Malaria Species Positivity Rates Among Symptomatic Individuals Across Regions of Differing Transmission Intensities in Mainland Tanzania.

BACKGROUND: Recent data indicate that non-Plasmodium falciparum species may be more prevalent than thought in sub-Saharan Africa. Although Plasmodium malariae, Plasmodium ovale spp., and Plasmodium vivax are less severe than P. falciparum, treatment and control are more challenging, and their geographic distributions are not well characterized. METHODS: We randomly selected 3284 of 12 845 samples collected from cross-sectional surveys in 100 health facilities across 10 regions of Mainland Tanzania and performed quantitative real-time PCR to determine presence and parasitemia of each malaria species. RESULTS: P. falciparum was most prevalent, but P. malariae and P. ovale were found in all but 1 region, with high levels (>5%) of P. ovale in 7 regions. The highest P. malariae positivity rate was 4.5% in Mara and 8 regions had positivity rates ≥1%. We only detected 3 P. vivax infections, all in Kilimanjaro. While most nonfalciparum malaria-positive samples were coinfected with P. falciparum, 23.6% (n = 13 of 55) of P. malariae and 14.7% (n = 24 of 163) of P. ovale spp. were monoinfections. CONCLUSIONS: P. falciparum remains by far the largest threat, but our data indicate that malaria elimination efforts in Tanzania will require increased surveillance and improved understanding of the biology of nonfalciparum species.

Potentially Zoonotic Enteric Infections in Gorillas and Chimpanzees, Cameroon and Tanzania.

Despite zoonotic potential, data are lacking on enteric infection diversity in wild apes. We employed a novel molecular diagnostic platform to detect enteric infections in wild chimpanzees and gorillas. Prevalent Cryptosporidium parvum, adenovirus, and diarrheagenic Escherichia coli across divergent sites and species demonstrates potential widespread circulation among apes in Africa.

Crimean-Congo Hemorrhagic Fever Virus Seroprevalence in Human and Livestock Populations, Northern Tanzania.

We conducted a cross-sectional study of Crimean-Congo hemorrhagic fever virus (CCHFV) in northern Tanzania. CCHFV seroprevalence in humans and ruminant livestock was high, as were spatial heterogeneity levels. CCHFV could represent an unrecognized human health risk in this region and should be included as a differential diagnosis for febrile illness.

Costs of Digital Adherence Technologies for Tuberculosis Treatment Support, 2018-2021.

Digital adherence technologies are increasingly used to support tuberculosis (TB) treatment adherence. Using microcosting, we estimated healthcare system costs (in 2022 US dollars) of 2 digital adherence technologies, 99DOTS medication sleeves and video-observed therapy (VOT), implemented in demonstration projects during 2018-2021. We also obtained cost estimates for standard directly observed therapy (DOT). Estimated per-person costs of 99DOTS for drug-sensitive TB were $98 in Bangladesh (n = 719), $119 in the Philippines (n = 396), and $174 in Tanzania (n = 976). Estimated per-person costs of VOT were $1,154 in Haiti (87 drug-sensitive), $304 in Moldova (173 drug-sensitive), $452 in Moldova (135 drug-resistant), and $661 in the Philippines (110 drug-resistant). 99DOTS costs may be similar to or less expensive than standard DOT. VOT is more expensive, although in some settings, labor cost offsets or economies of scale may yield savings. 99DOTS and VOT may yield savings to local programs if donors cover infrastructure costs.

The impact of in-house pathology services on downstaging cervical cancer in Tanzania over an 18-year period.

PURPOSE: Reducing time between cancer screening, diagnosis, and initiation of treatment is best achieved when services are available in the same hospital. Yet, comprehensive cancer centers are typically unavailable in low- and middle-income countries (LMICs), where resources are limited and services scattered. This study explored the impact of establishing an in-house pathology laboratory at the largest public cancer hospital in Tanzania on the downstaging of cervical cancer. METHODS: We examined clinical datasets of 8,322 cervical cancer patients treated at the Ocean Road Cancer Institute (ORCI). The first period included patients treated from 2002 to 2016, before establishment of the pathology laboratory at ORCI; the second period (post-pathology establishment) included data from 2017 to 2020. Logistic regression analysis evaluated the impact of the pathology laboratory on stage of cervical cancer diagnosis. RESULTS: Patients treated during the post-pathology period were more likely to be clinically diagnosed at earlier disease stages compared to patients in the pre-pathology period (pre-pathology population diagnosed at early disease stage: 44.08%; post-pathology population diagnosed at early disease stage: 59.38%, p < 0.001). After adjustment for age, region of residence, and place of biopsy, regression results showed patients diagnosed during the post-pathology period had higher odds of early stage cervical cancer diagnosis than patients in the pre-pathology period (OR 1.35, 95% CI (1.16, 1.57), p < 0.001). CONCLUSIONS: Integrated and comprehensive cancer centers can overcome challenges in delivering expedited cervical cancer diagnosis and treatment. In-house pathology laboratories play an important role in facilitating timely diagnosis and rapid treatment of cervical and possibly other cancers in LMICs.

Derivation and Internal Validation of a Novel Risk Assessment Tool to Identify Infants and Young Children at Risk for Post-Discharge Mortality in Dar es Salaam, Tanzania and Monrovia, Liberia.

OBJECTIVE: To derive and validate internally a novel risk assessment tool to identify young children at risk for all-cause mortality ≤60 days of discharge from hospitals in sub-Saharan Africa. STUDY DESIGN: We performed a prospective observational cohort study of children aged 1-59 months discharged from Muhimbili National Hospital in Dar es Salaam, Tanzania and John F. Kennedy Medical Center in Monrovia, Liberia (2019-2022). Caregivers received telephone calls up to 60 days after discharge to ascertain participant vital status. We collected socioeconomic, demographic, clinical, and anthropometric data during hospitalization. Candidate variables with P < .20 in bivariate analyses were included in a multivariable logistic regression model with best subset selection to identify risk factors for the outcome. We internally validated our tool using bootstrapping with 500 repetitions. RESULTS: There were 1933 young children enrolled in the study. The median (IQR) age was 11 (4, 23) months and 58.7% were males. In total, 67 (3.5%) died during follow-up. Ten variables contributed to our tool (total possible score 82). Cancer (aOR 10.6, 95% CI 2.58, 34.6), pedal edema (aOR 6.94, 95% CI 1.69, 22.6), and leaving against medical advice (aOR 6.46, 95% CI 2.46, 15.3) were most predictive of post-discharge mortality. Our risk assessment tool demonstrated good discriminatory value (optimism corrected area under the receiver operating characteristic curve 0.77), high precision, and sufficient calibration. CONCLUSIONS: After validation, this tool may be used to identify young children at risk for post-discharge mortality to direct resources for follow-up of high-risk children.

Comparison between interventional versus medical therapy in patients with rheumatic mitral valve stenosis in Tanzania.

BACKGROUND: Rheumatic heart disease remains the most common cardiovascular disease in children and young adults. The outcome of interventional versus medical therapy on the long term is not fully elucidated yet. This study provides contemporary data on the clinical profile, treatment and follow up of patients with rheumatic mitral stenosis (MS) in Tanzania. METHODS: Patients' medical information, investigations and treatment data were recorded in this prospective cohort study. They were followed up for 6-24 months to determine the long-term outcome. Interventional therapy was defined as a combination of surgery and percutaneous balloon mitral valvuloplasty. Kaplan-Meier curves and Cox proportional hazards model were used in analyses. p-Value < 0.05 was considered statistically significant. RESULTS: We enrolled 290 consecutive patients. Interventions were done in half of the patients. Median follow up was 23.5 months. Mortality was higher in the medical than interventional treatment (10.4% vs. 4%, log-rank p = 0.001). Median age was 36 years, females (68.3%) and low income (55.5%). Multivalvular disease was found in 116 (40%) patients, atrial fibrillation (31.4%), stroke/transient ischaemic attack (18.9%) and heart failure class III-IV (44.1%). Median (IQR) duration of disease was 3 (4) years, secondary prophylaxis (27.7%) and oral anticoagulants use (62.3%). In multivariable analysis, the risk of death among patients on medical was 3.07 times higher than those on interventional treatment (crude HR 3.07, 95% CI 1.43-6.56, p = 0.004), 2.44 times higher among patients with arrhythmias versus without arrhythmias (crude HR 2.44, 95% CI 1.19-4.49, p = 0.015) and 2.13 times higher among patients with multivalvular than single valve disease (crude HR 2.13, 95% CI 1.09-4.16, p = 0.026). CONCLUSIONS: Intervention is carrying low mortality compared to medical treatment. Arrhythmias and multivalvular disease are associated with a high mortality. Rheumatic MS is more prevalent in young people, females and individuals with low income. There is a late hospital presentation and a low use of both secondary prophylactic antibiotics and anticoagulants.

Effects of Zinc Supplementation on Metabolomic Profiles in Tanzanian Infants: A Randomized Trial.

BACKGROUND: Provision of zinc supplementation to young children has been associated with reduced infectious morbidity and better growth outcomes. However, the metabolic pathways underlying these outcomes are unclear, and metabolomic data from humans undergoing zinc supplementation, particularly infants, are generally lacking. OBJECTIVES: This study aimed to examine the effect of zinc supplementation on metabolic profiles in Tanzanian infants aged 6 wk and 6 mo. METHODS: Blood samples were collected at age 6 wk and 6 mo from 50 Tanzanian infants who were enrolled in a randomized placebo-controlled trial of zinc supplementation (5 mg oral daily). Metabolomic analysis using an ultrahigh-performance liquid chromatography/tandem mass spectroscopy platform was performed to identify potential metabolomic profiles and biomarkers associated with zinc supplementation. Principal component analysis (PCA) was used to summarize metabolomic data from all samples. Two-way repeated measures analysis of variance with compound symmetry covariance structures were used to compare metabolome levels over time between infants in the 2 treatment arms. RESULTS: In PCA, the samples tended to be more separated by child age (6 wk compared with 6 mo) than by zinc supplementation status. We found that zinc supplementation affected a variety of metabolites associated with amino acid, lipid, nucleotide, and xenobiotic metabolism, including indoleacetate in the tryptophan metabolism pathway; 3-methoxytrosine and 4-hydrxoyphenylphruvate in the tyrosine pathway; eicosanedioate, 2-aminooctanoate, and N-acetyl-2-aminooctanoate in the fatty acid pathway; and N6-succinyladenosine in the purine metabolism pathway. Compared to the relatively small number of metabolites associated with zinc supplements, many infant metabolites changed significantly from age 6 wk to 6 mo. CONCLUSIONS: Zinc supplementation, despite having overall clinical benefits, appears to induce limited metabolomic changes in blood metabolites in young infants. Future larger studies may be warranted to further examine metabolic pathways associated with zinc supplementation. The parent trial was registered at clinicaltrials.gov as NCT00421668.

Impact of the COVID-19 pandemic in childhood and adolescent cancer care in northern Tanzania: a cross-sectional study.

INTRODUCTION: The SARS-CoV-2 (COVID-19) pandemic has strained healthcare systems and presented unique challenges for children requiring cancer care, particularly in low- and middle-income countries. This study aimed to assess the impact of the COVID-19 pandemic on access to cancer care for children and adolescents in Northern Tanzania. METHODS: In this cross-sectional study, we assessed the demographic and clinical characteristics of 547 pediatric and adolescent cancer patients (ages 0-19 years old) between 2016 and 2022 using the population-based Kilimanjaro Cancer Registry (KCR). We categorized data into pre-COVID-19 (2016-2019) and COVID-19 (2020-2022) eras, and performed descriptive analyses of diagnostic, treatment, and demographic information. A secondary analysis was conducted on a subset of 167 patients with stage of diagnosis at presentation. RESULTS: Overall admissions nearly doubled during the pandemic (n = 190 versus 357). The variety of diagnoses attended at KCMC increased during the pandemic, with only five groups of diseases reported in 2016 to twelve groups of diseases in 2021. Most patients were diagnosed at a late stage (stage III or IV) across eras, with the proportion of under-five years old patients increasing late-diagnoses from 29.4% (before the pandemic), 52.8% (during the pandemic), when compared to the overall cohort. Around 95% of children in this age category reported late-stage diagnosis during the pandemic. Six out of the twelve cancer site groups also reported an increase in late-stage diagnosis. During the pandemic, the proportion of children receiving surgery increased from 15.8 to 30.8% (p < 0.001). CONCLUSION: Childhood and adolescent cancer care changed in Northern Tanzania during the COVID-19 pandemic, with increased late-stage diagnoses presentations among younger patients and the increased use of surgical therapies in the context of a growing practice. Understanding the impact of the COVID-19 pandemic on pediatric and adolescent cancer care can help us better adapt healthcare systems and interventions to the emerging needs of children and adolescents with cancer in the midst of a health crisis.

Contribution of Food from Market Purchases and Home Production to Child Nutrient Intake: Evidence from the EFFECTS Study Baseline Data.

BACKGROUND: Child undernutrition is prevalent in Tanzania, and households rely primarily on local markets and home production as food sources. However, little is known about the contribution of food market purchases to nutrient intakes among children consuming complementary foods. OBJECTIVES: To quantify the relationships between diversity of foods purchased and produced by households and adequate child nutrient intake in Mara, Tanzania. METHODS: Cross-sectional baseline dietary and household food source data from the Engaging Fathers for Effective Child Nutrition and Development in Tanzania study were collected from mothers of 586 children aged 9-23 mo clustered in 80 villages in Mara, Tanzania. We conducted mixed effects linear regressions to quantify the association between the diversity of foods consumed at home, from market purchases and home production, and nutrient intake adequacy (based on 24-h food recalls). RESULTS: Children had inadequate diets, with fewer than half of children consuming adequate amounts of vitamin A, vitamin B1 (thiamine), vitamin B2 (riboflavin), vitamin B9 (folate), calcium, iron, and zinc. Breastfeeding was associated with higher overall mean adequacy (b = 0.15-0.19 across models, P < 0.001). Diversity of foods purchased was positively associated with the intake of vitamin B12 and calcium (both P < 0.001); this effect was attenuated among breastfed children. Among nonbreastfed children, production diversity was positively associated with vitamin A intake (b=0.04; P < .05) but not with intake of other nutrients. CONCLUSIONS: Both household food purchase and food production diversities were positively associated with children's nutrient intake in rural Mara, Tanzania. Nutrition programming should consider the role of food markets in addition to home food production to improve child diets. This trial was registered at clinicaltrials.gov as NCT03759821, https://clinicaltrials.gov/study/NCT03759821.

Long-term impact of an integrated HIV/non-communicable disease care intervention on patient retention in care and clinical outcomes in East Africa.

OBJECTIVE: To describe rates of retention in care and control of hypertension, diabetes and HIV among participants receiving integrated care services for a period of up to 24 months in East Africa. METHODS: Between 5 October 2018 and 23 June 2019 participants enrolled into a prospective cohort study evaluating the feasibility of integrated care delivery for HIV, diabetes and hypertension from a single point of care in Tanzania and Uganda (MOCCA study). Integrated care clinics were established in 10 primary healthcare facilities and care was provided routinely according to national guidelines. Initial follow-up was 12 months. Outcomes were rates of retention in care, proportions of participants with controlled hypertension (blood pressure <140/90 mmHg), diabetes (fasting blood glucose <7.0 mmol/L) and HIV (plasma viral load <1000 copies/ml). The study coincided with the COVID-19 pandemic response. Afterwards, all participants were approached for extended follow-up by a further 12 months in the same clinics. We evaluated outcomes of the cohort at the end of long-term follow-up. RESULTS: The MOCCA study enrolled 2273 participants of whom 1911 (84.5%) were retained in care after a median follow-up of 8 months (Interquartile range: 6.8-10.7). Among these, 1283/1911 (67.1%) enrolled for a further year of follow-up, 458 (24.0%) were unreachable, 71 (3.7%) reverted to vertical clinics (clinics providing services dedicated to study conditions), 31 (1.6%) died and 68 (3.6%) refused participation. Among participants who enrolled for longer follow-up, mean age was 51.4 ± 11.7 years, 930 (72.5%) were female and 509 (39.7%) had multiple chronic conditions. Overall, 1236 (96.3%) [95% confidence interval 95.2%-97.3%] participants were retained in care, representing 1236/2273 (54.3%) [52.3%-56.4%] of participants ever enrolled in the study. Controlled hypertension, diabetes and HIV at the end of follow-up was, 331/618 (53.6%) [49.5%-57.5%], 112/354 (31.6%) [26.8%-36.8%] and 332/343 (96.7%) [94.3%-98.4%] respectively. CONCLUSION: Integrated care can achieve high rates of retention in care long term, but control of blood pressure and blood sugar remains low.

Stability in care and risk of loss to follow-up among clients receiving community health worker-led differentiated HIV care: Results from a prospective cohort study in northern Tanzania.

BACKGROUND: HIV services in Tanzania are facility-based but facilities are often overcrowded. Differentiated care models (DCM) have been introduced into the National Guidelines. We piloted a Community Health Worker (CHW)-led HIV treatment club model (CHW-DCM) in an urban region, and assessed its effectiveness in comparison to the standard of care (SoC, facility-based model), in terms of stability in care, loss to follow-up (LTFU) and treatment adherence. METHODS: In two clinics in the Shinyanga region, clients established on ART (defined as stable clients by national guidelines as on first-line ART >6 months, undetectable viral load, no opportunistic infections or pregnancy, and good adherence) were offered CHW-DCM. This prospective cohort study included all stable clients who enrolled in CHW-DCM between July 2018 and March 2020 (CHW-DCM) and compared them to stable clients who remained in SoC during that period. Multivariable Cox regression models were used to analyse factors associated with continued stability in care and the risk of LTFU during 18 months of follow-up; treatment adherence was assessed by pill count and compared using Chi-square tests. RESULTS: Of 2472 stable clients, 24.5% received CHW-DCM and 75.5% SoC. CHW-DCM clients were slightly older (mean 42.8 vs. 37.9 years) and more likely to be female (36.2% vs. 32.2%). Treatment adherence was better among CHW-DCM than SoC: 96.6% versus 91.9% and 98.5% versus 92.2%, respectively (both p = 0.001). SoC clients were more likely to not remain stable over time than CHW-DCM (adjusted Hazard ratio [AHR] = 2.68; 95% CI: 1.86-3.90). There was no difference in LTFU (adjusted hazard ratio [AHR] = 1.54; 95%CI: 0.82-2.93). CONCLUSION: Clients attending CHW-DCM demonstrated better stability in care and treatment adherence than SoC, and the risk of LTFU was not increased. These findings demonstrate the potential of CHW in delivering community-based HIV services in the local Tanzanian context. These results could be used to extend this CHW-DCM model to similar settings.

Effects of engaging fathers and bundling parenting and nutrition interventions on early child development and maternal and paternal parenting in Mara, Tanzania: a factorial cluster-randomized controlled trial.

BACKGROUND: Multicomponent interventions are needed to address the various co-occurring risks that compromise early child nutrition and development. We compared the independent and combined effects of engaging fathers and bundling parenting components into a nutrition intervention on early child development (ECD) and parenting outcomes. METHODS: We conducted a 2×2 factorial cluster-randomized controlled trial across 80 villages in Mara Region, Tanzania, also known as EFFECTS (Engaging Fathers for Effective Child Nutrition and Development in Tanzania; ClinicalTrials.gov, NCT03759821). Households with children under 18 months of age residing with their mother and father were enrolled. Villages were randomly assigned to one of five groups: a nutrition intervention for mothers, a nutrition intervention for couples, a bundled nutrition and parenting intervention for mothers, a bundled intervention for couples, and a standard-of-care control. Interventions were delivered by trained community health workers through peer groups and home visits over 12 months. Mothers, fathers, and children were assessed at baseline, midline, and endline or postintervention. We used a difference-in-difference approach with intention-to-treat analysis to estimate intervention effects on ECD (Bayley Scales of Infant and Toddler Development, third edition) and maternal and paternal parenting and psychosocial well-being. RESULTS: Between October 29, 2018, and May 24, 2019, 960 households were enrolled (n = 192 per arm). Compared to nutrition interventions, bundled interventions improved children's cognitive (ß = .18 [95% CI: 0.01, 0.36]) and receptive language development (ß = .23 [0.04, 0.41]). There were no differences between interventions for other ECD domains. Compared to nutrition interventions, bundled interventions achieved additional benefits on maternal stimulation (ß = .21 [0.04, 0.38]) and availability of home learning materials (ß = .25 [0.07-0.43]) and reduced paternal parenting distress (ß = -.34 [-0.55, -0.12]). Compared to interventions with mothers only, interventions that engaged fathers improved paternal stimulation (ß = .45 [0.27, 0.63]). CONCLUSIONS: Jointly bundling parenting components into nutrition interventions while also engaging both mothers and fathers is most effective for improving maternal and paternal parenting and ECD outcomes.

Microsatellites reveal high polymorphism and high potential for use in anti-malarial efficacy studies in areas with different transmission intensities in mainland Tanzania.

BACKGROUND: Tanzania is currently implementing therapeutic efficacy studies (TES) in areas of varying malaria transmission intensities as per the World Health Organization (WHO) recommendations. In TES, distinguishing reinfection from recrudescence is critical for the determination of anti-malarial efficacy. Recently, the WHO recommended genotyping polymorphic coding genes, merozoite surface proteins 1 and 2 (msp1 and msp2), and replacing the glutamate-rich protein (glurp) gene with one of the highly polymorphic microsatellites in Plasmodium falciparum to adjust the efficacy of antimalarials in TES. This study assessed the polymorphisms of six neutral microsatellite markers and their potential use in TES, which is routinely performed in Tanzania. METHODS: Plasmodium falciparum samples were obtained from four TES sentinel sites, Kibaha (Pwani), Mkuzi (Tanga), Mlimba (Morogoro) and Ujiji (Kigoma), between April and September 2016. Parasite genomic DNA was extracted from dried blood spots on filter papers using commercial kits. Genotyping was done using six microsatellites (Poly-α, PfPK2, TA1, C3M69, C2M34 and M2490) by capillary method, and the data were analysed to determine the extent of their polymorphisms and genetic diversity at the four sites. RESULTS: Overall, 83 (88.3%) of the 94 samples were successfully genotyped (with positive results for ≥ 50.0% of the markers), and > 50.0% of the samples (range = 47.6-59.1%) were polyclonal, with a mean multiplicity of infection (MOI) ranging from 1.68 to 1.88 among the four sites. There was high genetic diversity but limited variability among the four sites based on mean allelic richness (RS = 7.48, range = 7.27-8.03, for an adjusted minimum sample size of 18 per site) and mean expected heterozygosity (He = 0.83, range = 0.80-0.85). Cluster analysis of haplotypes using STRUCTURE, principal component analysis, and pairwise genetic differentiation (FST) did not reveal population structure or clustering of parasites according to geographic origin. Of the six markers, Poly-α was the most polymorphic, followed by C2M34, TA1 and C3M69, while M2490 was the least polymorphic. CONCLUSION: Microsatellite genotyping revealed high polyclonality and genetic diversity but no significant population structure. Poly-α, C2M34, TA1 and C3M69 were the most polymorphic markers, and Poly-α alone or with any of the other three markers could be adopted for use in TES in Tanzania.

Dynamics of malaria vector composition and Plasmodium falciparum infection in mainland Tanzania: 2017-2021 data from the national malaria vector entomological surveillance.

BACKGROUND: In 2015, Tanzania National Malaria Control Programme (NMCP) established a longitudinal malaria vector entomological surveillance (MVES). The MVES is aimed at a periodical assessment of malaria vector composition and abundance, feeding and resting behaviours, and Plasmodium falciparum infection in different malaria epidemiological strata to guide the NMCP on the deployment of appropriate malaria vector interventions. This work details the dynamics of malaria vector composition and transmission in different malaria epidemiological strata. METHODS: The MVES was conducted from 32 sentinel district councils across the country. Mosquitoes were collected by the trained community members and supervised by the NMCP and research institutions. Three consecutive night catches (indoor collection with CDC light trap and indoor/outdoor collection using bucket traps) were conducted monthly in three different households selected randomly from two to three wards within each district council. Collected mosquitoes were sorted and morphologically identified in the field. Thereafter, the samples were sent to the laboratory for molecular characterization using qPCR for species identification and detection of P. falciparum infections (sporozoites). ELISA technique was deployed for blood meal analysis from samples of blood-fed mosquitoes to determine the blood meal indices (BMI). RESULTS: A total of 63,226 mosquitoes were collected in 32 district councils from January 2017 to December 2021. Out of which, 39,279 (62%), 20,983 (33%) and 2964 (5%) were morphologically identified as Anopheles gambiae sensu lato (s.l.), Anopheles funestus s.l., and as other Anopheles species, respectively. Out of 28,795 laboratory amplified mosquitoes, 13,645 (47%) were confirmed to be Anopheles arabiensis, 9904 (34%) as An. funestus sensu stricto (s.s.), and 5193 (19%) as An. gambiae s.s. The combined average entomological inoculation rates (EIR) were 0.46 (95% CI 0.028-0.928) for An. gambiae s.s., 0.836 (95% CI 0.138-1.559) for An. arabiensis, and 0.58 (95% CI 0.165-0.971) for An. funestus s.s. with variations across different malaria transmission strata. Anopheles funestus s.s. and An. arabiensis were predominant in the Lake and South-Eastern zones, respectively, mostly in high malaria transmission areas. Monthly mosquito densities displayed seasonal patterns, with two peaks following the rainy seasons, varying slightly across species and district councils. CONCLUSION: Anopheles arabiensis remains the predominant vector species followed by An. funestus s.s. in the country. Therefore, strengthening integrated vector management including larval source management is recommended to address outdoor transmission by An. arabiensis to interrupt transmission particularly where EIR is greater than the required elimination threshold of less than one (< 1) to substantially reduce the prevalence of malaria infection.

Genetic polymorphism and evidence of signatures of selection in the Plasmodium falciparum circumsporozoite protein gene in Tanzanian regions with different malaria endemicity.

BACKGROUND: In 2021 and 2023, the World Health Organization approved RTS,S/AS01 and R21/Matrix M malaria vaccines, respectively, for routine immunization of children in African countries with moderate to high transmission. These vaccines are made of Plasmodium falciparum circumsporozoite protein (PfCSP), but polymorphisms in the gene raise concerns regarding strain-specific responses and the long-term efficacy of these vaccines. This study assessed the Pfcsp genetic diversity, population structure and signatures of selection among parasites from areas of different malaria transmission intensities in Mainland Tanzania, to generate baseline data before the introduction of the malaria vaccines in the country. METHODS: The analysis involved 589 whole genome sequences generated by and as part of the MalariaGEN Community Project. The samples were collected between 2013 and January 2015 from five regions of Mainland Tanzania: Morogoro and Tanga (Muheza) (moderate transmission areas), and Kagera (Muleba), Lindi (Nachingwea), and Kigoma (Ujiji) (high transmission areas). Wright's inbreeding coefficient (Fws), Wright's fixation index (FST), principal component analysis, nucleotide diversity, and Tajima's D were used to assess within-host parasite diversity, population structure and natural selection. RESULTS: Based on Fws (< 0.95), there was high polyclonality (ranging from 69.23% in Nachingwea to 56.9% in Muheza). No population structure was detected in the Pfcsp gene in the five regions (mean FST = 0.0068). The average nucleotide diversity (π), nucleotide differentiation (K) and haplotype diversity (Hd) in the five regions were 4.19, 0.973 and 0.0035, respectively. The C-terminal region of Pfcsp showed high nucleotide diversity at Th2R and Th3R regions. Positive values for the Tajima's D were observed in the Th2R and Th3R regions consistent with balancing selection. The Pfcsp C-terminal sequences revealed 50 different haplotypes (H_1 to H_50), with only 2% of sequences matching the 3D7 strain haplotype (H_50). Conversely, with the NF54 strain, the Pfcsp C-terminal sequences revealed 49 different haplotypes (H_1 to H_49), with only 0.4% of the sequences matching the NF54 strain (Hap_49). CONCLUSIONS: The findings demonstrate high diversity of the Pfcsp gene with limited population differentiation. The Pfcsp gene showed positive Tajima's D values, consistent with balancing selection for variants within Th2R and Th3R regions. The study observed differences between the intended haplotypes incorporated into the design of RTS,S and R21 vaccines and those present in natural parasite populations. Therefore, additional research is warranted, incorporating other regions and more recent data to comprehensively assess trends in genetic diversity within this important gene. Such insights will inform the choice of alleles to be included in the future vaccines.

High prevalence and risk of malaria among asymptomatic individuals from villages with high prevalence of artemisinin partial resistance in Kyerwa district of Kagera region, north-western Tanzania.

BACKGROUND: Although Tanzania adopted and has been implementing effective interventions to control and eventually eliminate malaria, the disease is still a leading public health problem, and the country experiences heterogeneous transmission. Recent studies reported the emergence of parasites with artemisinin partial resistance (ART-R) in Kagera region with high prevalence (> 10.0%) in two districts of Karagwe and Kyerwa. This study assessed the prevalence and predictors/risk of malaria infections among asymptomatic individuals living in a hyperendemic area where ART-R has emerged in Kyerwa District of Kagera region, north-western Tanzania. METHODS: This was a community-based cross-sectional survey which was conducted in July and August 2023 and involved individuals aged ≥ 6 months from five villages in Kyerwa district. Demographic, anthropometric, clinical, parasitological, type of house inhabited and socio-economic status (SES) data were collected using electronic capture tools run on Open Data Kit (ODK) software. Predictors/risks of malaria infections were determined by univariate and multivariate logistic regression, and the results were presented as crude (cORs) and adjusted odds ratios (aORs), with 95% confidence intervals (CIs). RESULTS: Overall, 4454 individuals were tested using rapid diagnostic tests (RDTs), and 1979 (44.4%) had positive results. The prevalence of malaria infections ranged from 14.4% to 68.5% and varied significantly among the villages (p < 0.001). The prevalence and odds of infections were significantly higher in males (aOR = 1.28, 95% CI 1.08 -1.51, p = 0.003), school children (aged 5-≤10 years (aOR = 3.88, 95% CI 3.07-4.91, p < 0.001) and 10-≤15 years (aOR = 4.06, 95% CI 3.22-5.13, p < 0.001)) and among individuals who were not using bed nets (aOR = 1.22, 95% CI 1.03-1.46, p = 0.024). The odds of malaria infections were also higher in individuals with lower SES (aOR = 1.42, 95% CI 1.17-1.72, p < 0.001), and living in houses without windows (aOR = 2.08, 95% CI 1.46-2.96, p < 0.001), partially open (aOR = 1.33, 95% CI 1.11-1.58, p = 0.002) or fully open windows (aOR = 1.30, 95%CI 1.05-1.61, p = 0.015). CONCLUSION: The five villages had a high prevalence of malaria infections and heterogeneity at micro-geographic levels. Groups with higher odds of malaria infections included school children, males, and individuals with low SES, living in poorly constructed houses or non-bed net users. These are important baseline data from an area with high prevalence of parasites with ART-R and will be useful in planning interventions for these groups, and in future studies to monitor the trends and potential spread of such parasites, and in designing a response to ART-R.

Trends of Plasmodium falciparum molecular markers associated with resistance to artemisinins and reduced susceptibility to lumefantrine in Mainland Tanzania from 2016 to 2021.

BACKGROUND: Therapeutic efficacy studies (TESs) and detection of molecular markers of drug resistance are recommended by the World Health Organization (WHO) to monitor the efficacy of artemisinin-based combination therapy (ACT). This study assessed the trends of molecular markers of artemisinin resistance and/or reduced susceptibility to lumefantrine using samples collected in TES conducted in Mainland Tanzania from 2016 to 2021. METHODS: A total of 2,015 samples were collected during TES of artemether-lumefantrine at eight sentinel sites (in Kigoma, Mbeya, Morogoro, Mtwara, Mwanza, Pwani, Tabora, and Tanga regions) between 2016 and 2021. Photo-induced electron transfer polymerase chain reaction (PET-PCR) was used to confirm presence of malaria parasites before capillary sequencing, which targeted two genes: Plasmodium falciparum kelch 13 propeller domain (k13) and P. falciparum multidrug resistance 1 (pfmdr1). RESULTS: Sequencing success was ≥ 87.8%, and 1,724/1,769 (97.5%) k13 wild-type samples were detected. Thirty-seven (2.1%) samples had synonymous mutations and only eight (0.4%) had non-synonymous mutations in the k13 gene; seven of these were not validated by the WHO as molecular markers of resistance. One sample from Morogoro in 2020 had a k13 R622I mutation, which is a validated marker of artemisinin partial resistance. For pfmdr1, all except two samples carried N86 (wild-type), while mutations at Y184F increased from 33.9% in 2016 to about 60.5% in 2021, and only four samples (0.2%) had D1246Y mutations. pfmdr1 haplotypes were reported in 1,711 samples, with 985 (57.6%) NYD, 720 (42.1%) NFD, and six (0.4%) carrying minor haplotypes (three with NYY, 0.2%; YFD in two, 0.1%; and NFY in one sample, 0.1%). Between 2016 and 2021, NYD decreased from 66.1% to 45.2%, while NFD increased from 38.5% to 54.7%. CONCLUSION: This is the first report of the R622I (k13 validated mutation) in Tanzania. N86 and D1246 were nearly fixed, while increases in Y184F mutations and NFD haplotype were observed between 2016 and 2021. Despite the reports of artemisinin partial resistance in Rwanda and Uganda, this study did not report any other validated mutations in these study sites in Tanzania apart from R622I suggesting that intensified surveillance is urgently needed to monitor trends of drug resistance markers and their impact on the performance of ACT.

CYP2B6 and ABCB1 genotypes predict methadone plasma exposure among patients on maintenance therapy against opioid addictions in Tanzania.

AIMS: Methadone maintenance therapy (MMT) exhibits significant variability in pharmacokinetics and clinical response, partly due to genetic variations. However, data from sub-Saharan African populations are lacking. We examined plasma methadone variability and pharmacogenetic influences among opioid-addicted Tanzanian patients. METHODS: Patients attending MMT clinics (n = 119) in Tanzania were genotyped for common functional variants of the CYP3A4, CYP3A5, CYP2A6, CYP2B6, CYP2C19, CYP2D6, ABCB1, UGT2B7 and SLCO1B1 genotypes. Trough plasma concentrations of total methadone, S-methadone (S-MTD) and R-methadone (R-MTD), with their respective metabolites, 2-ethylidene-1,5-dimethyl-3,3-diphenylpyrrolidine (EDDP), were quantified using liquid chromatography-tandem mass spectrometry (LC-MS/MS). The methadone-to-EDDP metabolic ratio (MMR) was used to categorize the phenotype. RESULTS: The proportions of MMR-predicted ultrarapid, extensive, intermediate and slow methadone metabolizer phenotypes were 2.5%, 58.2%, 23.7% and 15.6%, respectively. CYP2B6 genotype significantly correlated with S-methadone (P = .006), total methadone (P = .03), and dose-normalized methadone plasma concentrations (P = .001). Metabolic ratios of R-methadone (R-MTD/R-EDDP), S-methadone (S-MTD/S-EDDP), and total methadone (MMR) were significantly higher among patients homozygous for defective variants (*6 or *18) than heterozygous or CYP2B6*1/*1 genotypes (P < .001). The metabolic ratio for S-MTD and total methadone was significantly higher among ABCB1c.3435T/T than in the C/C genotype. No significant effect of CYP2D6, CYP2C19, CYP3A4, CYP3A5, CYP2A6, UGT2B7 and SLCO1B1 genotypes on S-methadone, R-methadone, or total methadone was observed. CONCLUSIONS: Approximately one in six opioid-addicted Tanzanian patients are methadone slow metabolizers, influenced by genetic factors. Both the CYP2B6 and ABCB1 genotypes are strong predictors of methadone metabolic capacity and plasma exposure. Further investigation is needed to determine their predictive value for methadone treatment outcomes and to develop genotype-based dosing algorithms for safe and effective therapy.

Socio-environmental predictors of diabetes incidence disparities in Tanzania mainland: a comparison of regression models for count data.

BACKGROUND: Diabetes is one of the top four non-communicable diseases that cause death and illness to many people around the world. This study aims to use an efficient count data model to estimate socio-environmental factors associated with diabetes incidences in Tanzania mainland, addressing lack of evidence on the efficient count data model for estimating factors associated with disease incidences disparities. METHODS: This study analyzed diabetes counts in 184 Tanzania mainland councils collected in 2020. The study applied generalized Poisson, negative binomial, and Poisson count data models and evaluated their adequacy using information criteria and Pearson chi-square values. RESULTS: The data were over-dispersed, as evidenced by the mean and variance values and the positively skewed histograms. The results revealed uneven distribution of diabetes incidence across geographical locations, with northern and urban councils having more cases. Factors like population, GDP, and hospital numbers were associated with diabetes counts. The GP model performed better than NB and Poisson models. CONCLUSION: The occurrence of diabetes can be attributed to geographical locations. To address this public health issue, environmental interventions can be implemented. Additionally, the generalized Poisson model is an effective tool for analyzing health information system count data across different population subgroups.