Anna M. Winters

Malaria elimination: surveillance and response

Abstract In the last decade, substantial progress has been made in reducing malaria-associated morbidity and mortality across the globe. Nevertheless, sustained malaria control is essential to continue this downward trend. In some countries, where aggressive malaria control has reduced malaria to a low burden level, elimination, either nationally or subnationally, is now the aim. As countries or areas with a low malaria burden move towards elimination, there is a transition away from programs of universal coverage towards a strategy of localized detection and response to individual malaria cases. To do so and succeed, it is imperative that a strong surveillance and response system is supported, that community cadres are trained to provide appropriate diagnostics and treatment, and that field diagnostics are further developed such that their sensitivity allows for the detection and subsequent treatment of malaria reservoirs in low prevalence environments. To be certain, there are big challenges on the road to elimination, notably the development of drug and insecticide resistance. Nevertheless, countries like Zambia are making great strides towards implementing systems that support malaria elimination in target areas. Continued development of new diagnostics and antimalarial therapies is needed to support progress in malaria control and elimination.

Targeting indoor residual spraying for malaria using epidemiological data: a case study of the Zambia experience

BackgroundIn Zambia and other sub-Saharan African countries affected by ongoing malaria transmission, indoor residual spraying (IRS) for malaria prevention has typically been implemented over large areas, e.g., district-wide, and targeted to peri-urban areas. However, there is a recent shift in some countries, including Zambia, towards the adoption of a more strategic and targeted IRS approach, in coordination with increased emphasis on universal coverage of long-lasting insecticidal nets (LLINs) and effective insecticide resistance management. A true targeted approach would deliver IRS to sub-district areas identified as high-risk, with the goal of maximizing the prevention of malaria cases and deaths.ResultsTogether with the Government of the Republic of Zambia, a new methodology was developed applying geographic information systems and satellite imagery to support a targeted IRS campaign during the 2014 spray season using health management information system data.Discussion/ConclusionThis case study focuses on the developed methodology while also highlighting the significant research gaps which must be filled to guide countries on the most effective strategy for IRS targeting in the context of universal LLIN coverage and evolving insecticide resistance.

Location, location, location: environmental factors better predict malaria-positive individuals during reactive case detection than index case demographics in Southern Province, Zambia

BackgroundDecreasing malaria transmission leads to increasing heterogeneity with increased risk in both hot spots (locations) and hot pops (certain demographics). In Southern Province, Zambia, reactive case detection has formed a part of malaria surveillance and elimination efforts since 2011. Various factors may be associated with finding malaria infections during case investigations, including the demographics of the incident case and environmental characteristics of the location of the incident case.MethodsCommunity health worker registries were used to determine what factors were associated with finding a malaria infection during reactive case detection.ResultsLocation was a more powerful predictor of finding malaria infections during case investigations than the demographics of the incident case. After accounting for environmental characteristics, no demographics around the incident case were associated with finding malaria infections during case investigations. Various time-invariant measures of the environment, such as median enhanced vegetation index, the topographic position index, the convergence index, and the topographical wetness index, were all associated as expected with increased probability of finding a malaria infection during case investigations.ConclusionsThese results suggest that targeting the locations highly at risk of malaria transmission is of importance in elimination settings.

Assessing the Impact of Leveraging Traditional Leadership on Access to Sanitation in Rural Zambia

Open defecation is practiced by more than one billion people throughout the world and leads to significant public health issues including infectious disease transmission and stunted growth in children. Zambia implemented community-led total sanitation (CLTS) as an intervention to eliminate open defecation in rural areas. To support CLTS and the attainment of open defecation free communities, chiefs were considered key agents of change and were empowered to drive CLTS and improve sanitation for their chiefdom. Chiefs were provided with data on access to sanitation in the chiefdom during chiefdom orientations prior to the initiation of CLTS within each community and encouraged to make goals of universal sanitation access within the community. Using a survival regression, we found that where chiefs were orientated and mobilized in CLTS, the probability that a village would achieve 100% coverage of adequate sanitation increased by 23% (hazard ratio = 1.263, 95% confidence interval = 1.080-1.478, P = 0.003). Using an interrupted time series, we found a 30% increase in the number of individuals with access to adequate sanitation following chiefdom orientations (95% confidence interval = 28.8-32.0%). The mobilization and support of chiefs greatly improved the uptake of CLTS, and empowering them with increased CLTS knowledge and authority of the program in their chiefdom allowed chiefs to closely monitor village sanitation progress and follow-up with their headmen/headwomen. These key agents of change are important facilitators of public health goals such as the elimination of open defecation in Zambia by 2020.

Accuracy and impact of spatial aids based upon satellite enumeration to improve indoor residual spraying spatial coverage

BackgroundIndoor residual spraying (IRS) is a key tool in the fight to control, eliminate and ultimately eradicate malaria. IRS protection is based on a communal effect such that an individual’s protection primarily relies on the community-level coverage of IRS with limited protection being provided by household-level coverage. To ensure a communal effect is achieved through IRS, achieving high and uniform community-level coverage should be the ultimate priority of an IRS campaign. Ensuring high community-level coverage of IRS in malaria-endemic areas is challenging given the lack of information available about both the location and number of households needing IRS in any given area. A process termed ‘mSpray’ has been developed and implemented and involves use of satellite imagery for enumeration for planning IRS and a mobile application to guide IRS implementation. This study assessed (1) the accuracy of the satellite enumeration and (2) how various degrees of spatial aid provided through the mSpray process affected community-level IRS coverage during the 2015 spray campaign in Zambia.MethodsA 2-stage sampling process was applied to assess accuracy of satellite enumeration to determine number and location of sprayable structures. Results indicated an overall sensitivity of 94% for satellite enumeration compared to finding structures on the ground.ResultsAfter adjusting for structure size, roof, and wall type, households in Nchelenge District where all types of satellite-based spatial aids (paper-based maps plus use of the mobile mSpray application) were used were more likely to have received IRS than Kasama district where maps used were not based on satellite enumeration. The probability of a household being sprayed in Nchelenge district where tablet-based maps were used, did not differ statistically from that of a household in Samfya District, where detailed paper-based spatial aids based on satellite enumeration were provided.ConclusionIRS coverage from the 2015 spray season benefited from the use of spatial aids based upon satellite enumeration. These spatial aids can guide costly IRS planning and implementation leading to attainment of higher spatial coverage, and likely improve disease impact.