Category: Case Studies

“With the report, we can approach our technical and financial partners, and even the country’s political authorities, to move towards implementing the evaluation’s recommendations.” –Dr. Vincent Sanogo, Consultant/Technical and Management Advisor at the Mali National Malaria Control Program

Estimated malaria case incidence in Mali has decreased from 384 to 354 confirmed cases per 1,000 population between 2010 and 2021 but remains a leading cause of illness and death in the country^[1]. To reduce the malaria burden, the Mali National Malaria Control Program (NMCP) has followed a universal coverage approach for insecticide-treated net (ITN) provision since 2011, distributing ITNs through mass campaigns and continuous distribution channels with the goal of reaching all households in the country. 

Past campaigns used standard pyrethroid ITNs. However, with widespread resistance to pyrethroids among local vector populations, the NMCP sought out new types of ITNs to use for the mass campaign and routine distribution channels in 2020. With support from the New Nets Project^[2], the NMCP obtained Interceptor^® G2 (IG2) ITNs, a new type of ITN which contains chlorfenapyr, a new active ingredient, and alpha-cypermethrin (a pyrethroid). Due to the higher cost of these new ITNs, the NMCP was interested in determining whether they had a greater impact compared to the standard pyrethroids nets before distributing them more broadly across the country. 

Unloading of IG2 ITNs for the July 2020 ITN campaign. Photo courtesy of the NMCP.

According to Dr. Vincent Sanogo, a consultant and Technical and Management Advisor at the NMCP, the impetus for this evaluation came from a similar evaluation being conducted in Burkina Faso by the New Nets Project. “We wanted an evaluation in our context, so we asked PMI [U.S. President’s Malaria Initiative] to support this, to provide us with the evidence on the effectiveness of new-generation mosquito nets compared with conventional nets,” he said.

Dr. Lansana Sangare, PMI Mali’s Project Management Specialist, noted that this evaluation allowed the NMCP and PMI to assess the effectiveness of IG2 ITNs despite limited funding by using Mali’s national health system data. 

With the support of the PMI VectorLink Project, the NMCP selected Sikasso Region (Figure 1) for the IG2 net distribution. In 2018, Sikasso Region had the highest prevalence of malaria in children under-five, according to the 2018 Demographic and Health Survey, and the highest malaria case incidence in the national health information system. Four out of the ten districts received IG2 nets via mass campaign in July 2020, while the remaining six districts received standard pyrethroid nets. Routine health system data collected between August 2018 to July 2022, two years before and after the July 2020 ITN campaign, was used to compare the effectiveness of the IG2s to standard pyrethroid nets.

Figure 1. Map of IG2 vs standard pyrethroid ITN distribution in Sikasso Region.

This evaluation found that the IG2 ITNs performed better than the standard pyrethroid ITNs:

• Compared to the pre-intervention period, the IG2 ITN districts were estimated to have a 27% reduction in confirmed malaria cases reported compared to only a 2% reduction in the standard ITN districts.
• Using a counterfactual analysis, in the two years following the campaign distribution, the districts that received IG2 ITNs averted an estimated 248,616 (89,161 to 465,808) malaria cases, or 171 (61 to 320) cases per 1,000 person-years compared to a modelled scenario in which standard ITNs were distributed within these districts.

Both nets, however, showed the greatest impact during the first-year post-distribution (Figure 2):

• Districts receiving IG2 ITNs showed a statistically significant decline in cases of 32% in the first year compared to only 22% in the second year.
• Districts receiving standard ITNs showed a statistically significant decline of 12% in the first year but incidence increased 8% over the baseline in the second year.

Figure 2. Case incidence per 1,000 population before and after IG2 and standard pyrethroid ITN distribution.

These evaluation findings bolstered the NMCP’s decision to distribute IG2 ITNs during the 2023 mass campaign in areas where malaria is highly prevalent and where indoor residual spraying (IRS) programs are no longer taking place.

“Now that the evaluation shows that IG2s really are much better than conventional nets, these results support our position [to invest in these higher cost nets],” said Sanogo. He believes that the results of this evaluation will also help to inform key decisions over the next year, including the next Global Fund application in 2024.

These results emphasize how timely evaluations using routine data can contribute valuable information for national governments and malaria control stakeholders. Sangare noted that while there is no single “magic bullet” that can completely inform all future malaria control decision making, this evaluation serves as a key resource to guide the process. In support of data-driven decision-making, Sangare made clear the value of country-specific evaluations: “We have data that can tell the real story behind this efficacy.”

Read this story in French: Plaidoyer en faveur de l’utilisation de nouvelles moustiquaires imprégnées d’insecticide au Mali

Download a PDF version of this story in English: Making the Case for Using New Insecticide-Treated Nets in Mali

 

 

[1] World malaria report 2022. Geneva: World Health Organization; 2022. Licence: CC BY-NC-SA 3.0 IGO.

[2] New Nets Project website. https://www.ivcc.com/market-access/new-nets-project/

“These results have reinforced the national program’s resolve to continue to leverage the evidence that is being produced from entomological surveillance activities.” — Philip Oyale Okoko, Deputy Director/Programme Manager, IMPACT Project, National Malaria Elimination Program, Nigeria

Insecticide-treated nets (ITNs) have been essential tools in the global effort to reduce the burden of malaria. ITNs are the primary vector control intervention in Nigeria, the country with the highest malaria burden globally. However, pyrethroid resistance has been widely documented throughout Nigeria, threatening the effectiveness of this tool. New types of ITNs, such as pyrethroid nets treated with piperonyl butoxide (PBO), have been developed to address this resistance and have been found to significantly lower malaria parasite prevalence compared to standard pyrethroid-only ITNs in countries such as Tanzania and Uganda. The U.S. President’s Malaria Initiative (PMI), through partnerships with local universities, has been monitoring changes in mosquito resistance profiles in Nigeria. Based on this evidence, the Nigeria National Malaria Elimination Program (NMEP) and PMI decided to deploy 1.7 million PBO ITNs in Ebonyi State in November 2019. This was the first PBO ITN campaign in Nigeria.

“Before the Ebonyi evaluation took place we had never deployed PBO nets in Nigeria,” said Philip Oyale Okoko, Deputy Director/Programme Manager for the NMEP. “And when you are talking about vector control and vector control tools, one of the first things you want to achieve is one that has [a] high level of impact.”

In collaboration with the NMEP, the PMI VectorLink Project designed an evaluation to assess both the epidemiological and entomological impact of the PBO ITN campaign in Ebonyi. According to Okoko, “We thought if we are going to be deploying ITNs in Ebonyi State, which has had high level resistance… it would be interesting to see how PBO [nets] are going to perform in such an environment.” The main questions the evaluation sought to answer were:

1. What is the impact of PBO ITNs on malaria case incidence in Ebonyi, where Anopheles gambiae s.l. has confirmed high intensity pyrethroid resistance (Figure 1)?
2. How does the impact of PBO ITNs on malaria case incidence in Ebonyi compare to the impact of standard ITNs in the neighboring state of Cross River (with a campaign in the same year), where An. gambiae s.l. are still susceptible to pyrethroids?
3. What is the impact of PBO ITNs on entomological indicators (human biting rate and indoor resting density) in a setting of confirmed high intensity pyrethroid resistance?

Figure 1. Resistance of An. gambiae s.l., the major malaria vector, to deltamethrin with or without PBO in Ebonyi and Cross River, 2019.

A core piece of this evaluation was the use of routine health systems data, which provides more timely data at a lower cost and at a more granular level. According to Jules Mihigo, PMI’s Resident Advisor in Nigeria, “The most available data is the routine data that’s available every month. For the Malaria Indicator Survey (MIS) results, you have to wait for a couple of years.” He added that there have been continued investments by the NMEP, PMI, and other key stakeholders in data quality, sharing, and use, and that a lot of work is done by partners on the ground to validate the data each month.

Using this routine data from the country’s National Health Management Information System (HMIS), a controlled interrupted time series analysis was conducted using monthly incidence data from two years before and after the PBO ITN campaign in Ebonyi State (December 2017 to November 2021). A pre/post analysis was also conducted to assess the impact of the PBO ITNs on two entomological indicators of interest—human biting rate and indoor resting density—during the high transmission season before and after the mass campaign. Results from these analyses found that:

• In Ebonyi, PBO ITNs were associated with a 46.7% decrease in malaria case incidence in the two years after the PBO ITN distribution compared to if no ITNs had been distributed, with a significant decrease from 269.6 predicted cases per 1,000 population to 143.6 (Figure 2).
• In Cross River, there was a significant 28.6% increase in malaria case incidence following the standard ITN distribution, with an increase from 71.2 predicted cases to 91.6 per 1,000 population.

During the high transmission season immediately following the PBO ITN campaign in Ebonyi, the human biting rate was 72% lower and indoor resting density was 73% lower compared to the high transmission season immediately before the campaign.

Figure 2. Monthly confirmed malaria cases per 1,000 population in Ebonyi and Cross River states, Nigeria in the two years before and after (December 2017-November 2021) the 2019 Ebonyi PBO ITN campaign with counterfactual of no ITN distribution.

“The reasons why the evaluation was conducted at all was (1) to determine the impact of this new technology and (2) to help us make decisions on future deployments beyond Ebonyi State,” remarked Okoko. “This evaluation helps us know that some of these decisions were right.”

These results were subsequently used in the NMEP’s Global Fund application to advocate for greater use of PBO ITNs in areas of documented pyrethroid resistance. According to Mihigo, Nigeria has since moved towards procuring new types of nets in areas with confirmed pyrethroid resistance for mass campaigns moving forward: “The result of entomological monitoring, then the results [from] the routine data, and then the Malaria Indicator Survey was something which informed people that it was time to switch.”

The results from these epidemiological and entomological analyses contribute to a set of ongoing evaluations designed to assess the impact of new types of ITNs in Nigeria. The New Nets Project, a partnership funded by Unitaid and the Global Fund and led by IVCC, evaluated the impact of dual active ingredient (AI) nets and PBO ITNs on malaria prevalence, malaria case incidence, and key entomological indicators in Osun and Kwara states. Final results from these evaluations are expected later this year.

Additionally, the NMEP and PMI made the joint decision to distribute PBO ITNs and Interceptor® G2 (IG2, a dual AI net) ITNs in Sokoto and Kebbi states, respectively, between September and November 2022. Future analyses will be conducted by PMI Evolving Vector Control to Fight Malaria (PMI Evolve) Project, over the three years following these campaigns to assess the relative epidemiological and entomological impacts of these ITNs in two states with some of the highest malaria prevalence rates in the country. Collectively, results from these evaluations will provide critical evidence to inform the Nigeria NMEP’s future ITN campaign planning to ensure that the most effective nets are selected based on the state’s insecticide resistance profile so that they benefit the population as intended to end malaria faster.      

Read this story in French: Évaluation de l’impact épidémiologique et entomologique de la première campagne de moustiquaires imprégnées de pyréthrinoïdes-PBO au Nigeria

Download a PDF version of this story in English: Evaluating the Epidemiological and Entomological Impact of Nigeria’s First PBO Insecticide-Treated Net Campaign

“All this is being done to make sure that we control malaria in Malawi.” – Austin Gumbo, Head of Monitoring and Evaluation, National Malaria Control Program Malawi

Indoor residual spraying (IRS) and insecticide-treated bed nets (ITNs) are key vector control interventions implemented in Malawi to mitigate malaria transmission. The Malawi National Malaria Control Program (NMCP) has used data to support targeting of vector control interventions since 2018, when IRS was re-introduced in one high burden district – Nkhotakota – and piperonyl butoxide (PBO) and standard pyrethroid ITNs were targeted based on data showing malaria-transmitting mosquitoes’ resistance to pyrethroids. To continue to address the threat of insecticide resistance, the NMCP planned the 2021 ITN mass campaign to take advantage of new dual-active ingredient ITNs – Interceptor G2 (IG2) ITNs and Royal Guard (RG) ITNs – while continuing to use PBO ITNs and IRS in select districts (see distribution map below). While the additional impact of these ITNs had been demonstrated in randomized control trials, the NMCP was interested in understanding how these new products worked in Malawi.

“We wanted to look at the districts that are implementing the different interventions and see if there is any impact of these interventions and compare the IRS and new ITNs,” said Austin Gumbo, Head of Monitoring and Evaluation for the NMCP.

The U.S. President’s Malaria Initiative (PMI), through the PMI VectorLink Project, partnered with the NMCP to evaluate the impact of the ITN and IRS campaigns on malaria case incidence, using the NMCP’s routine health system and entomological surveillance data. The evaluation was designed to directly address the NMCP’s most pressing questions and guide future vector control product selection. The key questions of interest were:

• What is the impact of IRS compared to the impact of any new ITN (PBO, IG2, and RG)?
• What is the impact of PBO ITNs compared to the impact of the dual-active ingredient ITNs (IG2 and RG)?
• What is the impact of IG2 ITNs compared to the impact of RG ITNs?

Less than one year after the ITN mass campaign took place, the NMCP was already working on their Global Fund application for the next funding cycle, the New Funding Model 4. They needed timely information on the initial impact of these new products to guide future procurement. The PMI VectorLink project rapidly conducted an interim analysis assessing the first six months after the ITN distribution demonstrating:

• The effect of IRS (received between 2018-2021) was not significantly different from the combined effect of PBO, IG2, and RG ITNs during their first six months of use (45.5% vs 42.2% reported malaria case reduction).
• The effect of PBO nets was not significantly different from the effect of both dual-active ingredient ITNs (33.4% vs 37.3% reported malaria case reduction).
• The IG2 ITNs, however, performed better than the RG ITNs with statistical significance (57.4% vs 39.7% reported malaria case reduction).

Having these interim results available allowed the national program to use locally generated data to justify the NMCP’s proposed vector control approach in the Global Fund application. “In order to maximize the impact of its [the Global Fund] allocation and achieve optimization and value for money while managing insecticide resistance in Malawi, we decided to withdraw IRS in specific districts and instead include them in the 2024 ITN mass campaign,” Gumbo said. “The decision to procure IG2 ITNs was made using the evaluation.”

PMI’s Malaria Program Management Specialist in Malawi, Pius Masache agreed: “Based on the results and what we’re seeing – that new nets are comparable to IRS, but IRS is more expensive – the country has moved to distributing [new nets] country-wide. This [evaluation] was one of the primary data sources we used to guide that decision.”

In addition to providing rigorous quantitative findings, this evaluation also demonstrated how locally collected data is important to guide national decisions. Gumbo described how use of routine data is a cost-effective approach with real-world applicability; Masache added that use of routine data in evaluations demonstrates value to the collection process itself: “People say, ‘We collect this data every day, but what do you use it for?’ [Using routine data] helps to add value to the team that is collecting and consolidating all this data so that they know that their work is being appreciated and they know the relevance of their work.”

Looking ahead, this ongoing evaluation will continue to provide important information on the impact of these new ITNs over their expected lifespan, with final results in 2024. Of key interest to the NMCP moving forward is analyzing how well the new ITNs perform over time. “Since it’s the first time Malawi implemented IG2 ITNs and the assessment was done after the first six months, we will need more information on this over time after one, two, and three years, and more on how IG2 ITNs compare to Royal Guard ITNs.” said Gumbo. “And we are looking forward to the results.”

Read this story in French: Exploiter les données de routine pour optimiser le ciblage des nouvelles interventions de lutte contre les vecteurs

Download a PDF version of this story in English: Leveraging Routine Data to Drive Targeting of New Vector Control Interventions in Malawi

Insecticide-treated nets (ITNs) are an essential tool in the global effort to eradicate malaria. ITNs provide the double benefit of providing a physical barrier protecting individuals while they sleep and repelling and killing mosquitoes. The use of ITNs has been incredibly successful—in Africa, estimates suggest that 68 percent of all averted malaria cases since 2001 are due to the use of ITNs.[1]

However, mosquito populations have begun developing resistance to pyrethroids, the primary class of insecticides used for ITNs. Pyrethroid resistance has been reported in more than 85 percent of countries that monitor insecticide resistance.[2] This resistance threatens the effectiveness of ITNs and could lead to an increase in malaria cases in countries like Nigeria, where pyrethroid resistance has become widespread.

New Nets: An Opportunity and Challenge

Pyrethroids are no longer the only class of insecticide that can be used to treat ITNs. In response to growing pyrethroid resistance, Nigeria has introduced three new types of ITNs. The first type uses a chemical called piperonyl butoxide (PBO nets) which can restore susceptibility and when treated in combination with a pyrethroid insecticide, can be lethal to pyrethroid-resistant mosquitoes. The two additional ITNs are called dual-active ingredient (dual-AI) nets which combine two or more insecticides with different modes of action in one ITN. While both ITNs contain a pyrethroid, one also contains chlorfenapyr (marketed under the brand name Interceptor G2 or IG2) the other contains pyriproxyfen (marketed under the brand name Royal Guard). In Nigeria, chlorfenapyr and pyriproxyfen remain effective against mosquitoes in many states. These new types of ITNs are more expensive than standard pyrethroid nets, necessitating difficult decisions on where to deploy them.

For governments with limited budgets and complex health system needs, deciding to invest in new technology can be challenging. Decision-makers rely on data to guide these decisions. The experience of other countries in moving to new types of ITNs provides insights into the effectiveness of this intervention. But governments also want assurances that new types of ITNs will be effective against local vector populations and ultimately contribute to national malaria control and elimination efforts. Analysis of data generated from communities in Nigeria helps the country’s national decision-makers build confidence in investing in these new types of ITNs.

Making nets work in Nigeria

Nigeria has invested in new ITN products to help overcome growing pyrethroid resistance throughout the country. In November 2019, Nigeria’s National Malaria Elimination Program (NMEP), with technical and operational support from the U.S. President’s Malaria Initiative (PMI), distributed 1.7 million PBO ITNs throughout all local government areas in Ebonyi State, enough ITNs to cover the estimated 3,112,560 population. With support from the Global Fund to Fight AIDS, Tuberculosis and Malaria in 2020, the NMEP also distributed 2.8 million PBO ITNs in Adamawa State, 3 million standard and PBO ITNs in Osun State, and 2.2 million Royal Guard and IG2 ITNs in Kwara State. In 2021, Kebbi State will receive IG2 ITNs, while Oyo State will receive IG2 and PBO ITNs.

With support from the PMI VectorLink project, Nigeria’s NMEP is monitoring the deployment of PBO ITNs in Ebonyi State. Monitoring activities include tracking the number and location of ITNs distributed and collecting enhanced entomological data to monitor the effect of the new ITNs on local mosquito populations. When paired with data on malaria incidence and evidence of pyrethroid resistance, decision-makers can see how the PBO ITN distribution contributes to malaria reduction efforts. PMI VectorLink compiled the various data sources and developed a series of interactive dashboards to make these insights accessible (Figure 1, Figure 2, Figure 3).

Figure 1: A dashboard of the entomological context of Ebonyi State, showing vector species composition, biting times and the geographic spread of pyrethroid insecticide resistance.

Figure 2: Dashboards with details on the mass ITN campaign provide data in an accessible format to decision-makers in Nigeria.

Figure 3: A dashboard showing the malaria case incidence in Ebonyi State to be updated annually to more easily assess changes in cases after the 2019 PBO net distribution.

Decision-makers can now view maps and other visualizations that overlay ITN distribution data, entomology data, and malaria case incidence. The NMEP is planning to use these dashboards during annual review meetings to guide vector control decision making. While data will be updated regularly, PMI VectorLink will also conduct a full assessment covering the lifetime of the ITNs in 2022. Both regularly available data and the long-term impact assessment will help inform ITN deployment in Nigeria—and increase the impact of vector control interventions in the future.

[1] Bhatt S, Weiss DJ, Cameron E, Bisanzio D, Mappin B, Dalrymple U, Battle K, Moyes CL, Henry A, Eckhoff PA, Wenger EA, Briët O, Penny MA, Smith TA, Bennett A, Yukich J, Eisele TP, Griffin JT, Fergus CA, Lynch M, Lindgren F, Cohen JM, Murray CLJ, Smith DL, Hay SI, Cibulskis RE, Gething PW. The effect of malaria control on Plasmodium falciparum in Africa between 2000 and 2015. Nature. 2015 Oct 8;526(7572):207-211. doi: 10.1038/nature15535. Epub 2015 Sep 16. PMID: 26375008; PMCID: PMC4820050.

[2] World Health Organization (WHO). World Malaria Report 2019. Geneva: WHO; 2019. 

To eliminate malaria, national malaria programs and partners widely acknowledge that a “business as usual” approach is not enough, and innovative, adaptable approaches are increasingly needed. With a growing need for localized interventions that address a diverse range of malaria challenges faced across a country, the importance of high-quality and granular malaria surveillance data is more important than ever.

One challenge faced by national malaria programs is the increasing resistance to insecticides used in both indoor residual spraying (IRS) and insecticide-treated nets (ITNs). While these vector control interventions have proven to be highly effective strategies in reducing mosquito populations, and thus malaria cases, their efficacy is threatened by increasing insecticide resistance. Resistance varies by specific mosquito population and can also vary geographically within a single country. As a result, national programs need to monitor markers of resistance and adjust their vector control plans as necessary. To maximize their significant investments in IRS campaigns, countries now must make important decisions about which insecticides to use and where. Adding to the complexity, decisions for the IRS campaigns can also affect future decisions around insecticide choice for ITNs as well, particularly as more types of ITNs become available.

PMI VectorLink has taken on the challenge of supporting this decision-making in Zambia, where IRS campaigns have been implemented annually by the National Malaria Elimination Program (NMEP), PMI VectorLink, and other partners in nearly every district of the country since 2015. IRS in Zambia has been associated with a 12% drop in malaria cases nationally[1]. However, mosquito resistance continues to threaten this progress.

Over the past decade, malaria elimination partners in Zambia have worked hard to cultivate a culture of data use. Many partners have come together to address the issue of insecticide resistance in Zambia’s mosquito populations, including NMEP, the PMI VectorLink project (and its Africa-IRS predecessor project), MACEPA, Tropical Diseases Research Center, and Macha Trust. These five partners, led by the NMEP, collect extensive entomological data at various sites around the country and meet annually as the Insecticide Resistance Monitoring and Management Working Group’s Technical Advisory Committee to choose the insecticide for the next year’s IRS campaign.

    

 

 

 

 

  Figure 1: These visuals illustrate the extensive data on insecticide resistance gathered by Zambia’s malaria elimination partners using varied parameters, which PMI VectorLink helped to streamline for effective decision-making. PC: NMEP, MACEPA, PMI VectorLink

To address this challenge, prior to the 2020 insecticide choice meeting, PMI VectorLink collaborated with the key partners to compile the entomological data and produce a series of integrated visualizations, incorporating over 600 data points on vector composition and insecticide resistance from 2000-2019. This was the first time that these datasets had been combined and viewed at the same time, and together they painted a comprehensive picture of insecticide resistance and species predominance across the country.

To develop the dashboards, PMI VectorLink interviewed Zambia’s NMEP stakeholders to document the step-by-step process the NMEP and partners used to determine insecticide selection. This was presented during the IRMM TAC meeting and modified with stakeholder input. PMI VectorLink then documented the final decision-making guide and used it to inform the dashboard design (Figure 2).

Figure 2.: Visual depiction of the IRMM TAC decision-making steps.

The end result? Simple, interactive dashboards showing which insecticides were effective in each district and which mosquitoes were showing signs of resistance by location, species, and insecticide (Figure 3).

Figure 3: The dashboard created through PMI VectorLink’s combined and streamlined data organized by site, species, and insecticide to guide Zambia’s IRS policy decision-making

The underlying data and visualizations supported the multi-million dollar insecticide procurements for Zambia’s 2020 IRS campaign, consistent with Zambia’s Insecticide Resistance Monitoring and Management Plan (IRMMP) guidelines to switch insecticides after two years (Figure 4).

 

 

 

 

 

 

 

 

 

 

Figure 4: Final map developed by the IRMM TAC using PMI VectorLink’s streamlined data visualization, providing recommendations for the 2020 IRS Campaign and clearly marking which districts should switch insecticides to combat resistance

“The VectorLink data visualizations brought the resistance data together in a way we haven’t seen it before. It helped us make this important IRS decision.” – Dr. Emmanuel Kooma, Lead Vector Control Specialist, NMEP

PMI VectorLink continues to support improved use of evidence in decision-making through better use of existing data. Currently, the team is working with partners to standardize the vector control data reporting processes in Zambia. This will build upon these recent successes and strengthen the overall decision-making system for years to come as the country strives towards malaria elimination.

The value of this approach extends beyond Zambia’s borders, providing an example of the power of effective collaboration and leveraging of routine data in vector control programming, with the goal of improving impact at the local level.

[1] NgenIRS. Evidence snapshot: cost and cost-effectiveness of 3rd generation IRS (3GIRS). NgenIRS Evidence: Cost Effectiveness Fact Sheet. Dec 2019. IVCC.

Insecticide resistance is a growing challenge for malaria control programs around the world. Insecticide-treated nets (ITNs) have been very impactful and are believed to be responsible for almost 70 percent of malaria cases averted in Africa since 2001[1]. But widespread use of a single class of insecticides on ITNs called pyrethroids has resulted in mosquito populations that are exhibiting varying levels of resistance. Pyrethroid-treated ITNs still protect individuals who sleep under them by creating a physical barrier, but as pyrethroids become less effective at repelling and killing mosquitoes, there may be a rise in malaria cases.

New types of ITNs, like Interceptor G2 (IG2) nets, use a different insecticide called chlorfenapyr that is still effective against pyrethroid-resistant mosquito populations.

A net gain

In 2020, Mali’s National Malaria Control Programme (NMCP) received 900,000 new IG2 ITNs as part of the country’s effort to address widespread high-intensity pyrethroid resistance throughout the country. Because this allocation of ITNs could not cover the entire country, the NMCP needed to decide where to distribute them to have the greatest impact.

First, the NMCP wanted to look at the regions with the highest malaria burden. Within those regions, they wanted to assess which districts had a high burden and could also be completely covered by the incoming IG2 nets. To support a future evaluation of these new nets, the NMCP was also interested in finding districts with ongoing entomological data collection. Finally, choosing districts close to the Burkina Faso border would provide an opportunity to compare evaluation results with results from a similar evaluation in Burkina Faso.

To help consider these different factors, the NMCP worked with the PMI VectorLink Project to develop data visualizations to support this decision-making process.

From data to decision

First, PMI VectorLink created a visualization summarizing malaria case incidence using data from the national health management information system and malaria prevalence data from the most recent Demographic and Health Survey (DHS). Combining these two data sets created a clear picture of the malaria burden in Mali’s regions. This analysis helped the NMCP identify the Sikasso region as a priority for new IG2 bed nets.

Figure 1: An example of a simple data visualization based on HMIS and DHS data.

To further refine which districts within the Sikasso region would receive the new ITNs, the next step was to build upon the incidence and prevalence data visualization by adding the projected number of ITNs required at the district level and mapping the location of entomological data collection sites.

Figure 2. This dashboard demonstrates how decision-makers in Mali can use data to evaluate different net distribution options. Reorder the table to see how many nets are needed based on which districts you prioritize.

This interactive dashboard allows users to change the order of districts to recalculate the cumulative number of ITNs required, as a running sum of the estimated ITN quantity. Using this tool, the NMCP selected four districts to receive new IG2 ITNs:

• Kadiolo and Yorosso districts were chosen because of their high burden of malaria. In addition, these districts share a border with Burkina Faso. Selecting these districts creates an opportunity for cross-border collaboration and information sharing. Kadiolo also contains an entomological site.
• Yanfolila was selected because it contains an entomological data collection site and has a fairly high malaria burden. Selingue was chosen because it was contiguous with Yanfolila, facilitating distribution, and contained a small enough population that the district could be completely covered with the nets available.

With this selection, the NMCP reserved 300,000 nets to distribute in these districts to sustain coverage with IG2 ITNs through continuous health facility distribution channels in the coming two years.

Planning for the future

The NMCP found great utility in these new data visualizations. The NMCP used these dashboards to create a shared understanding between the program, implementing partners, and donors of the priority districts. They were also helpful for NMCP staff to quickly see the location of entomological monitoring activities and other key information about the burden of malaria.

Over the next two years, the NMCP will work with PMI VectorLink to conduct an evaluation of the impact of IG2 ITNs. As these ITNs become more widely used, PMI VectorLink will help monitor malaria incidence in districts using IG2 ITNs and use this data to help inform the potential expansion of these ITNs to additional districts and regions.

[1] Bhatt S, Weiss DJ, Cameron E, Bisanzio D, Mappin B, Dalrymple U, Battle K, Moyes CL, Henry A, Eckhoff PA, Wenger EA, Briët O, Penny MA, Smith TA, Bennett A, Yukich J, Eisele TP, Griffin JT, Fergus CA, Lynch M, Lindgren F, Cohen JM, Murray CLJ, Smith DL, Hay SI, Cibulskis RE, Gething PW. The effect of malaria control on Plasmodium falciparum in Africa between 2000 and 2015. Nature. 2015 Oct 8;526(7572):207-211. doi: 10.1038/nature15535. Epub 2015 Sep 16. PMID: 26375008; PMCID: PMC4820050.