Therapeutic Efficacy of Sulfadoxine-Pyrimethamine and Prevalence of Resistance Markers in Tanzania Prior to Revision of Malaria Treatment Policy: Plasmodium Falciparum Dihydrofolate Reductase and Dihydropteroate Synthase Mutations in Monitoring in Vivo Resistance.

Prior to the 2001 malarial treatment policy change in Tanzania, we conducted trials to assess the efficacy of sulfadoxine-pyrimethamine (SP) and the usefulness of molecular markers in monitoring resistance. A total of 383 uncomplicated Plasmodium falciparum malaria patients (between 6 and 59 months old) were treated with SP and their responses were assessed. Mutations in the P. falciparum dihydrofolate reductase (pfdhfr) and dihydropteroate synthase (pfdhps) genes in admission day blood samples were analyzed. Results indicated that 85.6% of the patients showed an adequate clinical response, 9.7% an early treatment failure, and 4.7% a late treatment failure. The quintuple mutant genotype (pfdhfr 51 Ile, 59 Arg, and 108 Asn and pfdhps 437 Gly and 540 Glu) showed an association with treatment outcome (odds ratio = 2.1; 95% confidence interval = 0.94-4.48, P = 0.045). The prevalence of the triple pfdhfr mutant genotype (51 Ile, 59 Arg, and 108 Asn) at a site of high SP resistance (23.6%) was four times higher compared with that observed at sites of moderate SP resistance (6.8-14.4%) (P = 0.000001). The genotype failure index calculated by using this marker was invariable (1.96-2.1) at sites with moderate SP resistance, but varied (3.4) at a site of high SP resistance. In conclusion, our clinical and molecular findings suggest that SP may have a short useful therapeutic life in Tanzania; thus, its adoption as an interim first-line antimalarial drug. The findings also point to the potential of the triple pfdhfr mutant genotype as an early warning tool for increasing SP resistance. These data form the baseline SP efficacy and molecular markers profile in Tanzania prior to the policy change

Impact of insecticide treated mosquito nets and low dose monthly diethylcarbamazine on lymphatic filariasis infection between 1999 and 2004 in two endemic communities of north-eastern Tanzania

Lymphatic filariasis (LF) is among the poverty related neglected tropical diseases earmarked for elimination using mass drug administration (MDA) strategy. Additional use of insecticide treated mosquito nets (ITNs) might enhance elimination of LF infection. Between August 1998 and July 1999, all individuals aged ≥ 8 months from Magoda and Mpapayu villages in north-eastern Tanzania, were administered with monthly low dose diethylcarbamazine (DEC) at a dosage of 50mg in children aged < 15 years and 100mg in adults aged ≥ 15 years. ITNs were also distributed to Magoda in December 1998 and to Mpapayu in March 2001. The main objective of our study was to assess the impact of ITNs and low dose DEC on microfilaria (mf) prevalence and intensity and incidence of new mf infections. Four annual cross-sectional surveys were conducted between 1999 and 2004 in the two villages to screen for Wuchereria bancrofti microfilariae in individuals aged ≥ 1 year. Overall, 80% of the population in Magoda and 66% in Mpapayu were covered during these surveys. Results revealed a significant decrease in both mf prevalence and intensity in both villages. Furthermore, there was a steady decrease in mf incidence in Magoda; with 36.7 cases per 1000 person years in 2000 and 7.4 in 2004.  In Mpapayu, the incidence initially increased from 20.8 cases in 2000 to 24.3 in 2001 and then decreased to 7.2 cases in 2004.  Individuals using ITNs in Magoda had significantly lower risk of mf (OR=0.681; 95%CI: 0.496-0.934); and the risk of new infections was reduced by 58.8% (95%CI: 30.3-75.4). These results suggest that when MDA is complemented with ITNs there is high likelihood to half filariasis transmission within a shorter period than using chemotherapy alone

Acquisition of antibodies to merozoite surface protein 3 among residents of Korogwe, north eastern Tanzania

<p>Abstract</p> <p>Background</p> <p>A polymorphic malaria parasite antigen, merozoite surface protein 3 (MSP3), is among the blood stage malaria vaccine candidates. It is believed to induce immunity through cytophilic antibodies that disrupt the process of erythrocytes invasion by merozoites. This study aimed at assessing natural acquisition of antibodies to MSP3 in individuals living in an area with different malaria transmission intensity in preparation for malaria vaccine trials.</p> <p>Methods</p> <p>The study was conducted in individuals aged 0-19 years from villages located in lowland, intermediate and highland strata in Korogwe district, northeastern Tanzania. Blood samples from 492 study participants were collected between May and June 2006 for malaria diagnosis and immunological investigations. Reactivity of MSP3 to different types of antibodies (immunoglobulin M, G and IgG subclass 1 and 3) were analysed by Enzyme Linked ImmunoSorbent Assay (ELISA).</p> <p>Results</p> <p>Malaria parasite prevalence was higher in the lowland (50%) compared to the intermediate (23.1%) and highland (9.8%) strata. Immunogloblin G subclasses 1 and 3 (IgG1 & IgG3), total IgG and IgM were found to increase with increasing age. IgG3 levels were significantly higher than IgG1 (p < 0.001). Furthermore, <it>Plasmodium falciparum </it>infection was associated with higher IgG3 levels (p = 0.008). Adjusting by strata and age in individuals who had positive blood smears, both IgG and IgM were associated with parasite density, whereby IgG levels decreased by 0.227 (95%CI: 0.064 - 0.391; p = 0.007) while IgM levels decreased by 0.165 (95%CI: 0.044 - 0.286; p = 0.008).</p> <p>Conclusion</p> <p>Individuals with higher levels of IgG3 might be partially protected from malaria infection. Higher levels of total IgG and IgM in highlands might be due to low exposure to malaria infection, recent infection or presence of cross-reactive antigens. Further studies of longitudinal nature are recommended. Data obtained from this study were used in selection of one village (Kwashemshi) for conducting MSP3 phase 1b malaria vaccine trial in Korogwe.</p

Using Community-Owned Resource Persons to Provide Early Diagnosis and Treatment and Estimate Malaria Burden at Community Level in North-Eastern Tanzania.

Although early diagnosis and prompt treatment is an important strategy for control of malaria, using fever to initiate presumptive treatment with expensive artemisinin combination therapy is a major challenge; particularly in areas with declining burden of malaria. This study was conducted using community-owned resource persons (CORPs) to provide early diagnosis and treatment of malaria, and collect data for estimation of malaria burden in four villages of Korogwe district, north-eastern Tanzania.In 2006, individuals with history of fever within 24 hours or fever (axillary temperature ≥37.5°C) at presentation were presumptively treated using sulphadoxine/pyrimethamine. Between 2007 and 2010, individuals aged five years and above, with positive rapid diagnostic tests (RDTs) were treated with artemether/lumefantrine (AL) while under-fives were treated irrespective of RDT results. Reduction in anti-malarial consumption was determined by comparing the number of cases that would have been presumptively treated and those that were actually treated based on RDTs results. Trends of malaria incidence and slide positivity rates were compared between lowlands and highlands. Of 15,729 cases attended, slide positivity rate was 20.4% and declined by >72.0% from 2008, reaching <10.0% from 2009 onwards; and the slide positivity rates were similar in lowlands and highlands from 2009 onwards. Cases with fever at presentation declined slightly, but remained at >40.0% in under-fives and >20.0% among individuals aged five years and above. With use of RDTs, cases treated with AL decreased from <58.0% in 2007 to <11.0% in 2010 and the numbers of adult courses saved were 3,284 and 1,591 in lowlands and highlands respectively. Malaria incidence declined consistently from 2008 onwards; and the highest incidence of malaria shifted from children aged <10 years to individuals aged 10-19 years from 2009. With basic training, supervision and RDTs, CORPs successfully provided early diagnosis and treatment and reduced consumption of anti-malarials. Progressively declining malaria incidence and slide positivity rates suggest that all fever cases should be tested with RDTs before treatment. Data collected by CORPs was used to plan phase 1b MSP3 malaria vaccine trial and will be used for monitoring and evaluation of different health interventions. The current situation indicates that there is a remarkable changing pattern of malaria and these areas might be moving from control to pre-elimination levels

Performance of Rapid Diagnostic Test, Blood-film Microscopy and PCR for the Diagnosis of Malaria Infection among Febrile Children from Korogwe District, Tanzania.

Rapid diagnostic tests (RDT) and light microscopy are still recommended for diagnosis to guide the clinical management of malaria despite difficult challenges in rural settings. The performance of these tests may be affected by several factors, including malaria prevalence and intensity of transmission. The study evaluated the diagnostic performance of malaria RDT, light microscopy and polymerase chain reaction (PCR) in detecting malaria infections among febrile children at outpatient clinic in Korogwe District, northeastern Tanzania. The study enrolled children aged 2-59 months with fever and/or history of fever in the previous 48 h attending outpatient clinics. Blood samples were collected for identification of Plasmodium falciparum infection using histidine-rich-protein-2 (HRP-2)-based malaria RDT, light microscopy and conventional PCR. A total of 867 febrile patients were enrolled into the study. Malaria-positive samples were 85/867 (9.8 %, 95 % CI, 7.9-12.0 %) by RDT, 72/867 (8.3 %, 95 % CI, 6.5-10.1 %) by microscopy and 79/677 (11.7 %, 95 % CI, 9.3-14.3 %) by PCR. The performance of malaria RDT compared with microscopy results had sensitivity and positive predictive value (PPV) of 88.9 % (95 % CI, 79.3-95.1 %) and 75.3 % (95 % CI, 64.8-84.0 %), respectively. Confirmation of P. falciparum infection with PCR analysis provided lower sensitivity and PPV of 88.6 % (95 % CI, 79.5-94.7 %) and 84.3 % (95 % CI, 74.7-91.4 %) for RDT compared to microscopy. Diagnosis of malaria infection is still a challenge due to variation in results among diagnostic methods. HRP-2 malaria RDT and microscopy were less sensitive than PCR. Diagnostic tools with high sensitivity are required in areas of low malaria transmission

Bloodstream Bacterial Infection among Outpatient Children with Acute Febrile Illness in North-eastern Tanzania.

Fever is a common clinical symptom in children attending hospital outpatient clinics in rural Tanzania, yet there is still a paucity of data on the burden of bloodstream bacterial infection among these patients. The present study was conducted at Korogwe District Hospital in north-eastern Tanzania. Patients aged between 2 and 59 months with a history of fever or measured axillary temperature ≥37.5°C attending the outpatient clinic were screened for enrolment into the study. Blood culturing was performed using the BACTEC 9050® system. A biochemical analytical profile index and serological tests were used for identification and confirmation of bacterial isolates. In-vitro antimicrobial susceptibility testing was performed using the Kirby-Bauer disc diffusion method. The identification of Plasmodium falciparum malaria was performed by microscopy with Giemsa stained blood films. A total of 808 blood cultures were collected between January and October 2013. Bacterial growth was observed in 62/808 (7.7%) of the cultured samples. Pathogenic bacteria were identified in 26/808 (3.2%) cultures and the remaining 36/62 (58.1%) were classified as contaminants. Salmonella typhi was the predominant bacterial isolate detected in 17/26 (65.4%) patients of which 16/17 (94.1%) were from patients above 12 months of age. Streptococcus pneumoniae was the second leading bacterial isolate detected in 4/26 (15.4%) patients. A high proportion of S. typhi 11/17 (64.7%) was isolated during the rainy season. S. typhi isolates were susceptible to ciprofloxacin (n = 17/17, 100%) and ceftriaxone (n = 13/17, 76.5%) but resistant to chloramphenicol (n = 15/17, 88.2%). P. falciparum malaria was identified in 69/808 (8.5%) patients, none of whom had bacterial infection. Bloodstream bacterial infection was not found to be a common cause of fever in outpatient children; and S. typhi was the predominant isolate. This study highlights the need for rational use of antimicrobial prescription in febrile paediatric outpatients presenting at healthcare facilities in rural Tanzania

Retired Nurses Can Improve Retention in Prevention of Mother-to-Child Transmission Programmes

Background:&nbsp;The success of prevention of mother-to-child transmission (PMTCT) programmes depends on retention of mothers throughout the PMTCT cascade. &nbsp; Methods:&nbsp;In a clinical trial of short-course combination antiretroviral therapy (cART) for PMTCT in Tanzania, senior nurses were employed to reduce the substantial loss-to-follow up (LTFU) rate. &nbsp; Results:&nbsp;Following intervention, the relative risk (RR) of receiving a CD4 count result and antiretroviral therapy was 1.16 (95% confidence interval [CI], 1.05 to 1.27), the RR of delivery at clinic was 2.51 (95% CI, 2.06 to 3.06), the RR for reporting for follow-up at 6 to 8 weeks postpartum was 4.63 (95% CI, 3.41 to 6.27), and the RR for being retained until 9 months postpartum was 28.19 (95% CI, 11.81 to 67.28). No significant impact on transmission was found. &nbsp; Conclusion:&nbsp;Significantly higher retention was found after senior nurses were employed. No impact on transmission was found. Relatively low transmission was found in both study arms

Development and validation of climate and ecosystem-based early malaria epidemic prediction models in East Africa

Process-based models were constructed for computing the risk of malaria epidemic using temperature and rainfall data. The model has a lead-time of two to four months between detection of the epidemic signal and evolution of the epidemic. Malaria data was collected from eight sites in Kenya, Tanzania and Uganda with temperature and rainfall data from meteorological stations closest to the source of the malaria data. The sensitivity, specificity and positive predictive power were used to validate the models. Results validate the additive and multiplicative models, which were shown to be robust and with high climate-based, early epidemic predictive power

Rapid screening for glucose-6-phosphate dehydrogenase deficiency and haemoglobin polymorphisms in Africa by a simple high-throughput SSOP-ELISA method

BACKGROUND: Mutations in the haemoglobin beta-globin (HbB) and glucose-6-phosphate dehydrogenase (G6PD) genes cause widespread human genetic disorders such as sickle cell diseases and G6PD deficiency. In sub-Saharan Africa, a few predominant polymorphic variants of each gene account for a majority of these deficiencies. Examining at a larger scale the clinical importance of these independent genetic disorders, their possible association with malaria pathogenesis and innate resistance, and their relevance for antimalarial drug treatment, would be easier if an accurate screening method with limited costs was available. METHODS: A simple and rapid technique was developed to detect the most prominent single nucleotide polymorphisms (SNPs) in the HbB and G6PD genes. The method is able to detect the different haemoglobin polymorphisms A, S, C and E, as well as G6PD polymorphisms B, A and A- based on PCR-amplification followed by a hybridization step using sequence-specific oligonucleotide probes (SSOPs) specific for the SNP variants and quantified by ELISA. RESULTS: The SSOP-ELISA method was found to be specific, and compared well to the commonly used PCR-RFLP technique. Identical results were obtained in 98% (haemoglobin) and 95% (G6PD) of the tested 90 field samples from a high-transmission area in Tanzania, which were used to validate the new technique. CONCLUSION: The simplicity and accuracy of the new methodology makes it suitable for application in settings where resources are limited. It would serve as a valuable tool for research purposes by monitoring genotype frequencies in relation to disease epidemiology

Addressing the fear and consequences of stigmatization - a necessary step towards making HAART accessible to women in Tanzania: a qualitative study

<p>Abstract</p> <p>Background</p> <p>Highly Active Antiretroviral Therapy (HAART) has been available free of charge in Tanga, Tanzania since 2005. However we have found that a high percentage of women referred from prevention of mother-to-child transmission services to the Care and Treatment Clinics (CTC) for HAART never registered at the CTCs. Few studies have focused on the motivating and deterring factors to presenting for HAART particularly in relation to women. This study seeks to remedy this gap in knowledge.</p> <p>Methodology</p> <p>A qualitative approach using in-depth interviews and focus group discussions was chosen to understand these issues as perceived and interpreted by HIV infected women themselves.</p> <p>Results</p> <p>The main deterrent to presenting for treatment appears to be fear of stigmatization including fear of ostracism from the community, divorce and financial distress. Participants indicated that individual counselling and interaction with other people living with HIV encourages women, who are disinclined to present for HAART, to do so, and that placing the entrance to the CTC so as to provide discrete access increases the accessibility of the clinic.</p> <p>Conclusion</p> <p>Combating stigma in the community, although it is essential, will take time. Therefore necessary steps towards encouraging HIV infected women to seek treatment include reducing self-stigma, assisting them to form empowering relationships and to gain financial independence and emphasis by example of the beneficial effect of treatment for themselves and for their children. Furthermore ensuring a discrete location of the CTC can increase its perceived accessibility.</p