Impact of Indoor Residual Spraying of Lambda-Cyhalothrin on Malaria Prevalence and Anemia in an Epidemic-Prone District of Muleba, North-Western Tanzania

Mashauri, Fabian; Kinung’hi, Safari; Kaatano, Godfrey M.; Magesa, Stephen; Kishamawe, Coleman; Mwanga, Joseph R.; Nnko, Soori; Malima, Robert; Mero, Chacha N.; Mboera, Leonard E. G.

doi:10.4269/ajtmh.12-0412

Cited by 39 publications

(82 citation statements)

References 33 publications

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“…A consistent finding among studies carried out in other African countries comparing malariometric indices between areas of IRS-implementation and non-implementation is a significantly lower prevalence of parasitaemia, anaemia and splenomegaly in the IRS-implementing area compared to the non-IRS-implementing area [8, 9, 22]. In this study, there was a statistically significant difference in levels of parasitaemia alone.…”

Section: Discussionsupporting

confidence: 89%

A malariometric survey of under-fives residing in indoor residual spraying-implementing and non-implementing communities of Lagos, Nigeria

Odugbemi

Wright

Onajole

et al. 2016

Malar J

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BackgroundIndoor residual spraying (IRS) is used as part of the integrated vector management strategy for the control of malaria in Lagos, Nigeria. The purpose of this study was to compare the malariometric indices of children under 5 years old living in IRS-implementing and non-IRS-implementing communities of Lagos, Nigeria.MethodsThe study was a community-based, comparative, cross-sectional study of 480 children under five recruited using a multi-stage sampling method. Data on each child were collected using a household questionnaire administered to the consenting care-giver of each selected child. Each child underwent a comprehensive physical examination. On-the-spot malaria rapid diagnostic testing and haemoglobin estimation to assess parasitaemia and anaemia, respectively, were also carried out. Risk factors for parasitaemia and anaemia were identified using multivariate logistic regression.ResultsA total of 238 children were studied in the IRS-implementing group while 242 children were studied in the non-IRS-implementing group. The IRS -implementing community had a lower level of parasitaemia (1.3 %) compared to the non-IRS-implementing community (5.8 %) (p < 0.001). There was no significant difference in anaemia, spleen rate and fever in the IRS-implementing group (10.9, 9.7 and 5 %) and the non-IRS-implementing group (9.9, 8.8 and 8.7 %), respectively. Residing in an IRS-implementing community was associated with lower odds of parasitaemia (OR 0.17, p < 0.01). Sleeping under a bed net was the only factor associated with anaemia (p < 0.01).ConclusionIRS has led to a reduction in the level of parasitaemia in the under-fives in the study areas.

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Section: Discussionsupporting

confidence: 89%

A malariometric survey of under-fives residing in indoor residual spraying-implementing and non-implementing communities of Lagos, Nigeria

Odugbemi

Wright

Onajole

et al. 2016

Malar J

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“…insecticide-treated nets (ITNs), indoor residual spraying (IRS) and artemisinin-based combination therapy (ACT) are credited with 663 million clinical cases of malaria averted between 2000 and 2015 [2]. In Tanzania, the impact of these interventions has been demonstrated by multiple investigators [3][4][5][6], as well as national surveys, which show significant overall reduction in burden [7]. Despite these gains, there is also evidence that the anti-malaria progress is levelling off and that the gains may be lost [1].…”

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confidence: 99%

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

Msugupakulya

Kaindoa

Ngowo

et al. 2020

Malar J

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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 southeastern 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.

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“…In mainland Tanzania, IRS implementation funded by the United States (U.S.) President's Malaria Initiative (PMI) was launched in 2007 in Muleba and Karagwe districts, located in Kagera Region. The initial locations were supported in response to a malaria epidemic in 2006 [5]. Thereafter, IRS activities with pyrethroid insecticides were progressively expanded to other districts in the Lake Victoria basin including the remaining ve districts of Kagera Region in 2009; and in 2010 and 2011 to all 18 districts of Kagera, Mwanza, and Mara, covering 1.1 million structures and targeting nearly 6.3 million people [6].…”

Section: Introductionmentioning

confidence: 99%

“…Despite widespread pyrethroid resistance being detected in malaria vectors throughout Tanzania [9,10], IRS in combination with pyrethroid LLINs have proven effective in mainland Tanzania [5,11] and also in Zanzibar [12]. Partly due to vector control, reported malaria deaths in mainland Tanzania reduced bỹ 32%, from 15,819 in 2010 to 5,045 in 2016 [13].…”

Section: Introductionmentioning

confidence: 99%

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

Kakilla

Manjurano

Nelwin

et al. 2020

Preprint

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Background: Vector control through long lasting insecticidal nets 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 ten sprayed and four 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 (un-baited) as a proxy measure for indoor and outdoor biting rate and time of biting. Prokopack aspirators were used indoors to capture potentially resting malaria vector. A sub-sample of Anopheles were 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 An. arabiensis (58.1%, n=4,403 IRS sites, 58%, n=2,441 unsprayed sites). There was a greater proportion of An. funestus s.s. in unsprayed sites (20.4%, n=858) than sprayed sites (7.9%, n=595) and fewer An. parensis (2%, n=85 unsprayed, 7.8%, n=591 sprayed). Biting peaks of An. gambiae 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, behavior and transmission risk following IRS around Lake Victoria and can be used to guide malaria vector control strategies in Tanzania.

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Impact of Indoor Residual Spraying of Lambda-Cyhalothrin on Malaria Prevalence and Anemia in an Epidemic-Prone District of Muleba, North-Western Tanzania

Cited by 39 publications

References 33 publications

A malariometric survey of under-fives residing in indoor residual spraying-implementing and non-implementing communities of Lagos, Nigeria

A malariometric survey of under-fives residing in indoor residual spraying-implementing and non-implementing communities of Lagos, Nigeria

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

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

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