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Prevalence and risk factors associated with Sexually Transmitted Infections among women of reproductive age attending reproductive and child health clinics in Dodoma and Dar es Salaam Tanzania
(Tanzania Journal of Health Research, 2024-01) Senkoro, Rehesina H.
Introduction: Sexually transmitted infections (STIs) continue to cause reproductive morbidity worldwide. Socio-demographics and behaviour influence the likelihood of contracting reproductive tract infections and significantly predict STI acquisition. Determining prevalence and analysing the population’s socio-demographic and sexual behaviour can assist in determining its risk profile and prevention strategies. This study aimed to determine the prevalence and risk factors of curable STIs, bacterial vaginosis and vaginal candidiasis among women of reproductive age attending reproductive and maternal health clinics in Dar es Salaam and Dodoma.Method:This was a cross-sectional study where high vaginal and endocervical swabs from 400 women were collected and tested for the presence of reproductive tract infections using culture, wet mount preparation, and Gram stain.Women were interviewed on sociodemographic factors, sexual behaviours and clinical symptoms using a pretested questionnaire. Achi-squaretest was conducted to determine the factors associated with curable STIs. Logistic regression was done to determine independent predictors for STIs using SPSS version 23. Results:Prevalence of Neisseria gonorrhoea, Trichomonas vaginalis, vaginal candidiasis and bacterial vaginosis was 2.5%,9.8%,13.5%, and 23.3% respectively. High education level was associated with a reduction in the likelihood of having STIs (AOR=0.41, 95%CI: 0.17-0.97). Likewise,consistent condom use was associated with a reduction in the likelihood of having STIs (AOR=0.16, 95% CI: (0.073-0.34). Participants with the recent history of STI were more likely to have STIs (AOR=2.4, 95%CI:1.05-5.27). Conclusion:High prevalence of Trichomonas vaginalis,bacterial vaginosis and vaginal candidiasis in studied women calls for an intervention to prevent infection complications. We recommend health education and screening interventions to all reproductive-age women to reduce transmission of curable STIs and bacterial vaginosis. Keywords: STIs, prevalence, reproductive age women, Tanzania
Efficacy of artesunate-amodiaquine for treatment of uncomplicated Plasmodium falciparum malaria in mainland Tanzania.
(Malaria Journal, 2024-03-29) Mwaiswelo, Richard O.
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
(Scientific Reports, 2024-01-25) Mwaiswelo, Richard O.
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
(Frontiers in Public Health, 2023-02-14) Mwaiswelo, Richard O.
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 x2 = 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 x2 = 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
(BMC medicine, 2022-09-16) Mwaiswelo, Richard O.
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.
Anemia and co-infection of P. falciparum and hookworm among school children in Kinondoni district Dar es Salaam Tanzania
(International Journal of Science and Research, 2019) Senkoro, Rehesina H.; Kabalimu, Titus K.
This was a cross-sectional study conducted in Kinondoni district from January to June 2015. The aim of the study was to determine the prevalence of co-infection of malaria and hookworm plus anemia in school-aged children. Stool and blood samples were collected from 332 children aged 6-14 years. Hemoglobin concentration (Hb) was determined by using portable HaemoCue. Giemsa- stained blood film was examined to detect malaria parasites while Kato Katz technique was used to detect hookworm ova. The Pearson’s chi-square, Student’s T-test, and Multivariate analysis were performed using SPSS version 20. The prevalence of malaria, hookworm, co-infection, and anemia were 13.5% 27.7% 7.5% and 22% respectively. The mean Hb was 10.51 g/dl (±1.31). Mean Hb in co-infected children was low compared to those with a single infection. The prevalence of co-infection was high among 6-11 years. Ascaris lumbricoides was another parasite that was isolated in this study. This study showed that anaemia, malaria and hookworm co-infection are prevalent in school-aged children and an intervention to address the rate of malaria, hookworm, and anemia in the study area should be considered.
Nutritional status of children under five years old involved in a seasonal malaria chemoprevention study in the Nanyumbu and Masasi districts in Tanzania
(PloS one, 2022-04-29) Mwaiswelo, Richard O.
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.
Evaluation of residual submicroscopic Plasmodium falciparum parasites 3 days after initiation of treatment with artemisinin-based combination therapy.
(Malaria Journal, 2020) Mwaiswelo, Richard O.
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.
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
(Malaria journal, 2016) Mwaiswelo, Richard O.
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.
Sickle cell disease and malaria: decreased exposure and asplenia can modulate the risk from Plasmodium falciparum
(Malaria Journal, 2020) Mwaiswelo, Richard O.
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.
Sustained High Cure Rate of Artemether–Lumefantrine against Uncomplicated Plasmodium falciparum Malaria after 8 Years of Its Wide-Scale Use in Bagamoyo District, Tanzania
(The American Journal of Tropical Medicine and Hygiene, 2017) Mwaiswelo, Richard O.
Abstract. 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 (χ2 trend 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.
Efficacy of Single-Dose Primaquine With Artemisinin Combination Therapy on Plasmodium falciparum Gametocytes and Transmission: An Individual Patient Meta-Analysis.
(Journal of Infectious Disease, 2020) Mwaiswelo, Richard O.
Background Since the World Health Organization recommended single low-dose (0.25 mg/kg) primaquine (PQ) in combina-tion with artemisinin-based combination therapies (ACTs) in areas of low transmission or artemisinin-resistant Plasmodium falcip-arum, 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 combina-tion with different ACTs was conducted. Random effects logistic regression was used to quantify PQ effect on (1) gametocyte car-riage 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 ap-parently 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 associ-ated 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. Keywords. single low-dose primaquine; Plasmodium falciparum; gametocytemia.
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
(International Journal of Infectious Diseases, 2020) Mwaiswelo, Richard O.
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.
Occurrence of day 3 submicroscopic plasmodium falciparum parasitaemia before and after implementation of artemether-lumefantrine treatment policy in Tanzania.
(BMJ Global Health, 2017) Mwaiswelo, Richard O.
Background Emergence ofPlasmodium falciparumresistanceagainst artemisinin in Southeast Asia raises a serious concernabout the long-term efficacy of artemisinin-based combinationtherapy (ACT) globally. In Africa, ACT has remained highlyefficacious with a microscopy determined asexual parasites clear-ance occurring within 48 hours post-treatment in most patients.However, submicroscopic parasitaemia has been reported onDay 3 after ACT treatment. We assessed the prevalence ofpatients with submicroscopic parasitaemia on Day 3 and its asso-ciated factors following treatment with artemether-lumefantrine(AL) from 2006 to 2014 in Bagamoyo district, Tanzania.MethodsCytochrome b-nested polymerase chain reaction(PCR) was used for screening of submicroscopic parasitaemiafrom blood samples collected onfilter paper on Day 3 post-ALtreatment for acute uncomplicatedP. falciparummalaria.Primary outcome was proportion of patients with submicro-scopic parasitaemia on Day 3 from 2006 to 2014. Secondaryoutcomes included proportional difference in submicroscopicparasitaemia across years, association of pre-treatment character-istics with submicroscopic parasitaemia, and association of sub-microscopic parasitaemia with recurrent infection ResultsOnly 2/584 (0.34%) of the screened patients hadmicroscopy determined parasitaemia on Day 3, whereas, 256/584 (43.8%) had submicroscopic parasitaemia. Submicroscopicparasitaemia prevalence increased from 28% (14/50) in 2006 to74.2% (132/178) in 2007–8, and thereafter declined to 36%(50/139) in 2012–13 and 27.6% (60/217) in 2014, with thelikelihood of being positive for submicroscopic parasitaemiadecreasing by 14.7% (95% CI: 9.5–19.7%, p<0.001) for anincrease in year by one. Pre-treatment parasitaemia >100,000/mL, haemoglobin <10 g/dL, fever, being aged <5 years andyear of study 2007–8 and 2012–13 were associated with thepresence of submicroscopic parasitaemia. There was no associ-ation between submicroscopic parasitaemia and recurrentinfection.ConclusionsDay 3 submicroscopic parasitaemia was commonin patients treated with AL before and after implementation ofthe policy, and changed considerably across years from 2006 to2014, however, its presence was associated with pre-treatmentcharacteristics.
Malaria infection and anemia status in under-five children from Southern Tanzania where seasonal malaria chemoprevention is being implemented.
(PloS one, 2021) Mwaiswelo, Richard O.
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.
Is it time for Africa to adopt primaquine in the era of malaria control and elimination?
(Tropical Medicine and Health, 2022-02-25) Mwaiswelo, Richard O.; Kabuga, Hamis
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. falci-parum 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”, “pri-maquine”, “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 administra-tion of SLD primaquine. Available evidence shows that the WHO-recommended SLD primaquine dose added to effec-tive 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.
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.
(Malaria Journal, 2022-03-12) Mwaiswelo, Richard O.
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.
Sex Bias and Effect of Glutathione S-Transferase Mu1 and Theta 1 genotypes in Drug Resistance Tuberculosis
(African Journal of Applied Research, 2021) Mayanda, Ashura; Sylvester, Boniphace
Purpose: Genotypes of human Glutathione S-Transferase Mu1 (GSTM1) and Theta 1 (GSTT1) have been reported to associate with drug resistance in cancer patients and also reported to influence the severity of malaria. This work aims to assess the effect of sex and human glutathione transferase null genotypes on TB drug resistance. The objectives were to determine the association between sex and TB drug resistance and to find the association of Glutathione null genotypes with TB Drug resistance. Design/Methodology/ Approach: A total of 81 TB patients on treatment were purposively recruited in a hospital-based cross-sectional study. Among them 41% (n= 33) were known DRTB patients (cases) while 59% (n=48) were non-resistance Tb patients (control). Data on genotypes of human GST Mu1 and Theta1 were generated using conventional polymerase chain reaction (PCR). Descriptive statistics were used to determine the frequency distribution of the genotypes. The association of sex of research participants and human GST Mu 1 and Theta 1 genotypes with drug resistance to DR-TB were analyzed using a binary logistic regression model at a confidence level of 95% and the significance of results were judged at p-value less than 0.05 . Findings: Sex of patients significantly associated with increased risk to DR-TB (OR 5.51, 95% CI: 1.88-16.17, P= 0.002) while GSTM1 and GSTT1 genotypes did not statistically associate with drug resistance in tuberculosis (P=0.418). Frequencies of GSTM1, GSTT1 and combined GSTM1/GST1 null genotypes were higher in DR-TB patients (39.4%, 42.4% and 21.21% respectively) against (31.3%, 39.6% and 12.5%, respectively) in controls. Sex of TB patients significantly associated with Drug resistance Tuberculosis while GSTT1 and M1 genotypes did not associate with DR-TB. Research Limitation/Implication: This study has therefore explored the effect of human GSTs and the association of gender with drug-resistant tuberculosis. Practical Implications: Sex is an important factor to consider in the management of MDR-TB patients. Originality/ Value: Understanding the association of sex and human genetic factors associated with drug resistance to tuberculosis is also an important way of controlling the disease.
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
(The American journal of tropical medicine and hygiene, 2019) Mwaiswelo, Richard O.
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.
Studies on Spore Germination and Early Development in Stoechospermum marginatum (C Ag ) Kütz. (Phaeophyta, Dictyotales)
(Botanica Marina, 1979) Mshigeni, Keto E.
Abstract Investigations were conducted on the germination of tetraspores of the intertidal seaweed Stoechospermummarginatum (C. Ag.) Kutz. The influence of light on the polarity of the spores was also studied, and preliminarystudies were carried out on the response of the germlings to different salinities. A wide range in tetraspore size was observed. After the first cell division one cell developed into a rhizoid, and the other into a mass of cells, the central nodule, from which a primary shoot with a single apical cell arose. This shoot developed into a broad and flat structure, which subsequently branched dichotomously. Secondary shoots were formed in two ways: from the central nodule and from the primary rhizoid. The spores showed light induced polarity. Very high and very low salinities were not tolerated.

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