BackgroundMalaria in pregnancy (MiP) remains a major public health challenge in areas of high malaria transmission. Intermittent preventive treatment in pregnancy (IPTp) with sulfadoxine-pyrimethamine (SP) is recommended to prevent the adverse consequences of MiP. The effectiveness of SP for IPTp may be reduced in areas where the dhps581 mutation (a key marker of high level SP resistance) is found; this mutation was previously reported to be common in the Tanga Region of northern Tanzania, but there are limited data from other areas. The frequency of molecular markers of SP resistance was investigated in malaria parasites from febrile patients at health centres (HC) in seven regions comprising the Lake and Southern Zones of mainland Tanzania as part of the ongoing efforts to generate national-wide data of SP resistance.MethodsA cross-sectional survey was conducted in the outpatient departments of 14 HCs in seven regions from April to June, 2015. 1750 dried blood spot (DBS) samples were collected (117 to 160 per facility) from consenting patients with positive rapid diagnostic tests for malaria, and no recent (within past 2 months) exposure to SP or related drugs. DNA was extracted from the DBS, pooled by HC, and underwent pooled targeted amplicon deep sequencing to yield estimates of mutated parasite allele frequency at each locus of interest.ResultsThe dhps540 mutation was common across all 14 sites, ranging from 55 to 98.4% of sequences obtained. Frequency of the dhps581 mutation ranged from 0 to 2.4%, except at Kayanga HC (Kagera Region, Lake Zone) where 24.9% of sequences obtained were mutated. The dhfr164 mutation was detected only at Kanyanga HC (0.06%).ConclusionBy pooling DNA extracts, the allele frequency of mutations in 14 sites could be directly determined on a single deep-sequencing run. The dhps540 mutant was very common at all locations. Surprisingly, the dhps581 was common at one health center, but rare in all the others, suggesting that there is geographic micro-heterogeneity in mutant distribution and that accurate surveillance requires inclusion of multiple sites. A better understanding of the effect of the dhps581 mutant on the efficacy of IPTp-SP is needed.
A school-based net distribution program, piloted in the Southern Zone of Tanzania to sustain ≥80% universal net coverage previously attained through mass campaigns, successfully issued nets to nearly all eligible students and teachers. Keys to success included: Effective collaboration between the Ministry of Health, local government, and implementing partnersSocial mobilization to sensitize the community about the importance of net useDevelopment of a mobile application to facilitate data collection and analysis
BackgroundBendiocarb was introduced for the first time for Indoor Residual Spraying (IRS) in Tanzania in 2012 as part of the interim national insecticide resistance management plan. This move followed reports of increasingly alarming levels of pyrethroid resistance across the country. This study used the insecticide quantification kit (IQK) to investigate the intra-operational IRS coverage and quality of spraying, and decay rate of bendiocarb on different wall surfaces in Kagera region.MethodsTo assess intra-operational IRS coverage and quality of spraying, 104 houses were randomly selected out of 161,414 sprayed houses. A total of 509 samples (218 in Muleba and 291 in Karagwe) were obtained by scraping the insecticide samples from wall surfaces. To investigate decay rate, 66 houses (36 in Muleba and 30 in Karagwe) were selected and samples were collected monthly for a period of five months. Laboratory testing of insecticide concentration was done using IQKTM [Innovative Vector Control Consortium].ResultsOf the 509 samples, 89.5% met the World Health Organization (WHO) recommended concentration (between 100–400 mg/m2) for IRS target dosage. The proportion of samples meeting WHO standards varied between Karagwe (84.3%) and Muleba (96.3%) (p < 0.001). Assessment of quality of spraying at house level revealed that Muleba (84.8%) had a significantly higher proportion of households that met the expected target dosage (100–400 mg/m2) compared to Karagwe (68.9%) (p < 0.001). The quality of spraying varied across different wall substrates in both districts. Evaluation of bendiocarb decay showed that the proportion of houses with recommended concentration declined from 96.9%, 93.5% and 76.2% at months one, two, and three post IRS, respectively (p-trend = 0.03). The rate of decay increased in the fourth and fifth month post spraying with only 55.9% and 26.3% houses meeting the WHO recommendations, respectively.ConclusionIQK is an important tool for assessing IRS coverage and quality of spraying. The study found adequate coverage of IRS; however, residual life of bendiocarb was observed to be three months. Results suggest that in order to maintain the recommended concentrations with bendiocarb, a second spray cycle should be carried out after three months.Electronic supplementary materialThe online version of this article (doi:10.1186/s13071-015-0859-5) contains supplementary material, which is available to authorized users.
BackgroundDespite high coverage of malaria interventions, malaria elimination in Zanzibar remains elusive, with the annual number of cases increasing gradually over the last 3 years.ObjectiveThe aims of the study were to (1) assess the spatiotemporal dynamics of malaria in Zanzibar between 2015 and 2020 and (2) identify malaria hotspots that would allow Zanzibar to develop an epidemiological stratification for more effective and granular intervention targeting.MethodsIn this study, we analysed data routinely collected by Zanzibar’s Malaria Case Notification (MCN) system. The system collects sociodemographic and epidemiological data from all malaria cases. Cases are passively detected at health facilities (ie, primary index cases) and through case follow-up and reactive case detection (ie, secondary cases). Analyses were performed to identify the spatial heterogeneity of case reporting at shehia (ward) level during transmission seasons.ResultsFrom 1 January 2015 to 30 April 2020, the MCN system reported 22 686 index cases. Number of cases reported showed a declining trends from 2015 to 2016, followed by an increase from 2017 to 2020. More than 40% of cases had a travel history outside Zanzibar in the month prior to testing positive for malaria. The proportion of followed up index cases was approximately 70% for all years. Out of 387 shehias, 79 (20.4%) were identified as malaria hotspots in any given year; these hotspots reported 52% of all index cases during the study period. Of the 79 hotspot shehias, 12 were hotspots in more than 4 years, that is, considered temporally stable, reporting 14.5% of all index cases.ConclusionsOur findings confirm that the scale-up of malaria interventions has greatly reduced malaria transmission in Zanzibar since 2006. Analyses identified hotspots, some of which were stable across multiple years. Malaria efforts should progress from a universal intervention coverage approach to an approach that is more tailored to a select number of hotspot shehias.
Using a decision-tree approach, we examined the cost-effectiveness of indoor residual spraying (IRS) of households with insecticide combined with insecticide-treated bed net (ITN) distribution (IRS + ITN), compared with ITN distribution alone in the programmatic context of mainland Tanzania. The primary outcome of our model was the expected economic cost to society per case of malaria averted in children ≤ 5 years of age. Indoor residual spraying of households with insecticide data came from a program implemented in northwest Tanzania from 2008 to 2012; all other data originated from the published literature. Through sensitivity and scenario analyses, the model also examined the effects of variations in insecticide resistance, malaria prevalence, and different IRS modalities. In the base case, IRS + ITN is expected to be more expensive and more effective than the ITN-only intervention (incremental cost-effectiveness ratio [ICER]: $152.36). The number of IRS rounds, IRS insecticide costs, ITN use, malaria prevalence, and the probability that a child develops symptoms following infection drove the interventions' cost-effectiveness. Compared with universal spraying, targeted spraying is expected to lead to a higher number of malaria cases per person targeted (0.211-0.256 versus 0.050-0.076), but the incremental cost per case of malaria averted is expected to be lower (ICER: $41.70). In a scenario of increasing pyrethroid resistance, the incremental expected cost per case of malaria averted is expected to increase compared with the base case (ICER: $192.12). Tanzania should pursue universal IRS only in those regions that report high malaria prevalence. If the cost per case of malaria averted of universal IRS exceeds the willingness to pay, targeted spraying could provide an alternative, but may result in higher malaria prevalence.
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