting surfaces of two major malaria vectors, Anopheles funestus and Anopheles arabiensis, inside four common house types in rural south-eastern Tanzania. METHODS:The assessment was done inside 80 houses including: 20 with thatched roofs and mud walls, 20 with thatched roofs and un-plastered brick walls, 20 with metal roofs and un-plastered brick walls, and 20 with metal roofs and plastered brick walls, across four villages. In each house, resting mosquitoes were sampled in mornings (6 a.m.-8 a.m.), evenings (6 p.m.-8 p.m.) and at night (11 p.m.-12.00 a.m.) using Prokopack aspirators from multiple surfaces (walls, undersides of roofs, floors, furniture, utensils, clothing, curtains and bed nets). RESULTS:Overall, only 26% of An. funestus and 18% of An. arabiensis were found on walls. In grass-thatched houses, 33-55% of An. funestus and 43-50% of An. arabiensis rested under roofs, while in metal-roofed houses, only 16-20% of An. funestus and 8-30% of An. arabiensis rested under roofs. Considering all data together, approximately 40% of mosquitoes rested on surfaces not typically targeted by IRS, i.e. floors, furniture, utensils, clothing and bed nets. These proportions were particularly high in metal-roofed houses (47-53% of An. funestus; 60-66% of An. arabiensis). CONCLUSION:While IRS typically uses contact insecticides to target adult mosquitoes on walls, and occasionally roofs and ceilings, significant proportions of vectors rest on surfaces not usually sprayed. This gap exceeds one-third of malaria mosquitoes in grass-thatched houses, and can reach two-thirds in metal-roofed houses. Where field operations exclude roofs during IRS, the gaps can be much greater. In conclusion, there is need for locally-obtained data on mosquito resting behaviours and how these influence the overall impact and costs of IRS. This study also emphasizes the need for alternative approaches, e.g. house screening, which broadly tackle mosquitoes beyond areas reachable by IRS and ITNs.

SUBMITTER: Msugupakulya BJ

PROVIDER: S-EPMC6964015 | biostudies-literature | 2020 Jan

REPOSITORIES: biostudies-literature

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Preferred resting surfaces of dominant malaria vectors inside different house types in rural south-eastern Tanzania.

Msugupakulya Betwel J BJ Kaindoa Emmanuel W EW Ngowo Halfan S HS Kihonda Japhet M JM Kahamba Najat F NF Msaky Dickson S DS Matoke-Muhia Damaris D Tungu Patrick K PK Okumu Fredros O FO

Malaria journal 20200115 1

<h4>Background</h4>Malaria control in Africa relies extensively on indoor residual spraying (IRS) and insecticide-treated nets (ITNs). IRS typically targets mosquitoes resting on walls, and in few cases, roofs and ceilings, using contact insecticides. Unfortunately, little attention is paid to where malaria vectors actually rest indoors, and how such knowledge could be used to improve IRS. This study investigated preferred resting surfaces of two major malaria vectors, Anopheles funestus and Ano ...[more]

PMID: 31941508

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Project description:BACKGROUND: Monitoring densities of adult mosquito populations is a major challenge in efforts to evaluate the epidemiology of mosquito-borne diseases, and their response to vector control interventions. In the case of malaria, collection of outdoor-resting Anophelines is rarely incorporated into surveillance and control, partially due to the lack of standardized collection tools. Such an approach, however, is increasingly important to investigate possible changes in mosquito behaviour in response to the scale up of Insecticide Treated Nets and Indoor Residual Spraying. In this study we evaluated the Sticky Resting Box (SRB) - i.e. a sticky variant of previously investigated mosquito Resting Box, which allows passive collection of mosquitoes entering the box - and compared its performance against traditional methods for indoor and outdoor resting mosquito sampling. METHODS: Daily collections were carried out in two neighbouring villages of Burkina Faso during rainy season 2011 and dry season 2012 by SRB located indoors and outdoors, and by Back-Pack aspiration inside houses (BP) and in ad hoc built outdoor pit-shelters (PIT). RESULTS: Overall, almost 20,000 Culicidae specimens belonging to 16 species were collected and morphologically identified. Malaria vectors included Anopheles coluzzii (53%), An. arabiensis (12%), An. gambiae s.s. (2.0%) and An. funestus (4.5%). The diversity of species collected in the two villages was similar for SRB and PIT collections outdoors, and significantly higher for SRB than for BP indoors. The population dynamics of An. gambiae s.l. mosquitoes, as obtained by SRB-collections was significantly correlated with those obtained by the traditional methods. The predicted mean estimates of An. gambiae s.l. specimens/sampling-unit/night-of-collections was 6- and 5-times lower for SRB than for BP indoors and PIT outdoors, respectively. CONCLUSIONS: Overall, the daily performance of SRB in terms of number of malaria vectors/trap was lower than that of traditionally used approaches for in- and outdoor collections. However, unlike these methods, SRB could be set up to collect mosquitoes passively over at least a week. This makes SRB a promising tool for passively monitoring anopheline resting populations, with data presented here providing guidance for how to set up SRB-based collections to acquire information comparable to those obtained with other methods.

Project description:BackgroundIn specific populations, including those at risk of falls or foot ulcers, indoor footwear is an important aspect of preventative care. This study aims to describe the indoor footwear worn most over the previous year in a sample representative of the Australian inpatient population, and to explore the sociodemographic, medical, foot condition and foot treatment history factors associated with the indoor footwear worn.MethodsThis was a secondary analysis of data collected from inpatients admitted to five hospitals across Queensland, Australia. Sociodemographic information, medical history, foot conditions and foot treatment history were collected as explanatory variables. Outcomes included the self-reported type of indoor footwear (from 16 standard footwear types) worn most in the year prior to hospitalisation, and the category in which the self-reported footwear type was defined according to its features: 'protective', 'non-protective' and 'no footwear'. Multivariate analyses determined explanatory variables independently associated with each type and category.ResultsProtective footwear was worn by 11% of participants (including 4% walking shoes, 4% running shoes, 2% oxford shoes), and was independently associated with education above year 10 level (OR 1.78, p = 0.028) and having had foot treatment by a specialist physician (5.06, p = 0.003). Most participants (55%) wore non-protective footwear (including 21% slippers, 15% thongs/flip flops, 7% backless slippers), which was associated with older age (1.03, p < 0.001). No footwear was worn by 34% of participants (30% barefoot, 3% socks only). Those of older age (0.97, p < 0.001) and those in the most disadvantaged socioeconomic group (0.55, p = 0.019) were less likely to wear no footwear (socks or barefoot).ConclusionsOnly one in nine people in a large representative inpatient population wore a protective indoor footwear most of the time in the previous year. Whilst having education levels above year 10 and having received previous foot treatment by a specialist physician were associated with wearing protective footwear indoors, the presence of a range of other medical and foot conditions were not. These findings provide information to enable clinicians, researchers and policymakers to develop interventions aimed at improving indoor footwear habits that may help prevent significant health burdens such as falls and foot ulcers.

Dataset Information

Preferred resting surfaces of dominant malaria vectors inside different house types in rural south-eastern Tanzania.

Publications

Preferred resting surfaces of dominant malaria vectors inside different house types in rural south-eastern Tanzania.

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