Combining long-lasting insecticidal nets and indoor residual spraying for malaria prevention in Ethiopia: study protocol for a cluster randomized controlled trial
Abstract:BackgroundLong-lasting insecticidal nets (LLINs) and indoor residual spraying (IRS) are the main malaria prevention interventions in Ethiopia. There is conflicting evidence that the combined application of both interventions is better than either LLINs or IRS used alone. This trial aims to investigate whether the combination of LLINs (PermaNet 2.0, Vestergaard Frandsen, Lausanne, Switzerland) with IRS using propoxur will enhance the protective benefits and cost-effectiveness of the interventions against malari… Show more
“…The study area has been described in detail elsewhere [25, 26, 30]. In brief, the study was conducted in Edo Kontola, in Adami Tullu district, central Ethiopia (Fig.…”
Section: Methodsmentioning
confidence: 99%
“…Most of the population in the district is living in rural areas in houses made of mud or cement walls and thatched or corrugated iron roofs. Local residents primarily depend on farming, livestock rearing, and fishing for subsistence from Lake Zeway [26]. Fig.…”
Section: Methodsmentioning
confidence: 99%
“…The ethical considerations for this study is described in more details in the published protocol [26] and is specifically outlined as follows:…”
Section: Methodsmentioning
confidence: 99%
“…Ethical approval for the study was obtained from the Institutional Review Board of the College of Health Sciences at Addis Ababa University, the Ministry of Science and Technology in Ethiopia (Ref: 3.10/446/06), and the Regional Committee for Medical and Health Research Ethics, (Ref: 2013/986/REK Vest) Western Norway [26]. The protocol for the trial was registered at the Pan African Clinical Trials Registry under the Registration Number PACTR201411000882128.…”
Section: Methodsmentioning
confidence: 99%
“…To generate evidence on the effect of IRS and LLIN combined interventions, a cluster randomized controlled trial was implemented in Adami Tullu district in south-central Ethiopia [26]. For this trial, an appropriate mosquito sampling method was required to monitor the impact of the interventions on An.…”
BackgroundThe human landing catch (HLC) is the standard reference method for measuring human exposure to mosquito bites. However, HLC is labour-intensive, exposes collectors to infectious mosquito bites and is subjected to collector bias. These necessitate local calibration and application of alternative methods. This study was undertaken to determine the relative sampling efficiency (RSE) of light traps with or without yeast-produced carbon dioxide bait vs. HLC in south-central Ethiopia.MethodsThe experiment was conducted for 39 nights in a 3 × 3 Latin square randomized design with Anopheles arabiensis as the target species in the period between July and November 2014 in Edo Kontola village, south-central Ethiopia. Center for Disease Control and Prevention light trap catches (LTC) and yeast-generated carbon dioxide-baited light trap catches (CB-LTC) were each evaluated against HLC. The total nightly mosquito catches for each Anopheles species in either method was compared with HLC by Pearson correlation and simple linear regression analysis on log-transformed [log10(x + 1)] values. To test if the RSE of each alternative method was affected by mosquito density, the ratio of the number of mosquitoes in each method to the number of mosquitoes in HLC was plotted against the average mosquito abundance.ResultsOverall, 7606 Anopheles females were collected by the three sampling methods. Among these 5228 (68.7%) were Anopheles ziemanni, 1153 (15.2%) An. arabiensis, 883 (11.6%) Anopheles funestus s.l., and 342 (4.5%) Anopheles pharoensis. HLC yielded 3392 (44.6%), CB-LTC 2150 (28.3%), and LTC 2064 (27.1%) Anopheles females. The RSEs of LTC and HLC for An. arabiensis were significantly correlated (p < 0.001) and density independent (p = 0.65). However, for outdoor collection of the same species, RSEs of LTC and CB-LTC were density dependent (p < 0.001). It was estimated that on average, indoor LTC and CB-LTC each caught 0.35 and 0.44 times that of indoor HLC for An. arabiensis respectively.ConclusionsResults showed that HLC was the most efficient method for sampling An. arabiensis. LTC can be used for large-scale indoor An. arabiensis surveillance and monitoring when it is difficult to use HLC. CB-LTC does not substantially improve sampling of this major vector compared to LTC in this setting.
Trial registration PACTR201411000882128 (retrospectively registered 8 September, 2014)
“…The study area has been described in detail elsewhere [25, 26, 30]. In brief, the study was conducted in Edo Kontola, in Adami Tullu district, central Ethiopia (Fig.…”
Section: Methodsmentioning
confidence: 99%
“…Most of the population in the district is living in rural areas in houses made of mud or cement walls and thatched or corrugated iron roofs. Local residents primarily depend on farming, livestock rearing, and fishing for subsistence from Lake Zeway [26]. Fig.…”
Section: Methodsmentioning
confidence: 99%
“…The ethical considerations for this study is described in more details in the published protocol [26] and is specifically outlined as follows:…”
Section: Methodsmentioning
confidence: 99%
“…Ethical approval for the study was obtained from the Institutional Review Board of the College of Health Sciences at Addis Ababa University, the Ministry of Science and Technology in Ethiopia (Ref: 3.10/446/06), and the Regional Committee for Medical and Health Research Ethics, (Ref: 2013/986/REK Vest) Western Norway [26]. The protocol for the trial was registered at the Pan African Clinical Trials Registry under the Registration Number PACTR201411000882128.…”
Section: Methodsmentioning
confidence: 99%
“…To generate evidence on the effect of IRS and LLIN combined interventions, a cluster randomized controlled trial was implemented in Adami Tullu district in south-central Ethiopia [26]. For this trial, an appropriate mosquito sampling method was required to monitor the impact of the interventions on An.…”
BackgroundThe human landing catch (HLC) is the standard reference method for measuring human exposure to mosquito bites. However, HLC is labour-intensive, exposes collectors to infectious mosquito bites and is subjected to collector bias. These necessitate local calibration and application of alternative methods. This study was undertaken to determine the relative sampling efficiency (RSE) of light traps with or without yeast-produced carbon dioxide bait vs. HLC in south-central Ethiopia.MethodsThe experiment was conducted for 39 nights in a 3 × 3 Latin square randomized design with Anopheles arabiensis as the target species in the period between July and November 2014 in Edo Kontola village, south-central Ethiopia. Center for Disease Control and Prevention light trap catches (LTC) and yeast-generated carbon dioxide-baited light trap catches (CB-LTC) were each evaluated against HLC. The total nightly mosquito catches for each Anopheles species in either method was compared with HLC by Pearson correlation and simple linear regression analysis on log-transformed [log10(x + 1)] values. To test if the RSE of each alternative method was affected by mosquito density, the ratio of the number of mosquitoes in each method to the number of mosquitoes in HLC was plotted against the average mosquito abundance.ResultsOverall, 7606 Anopheles females were collected by the three sampling methods. Among these 5228 (68.7%) were Anopheles ziemanni, 1153 (15.2%) An. arabiensis, 883 (11.6%) Anopheles funestus s.l., and 342 (4.5%) Anopheles pharoensis. HLC yielded 3392 (44.6%), CB-LTC 2150 (28.3%), and LTC 2064 (27.1%) Anopheles females. The RSEs of LTC and HLC for An. arabiensis were significantly correlated (p < 0.001) and density independent (p = 0.65). However, for outdoor collection of the same species, RSEs of LTC and CB-LTC were density dependent (p < 0.001). It was estimated that on average, indoor LTC and CB-LTC each caught 0.35 and 0.44 times that of indoor HLC for An. arabiensis respectively.ConclusionsResults showed that HLC was the most efficient method for sampling An. arabiensis. LTC can be used for large-scale indoor An. arabiensis surveillance and monitoring when it is difficult to use HLC. CB-LTC does not substantially improve sampling of this major vector compared to LTC in this setting.
Trial registration PACTR201411000882128 (retrospectively registered 8 September, 2014)
BackgroundInsecticide‐treated nets (ITNs) and indoor residual spraying (IRS) are used to control malaria vectors. Both strategies use insecticides to kill mosquitoes that bite and rest indoors. For ITNs, the World Health Organization (WHO) only recommended pyrethroids until 2018, but mosquito vectors are becoming resistant to this insecticide. For IRS, a range of insecticides are recommended. Adding IRS to ITNs may improve control, simply because two interventions may be better than one; it may improve malaria control where ITNs are failing due to pyrethroid resistance; and it may slow the emergence and spread of pyrethroid resistance.ObjectivesTo summarize the effect on malaria of additionally implementing IRS, using non‐pyrethroid‐like or pyrethroid‐like insecticides, in communities currently using ITNs.Search methodsWe searched the Cochrane Infectious Diseases Group Specialized Register; the Cochrane Central Register of Controlled Trials (CENTRAL); MEDLINE; Embase; LILACS; the WHO International Clinical Trials Registry Platform; ClinicalTrials.gov; and the ISRCTN registry up to 18 March 2019.Selection criteriaCluster‐randomized controlled trials (cRCTs), interrupted time series (ITS), or controlled before‐and‐after studies (CBAs) comparing IRS plus ITNs with ITNs alone.Data collection and analysisTwo review authors independently assessed trials for eligibility, analyzed risk of bias, and extracted data. We used risk ratio (RR) and 95% confidence intervals (CI). We stratified by type of insecticide, ‘pyrethroid‐like’ and ‘non‐pyrethroid‐like’; the latter could improve malaria control better than adding IRS insecticides that have the same way of working as the insecticide on ITNs (‘pyrethroid‐like'). We used subgroup analysis of ITN usage in the trials to explore heterogeneity. We assessed the certainty of evidence using the GRADE approach.Main resultsSix cRCTs (eight comparisons) met our inclusion criteria conducted since 2008 in sub‐Saharan Africa. Malaria transmission in all sites was from mosquitoes belonging to the Anopheles gambiae s.l. complex species; two trials in Benin and Tanzania also reported the vector Anopheles funestus. Three trials used insecticide with targets different to pyrethroids (two used bendiocarb and one used pirimiphos‐methyl); two trials used dichloro‐diphenyl‐trichlorethane (DDT), an insecticide with the same target as pyrethroids; and one trial used both types of insecticide (pyrethroid deltamethrin in the first year, switching to bendiocarb for the second‐year). ITN usage was greater than 50% in three trials, and less than 50% in the remainder.Indoor residual spraying using ‘non‐pyrethroid‐like' insecticidesAdding IRS with a non‐pyrethroid‐like insecticide had mixed results. Overall, we do not know if the addition of IRS impacted on malaria incidence (rate ratio 0.93, 95% CI 0.46 to 1.86; 2 cRCTs, 566 child‐years; very low‐certainty evidence); it may have reduced malaria parasite prevalence (0.67, 95% CI 0.35 to 1.28; 5 comparisons from 4 cRCTs, 10,440 participants; low‐certainty e...
Background
Insecticide‐treated nets (ITNs) and indoor residual spraying (IRS) are used to prevent malaria transmission. Both interventions use insecticides to kill mosquitoes that bite and rest indoors. Adding IRS to ITNs may improve malaria control simply because two interventions can be better than one. Furthermore, IRS may improve malaria control where ITNs are failing due to insecticide resistance. Pyrethroid insecticides are the predominant class of insecticide used for ITNs, as they are more safe than other insecticide classes when in prolonged contact with human skin. While many mosquito populations have developed some resistance to pyrethroid insecticides, a wider range of insecticides can be used for IRS. This review is an update of the previous Cochrane 2019 edition.
Objectives
To summarize the effect on malaria of additionally implementing IRS, using non‐pyrethroid‐like or pyrethroid‐like insecticides, in communities currently using ITNs.
Search methods
We searched the Cochrane Infectious Diseases Group Specialized Register; CENTRAL; MEDLINE; and five other databases for records from 1 January 2000 to 8 November 2021, on the basis that ITN programmes did not begin to be implemented as policy before the year 2000.
Selection criteria
We included cluster‐randomized controlled trials (cRCTs), interrupted time series (ITS), or controlled before‐after studies (CBAs) comparing IRS plus ITNs with ITNs alone. We included studies with at least 50% ITN ownership (defined as the proportion of households owning one or more ITN) in both study arms.
Data collection and analysis
Two review authors independently assessed studies for eligibility, analyzed risk of bias, and extracted data. We used risk ratio (RR) and 95% confidence intervals (CI). We stratified by type of insecticide, 'pyrethroid‐like' and 'non‐pyrethroid‐like'; the latter could improve malaria control better than adding IRS insecticides that have the same way of working as the insecticide on ITNs ('pyrethroid‐like'). We used subgroup analysis of ITN usage in the studies to explore heterogeneity. We assessed the certainty of evidence using the GRADE approach.
Main results
Eight cRCTs (10 comparisons), one CBA, and one ITS study, all conducted since 2008 in sub‐Saharan Africa, met our inclusion criteria. The primary vectors in all sites were mosquitoes belonging to the
Anopheles gambiae s.l.
complex species; five studies in Benin, Mozambique, Ghana, Sudan, and Tanzania also reported the vector
Anopheles funestus
. Five cRCTs and both quasi‐experimental design studies used insecticides with targets different to pyrethroids (two used bendiocarb, three used pirimiphos‐methyl, and one used propoxur. Each of these studies were conducted in areas where the vectors were described as resistant or highly resistant to pyrethroids. Two...
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