Efficacy of artesunate-amodiaquine for treatment of uncomplicated Plasmodium falciparum malaria in mainland Tanzania.

BACKGROUND: Diversification of artemisinin-based combination therapy (ACT) is suggested as one of the strategies that can be used to contain artemisinin resistance. Artesunate-amodiaquine (ASAQ) is one of the artemisinin-based combinations that can be used in the diversification strategy as an alternative first-line treatment for uncomplicated malaria in mainland Tanzania. There is however limited data on the efficacy of ASAQ in mainland Tanzania. This study assessed the efficacy of ASAQ for treatment of uncomplicated Plasmodium falciparum malaria in selected sentinel sites for therapeutic efficacy studies in mainland Tanzania. METHODS: Between December 2018 and March 2020, children aged between 6 months and 10 years, attending at Nagaga, Mkuzi, and Mlimba primary health facilities, and with suspected uncomplicated malaria infection were screened for eligibility to participate in the study. Malaria infection was screened using microscopy. Children with uncomplicated P. falciparum monoinfection and who fulfilled all other inclusion criteria, and had none of the exclusion criteria, according to the World Health Organization (WHO) guidelines, were treated with ASAQ. Follow-up visits were scheduled on days 0, 1, 2, 3, 7, 14, 21, and 28 or on any day of recurrent infection for clinical and laboratory assessment. Polymerase chain reaction (PCR)-corrected cure rate on day 28 was the primary outcome. RESULTS: A total of 264 children, 88 in each of the three study sites (Mlimba, Mkuzi and Nagaga health facilities) were enrolled and treated with ASAQ. The ASAQ PCR-corrected cure rate was 100% at all the three study sites. None of the participants had early treatment failure or late clinical failure. Furthermore, none of the participants had a serious adverse event. CONCLUSION: ASAQ was highly efficacious for the treatment of uncomplicated P. falciparum malaria in mainland Tanzania, therefore, it can be deployed as an alternative first-line treatment for uncomplicated malaria as part of diversification strategy to contain the spread of partial artemisinin resistance in the country.

Dihydroartemisinin-piperaquine effectiveness for seasonal malaria chemoprevention in settings with extended seasonal malaria transmission in Tanzania.

Effectiveness of dihydroartemisinin-piperaquine (DP) as seasonal malaria chemoprevention (SMC) was assessed in Nanyumbu and Masasi Districts. Between March and June 2021, children aged 3-59 months were enrolled in a cluster randomized study. Children in the intervention clusters received a monthly, 3-days course of DP for three consecutive months regardless of malaria infection status, and those in the control clusters received no intervention. Malaria infection was assessed at before the first-round and at 7 weeks after the third-round of DP in both arms. Malaria prevalence after the third-round of DP administration was the primary outcome. Chi-square tests and logistic regression model were used to compare proportions and adjust for explanatory variables. Before the intervention, malaria prevalence was 13.7% (161/1171) and 18.2% (212/1169) in the intervention and control clusters, respectively, p < 004. Malaria prevalence declined to 5.8% (60/1036) in the intervention clusters after three rounds of DP, and in the control clusters it declined to 9.3% (97/1048), p = 0.003. Unadjusted and adjusted prevalence ratios between the intervention and control arms were 0.42 (95%CI 0.32-0.55, p < 0.001) and 0.77 (95%CI 0.53-1.13, p = 0.189), respectively. SMC using DP was effective for control of malaria in the two Districts.Trial registration: NCT05874869, https://clinicaltrials.gov/ 25/05/2023.

Malaria knowledge, attitude, and practice among communities involved in a seasonal malaria chemoprevention study in Nanyumbu and Masasi districts, Tanzania.

Background: Utilization of malaria interventions is influenced by, among other things, the level of knowledge and attitude that the community has toward the infection as well as the available interventions. This study assessed malaria knowledge, attitudes, and practices on malaria infection and interventions in Masasi and Nanyumbu districts, Tanzania. Methods: A community-based cross-sectional survey was conducted between August and September 2020, among the heads of households having at least one under-five child. Information on knowledge, attitudes, and practices on malaria infection and interventions was gathered from the heads of the households using a structured questionnaire. The knowledge level was classified into low, moderate, and high. Attitudes were classified into positive and negative, whereas the practices were classified into good and poor. Children aged between 3 and 59 months were screened for malaria infection using a malaria rapid diagnostic test (mRDT). The proportion of the households' heads with high level of knowledge was the primary outcome. Proportions were compared using Chi-square or fisher's test, and logistic regression analysis was used as appropriate. Results: A total of 1,556 household heads were interviewed, 1,167 (75.00%) were male, and according to marital status, 1,067 (68.57%) were couples. All the household heads had some knowledge of malaria, but 47.33% (736/1,555) and 13.83% (215/1,555) of them had moderate and high knowledge, respectively. The level of knowledge on malaria was significantly influenced by gender [adjusted odds ratio (aOR) = 0.72, 95.00% confidence interval (CI) = 0.56-0.94, p = 0.017], level of education (aOR = 1.50, 95.00% CI = 1.04-2.16, p = 0.03), and the occupation of the household head (aOR = 1.90, 95.00% CI = 1.22-2.96, p = 0.004). Majority of the households [83.87% (1,305/1,556)] had bed nets hanging on the sleeping spaces. Of the household heads possessing bed nets, 85.10% (514/604), 79.62% (586/736), and 95.35% (205/215) of them had a low, moderate, and high level of knowledge on malaria infection, respectively (trend x 2 = 31.53, p < 0.001). The majority [95.04% (1,474/1,551)] of the household heads perceived sleeping under the bed net to be beneficial. Furthermore, 15.56% (94/604), 14.67% (108/736), and 7.44% (16/215) of the household heads with low, moderate, and high knowledge, respectively, had children with malaria infection (trend x 2 = 9.172, p = 0.01). Conclusion: The study population had a good level of knowledge about malaria infection, and a good attitude toward malaria interventions, and the majority of them were using bed nets.

Safety of single-dose primaquine as a Plasmodium falciparum gametocytocide: a systematic review and meta-analysis of individual patient data.

BACKGROUND: In 2012, the World Health Organization (WHO) recommended single low-dose (SLD, 0.25 mg/kg) primaquine to be added as a Plasmodium (P.) falciparum gametocytocide to artemisinin-based combination therapy (ACT) without glucose-6-phosphate dehydrogenase (G6PD) testing, to accelerate malaria elimination efforts and avoid the spread of artemisinin resistance. Uptake of this recommendation has been relatively slow primarily due to safety concerns. METHODS: A systematic review and individual patient data (IPD) meta-analysis of single-dose (SD) primaquine studies for P. falciparum malaria were performed. Absolute and fractional changes in haemoglobin concentration within a week and adverse effects within 28 days of treatment initiation were characterised and compared between primaquine and no primaquine arms using random intercept models. RESULTS: Data comprised 20 studies that enrolled 6406 participants, of whom 5129 (80.1%) had received a single target dose of primaquine ranging between 0.0625 and 0.75 mg/kg. There was no effect of primaquine in G6PD-normal participants on haemoglobin concentrations. However, among 194 G6PD-deficient African participants, a 0.25 mg/kg primaquine target dose resulted in an additional 0.53 g/dL (95% CI 0.17-0.89) reduction in haemoglobin concentration by day 7, with a 0.27 (95% CI 0.19-0.34) g/dL haemoglobin drop estimated for every 0.1 mg/kg increase in primaquine dose. Baseline haemoglobin, young age, and hyperparasitaemia were the main determinants of becoming anaemic (Hb < 10 g/dL), with the nadir observed on ACT day 2 or 3, regardless of G6PD status and exposure to primaquine. Time to recovery from anaemia took longer in young children and those with baseline anaemia or hyperparasitaemia. Serious adverse haematological events after primaquine were few (9/3, 113, 0.3%) and transitory. One blood transfusion was reported in the primaquine arms, and there were no primaquine-related deaths. In controlled studies, the proportions with either haematological or any serious adverse event were similar between primaquine and no primaquine arms. CONCLUSIONS: Our results support the WHO recommendation to use 0.25 mg/kg of primaquine as a P. falciparum gametocytocide, including in G6PD-deficient individuals. Although primaquine is associated with a transient reduction in haemoglobin levels in G6PD-deficient individuals, haemoglobin levels at clinical presentation are the major determinants of anaemia in these patients. TRIAL REGISTRATION: PROSPERO, CRD42019128185.

Nutritional status of children under five years old involved in a seasonal malaria chemoprevention study in the Nanyumbu and Masasi districts in Tanzania.

BACKGROUND: Malnutrition and malaria are common co-morbidities in low-income countries, especially among under-fives children. But the malnutrition situation in Masasi and Nanyumbu districts, its interaction with malaria infection and the influence of socioeconomic factors are not well understood. METHODS: Children aged between 3-59 months in Masasi and Nanyumbu were screened for nutritional status and malaria infection in the community. Nutritional status was determined using age and anthropometric parameters. Z-scores (weight for age (WAZ), height for age (HAZ) and weight for height (WHZ)) were calculated based on the World Health Organisation (WHO) growth reference curves. Malaria infection was determined using malaria rapid diagnostic test and microscopy. Hemoglobin concentration was assessed using HemoCue spectrophotometer, and anemia was classified as hemoglobin concentration < 11.0g/dL. Structured questionnaire was used to collect socio- demographic information electronically. RESULTS: A total of 2242 children, 1539 (68.6%) from Masasi and 1169 (52.1%) females were involved in the study. The mean z-scores (WAZ = -0.60 and HAZ = -1.56) were lower than the WHO reference population. The overall prevalence of malnutrition was 49%, and it was significantly higher in Nanyumbu (52.5%) than in Masasi (47.3%), (x2 = 5.045, p = 0.025). Prevalence of malnutrition was higher in boys (53.0%) than in girls (45.0%) (x2 = 13.9, p < 0.001). Stunting was the most prevalent component of undernutrition; it was slightly prevalent in Nanyumbu (46.5%) compared to Masasi (42.0%), (x2 = 3.624, p = 0.057) and in boys (48.2%) than in girls (39.1%), x2 = 17.44, p<0.001. Only 15.8% of the undernourished children had malaria infection. Sex, age group and anaemia were significantly associated with undernourishment (p<0.05), while district and malaria infection were marginally (p≤0.06) associated with undernourishment. None of the undernutrition indices was associated with malaria infection. CONCLUSION: Undernutrition was highly prevalent in the study population and was influenced sex, age, anaemia and malaria infection. More emphasis is needed to address the malnutrition problem especially stunting in Masasi and Nanyumbu districts.

A single low dose of primaquine is safe and sufficient to reduce transmission of Plasmodium falciparum gametocytes regardless of cytochrome P450 2D6 enzyme activity in Bagamoyo district, Tanzania.

BACKGROUND: Primaquine is a pro-drug and its active metabolite is potent against mature Plasmodium falciparum gametocytes. Primaquine is metabolized by a highly polymorphic cytochrome P450 2D6 (CYP2D6) enzyme. Mutations in the gene encoding this enzyme may lead to impaired primaquine activity. This study assessed if 0.25 mg/kg single-dose primaquine is safe and sufficient to reduce transmission of gametocytes in individuals with no, reduced, or increased CYP2D6 enzyme activity. METHODS: Between June 2019 and January 2020 children aged 1-10 years, attending at Yombo dispensary, Bagamoyo district, with confirmed microcopy-determined uncomplicated P. falciparum malaria were enrolled in the study. The enrolled patients were treated with a standard artemether-lumefantrine regimen plus 0.25 mg/kg single-dose primaquine and followed up for 28 days for clinical and laboratory assessment. Primaquine was administered with the first dose of artemether-lumefantrine. Safety assessment involved direct questioning and recording of the nature and incidence of clinical signs and symptoms, and measurement of haemoglobin (Hb) concentration. Blood samples collected from 100 patients were used for assessment of post-treatment infectiousness on day 7 using mosquito membrane feeding assays. Molecular methods were used to determine CYP2D6 and glucose-6-phosphate dehydrogenase (G6PD) status. The primary outcome was the safety of 0.25 mg/kg single-dose primaquine based on CYP2D6 status. RESULTS: In total, 157 children [median age 6.4 (Interquartile range 4.0-8.2) years] were recruited, of whom 21.0% (33/157) and 12.7% (20/157) had reduced CYP2D6 and deficient G6PD activity, respectively. Day 3 mean absolute Hb concentration reduction was 1.50 g/dL [95% confidence interval (CI) 1.10-1.90] and 1.51 g/dL (95% CI 1.31-1.71) in reduced and normal CYP2D6 patients, respectively (t = 0.012, p = 0.990). The day 3 mean absolute Hb concentration reduction in G6PD deficient, G6PD normal and heterozygous female was 1.82 g/dL (95% CI 1.32-2.32), 1.48 g/dL (95% CI 1.30-1.67) and 1.47 g/dL (95% CI 0.76-2.18), respectively (F = 0.838, p = 0.435). Sixteen percent (16/98) of the patients each infected at least one mosquito on day 7, and of these, 10.0% (2/20) and 17.9% (14/78) had reduced and normal CYP2D6 enzyme activity, respectively (x2 = 0.736, p = 0.513). CONCLUSION: Single-dose 0.25 mg/kg primaquine was safe and sufficient for reducing transmission of P. falciparum gametocytes regardless of CYP2D6 or G6PD status. Trial registration Study registration number: NCT03352843.

Is it time for Africa to adopt primaquine in the era of malaria control and elimination?

Primaquine is a gametocytocidal drug known to significantly reduce malaria transmission. However, primaquine induces a dose-dependent acute hemolytic anemia (AHA) in individuals with glucose-6-phosphate dehydrogenase (G6PD) deficiency that has led to a limited use of the drug especially in Africa where the condition is common. The World Health Organization (WHO) now recommends a single low dose (SLD) of primaquine (0.25 mg/kg) as P. falciparum gametocytocidal without the need for prior screening of G6PD status. Adoption and implementation of SLD primaquine in Africa may probably reduce malaria transmission, a pre-requisite for malaria elimination. This review therefore, focused on the safety of primaquine for control of malaria in Africa. The literature search was performed using online database Google Scholar, PubMed, HINARI, and Science Direct. Search terms used were "malaria", "primaquine", "safety", "G6PD deficiency", "large scale" or "mass administration". Clinical trials in many African countries have shown SLD primaquine to be safe especially in a milder African G6PD A- variant. Likewise, large-scale primaquine administrations outside Africa involving hundreds of thousands to tenths of millions of participants and with severe variants of G6PD deficiency have also shown primaquine to be safe and well-tolerated. Fourteen deaths associated with primaquine have been reported globally over the past 6 decades, but none occurred following the administration of SLD primaquine. Available evidence shows that the WHO-recommended SLD primaquine dose added to effective schizonticides is safe and well-tolerated even in individuals with G6PD deficiency, and therefore, it can be safely used in the African population with the mildest G6PD A- variant.

Efficacy of Single-Dose Primaquine With Artemisinin Combination Therapy on Plasmodium falciparum Gametocytes and Transmission: An Individual Patient Meta-Analysis.

BACKGROUND: Since the World Health Organization recommended single low-dose (0.25 mg/kg) primaquine (PQ) in combination with artemisinin-based combination therapies (ACTs) in areas of low transmission or artemisinin-resistant Plasmodium falciparum, several single-site studies have been conducted to assess efficacy. METHODS: An individual patient meta-analysis to assess gametocytocidal and transmission-blocking efficacy of PQ in combination with different ACTs was conducted. Random effects logistic regression was used to quantify PQ effect on (1) gametocyte carriage in the first 2 weeks post treatment; and (2) the probability of infecting at least 1 mosquito or of a mosquito becoming infected. RESULTS: In 2574 participants from 14 studies, PQ reduced PCR-determined gametocyte carriage on days 7 and 14, most apparently in patients presenting with gametocytemia on day 0 (odds ratio [OR], 0.22; 95% confidence interval [CI], .17-.28 and OR, 0.12; 95% CI, .08-.16, respectively). Rate of decline in gametocyte carriage was faster when PQ was combined with artemether-lumefantrine (AL) compared to dihydroartemisinin-piperaquine (DP) (P = .010 for day 7). Addition of 0.25 mg/kg PQ was associated with near complete prevention of transmission to mosquitoes. CONCLUSIONS: Transmission blocking is achieved with 0.25 mg/kg PQ. Gametocyte persistence and infectivity are lower when PQ is combined with AL compared to DP.

Malaria infection and anemia status in under-five children from Southern Tanzania where seasonal malaria chemoprevention is being implemented.

BACKGROUND: Malaria and anemia remain major public health challenges in Tanzania. Household socioeconomic factors are known to influence these conditions. However, it is not clear how these factors influence malaria transmission and anemia in Masasi and Nanyumbu Districts. This study presents findings on malaria and anemia situation in under-five children and its influencing socioeconomic factors in Masasi and Nanyumbu Districts, surveyed as part of an ongoing seasonal malaria chemoprevention operational study. METHODS: A community-based cross-sectional survey was conducted between August and September 2020. Finger-prick blood samples collected from children aged 3-59 months were used to test for malaria infection using malaria rapid diagnostic test (mRDT), thick smears for determination of asexual and sexual parasitemia, and thin smear for parasite speciation. Hemoglobin concentration was measured using a HemoCue spectrophotometer. A structured questionnaire was used to collect household socioeconomic information from parents/caregivers of screened children. The prevalence of malaria was the primary outcome. Chi-square tests, t-tests, and logistic regression models were used appropriately. RESULTS: Overall mRDT-based malaria prevalence was 15.9% (373/2340), and was significantly higher in Nanyumbu (23.7% (167/705) than Masasi District (12.6% (206/1635), p<0.001. Location (Nanyumbu), no formal education, household number of people, household number of under-fives, not having a bed net, thatched roof, open/partially open eave, sand/soil floor, and low socioeconomic status were major risks for malaria infection. Some 53.9% (1196/2218) children had anemia, and the majority were in Nanyumbu (63.5% (458/705), p<0.001. Location (Nanyumbu), mRDT positive, not owning a bed net, not sleeping under bed net, open/partially open eave, thatched window, sex of the child, and age of the child were major risk factors for anemia. CONCLUSION: Prevalence of malaria and anemia was high and was strongly associated with household socioeconomic factors. Improving household socioeconomic status is expected to reduce the prevalence of the conditions in the area.

Sickle cell disease and malaria: decreased exposure and asplenia can modulate the risk from Plasmodium falciparum.

BACKGROUND: Patients with sickle cell disease (SCD), an inherited haemoglobinopathy, have increased risk of malaria, at least in part due to impaired splenic function. Infection with Plasmodium falciparum in SCD patients can trigger painful vaso-occlusive crisis, increase the severity of anaemia, and contribute to early childhood mortality. CASE PRESENTATION: A 17 year-old Tanzanian male with known SCD was admitted to Muhimbili National Hospital, a tertiary referral centre in Dar-es-Salaam, following an attack of malaria. From 2004 to 2007 the patient had lived in USA, and from 2010 to 2016 in France where, on account of hypersplenism and episodes of splenic sequestrations, in 2014 the spleen was removed. After appropriate clinical and laboratory assessment the patient was re-started on hydroxyurea; and anti-malarial-prophylaxis with proguanil was instituted. The patient has remained well and malaria-free for the following 15 months. CONCLUSION: SCD patients are highly vulnerable to malaria infection, and impaired splenic function is a feature of SCD patients, even in those who still anatomically have a spleen. This patient had a surgical splenectomy and, in addition, had probably lost some of the acquired malaria-immunity by having lived for several years in malaria-free areas. This patient is a compelling reminder that long-term anti-malarial prophylaxis should be offered to all patients with SCD who live in malaria-endemic areas.

Evaluation of residual submicroscopic Plasmodium falciparum parasites 3 days after initiation of treatment with artemisinin-based combination therapy.

Plasmodium falciparum resistance against artemisinin has not emerged in Africa; however, there are reports of the presence of polymerase chain reaction-determined residual submicroscopic parasitaemia detected on day 3 after artemisinin-based combination therapy (ACT). These residual submicroscopic parasites are thought to represent tolerant/resistant parasites against artemisinin, the fast-acting component of the combination. This review focused on residual submicroscopic parasitaemia, what it represents, and its significance on the emergence and spread of artemisinin resistance in Africa. Presence of residual submicroscopic parasitemia on day 3 after treatment initiation leaves question on whether successful treatment is attained with ACT. Thus there is a need to determine the potential public health implication of the PCR-determined residual submicroscopic parasitaemia observed on day 3 after ACT. Robust techniques, such as in vitro cultivation, should be used to evaluate if the residual submicroscopic parasites detected on day 3 after ACT are viable asexual parasites, or gametocytes, or the DNA of the dead parasites waiting to be cleared from the circulation. Such techniques would also evaluate the transmissibility of these residual parasites.

The usefulness of indirect diagnostic tests for Schistosoma haematobium infection after repeated rounds of mass treatment with praziquantel in Mpwapwa and Chakechake districts in Tanzania.

BACKGROUND: Indirect diagnostic tests are used to assess the disease burden and to monitor the impact of different interventions in areas endemic for urinary schistosomiasis. This study was performed to assess their accuracy in the diagnosis of urinary schistosomiasis among primary school children in low and moderate transmission areas in the districts of Mpwapwa and Chakechake, respectively. METHODS: School children were interviewed regarding their history of haematuria and participation in treatment campaigns. Urine samples were collected and inspected for macro-haematuria (visual haematuria) and tested for micro-haematuria using urine reagent strips and Schistosoma haematobium eggs by urine filtration method. RESULTS: The prevalence of S. haematobium was 6.8% in Mtera Dam area and 38.7% in Uwandani Shehia. In Mtera Dam area, a history of haematuria and visual haematuria had low sensitivity (<60%) with high specificity (>90%). The urine reagent strips had high sensitivity and specificity (≥75%). In Uwandani Shehia, a history of haematuria had high sensitivity and specificity (>60%). Visual haematuria had low sensitivity (<50%) but high specificity (>80%). The urine reagent strips maintained high performance in all parameters assessed. CONCLUSIONS: The study findings suggest that urine reagent strips will continue to serve as a very useful adjunct test for monitoring the prevalence of urinary schistosomiasis in endemic areas.

Anemia among Schoolchildren with Malaria and Soil-Transmitted Helminth Coinfections after Repeated Rounds of Mass Drug Administration in Muheza District, Tanzania.

Coinfections with malaria and soil-transmitted helminths (STHs) has been common among school-aged children in Tanzania. However, after a countrywide scaling up of interventions for malaria and STHs, there are limited data on the prevalence of malaria-STH coinfections and its effect on anemia in schoolchildren in Tanzania. We assessed the distribution and risk factors for malaria, STHs, and malaria-STH coinfections, and its relation to anemia among 445 primary schoolchildren in Muheza district. A semi-structured questionnaire was used to collect demographic characteristics of the children. Malaria rapid diagnostic test (mRDT) was used to diagnose malaria infection. Soil-transmitted helminths were diagnosed using the Kato-Katz technique. Primary outcome was anemia, defined as hemoglobin concentration < 11 g/dL. Chi-square (χ2) or Fisher's exact tests, Kruskal-Wallis or t-test, and logistic models were used as appropriate. Overall, the prevalence of malaria, STHs, malaria-STH coinfection, and anemia were 18.4%, 6.1%, 1.6%, and 19.8%, respectively. Anemic children were more likely to have malaria (adjusted odds ratio [aOR] = 4.538, 95% CI: 2.189-9.409), whereas frequent use of bed nets was associated with reduced risk of malaria (aOR = 0.234, 95% CI: 0.130-0.42). On the other hand, not always using latrines and eating raw uncooked food increased the risk of STH infection. The prevalence of anemia was high and was associated with both malaria and malaria-STH infections, therefore calling for more integrated malaria-STH control approaches to target school-aged children.

Diagnostic Performance of Malaria Rapid Diagnostic Test and Microscopy Compared with PCR for Detection of Plasmodium falciparum Infections among Primary Schoolchildren in Kibiti District, Eastern Tanzania: An Area with Moderate Malaria Transmission.

A substantial decline of malaria transmission intensity has been observed in sub-Saharan Africa over the past two decades and may affect the diagnostic performance of malaria rapid diagnostic test (mRDT) and microscopy. Diagnostic performance of histidine-rich protein II (HRP-II)/pan-lactate dehydrogenase (pLDH)-based mRDT and microscopy was evaluated against polymerase chain reaction (PCR) for the diagnosis of Plasmodium falciparum infection among 316 primary schoolchildren in Kibiti district, in 2016. Polymerase chain reaction detected more cases of P. falciparum infection than mRDT or microscopy. Using PCR as reference, the sensitivity and specificity of mRDT were 75.9% (95% CI = 62.8-86.1) and 96.9% (95% CI = 94.0-98.7), respectively, whereas that of microscopy were 63.8% (95% CI = 50.1-76.0) and 95.7% (95% CI = 92.5-97.9), respectively. Polymerase chain reaction and other molecular methods should be considered for use in schools and other epidemiological surveys as supplement to mRDT or microscopy.

Prevalence of and Risk Factors Associated with Polymerase Chain Reaction-Determined Plasmodium falciparum Positivity on Day 3 after Initiation of Artemether-Lumefantrine Treatment for Uncomplicated Malaria in Bagamoyo District, Tanzania.

Prevalence of and risk factors associated with polymerase chain reaction (PCR)-determined Plasmodium falciparum positivity were assessed on day 3 after initiation of treatment, pre-implementation and up to 8 years post-deployment of artemether-lumefantrine as first-line treatment for uncomplicated malaria in Bagamoyo district, Tanzania. Samples originated from previously reported trials conducted between 2006 and 2014. Cytochrome b-nested PCR was used to detect malaria parasites from blood samples collected on a filter paper on day 3. Chi-square and McNemar chi-squared tests, logistic regression models, and analysis of variance were used as appropriate. Primary outcome was based on the proportion of patients with day 3 PCR-determined P. falciparum positivity. Overall, 256/584 (43.8%) of screened patients had day 3 PCR-determined positivity, whereas only 2/584 (0.3%) had microscopy-determined asexual parasitemia. Day 3 PCR-determined positivity increased from 28.0% (14/50) in 2006 to 74.2% (132/178) in 2007-2008 and declined, thereafter, to 36.0% (50/139) in 2012-2013 and 27.6% (60/217) in 2014. When data were pooled, pretreatment microscopy-determined asexual parasitemia ≥ 100,000/µL, hemoglobin < 10 g/dL, age < 5 years, temperature ≥ 37.5°C, and year of study 2007-2008 and 2012-2013 were significantly associated with PCR-determined positivity on day 3. Significant increases in P. falciparum multidrug resistance gene 1 N86 and P. falciparum chloroquine resistant transporter K76 across years were not associated with PCR-determined positivity on day 3. No statistically significant association was observed between day 3 PCR-determined positivity and PCR-adjusted recrudescence. Day 3 PCR-determined P. falciparum positivity remained common in patients treated before and after implementation of artemether-lumefantrine in Bagamoyo district, Tanzania. However, its presence was associated with pretreatment characteristics. Trials registration numbers: NCT00336375, ISRCTN69189899, NCT01998295, and NCT02090036.

Sustained High Cure Rate of Artemether-Lumefantrine against Uncomplicated Plasmodium falciparum Malaria after 8 Years of Its Wide-Scale Use in Bagamoyo District, Tanzania.

We assessed the temporal trend of artemether-lumefantrine (AL) cure rate after 8 years of its wide-scale use for treatment of uncomplicated Plasmodium falciparum malaria from 2006 to 2014 in Bagamoyo district, Tanzania. Trend analysis was performed for four studies conducted in 2006, 2007-2008, 2012-2013, and 2014. Patients with acute uncomplicated P. falciparum malaria were enrolled, treated with standard AL regimen and followed-up for 3 (2006), 28 (2014), 42 (2012-2013), or 56 (2007-2008) days for clinical and laboratory evaluation. Primary outcome was day 28 polymerase chain reaction (PCR)-adjusted cure rate across years from 2007 to 2014. Parasite clearance was slower for the 2006 and 2007-2008 cohorts with less than 50% of patients cleared of parasitemia on day 1, but was rapid for the 2012-2013 and 2014 cohorts. Day 28 PCR-adjusted cure rate was 168/170 (98.8%) (95% confidence interval [CI], 97.2-100), 122/127 (96.1%) (95% CI, 92.6-99.5), and 206/207 (99.5%) (95% CI, 98.6-100) in 2007-2008, 2012-2013, and 2014, respectively. There was no significant change in the trend of cure rate between 2007 and 2014 (χ2trend test = 0.06, P = 0.90). Pretreatment P. falciparum multidrug-resistant gene 1 (Pfmdr1) N86 prevalence increased significantly across years from 13/48 (27.1%) in 2006 to 183/213 (85.9%) in 2014 (P < 0.001), and P. falciparum chloroquine resistance transporter gene (Pfcrt) K76 prevalence increased significantly from 24/47 (51.1%) in 2006 to 198/205 (96.6%) in 2014 (P < 0.001). The AL cure rate remained high after 8 years of its wide-scale use in Bagamoyo district for the treatment of uncomplicated P. falciparum malaria despite an increase in prevalence of pretreatment Pfmdr1 N86 and Pfcrt K76 between 2006 and 2014.

Adding a single low-dose of primaquine (0.25 mg/kg) to artemether-lumefantrine did not compromise treatment outcome of uncomplicated Plasmodium falciparum malaria in Tanzania: a randomized, single-blinded clinical trial.

BACKGROUND: The World Health Organization (WHO) recently recommended the addition of a single low-dose of the gametocytocidal drug primaquine (PQ) to artemisinin-based combination therapy (ACT) in low transmission settings as a component of pre-elimination or elimination programmes. However, it is unclear whether that influences the ACT cure rate. The study assessed treatment outcome of artemether-lumefantrine (AL) plus a single PQ dose (0.25 mg/kg) versus standard AL regimen for treatment of acute uncomplicated Plasmodium falciparum malaria in Tanzania. METHODS: A randomized, single-blinded, clinical trial was conducted in Yombo, Bagamoyo district, Tanzania. Acute uncomplicated P. falciparum malaria patients aged ≥1 year, with the exception of pregnant and lactating women, were enrolled and treated with AL plus a single PQ dose (0.25 mg/kg) or AL alone under supervision. PQ was administered together with the first AL dose. Clinical and laboratory assessments were performed at 0, 8, 24, 36, 48, 60, and 72 h and on days 7, 14, 21, and 28. The primary end-point was a polymerase chain reaction (PCR)-adjusted adequate clinical and parasitological response (ACPR) on day 28. Secondary outcomes included: fever and asexual parasitaemia clearance, proportion of patients with PCR-determined parasitaemia on day 3, and proportion of patients with Pfmdr1 N86Y and Pfcrt K76T on days 0, 3 and day of recurrent infection. RESULTS: Overall 220 patients were enrolled, 110 were allocated AL + PQ and AL, respectively. Parasite clearance by microscopy was fast, but PCR detectable parasitaemia on day 3 was 31/109 (28.4 %) and 29/108 (26.9 %) in patients treated with AL + PQ and AL, respectively (p = 0.79). Day 28 PCR-adjusted ACPR and re-infection rate was 105/105 (100 %) and 101/102 (99 %) (p = 0.31), and 5/107 (4.7 %) and 5/8 (4.8 %) (p = 0.95), in AL + PQ and AL arm, respectively. There was neither any statistically significant difference in the proportion of Pfmdr1 N86Y or Pfcrt K76T between treatment arms on days 0, 3 and day of recurrent infection, nor within treatment arms between days 0 and 3 or day 0 and day of recurrent infection. CONCLUSION: The new WHO recommendation of adding a single low-dose of PQ to AL did not compromise treatment outcome of uncomplicated P. falciparum malaria in Tanzania. Trial registration number NCT02090036.

Safety of a single low-dose of primaquine in addition to standard artemether-lumefantrine regimen for treatment of acute uncomplicated Plasmodium falciparum malaria in Tanzania.

BACKGROUND: This study assessed the safety of the new World Health Organization (WHO) recommendation of adding a single low-dose of primaquine (PQ) to standard artemisinin-based combination therapy (ACT), regardless of individual glucose-6-phosphate dehydrogenase (G6PD) status, for treatment of acute uncomplicated Plasmodium falciparum malaria in Tanzania. METHODS: Men and non-pregnant, non-lactating women aged ≥1 year with uncomplicated P. falciparum malaria were enrolled and randomized to either standard artemether-lumefantrine (AL) regimen alone or with a 0.25 mg/kg single-dose of PQ. PQ was administered concomitantly with the first AL dose. All drug doses were supervised. Safety was evaluated between days 0 and 28. G6PD status was assessed using rapid test (CareStart™) and molecular genotyping. The primary endpoint was mean percentage relative reduction in haemoglobin (Hb) concentration (g/dL) between days 0 and 7 by genotypic G6PD status and treatment arm. RESULTS: Overall, 220 patients, 110 per treatment arm, were enrolled, of whom 33/217 (15.2 %) were phenotypically G6PD deficient, whereas 15/110 (13.6 %) were genotypically hemizygous males, 5/110 (4.5 %) homozygous females and 22/110 (20 %) heterozygous females. Compared to genotypically G6PD wild-type/normal [6.8, 95 % confidence interval (CI) 4.67-8.96], only heterozygous patients in AL arm had significant reduction in day-7 mean relative Hb concentration (14.3, 95 % CI 7.02-21.55, p=0.045), however, none fulfilled the pre-defined haemolytic threshold value of ≥25 % Hb reduction. After adjustment for baseline parasitaemia, Hb, age and sex the mean relative Hb reduction was not statistically significant in both heterozygous and hemizygous/homozygous patients in both arms. A majority of the adverse events (AEs) were mild and unrelated to the study drugs. However, six (4.4 %) episodes, three per treatment arm, of acute haemolytic anaemia occurred between days 0 and 7. Three occurred in phenotypically G6PD deficient patients, two in AL and one in AL + PQ arm, but none in genotypically hemizygous/homozygous patients. All patients with acute haemolytic anaemia recovered without medical intervention. CONCLUSION: The findings support that the WHO recommendation of adding a single low-dose of PQ to standard AL regimen is safe for the treatment of acute uncomplicated P. falciparum malaria regardless of G6PD status in Tanzania. Trial registration number NCT02090036.