Mulakwa Kamuliwo

Insecticide resistance and the future of malaria control in Zambia.

Background In line with the Global trend to improve malaria control efforts a major campaign of insecticide treated net distribution was initiated in 1999 and indoor residual spraying with DDT or pyrethroids was reintroduced in 2000 in Zambia. In 2006, these efforts were strengthened by the Presidents Malaria Initiative. This manuscript reports on the monitoring and evaluation of these activities and the potential impact of emerging insecticide resistance on disease transmission. Methods Mosquitoes were captured daily through a series of 108 window exit traps located at 18 sentinel sites. Specimens were identified to species and analyzed for sporozoites. Adult Anopheles mosquitoes were collected resting indoors and larva collected in breeding sites were reared to F1 and F0 generations in the lab and tested for insecticide resistance following the standard WHO susceptibility assay protocol. Annual cross sectional household parasite surveys were carried out to monitor the impact of the control programme on prevalence of Plasmodium falciparum in children aged 1 to 14 years. Results A total of 619 Anopheles gambiae s.l. and 228 Anopheles funestus s.l. were captured from window exit traps throughout the period, of which 203 were An. gambiae malaria vectors and 14 An. funestus s.s.. In 2010 resistance to DDT and the pyrethroids deltamethrin, lambda-cyhalothrin and permethrin was detected in both An. gambiae s.s. and An. funestus s.s.. No sporozoites were detected in either species. Prevalence of P. falciparum in the sentinel sites remained below 10% throughout the study period. Conclusion Both An. gambiae s.s. and An. funestus s.s. were controlled effectively with the ITN and IRS programme in Zambia, maintaining a reduced disease transmission and burden. However, the discovery of DDT and pyrethroid resistance in the country threatens the sustainability of the vector control programme.

Operational scale entomological intervention for malaria control: strategies, achievements and challenges in Zambia.

BackgroundWhile consensus on malaria vector control policy and strategy has stimulated unprecedented political-will, backed by international funding organizations and donors, vector control interventions are expansively being implemented based on assumptions with unequaled successes. This manuscript reports on the strategies, achievements and challenges of the past and contemporary malaria vector control efforts in Zambia.Case descriptionAll available information and accessible archived documentary records on malaria vector control in Zambia were reviewed. Retrospective analysis of routine surveillance data from the Health Management Information System (HMIS), data from population-based household surveys and various operations research reports was conducted to assess the status in implementing policies and strategies.Discussion and evaluationEmpirical evidence is critical for informing policy decisions and tailoring interventions to local settings. Thus, the World Health Organization (WHO) encourages the adoption of the integrated vector management (IVM) strategy which is a rational decision making process for optimal use of available resources. One of the key features of IVM is capacity building at the operational level to plan, implement, monitor and evaluate vector control and its epidemiological and entomological impact. In Zambia, great progress has been made in implementing WHO-recommended vector control policies and strategies within the context of the IVM Global Strategic framework with strong adherence to its five key attributes.ConclusionsThe country has solid, consistent and coordinated policies, strategies and guidelines for malaria vector control. The Zambian experience demonstrates the significance of a coordinated multi-pronged IVM approach effectively operationalized within the context of a national health system.

Review of the malaria epidemiology and trends in Zambia

A comprehensive desk review of malaria trends was conducted between 2000-2010 in Zambia to study malaria epidemiology and trends to guide strategies and approaches for effective malaria control. This review considered data from the National Health Information Management System, Malaria Surveys and Programme Review reports and analyzed malaria in-patient cases and deaths in relation to intervention coverage for all ages. Data showed three distinct epidemiological strata after a notable malaria reduction (66%) in in-patient cases and deaths, particularly between 2000-2008. These changes occurred following the (re-)introduction and expansion of indoor residual spraying up to 90% coverage, scale-up of coverage of long-lasting insecticide-treated nets in household from 50% to 70%, and artemisin-based combination therapy nationwide. However, malaria cases and deaths re-surged, increasing in 2009-2010 in the northern-eastern parts of Zambia. Delays in the disbursement of funds affected the implementation of interventions, which resulted in resurgence of cases and deaths. In spite of a decline in malaria disease burden over the past decade in Zambia, a reversal in impact is notable in the year 2009-2010, signifying that control gains are fragile and must be sustained to eliminate malaria.

High burden of malaria following scale-up of control interventions in Nchelenge District, Luapula Province, Zambia

BackgroundMalaria control interventions have been scaled-up in Zambia in conjunction with a malaria surveillance system. Although substantial progress has been achieved in reducing morbidity and mortality, national and local information demonstrated marked heterogeneity in the impact of malaria control across the country. This study reports the high burden of malaria in Nchelenge District, Luapula Province, Zambia from 2006 to 2012 after seven years of control measures.MethodsYearly aggregated information on cases of malaria, malaria deaths, use of malaria diagnostics, and malaria control interventions from 2006 to 2012 were obtained from the Nchelenge District Health Office. Trends in the number of malaria cases, methods of diagnosis, malaria positivity rate among pregnant women, and intervention coverage were analysed using descriptive statistics.ResultsMalaria prevalence remained high, increasing from 38% in 2006 to 53% in 2012. Increasing numbers of cases of severe malaria were reported until 2010. Intense seasonal malaria transmission was observed with seasonal declines in the number of cases between April and August, although malaria transmission continued throughout the year. Clinical diagnosis without accompanying confirmation declined from 95% in 2006 to 35% in 2012. Intervention coverage with long-lasting insecticide-treated nets and indoor residual spraying increased from 2006 to 2012.ConclusionsDespite high coverage with vector control interventions, the burden of malaria in Nchelenge District, Zambia remained high. The high parasite prevalence could accurately reflect the true burden, perhaps in part as a consequence of population movement, or improved access to care and case reporting. Quality information at fine spatial scales will be critical for targeting effective interventions and measurement of progress.

Underpinning sustainable vector control through informed insecticide resistance management.

Background There has been rapid scale-up of malaria vector control in the last ten years. Both of the primary control strategies, long-lasting pyrethroid treated nets and indoor residual spraying, rely on the use of a limited number of insecticides. Insecticide resistance, as measured by bioassay, has rapidly increased in prevalence and has come to the forefront as an issue that needs to be addressed to maintain the sustainability of malaria control and the drive to elimination. Zambias programme reported high levels of resistance to the insecticides it used in 2010, and, as a result, increased its investment in resistance monitoring to support informed resistance management decisions. Methodology/Principal Findings A country-wide survey on insecticide resistance in Zambian malaria vectors was performed using WHO bioassays to detect resistant phenotypes. Molecular techniques were used to detect target-site mutations and microarray to detect metabolic resistance mechanisms. Anopheles gambiae s.s. was resistant to pyrethroids, DDT and carbamates, with potential organophosphate resistance in one population. The resistant phenotypes were conferred by both target-site and metabolic mechanisms. Anopheles funestus s.s. was largely resistant to pyrethroids and carbamates, with potential resistance to DDT in two locations. The resistant phenotypes were conferred by elevated levels of cytochrome p450s. Conclusions/Significance Currently, the Zambia National Malaria Control Centre is using these results to inform their vector control strategy. The methods employed here can serve as a template to all malaria-endemic countries striving to create a sustainable insecticide resistance management plan.

Impact of Sulfadoxine-Pyrimethamine Resistance on Effectiveness of Intermittent Preventive Therapy for Malaria in Pregnancy at Clearing Infections and Preventing Low Birth Weight

BACKGROUND Owing to increasing sulfadoxine-pyrimethamine (SP) resistance in sub-Saharan Africa, monitoring the effectiveness of intermittent preventive therapy in pregnancy (IPTp) with SP is crucial. METHODS Between 2009 and 2013, both the efficacy of IPTp-SP at clearing existing peripheral malaria infections and the effectiveness of IPTp-SP at reducing low birth weight (LBW) were assessed among human immunodeficiency virus-uninfected participants in 8 sites in 6 countries. Sites were classified as high, medium, or low resistance after measuring parasite mutations conferring SP resistance. An individual-level prospective pooled analysis was conducted. RESULTS Among 1222 parasitemic pregnant women, overall polymerase chain reaction-uncorrected and -corrected failure rates by day 42 were 21.3% and 10.0%, respectively (39.7% and 21.1% in high-resistance areas; 4.9% and 1.1% in low-resistance areas). Median time to recurrence decreased with increasing prevalence of Pfdhps-K540E. Among 6099 women at delivery, IPTp-SP was associated with a 22% reduction in the risk of LBW (prevalence ratio [PR], 0.78; 95% confidence interval [CI], .69-.88; P < .001). This association was not modified by insecticide-treated net use or gravidity, and remained significant in areas with high SP resistance (PR, 0.81; 95% CI, .67-.97; P = .02). CONCLUSIONS The efficacy of SP to clear peripheral parasites and prevent new infections during pregnancy is compromised in areas with >90% prevalence of Pfdhps-K540E. Nevertheless, in these high-resistance areas, IPTp-SP use remains associated with increases in birth weight and maternal hemoglobin. The effectiveness of IPTp in eastern and southern Africa is threatened by further increases in SP resistance and reinforces the need to evaluate alternative drugs and strategies for the control of malaria in pregnancy.

The changing burden of malaria and association with vector control interventions in Zambia using district-level surveillance data, 2006-2011.

BackgroundMalaria control was strengthened in Zambia over the past decade. The two primary interventions for vector control are indoor residual spraying (IRS) and long-lasting insecticide-treated nets (LLINs). Using passive malaria surveillance data collected from 2006 to 2011 through the Zambian District Health Information System, the associations between increased coverage with LLINs and IRS and the burden of malaria in Zambia were evaluated.MethodsNational passive malaria surveillance data from 2006 to 2011 were analysed. A district-level, random-effects model with Poisson regression was used to explore the association between malaria cases and coverage with LLINs and IRS. Malaria cases and LLINs and IRS coverage were mapped to visualize spatiotemporal variation in malaria for each year.ResultsFrom 2006–2011, 24.6 million LLINs were distributed and 6.4 million houses were sprayed with insecticide. Coverage with LLINs was not uniformly distributed over the study period and IRS was targeted to central and southern districts where malaria transmission was low. LLIN coverage was associated with a reduction in malaria cases, although an increase in the number of malaria cases was reported in some districts over the study period. A high burden of malaria persisted in north-eastern Zambia, whereas a reduction in the number of reported malaria cases was observed in western and southern Zambia.ConclusionEnhanced and targeted interventions in north-eastern Zambia where the burden of malaria remains high, as well as efforts to sustain low malaria transmission in the south-west, will be necessary for Zambia to achieve the national goal of being malaria free by 2030.

Monitoring, characterization and control of chronic, symptomatic malaria infections in rural Zambia through monthly household visits by paid community health workers

BackgroundActive, population-wide mass screening and treatment (MSAT) for chronic Plasmodium falciparum carriage to eliminate infectious reservoirs of malaria transmission have proven difficult to apply on large national scales through trained clinicians from central health authorities.MethodologyFourteen population clusters of approximately 1,000 residents centred around health facilities (HF) in two rural Zambian districts were each provided with three modestly remunerated community health workers (CHWs) conducting active monthly household visits to screen and treat all consenting residents for malaria infection with rapid diagnostic tests (RDT). Both CHWs and HFs also conducted passive case detection among residents who self-reported for screening and treatment.ResultsDiagnostic positivity was higher among symptomatic patients self-reporting to CHWs (42.5%) and HFs (24%) than actively screened residents (20.3%), but spatial and temporal variations of diagnostic positivity were highly consistent across all three systems. However, most malaria infections (55.6%) were identified through active home visits by CHWs rather than self-reporting to CHWs or HFs. Most (62%) malaria infections detected actively by CHWs reported one or more symptoms of illness. Most reports of fever and vomiting, plus more than a quarter of history of fever, headache and diarrhoea, were attributable to malaria infection. The minority of residents who participated >12 times had lower rates of malaria infection and associated symptoms in later contacts but most residents were tested <4 times and high malaria diagnostic positivity (32%) in active surveys, as well as incidence (1.7 detected infections per person per year) persisted in the population. Per capita cost for active service delivery by CHWs was US

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

5.14 but this would rise to US

Short-term Impact of Mass Drug Administration With Dihydroartemisinin Plus Piperaquine on Malaria in Southern Province Zambia: A Cluster-Randomized Controlled Trial

10.68 with full community compliance with monthly testing at current levels of transmission, and US