Measurement of malaria transmission and impact of malaria control interventions using health facility and community-based routine reporting systems

Globally malaria still remains the most important parasitic disease of public health interest. In the recent past, most endemic countries have deployed and scaled up both preventive and curative interventions to reduce malaria transmission and, ideally, eliminate it. This has lead to global reductions in both mortality and incidence of malaria. These declines have been attributed to the reinvigoration of the global malaria control agenda by the explicit ambition of achieving elimination, which has lead to an increase in funding for national control programmes to increase coverage of preventive interventions, field compatible diagnostic tools for confirming parasite infection, and increased access to effective treatment. As a result of declines in malaria transmission, the focal nature of malaria transmission has become much more evident and has lead to consideration of surveillance as a key intervention for malaria control/elimination in its own right. Surveillance systems have been well established in most formal health facilities but the incorporation of these systems at community level and operationalised by community health workers (CHWs) still remains limited. Additionally, these few examples of CHW-implemented surveillance systems have been typically only reporting indicators of malaria infection burden, without capturing indicators of intervention availability, deployment, coverage and utilisation, thus representing a missed opportunity for routine monitoring and evaluation of impact of interventions in “real time” to inform program planning and implementation. The study was established as part of a multi-country study under the Malaria Transmission Consortium Project whose primary objective was to develop and evaluate new or improved methods for measuring malaria transmission. Thus the overall goal of this study was to demonstrate how malaria transmission, and impact of interventions, could be routinely measured through a novel longitudinal community based surveillance system (CBSS) operationalised by modestly paid CHWs. The CBSS included both passive and active surveillance activities using field – compatible test kits for in situ parasitological detection of malaria infections, based on which confirmed cases were treated with anti-malarial drugs, coupled with a detailed questionnaire on access and use of malaria control interventions and population characteristics. Passive surveillance was achieved conventionally whenever community members self-reported to the CHWs and active surveillance was achieved through monthly active visits to all households in their catchment populations to offer testing and treatment. In addition to recording detailed details of each patient contact in a paper patient register, weekly summaries of selected data elements were submitted by the CHWs using a mobile phone platform via short messaging system (SMS). The detailed reference data recorded in the patient register was then used to monitor malaria infection dynamics in the study population, evaluate the impact of preventative measures, such as indoor residual spraying (IRS) and long-lasting insecticidal nets (LLINs) and validate the electronic summaries submitted via SMS. Overall, the CBSS did not routinely capture all malaria infections in the study population and was insufficient to eliminate the human parasite reservoir. This was primarily due to limited study participant participation with the monthly active testing and treatment offered by the CHWs. However, the CBSS clearly demonstrated the incremental and residual impact to supplementation of pyrethroid-treated LLINs with non - pyrethroid insecticides applied by IRS in areas where the dominant malaria vector is highly resistant to pyrethroids. The adequacy of the SMS reports submitted by the CHWs confirms the great potential of mobile phone technology for facilitating and improving the effectiveness of community based reporting. Despite its limitations, the CBSS successfully provided programmatically relevant information regarding malaria infection dynamics across the large study area at a very affordable cost. The CHWs demonstrated their ability to not only provide treatment services but also adequately report their findings both electronically and on paper. CHWs are primarily tasked with providing routine health services at community level but clearly also have a valuable auxiliary role to play in “real time” surveillance of malaria, and most probably a range of other diseases. If the full potential of CHWs as agents of health surveillance can be realized, control programme progress can be measured through spatial and temporal mapping of transmission with greater sensitivity and at finer scales than is possible with health facilities alone, to enable improved, better-informed program planning, resource allocation and implementation

Near-term climate change impacts on sub-national malaria transmission

Abstract The role of climate change on global malaria is often highlighted in World Health Organisation reports. We modelled a Zambian socio-environmental dataset from 2000 to 2016, against malaria trends and investigated the relationship of near-term environmental change with malaria incidence using Bayesian spatio-temporal, and negative binomial mixed regression models. We introduced the diurnal temperature range (DTR) as an alternative environmental measure to the widely used mean temperature. We found substantial sub-national near-term variations and significant associations with malaria incidence-trends. Significant spatio-temporal shifts in DTR/environmental predictors influenced malaria incidence-rates, even in areas with declining trends. We highlight the impact of seasonally sensitive DTR, especially in the first two quarters of the year and demonstrate how substantial investment in intervention programmes is negatively impacted by near-term climate change, most notably since 2010. We argue for targeted seasonally-sensitive malaria chemoprevention programmes

Modelling of Malaria Risk, Rates, and Trends: A Spatiotemporal approach for identifying and targeting sub-national Areas of High and Low Burden

While mortality from malaria continues to decline globally, incidence rates in many countries are rising. Within countries, spatial and temporal patterns of malaria vary across communities due to many different physical and social environmental factors. To identify those areas most suitable for malaria elimination or targeted control interventions, we used Bayesian models to estimate the spatiotemporal variation of malaria risk, rates, and trends to determine areas of high or low malaria burden compared to their geographical neighbours. We present a methodology using Bayesian hierarchical models with a Markov Chain Monte Carlo (MCMC) based inference to fit a generalised linear mixed model with a conditional autoregressive structure. We modelled clusters of similar spatiotemporal trends in malaria risk, using trend functions with constrained shapes and visualised high and low burden districts using a multi-criterion index derived by combining spatiotemporal risk, rates and trends of districts in Zambia. Our results indicate that over 3 million people in Zambia live in high-burden districts with either high mortality burden or high incidence burden coupled with an increasing trend over 16 years (2000 to 2015) for all age, under-five and over-five cohorts. Approximately 1.6 million people live in high-incidence burden areas alone. Using our method, we have developed a platform that can enable malaria programs in countries like Zambia to target those high-burden areas with intensive control measures while at the same time pursue malaria elimination efforts in all other areas. Our method enhances conventional approaches and measures to identify those districts which had higher rates and increasing trends and risk. This study provides a method and a means that can help policy makers evaluate intervention impact over time and adopt appropriate geographically targeted strategies that address the issues of both high-burden areas, through intensive control approaches, and low-burden areas, via specific elimination programs

Optimal population-level infection detection strategies for malaria control and elimination in a spatial model of malaria transmission

Mass campaigns with antimalarial drugs are potentially a powerful tool for local elimination of malaria, yet current diagnostic technologies are insufficiently sensitive to identify all individuals who harbor infections. At the same time, overtreatment of uninfected individuals increases the risk of accelerating emergence of drug resistance and losing community acceptance. Local heterogeneity in transmission intensity may allow campaign strategies that respond to index cases to successfully target subpatent infections while simultaneously limiting overtreatment. While selective targeting of hotspots of transmission has been proposed as a strategy for malaria control, such targeting has not been tested in the context of malaria elimination. Using household locations, demographics, and prevalence data from a survey of four health facility catchment areas in southern Zambia and an agent-based model of malaria transmission and immunity acquisition, a transmission intensity was fit to each household based on neighborhood age-dependent malaria prevalence. A set of individual infection trajectories was constructed for every household in each catchment area, accounting for heterogeneous exposure and immunity. Various campaign strategies (mass drug administration, mass screen and treat, focal mass drug administration, snowball reactive case detection, pooled sampling, and a hypothetical serological diagnostic) were simulated and evaluated for performance at finding infections, minimizing overtreatment, reducing clinical case counts, and interrupting transmission. For malaria control, presumptive treatment leads to substantial overtreatment without additional morbidity reduction under all but the highest transmission conditions. Selective targeting of hotspots with drug campaigns is an ineffective tool for elimination due to limited sensitivity of available field diagnostics

Community case management of malaria using ACT and RDT in two districts in Zambia: achieving high adherence to test results using community health workers

<p>Abstract</p> <p>Background</p> <p>Access to prompt and effective treatment is a cornerstone of the current malaria control strategy. Delays in starting appropriate treatment is a major contributor to malaria mortality. WHO recommends home management of malaria using artemisininbased combination therapy (ACT) and Rapid Diagnostic tests (RDTs) as one of the strategies for improving access to prompt and efective malaria case management.</p> <p>Methods</p> <p>A prospective evaluation of the effectiveness of using community health workers <b>(</b>CHWs) as delivery points for ACT and RDTs in the home management of malaria in two districts in Zambia.</p> <p>Results</p> <p>CHWs were able to manage malaria fevers by correctly interpreting RDT results and appropriately prescribing antimalarials. All severe malaria cases and febrile non-malaria fevers were referred to a health facility for further management. There were variations in malaria prevalence between the two districts and among the villages in each district. 100% and 99.4% of the patients with a negative RDT result were not prescribed an antimalarial in the two districts respectively. No cases progressed to severe malaria and no deaths were recorded during the study period. Community perceptions were positive.</p> <p>Conclusion</p> <p>CHWs are effective delivery points for prompt and effective malaria case management at community level. Adherence to test results is the best ever reported in Zambia. Further areas of implementation research are discussed.</p

Malaria elimination campaigns in the Lake Kariba region of Zambia: a spatial dynamical model

Background As more regions approach malaria elimination, understanding how different interventions interact to reduce transmission becomes critical. The Lake Kariba area of Southern Province, Zambia, is part of a multi-country elimination effort and presents a particular challenge as it is an interconnected region of variable transmission intensities. Methods In 2012-13, six rounds of mass-screen-and-treat drug campaigns were carried out in the Lake Kariba region. A spatial dynamical model of malaria transmission in the Lake Kariba area, with transmission and climate modeled at the village scale, was calibrated to the 2012-13 prevalence survey data, with case management rates, insecticide-treated net usage, and drug campaign coverage informed by surveillance. The model was used to simulate the effect of various interventions implemented in 2014-22 on reducing regional transmission, achieving elimination by 2022, and maintaining elimination through 2028. Findings The model captured the spatio-temporal trends of decline and rebound in malaria prevalence in 2012-13 at the village scale. Simulations predicted that elimination required repeated mass drug administrations coupled with simultaneous increase in net usage. Drug campaigns targeted only at high-burden areas were as successful as campaigns covering the entire region. Interpretation Elimination in the Lake Kariba region is possible through coordinating mass drug campaigns with high-coverage vector control. Targeting regional hotspots is a viable alternative to global campaigns when human migration within an interconnected area is responsible for maintaining transmission in low-burden areas

Exploring the use of routinely-available, retrospective data to study the association between malaria control scale-up and micro-economic outcomes in Zambia

Additional file 1. Additional tables that share additional results of the generalized propensity score matching analysis, as well as a table covering malaria control coverage at the district level

Evaluation of a game-based training course to build capacity for insecticide resistance management in vector control programmes

Across Africa, malaria control programmes are increasingly challenged with the emergence of insecticide resistance among malaria vector populations. Confronted with this challenge, vector control staff must understand insecticide resistance management, think comprehensively and react positively when confronted with new problems. However, information on the subject is often only available through written guidelines that are difficult to put into practice. Based on the successes and strengths of educational games for health, we developed and evaluated a novel game-based course to fill the gap in training resources for insecticide resistance management. The training was evaluated by analysing results of pre- and post-course knowledge tests and self-efficacy surveys, as well as post-course interviews. At the start of the training, fundamental concepts of insecticide resistance were reviewed through Resistance101, a mobile app game. Subsequently, insecticide resistance management strategies were explored using the simulation game ResistanceSim, which was introduced by mini-lectures and complemented by class discussions and group work. The game-based training was conducted and evaluated in two African countries (Ethiopia and Zambia) using a mixed-methods approach. Quantitative outcome measures included knowledge acquisition and change in self-efficacy. We completed a qualitative inductive thematic analysis of participant interviews to explore the views and experiences of participants with the games and training, and the impact of the training on professional practices and attitudes. The game-based training increased knowledge in the short-term and improved self-efficacy scores. The training increased participants’ knowledge base, stimulated knowledge sharing and changed work practices. The game-based training offers scalable training opportunities that could nurture and capacitate the next generation of professionals in vector control

A cost-effective, community-based, mosquito-trapping scheme that captures spatial and temporal heterogeneities of malaria transmission in rural Zambia

Background Monitoring mosquito population dynamics is essential to guide selection and evaluation of malaria vector control interventions but is typically implemented by mobile, centrally-managed teams who can only visit a limited number of locations frequently enough to capture longitudinal trends. Community-based (CB) mosquito trapping schemes for parallel, continuous monitoring of multiple locations are therefore required that are practical, affordable, effective, and reliable. Methods A CB surveillance scheme, with a monthly sampling and reporting cycle for capturing malaria vectors, using Centers for Disease Control and Prevention light traps (LT) and Ifakara Tent Traps (ITT), were conducted by trained community health workers (CHW) in 14 clusters of households immediately surrounding health facilities in rural south-east Zambia. At the end of the study, a controlled quality assurance (QA) survey was conducted by a centrally supervised expert team using human landing catch (HLC), LT and ITT to evaluate accuracy of the CB trapping data. Active surveillance of malaria parasite infection rates amongst humans was conducted by CHWs in the same clusters to determine the epidemiological relevance of these CB entomological surveys. Results CB-LT and CB-ITT exhibited relative sampling efficiencies of 50 and 7%, respectively, compared with QA surveys using the same traps. However, cost per sampling night was lowest for CB-LT ($13.6), followed closely by CB-ITT ($18.0), both of which were far less expensive than any QA survey (HLC: $138, LT:$289, ITT: $269). Cost per specimen of Anopheles funestus captured was lowest for CB-LT ($5.3), followed by potentially hazardous QA-HLC ($10.5) and then CB-ITT ($28.0), all of which were far more cost-effective than QA-LT ($141) and QA-ITT ($168). Time-trends of malaria diagnostic positivity (DP) followed those of An. funestus density with a one-month lag and the wide range of mean DP across clusters was closely associated with mean densities of An. funestus caught by CB-LT (P < 0.001). Conclusions CB trapping schemes appear to be far more affordable, epidemiologically relevant and cost-effective than centrally supervised trapping schemes and may well be applicable to enhance intervention trials and even enable routine programmatic monitoring of vector population dynamics on unprecedented national scales