Indoor Residual Spraying Programs Research Articles

Baseline susceptibility of Anopheles gambiae to clothianidin in northern Ghana

BackgroundClothianidin, an insecticide with a novel mode of action, has been deployed in the annual indoor residual spraying programme in northern Ghana since March 2021. To inform pragmatic management strategies and guide future studies, baseline data on local Anopheles gambiae sensu lato (s.l.) susceptibility to the clothianidin insecticide were collected in Kpalsogu, a village in the Northern region, Ghana.MethodsPhenotypic susceptibility of An. gambiae mosquitoes to clothianidin was assessed using the World Health Organization (WHO) insecticide resistance monitoring bioassay. The WHO cone bioassays were conducted on mud and cement walls sprayed with Sumishield 50 wettable granules (WG) (with clothianidin active ingredient). Daily mortalities were recorded for up to 7 days to observe for delayed mortalities. Polymerase chain reaction (PCR) technique was used to differentiate the sibling species of the An. gambiae complex and also for the detection of knock down resistance genes (kdr) and the insensitive acetylcholinesterase mutation (ace-1).ResultsThe WHO susceptibility bioassay revealed a delayed killing effect of clothianidin. Mosquitoes exposed to the cone bioassays for 5 min died 120 h after exposure. Slightly higher mortalities were observed in mosquitoes exposed to clothianidin-treated cement wall surfaces than mosquitoes exposed to mud wall surfaces. The kdr target-site mutation L1014F occurred at very high frequencies (0.89–0.94) across all vector species identified whereas the ace-1 mutation occurred at moderate levels (0.32–0.44). Anopheles gambiae sensu stricto was the most abundant species observed at 63%, whereas Anopheles arabiensis was the least observed at 9%.ConclusionsAnopheles gambiae s.l. mosquitoes in northern Ghana were susceptible to clothianidin. They harboured kdr mutations at high frequencies. The ace-1 mutation occurred in moderation. The results of this study confirm that clothianidin is an effective active ingredient and should be utilized in malaria vector control interventions.

Knowledge and Attitude of the Community People on Indoor Residual Spraying (IRS) Program at Kala-azar Endemic Area in Bangladesh

Visceral leishmaniasis also known as kala-azar is a chronic and potentially fatal parasitic disease in the world, affecting mainly the underprivileged people in the world. The success of the Kala-azar elimination program is mostly dependent on community participation which is an important aspect implemented by the world health organization in five south Asian countries. The participation of the community people mostly depends on the level of knowledge, attitude, and practice around risk factors associated with disease transmission among the population. This study was undertaken to assess the level of knowledge and attitude of the community people towards the indoor residual spraying (IRS) program in the Kala-azar endemic area. The study was carried out in 240 households by systemic random sampling on both hyper and moderate endemic areas in Bangladesh, and information was collected through a semi-structured questionnaire. Data from the study indicated that 44.6% of participants were illiterate, 99% had heard of kala-azar and 100% had heard about IRS. Team of IRS, family members, and neighbors play an important role as a source of information while the role of mass media was found to be limited. Almost all respondents who participate here seem to be that kala-azar is a serious health condition that drains family resources, but their attitude to doing beneficial activities of the IRS is not satisfactory because of their thought that it could be controlled by community effort. From the data, it is seen that people are knowledgeable about kala-azar, but disease transmission, infection origin, and control of the diseases are still not adequate. Their attitude toward indoor residual spraying program practice was not satisfactory. These findings suggest that it is necessary to continue and strengthen behavioral change through the implementation of the IRS program to progress the disease’s condition in the pandemic areas of Bangladesh.

A cost analysis to address issues of budget constraints on the implementation of the indoor residual spray programme in two districts of Maputo Province, Mozambique

BackgroundIt is frequently said that funding is essential to ensure optimal results from a malaria intervention control. However, in recent years, the capacity of the government of Mozambique to sustain the operational cost of indoor residual spraying (IRS) is facing numerous challenges due to restrictions of the Official Development Assistance. The purpose of the study was to estimate the cost of IRS operationalization in two districts of Maputo Province (Matutuíne and Namaacha) in Mozambique. The evidence produced in this study intends to provide decision-makers with insight into where they need to pay close attention in future planning in order to operationalize IRS with the existent budget in the actual context of budget restrictions.MethodsCost information was collected retrospectively from the provider perspective, and both economic and financial costs were calculated. A “one-way” deterministic sensitivity analysis was performed.ResultsThe average economic costs totaled US$117,351.34, with an average economic cost per household sprayed of US$16.35, and an average economic cost per person protected of US$4.09. The average financial cost totaled US$69,174.83, with an average financial cost per household sprayed and per person protected of US$9.84 and US$2.46, respectively. Vehicle, salary, and insecticide costs were the greatest contributors to overall cost in the economic and financial analysis, corresponding to 52%, 17%, and 13% in the economic analysis and 21%, 27%, and 22% in the financial analysis, respectively. The sensitivity analysis was adapted to a range of ± (above and under) 25% change. There was an approximate change of 14% in the average economic cost when vehicle costs were decreased by 25%. In the financial analysis, the average financial cost was lowered by 7% when salary costs were decreased by 25%.ConclusionsAltogether, the current cost analysis provides an impetus for the consideration of targeted IRS operationalization within the available governmental budget, by using locally-available human resources as spray operators to decrease costs and having IRS rounds be correctly timed to coincide with the build-up of vector populations.

Malaria Vectors and Vector Surveillance in Limpopo Province (South Africa): 1927 to 2018.

Despite the annual implementation of a robust and extensive indoor residual spraying programme against malaria vectors in Limpopo Province (South Africa), significant transmission continues and is a serious impediment to South Africa’s malaria elimination objectives. In order to gain a better understanding regarding possible causes of this residual malaria, we conducted a literature review of the historical species composition and abundance of malaria vector mosquitoes in the Limpopo River Valley region of the Vhembe District, northern Limpopo Province, the region with the highest remaining annual malaria cases in South Africa. In addition, mosquito surveys were carried out in the same region between October 2017 and October 2018. A total of 2225 adult mosquitoes were collected using CO2-baited tent and light traps, human landing catches and cow-baited traps. Of the 1443 Anopheles collected, 516 were members of the An. gambiae complex and 511 An. funestus group. In the malaria endemic rural areas outside the Kruger National Park, one specimen each of An. gambiae s.s. and An. funestus and only three of An. arabiensis were collected. The latter species was abundant at a remote hot spring in the neighboring Kruger National Park. Eighteen other species of Anopheles were collected. Our survey results support the historical findings that An. arabiensis, the species widely held to be the prime malaria vector in South Africa, is a rare species in the malaria endemic Limpopo River Valley. The implications of the mosquito surveys for malaria transmission, elimination and vector control in northern Limpopo Province and neighboring regions are discussed.

Prenatal exposure to DDT and pyrethroids and humoral response to vaccines among South African children from an area sprayed for malaria control

OPS 60: Social factors and environmental health across the world, Room 210, Floor 2, August 27, 2019, 1:30 PM - 3:00 PM Background/Aim: Animals studies strongly suggest that exposure to insecticides such as DDT and pyrethroids may inhibit immune response to vaccines. However, few human studies have investigated this question and none have done so in communities where insecticides are used to control malaria as part of Indoor Residual Spraying programs. These communities experience high exposure to insecticides and may be particularly susceptible to their toxic effects due to poverty, malnutrition and poor health. Our objective was thus to evaluate whether prenatal exposure to DDT and pyrethroids was associated with reduced immune response to vaccines at age 3.5 and 5 years among South African children participating in the Venda Health Examination of Mothers, Babies and their Environment (VHEMBE) birth cohort study. Methods: Between August 2012 and December 2013, we enrolled 752 women when they presented for delivery at Tshilidzini hospital in the city of Thohoyandou. We collected urine and blood samples at delivery for the measurement of pyrethroid metabolites and DDT via gas chromatography-mass spectrometry, respectively. At age 3.5 and 5 years, we measured measles, tetanus and Haemophilus influenzae b (Hib)-specific antibody titers in serum via enzyme-linked immunosorbent assay (ELISA). Results: Percentages of fully-vaccinated children with antibody titers below protective levels were 5.6% for measles, 31.1% for tetanus and 29.1% for Hib. Prenatal exposure to pyrethroids was associated with elevated risks of low measles (but not tetanus and Hib) antibody titers at 3.5 years. Each 10-fold increase in maternal urinary concentrations of 3-PBA, trans-DCCA and cis-DCCA was associated with relative risks of 1.85 (95%CI=0.98, 3.49), 1.84 (95%CI=1.09, 3.09) and 2.43 (95%CI=1.38, 4.29), respectively. No associations were found with DDT and DDE. Associations with antibody titers at age 5 will also be presented. Conclusion: Results suggest that prenatal exposure to pyrethroids may inhibit immune response to vaccines among South African children.

An observational analysis of the impact of indoor residual spraying with non-pyrethroid insecticides on the incidence of malaria in S\xe9gou Region, Mali: 2012\u20132015

BackgroundSégou Region in Central Mali is an area of high malaria burden with seasonal transmission, high access to and use of long-lasting insecticidal nets (LLINs), and resistance to pyrethroids and DDT well documented in Anopheles gambiae s.l. (the principal vector of malaria in Mali). Ségou has recently received indoor residual spraying (IRS) supported by Mali’s collaboration with the US President’s Malaria Initiative/Africa Indoor Residual Spraying programme. From 2012 to 2015, two different non-pyrethroid insecticides: bendiocarb in 2012 and 2013 and pirimiphos-methyl in 2014 and 2015, were used for IRS in two districts. This report summarizes the results of observational analyses carried out to assess the impact of these IRS campaigns on malaria incidence rates reported through local and district health systems before and after spraying.MethodsA series of retrospective time series analyses were performed on 1,382,202 rapid diagnostic test-confirmed cases of malaria reported by district routine health systems in Ségou Region from January 2012 to January 2016. Malaria testing, treatment, surveillance and reporting activities remained consistent across districts and years during the study period, as did LLIN access and use estimates as well as An. gambiae s.l. insecticide resistance patterns. Districts were stratified by IRS implementation status and all-age monthly incidence rates were calculated and compared across strata from 2012 to 2014. In 2015 a regional but variable scale-up of seasonal malaria chemoprevention complicated the region-wide analysis; however IRS operations were suspended in Bla District that year so a difference in differences approach was used to compare 2014 to 2015 changes in malaria incidence at the health facility level in children under 5-years-old from Bla relative to changes observed in Barouéli, where IRS operations were consistent.ResultsDuring 2012–2014, rapid reductions in malaria incidence were observed during the 6 months following each IRS campaign, though most of the reduction in cases (70% of the total) was concentrated in the first 2 months after each campaign was completed. Compared to non-IRS districts, in which normal seasonal patterns of malaria incidence were observed, an estimated 286,745 total fewer cases of all-age malaria were observed in IRS districts. The total cost of IRS in Ségou was around 9.68 million USD, or roughly 33.75 USD per case averted. Further analysis suggests that the timing of the 2012–2014 IRS campaigns (spraying in July and August) was well positioned to maximize public health impact. Suspension of IRS in Bla District after the 2014 campaign resulted in a 70% increase in under-5-years-old malaria incidence rates from 2014 to 2015, significantly greater (p = 0.0003) than the change reported from Barouéli District, where incidence rates remained the same.ConclusionsFrom 2012 to 2015, the annual IRS campaigns in Ségou are associated with several hundred thousand fewer cases of malaria. This work supports the growing evidence that shows that IRS with non-pyrethroid insecticides is a wise public health investment in areas with documented pyrethroid resistance, high rates of LLIN coverage, and where house structures and population densities are appropriate. Additionally, this work highlights the utility of quality-assured and validated routine surveillance and well defined observational analyses to rapidly assess the impact of malaria control interventions in operational settings, helping to empower evidence-based decision making and to further grow the evidence base needed to better understand when and where to utilize new vector control tools as they become available.

Indoor residual spraying with micro-encapsulated pirimiphos-methyl (Actellic® 300CS) against malaria vectors in the Lake Victoria basin, Tanzania.

BackgroundThe indoor residual spraying programme for malaria vectors control was implemented in four districts of the Lake Victoria basin of Tanzania namely Ukerewe, Sengerema, Rorya andSerengeti. Entomological monitoring activities were implemented in one sentinel village in each district to evaluate the efficacy of pirimiphos-methyl 300 CS sprayed on different wall surfaces and its impact against malaria vectors post-IRS intervention.MethodsThe residual decay rate of p-methyl 300 CS applied at a target dosage of 1g a.i./m2 on thesprayed wall surfaces was monitored for a period of 43 weeks post-IRSusing the WHO cone wall bioassay method. The bioassays were performed by exposing 2–5 days old unfed susceptible female Anopheles gambiae s.s. (Kisumu strain) to sprayed wall surfaces for a period of 30 minutes. In each sentinel village, mosquito collection was carried out by trained community mosquito collectors. Monthly mosquito collections were carried out from 6.00pm to 6.00am using CDC light traps and clay pot methods for indoors host seekingand outdoors resting mosquitoes respectively. Six traps (2 CDC light traps and 4 clay pots) were set per sentinel village per night for28 consecutive days in a moon. PCR and ELISA were used for mosquito species identification and sporozoite detection, respectively.ResultsBased on the WHOPES recommendation, insecticides should have a minimum efficacy of ≥ 80% mosquito mortality at 24 hours post exposure on the sprayed wall surfaces to be considered effective. In this study, p-methyl 300 CS was demonstrated to have a long residual efficacy of 21–43 weeks post-IRS on mud, cement, painted and wood wall surfaces. Numberof anopheline mosquitoes decreased post-IRS interventions in all sentinel villages. The highest numbers ofanopheline mosquitoes were collected in November-December, 38–43 weeks post-IRS. A total of 270 female anopheline mosquitoes were analyzed by PCR; out of which 236 (87.4%) were An. gambiae s.l. and 34 (12.6%) were An. funestus group. Of the 236 An. gambiae s.l.identified 12.6% (n = 34) were An. gambiae s.s. and 68.6% (n = 162) were An. arabiensis. Ofthe 34 An. funestus group indentified 91.2% (n = 31) were An. parensis and 8.8% (n = 3) were An. rivulorum. The overall Plasmodium falciparum sporozoite rate was 0.7% (n = 2,098).ConclusionsPirimiphos-methyl 300 CS was found to be effective for IRS in the Lake Victoria basin,Tanzania. P-methyl 300 CShas a long residual efficacy on sprayed wall surfaces and therefore it is effective in controlling principal malaria vectors of An. gambiae s.l and An. funestus which rest on wall surfaces after and before feeding.

Participatory Communication versus Communication Strategies of a Transnational NGO: Implementing the Indoor Residual Spraying Program in the Northern Region, Ghana

This descriptive case study of the communication strategies used by a US-based transnational non-governmental organization (NGO) contracted to implement an indoor residual spraying aid program in the Northern Region of Ghana with the goal of eradicating malaria holds that aid recipients should hold decision-making power, be provided with information to make decisions, and collaborate with NGOs in order for an aid program to be successful and sustainable. A top down management approach by the NGO worked in concert with traditional and democratic structures in this collectivistic culture with high power distance leaving out meaningful participatory communication with the intended aid recipients.

Preference Heterogeneity in the Structural Estimation of Efficient Pigovian Incentives for Insecticide Spraying to Reduce Malaria

This paper bridges the theoretical and empirical literatures on the role of preference heterogeneity in characterizing externalities related to disease transmission. We use a theoretical structure similar to locational sorting models, which characterize equilibria in terms of marginal individuals who are indifferent between locations. In our case, the ‘locations’ are binary, consisting of whether or not to take a discrete preventative action. Individual heterogeneity arises in this structure due to variation in the costs and disutility associated with prevention. We demonstrate application of this approach in the context of participation in insecticide-based indoor residual spraying programs for malaria control in northern Uganda. We identify the parameters of our theoretical model using a stated preference choice experiment combined with estimates from published epidemiological studies. The model implies that Pigovian subsidies for participation in this context should decrease household malaria risk by 19–25%. Our approach can be applied to other bioeconomic externalities with spillovers from discrete preventative actions, including agricultural pest management and the control of pest infestations and invasive species.

Laboratory Evaluation of Residual Efficacy of Actellic 300 CS (Pirimiphos-Methyl) and K-Othrine WG 250 (Deltamethrin) on Different Indoor Surfaces.

The nature and type of local indoor resting wall surfaces to certain level influences the residual bio-efficacy of insecticides used in indoor residual spraying programs. Knockdown and mortality effects of an organophosphate Actellic 300 CS and pyrethroid K-Othrine WG 250 insecticides on the field-collected Culex quinquefasciatus were assessed bimonthly from July to November 2014, using World Health Organization (WHO) cones bioassay test. Knockdown and mortality rates were subjected to statistical analysis using χ2 and Student t tests. Result of the bioassay test on C quinquefasciatus showed that plywood surfaces had the best residual knockdown activity of Actellic 300 CS with knockdown rate above the WHO-recommended threshold limit of ≥95% for 30 days after treatment. This was followed by mud surface with knockdown rates ≥95% threshold limit 15 days (97%) after treatment. The lowest knockdown rates of less than 95% were observed on cement surface throughout the assessment period. However, the knockdown rates of mosquitoes on deltamethrin WG 250–treated cement and plywood surfaces were 100% and ≥95%, respectively, at 30 days after treatment. But the knockdown activity was below the recommended threshold limit on mud surface during the 17 weeks trial. Knockdown activities varied significantly (p < .05), and it is a function of exposure periods, different surfaces, and insecticide formulations. The 24-hour mortality rates of Actellic 300 CS and K-Othrine WG 250 at 120 days after treatment were 83.6% and 86.7%, and 80% and 83.3%, on plywood and cement surfaces, respectively. A maximum residual period of 75 and 45 days were recorded for Actellic 300 CS and K-Othrine WG 250, respectively, on mud surface. Both Actellic 300 CS and K-Othrine 250 WG were highly effective against Culex mosquito. The extended residual activity of p-methyl CS compared with deltamethrin WG 250 makes it a suitable alternative insecticide against pyrethroid-resistant mosquitoes in Southwest Nigeria.

Anopheline mosquitoes behaviour and entomological monitoring in southwestern Ethiopia.

Despite a tremendous expansion in the financing and coverage of malaria control programmes, the disease continues to be a global health threat. This study was conducted to assess the entomological parameters of anopheline mosquitoes, viz. species composition, abundance, longevity, behaviour and infectivity rates in Kersa district, Jimma zone, southwestern Ethiopia. Mosquito collection was carried out from each selected household in each of the nine selected study villages of Kersa district, using CDC light-traps and pyrethrum spray catches (PSCs) for seven months (June to December 2014). Mosquito count data were log transformed before analysis and the data were analyzed using SPSS software package version 16.0. Analysis of variance (ANOVA) was employed to compare means and Tukey's post-hoc test was used for mean separation. In total, 1559 adult female anopheline mosquitoes, representing at least three species were collected from the study villages. Of these, 1122 were collected by CDC light-traps and the rest 437 were collected by PSCs. Anopheles gambiae s.1. (71.8%) was the most abundant species, followed by An. coustani s.1. (22%) and An. pharoensis (6.2%). The mean monthly density of anopheline mosquito species was highly significant (p < 0.001). Significantly (p <0.05) higher population of An. gambiae s.1. were trapped indoor than outdoor. However, outdoor mean densities of An. pharoensis and An. coustani s.1. were significantly (p < 0.001) higher than indoor mean densities. The longevity of An. gambiae s.1. was higher in the months of June, July and August (mean 7.32 days) and lower in the months of October, November and December (mean 2.94 days). Two An. gambiae s.1. specimens were found positive for Plasmodium vivax 210 polymorphs and the overall infectivity rate was estimated to be 1.04%. This study could contribute to the understanding of anopheline mosquitoes with respect to their composition, dynamics, distribution and behaviour in Kersa district, for evidence based malaria vector control programmes, mainly in the appropriate timing of the indoor residual spray programme.

Household perceptions and subjective valuations of indoor residual spraying programmes to control malaria in northern Uganda.

BackgroundInsecticide-based tools remain critical for controlling vector-borne diseases in Uganda. Securing public support from targeted populations for such tools is an important component in sustaining their long-run effectiveness. Yet little quantitative evidence is available on the perceived benefits and costs of vector control programmes among targeted households.MethodsA survey was administered to a clustered random sample of 612 households in Gulu and Oyam districts of northern Uganda during a period of very high malaria transmission and following a pilot indoor residual spray (IRS) programme. A discrete choice experiment was conducted within the survey, in which respondents indicated their preferences for different IRS programmes relative to money compensation in a series of experimentally controlled, hypothetical choice sets. The data were analysed using conditional logit regression models to estimate respondents’ willingness to accept (WTA) some amount of money compensation in lieu of foregone malaria risk reductions. Latent class models were used to analyse whether respondent characteristics predicted WTA.ResultsAverage WTA is estimated at $8.94 annually for a 10 % reduction in malaria risk, and additional co-benefits of IRS were estimated to be worth on average $54–$56 (depending on insecticide type) per round of IRS. Significant heterogeneity is observed: Four in five household heads in northern Uganda have high valuations for IRS programmes, while the remaining 20 % experience costly side effects of IRS (valued at between $2 and $3 per round). Statistically significant predictors of belonging to the high-value group include respondent gender, mean age of household members, participation in previous IRS, basic knowledge of mosquito reproduction, and the number of mosquito nets owned. Proxies for household income and wealth are not found to be statistically significant predictors of WTA.ConclusionsThis study suggests that the majority of people in areas of high malaria transmission like northern Uganda place a high value on vector control programmes using IRS. However, there is significant heterogeneity in terms of the perceived side effects (positive and negative). This has implications for sustaining public support for these programmes in the long-term.Electronic supplementary materialThe online version of this article (doi:10.1186/s40249-016-0190-1) contains supplementary material, which is available to authorized users.

Evaluation of Ongoing Indoor Residual Spray Programme in Some Malaria Endemic Districts of Andhra Pradesh, India

A survey was conducted in four malaria endemic, tribal dominated districts of Srikakulam, Vizainagaram, Visakhapatnam and West Godavari in Andhra Pradesh, to note the quality of ongoing Indoor Residual Spray (IRS). Both concurrent and consecutive supervision was done to find out house coverage, room coverage, house and room refusal rates, technical knowledge of spray crew and condition of pumps. A very high room refusal rate varying between 74.6 to 88.8 per cent was noted in the study areas. Outer surface of the houses and cattle sheds were sprayed with the insecticide which diluted the objective of IRS. There is a need to generate mass awareness through Behavioral Change Communication (BCC) about IRS operations in order to overcome the shortcomings.IRS operations should be carried out in accordance with World Health Organization (WHO) and National Programme guide lines on the subject under strict supervision.

Studying physical and sociological environment of malaria to implement an indoor insecticide spraying campaign in Oueme region, Benin

Malaria is among the main problems of public health in Africa. In Benin, indoor residual spraying (IRS) of bendiocarb has been proposed by the National Malaria Control Programme in the districts of Adjohoun, Dangbo, Misserete and Seme to help eradicate the malaria-causing mosquito. Prior to implementing an IRS program, a study of the local physical and sociological environment was assessed to identify the existing limits of this strategy. Cross-sectional study was conducted in April 2008. A total of 3,228 persons (adult male and female heads of household) were included in the study through systematic random sampling procedure for household survey. Both qualitative and quantitative methods were applied for data collection. The findings showed that the mosquito bite was the most feared (54.4%) for all districts. The most popular practices used for malaria treatment were traditional (56.3%) and modern (43.7%) medicine. IRS was accepted by 98.7% of respondents. Most of the walls (71.5%) were smooth and lend themselves well to the insecticide treatment. Habitats made ​​of bamboo and straw were not appropriate for IRSdue to pollution and poisoning risks. Free distribution of insecticide treated nets was the strategy recommended for households of these types of habitat. Key words: Malaria-causing mosquito, questionnaire-based interview, indoor residual spraying (IRS), insecticide-treated net, Benin.