Occurrence of pathogenic Vibrio cholerae serogroups 01 and 0139 in some estuaries of Tanzania

In this study, the occurrence of culturable Vibrio cholerae serogroup O1 and O139 in three selected Tanzanian Estuaries, Mzinga, Pangani and Ruvu were explored. A total of 480 water and plankton samples were collected along salinity gradients (fresh, brackish and marine waters). Samples were enriched in Alkaline Peptone Water (APW) and subsequently cultured on Thiosulfate Citrate Bile-Salt Sucrose (TCBS) agar. Resulting isolates were serially identified by oxidase test, API-20E test and monoclonal antibodies for V. cholerae serogroup O1 and O139. A total of 670 presumptive V. cholerae isolates were obtained from 416 samples (86.7%), where 137 (20.4%) were oxidase test positive. Out of the oxidase test positive, 96 (70.8%) were further confirmed by API 20E to be V. cholerae while only 8 isolates were ascertained by monoclonal antibodies to be V. cholerae O1 and 1 isolate to be V. cholerae O139. This indicated that, apart from the few V. cholerae O1 and O139 confirmed serogroups, there is still a large percentage of V. cholerae non-O1/O139. Similarly, both V. Cholerae serogroups O1 and non-O1/O139 were observed in clinical samples suggesting a close link between the existence of the bacterium in aquatic environments and cholera outbreak.Key words: Tanzanian Estuaries, V. cholerae, serogroupO1/O13

Characterisation and Antimicrobial Potential of Actinobacteria Isolated from Momela Soda Lakes, Tanzania

Extreme environments such as soda lakes are potential sources of microbes with biotechnological applications in different sectors. This study aimed at isolation, characterization and investigation of antibacterial potential of actinobacteria from Momela Soda Lakes, at Arusha National Park in Tanzania. One hundred and twenty (120) isolates were recovered from soil and water samples using the dilution plate technique. The isolates were morphologically and biochemically characterized, and further, screened for antimicrobial activity by disc diffusion method as well as the micro dilution technique. Cytotoxic effects were determined using the brine shrimp lethality test. Results showed that, all 120 isolates were Gram-positive rod-coccus shaped. Forty-four out of them showed antibacterial activity against Staphylococcus aureus and Escherichia coli. The Streptomyces (101TI) and Dietzia (56BI) strains exhibited exceptionally higher antibacterial activity compared to the rest with inhibition zones of 16.25 and 21.00 mm, respectively. These two strains were toxic against brine shrimp-larvae. Microbacterium (5LI), Hoyosella (113BI), Streptomyces (62BI), Dietzia (117SI), Hoyosella (37SI) and Microbacterium (3BI) strains had low antibacterial and cytotoxic activities. This study therefore revealed that Momela Soda Lakes harbour actinobacteria with antimicrobial potential. Keywords: Actinobacteria; antimicrobial activity; extremophiles; Momela soda lake

Co-variations of Cholera with Climatic and Environmental Parameters in Coastal Regions of Tanzania

The bacterium causing cholera, Vibrio cholerae, is essentially a marine organism and its ecological dynamics have been linked to oceanographic conditions and climate. We used autoregressive models with external inputs to identify potential relationships between number of cholera cases in the coastal regions of mainland Tanzania with climatic and environmental indices (maximum air temperature, sea surface temperature, wind speed and chlorophyll a). Results show that between 2004 and 2010 coastal regions of mainland Tanzania with approximately 21% of the total population accounted for approximately 50% of the cases and 40% of the total mortality. Significant co-variations were found between seasonally adjusted cases and coastal ocean chlorophyll a and to some degree sea surface temperature, both lagged by one to four months. Cholera cases in Dar es Salaam were also weakly related to the Indian Ocean Dipole Mode Index lagged by 5 months, suggesting that it may be possible to predict Cholera outbreaks for Dar es Salaam 5 months ahead of time. The results also suggest that the severity of cholera in coastal regions is set by conditions in the ocean and that longer-term environmental and climate parameters may be used to predict cholera outbreaks along the coastal regions

Characterization of bird, reptile, and insect community diversity in constructed wetlands and waste stabilization ponds across Tanzania

This research article was published in Ecological Engineering,Volume 196, 2023.Wastewater treatment systems, such as Constructed Wetlands (CWs) and Waste Stabilization Ponds (WSPs), have untapped biodiversity enhancement and development potential. Birds, insects, and reptiles, which are displaced by human development, might find refuge in these ecosystems. However, the lack of a detailed characterization of the biodiversity status of these wastewater treatment systems hinders their widespread adoption. Point counts, direct observations, and camera traps were used to assess bird diversity across five CWs and three WSPs in Tanzania in 2021. For insects and reptiles, pitfall and pan traps were laid along established transects, in addition, direct observations and fishnets were also used to assess the reptiles dwelling within the WSPs. Abundance, Shannon index, Simpson index, Margalef index, and evenness index were the diversity parameters used to analyze the diversity of birds, insects, and reptiles. Our results show that among the studied groups and between WSPs and CWs, birds had high species abundance (n = 1132), richness, Margalef index (D = 4.266), evenness (E = 0.815), Shannon diversity (H = 2.881) and Simpson index (λ =0.903). The abundance and diversity of studied groups differed significantly (P < 0.05) between WSPs and CWs. Our study also recorded four reptile species belonging to three orders. Molecular analyses confirmed that insect species belong to nine orders and 13 families, with the order Diptera dominating both CWs and WSPs, followed by Orthoptera, Hymenoptera, and Araneae. We conclude that CW and WSP wastewater treatment systems are important for hosting various populations of birds, reptiles, and insect species

Routine delivery of artemisinin-based combination treatment at fixed health facilities reduces malaria prevalence in Tanzania: an observational study

BACKGROUND Artemisinin-based combination therapy (ACT) has been promoted as a means to reduce malaria transmission due to their ability to kill both asexual blood stages of malaria parasites, which sustain infections over long periods and the immature derived sexual stages responsible for infecting mosquitoes and onward transmission. Early studies reported a temporal association between ACT introduction and reduced malaria transmission in a number of ecological settings. However, these reports have come from areas with low to moderate malaria transmission, been confounded by the presence of other interventions or environmental changes that may have reduced malaria transmission, and have not included a comparison group without ACT. This report presents results from the first large-scale observational study to assess the impact of case management with ACT on population-level measures of malaria endemicity in an area with intense transmission where the benefits of effective infection clearance might be compromised by frequent and repeated re-infection. METHODS A pre-post observational study with a non-randomized comparison group was conducted at two sites in Tanzania. Both sites used sulphadoxine-pyrimethamine (SP) monotherapy as a first-line anti-malarial from mid-2001 through 2002. In 2003, the ACT, artesunate (AS) co-administered with SP (AS + SP), was introduced in all fixed health facilities in the intervention site, including both public and registered non-governmental facilities. Population-level prevalence of Plasmodium falciparum asexual parasitaemia and gametocytaemia were assessed using light microscopy from samples collected during representative household surveys in 2001, 2002, 2004, 2005 and 2006. FINDINGS Among 37,309 observations included in the analysis, annual asexual parasitaemia prevalence in persons of all ages ranged from 11% to 28% and gametocytaemia prevalence ranged from <1% to 2% between the two sites and across the five survey years. A multivariable logistic regression model was fitted to adjust for age, socioeconomic status, bed net use and rainfall. In the presence of consistently high coverage and efficacy of SP monotherapy and AS + SP in the comparison and intervention areas, the introduction of ACT in the intervention site was associated with a modest reduction in the adjusted asexual parasitaemia prevalence of 5 percentage-points or 23% (p < 0.0001) relative to the comparison site. Gametocytaemia prevalence did not differ significantly (p = 0.30). INTERPRETATION The introduction of ACT at fixed health facilities only modestly reduced asexual parasitaemia prevalence. ACT is effective for treatment of uncomplicated malaria and should have substantial public health impact on morbidity and mortality, but is unlikely to reduce malaria transmission substantially in much of sub-Saharan Africa where individuals are rapidly re-infected.Financial support for IMPACT-Tz came primarily from CDC, the U.S. Agency for International Development and the Wellcome Trust

The impact of training on self-reported performance in reproductive, maternal, and newborn health service delivery among healthcare workers in Tanzania: a baseline- and endline-survey

Background: Delivery of quality reproductive health services has been documented to depend on the availability of healthcare workers who are adequately supported with appropriate training. However, unmet training needs among healthcare workers in reproductive, maternal, and newborn health (RMNH) in low-income countries remain disproportionately high. This study investigated the effectiveness of training with onsite clinical mentorship towards self-reported performance in RMNH among healthcare workers in Mwanza Region, Tanzania. Methods: The study used a quasi-experimental design with pre-and post-intervention evaluation strategy. The baseline was compared with two endline groups: those with intervention (training and onsite mentorship) and those without. The differences among the three groups in the sociodemographic characteristics were analyzed by using chi-square test for categorical variables, independent-sample t-test for continuous variables and Mann-Whitney U test for ordinal or skewed continuous data. The independent sample t-test was used to determine the effect of the intervention by comparing the computed self-reported performance on RMNH services between the intervention and control groups. The paired-samples t-test was used to measure the differences between before and after intervention groups. Significance was set at a 95% confidence interval with p ≤ 0.05. Results: The study included a sample of 216 participants with before and after intervention groups comprising of 95 (44.0%) and 121 (56.0%) in the control group. The comparison between before and after intervention groups revealed a statistically significant difference (p ≤ 0.05) in all the dimensions of the self-reported performance scores. However, the comparison between intervention groups and controls indicated a statistical significant difference on intra-operative care (t = 3.10, df = 216, p = 0.002), leadership skills (t = 1.85, df = 216, p = 0.050), Comprehensive emergency obstetric and newborn care (CEMONC) (t = 34.35, df = 216, p ≤ 0.001), and overall self-reported performance in RMNH (t = 3.15, df = 216, p = 0.002). Conclusions: This study revealed that the training and onsite clinical mentorship to have significant positive changes in self-reported performance in a wide range of RMNH services especially on intra-operative care, leadership skills and CEMONC. However, further studies with rigorous designs are warranted to evaluate the long-term effect of such training programs on RMNH outcomes

Impact of foot-and-mouth disease on mastitis and culling on a large-scale dairy farm in Kenya

Foot and mouth disease (FMD) is a highly transmissible viral infection of cloven hooved animals associated with severe economic losses when introduced into FMD-free countries. Information on the impact of the disease in FMDV-endemic countries is poorly characterised yet essential for the prioritisation of scarce resources for disease control programmes. A FMD (virus serotype SAT2) outbreak on a large-scale dairy farm in Nakuru County, Kenya provided an opportunity to evaluate the impact of FMD on clinical mastitis and culling rate. A cohort approach followed animals over a 12-month period after the commencement of the outbreak. For culling, all animals were included; for mastitis, those over 18 months of age. FMD was recorded in 400/644 cattle over a 29-day period. During the follow-up period 76 animals were culled or died whilst in the over 18 month old cohort 63 developed clinical mastitis. Hazard ratios (HR) were generated using Cox regression accounting for non-proportional hazards by inclusion of time-varying effects. Univariable analysis showed FMD cases were culled sooner but there was no effect on clinical mastitis. After adjusting for possible confounders and inclusion of time-varying effects there was weak evidence to support an effect of FMD on culling (HR = 1.7, 95% confidence intervals [CI] 0.88-3.1, P = 0.12). For mastitis, there was stronger evidence of an increased rate in the first month after the onset of the outbreak (HR = 2.9, 95%CI 0.97-8.9, P = 0.057)

Plasma Ang2 and ADAM17 levels are elevated during clinical malaria; Ang2 level correlates with severity and expression of EPCR-binding PfEMP1

The pathogenesis of Plasmodium falciparum malaria involves a complex interplay between parasite adhesion and inflammatory response that includes release of cytokines and activation of the endothelium with accompanying release of Angiopoitin 2 (Ang2) to the plasma. A-disintegrin and metalloproteinase 17 (ADAM17) is a protein responsible for releasing cytokines, including Tumor Necrosis Factor α (TNFα), and shedding of adhesion proteins. In this study, we show that plasma levels of ADAM17 are increased in Tanzanian children hospitalized with a malaria infection compared with asymptomatic children but similar to children hospitalized with other infectious diseases. The plasma levels of ADAM17 decreased during recovery after an acute malaria episode. Plasma levels of Ang2 were associated with markers of malaria severity and levels of var transcripts encoding P. falciparum Erythrocyte Membrane Protein 1 (PfEMP1) containing Cysteine Rich Inter Domain Region α1 (CIDRα1) domains predicted to bind Endothelial Protein C receptor (EPCR). ADAM17 levels were not associated with expression of var genes encoding different PfEMP1 types when controlling for age. These data are the first to report ADAM17 plasma levels in malaria-exposed individuals, and support the notion that parasite sequestration mediated by EPCR-binding PfEMP1 is associated with endothelial activation and pathology in severe paediatric malaria

Eave tubes for malaria control in Africa : Initial development and semi-field evaluations in Tanzania Lucy Tusting, Jo Lines

Background: Presented here are a series of preliminary experiments evaluating "eave tubes" - a technology that combines house screening with a novel method of delivering insecticides for control of malaria mosquitoes. Methods: Eave tubes were first evaluated with overnight release and recapture of mosquitoes in a screened compartment containing a hut and human sleeper. Recapture numbers were used as a proxy for overnight survival. These trials tested physical characteristics of the eave tubes (height, diameter, angle), and different active ingredients (bendiocarb, LLIN material, fungus). Eave tubes in a hut with closed eaves were also compared to an LLIN protecting a sleeper in a hut with open eaves. Eave tubes were then evaluated in a larger compartment containing a self-replicating mosquito population, vegetation, and multiple houses and cattle sheds. In this "model village", LLINs were introduced first, followed by eave tubes and associated house modifications. Results: Initial testing suggested that tubes placed horizontally and at eave height had the biggest impact on mosquito recapture relative to respective controls. Comparison of active ingredients suggested roughly equivalent effects from bendiocarb, LLIN material, and fungal spores (although speed of kill was slower for fungus). The impact of treated netting on recapture rates ranged from 50 to 70 % reduction relative to controls. In subsequent experiments comparing bendiocarb-treated netting in eave tubes against a standard LLIN, the effect size was smaller but the eave tubes with closed eaves performed at least as well as the LLIN with open eaves. In the model village, introducing LLINs led to an approximate 60 % reduction in larval densities and 85 % reduction in indoor catches of host-seeking mosquitoes relative to pre-intervention values. Installing eave tubes and screening further reduced larval density (93 % relative to pre intervention values) and virtually eliminated indoor host-seeking mosquitoes. When the eave tubes and screening were removed, larval and adult catches recovered to pre-eave tube levels. Conclusions: These trials suggest that the "eave tube" package can impact overnight survival of host-seeking mosquitoes and can suppress mosquito populations, even in a complex environment. Further testing is now required to evaluate the robustness of these findings and demonstrate impact under field conditions

The interaction between a sexually transferred steroid hormone and a female protein regulates oogenesis in the malaria mosquito anopheles gambiae

Molecular interactions between male and female factors during mating profoundly affect the reproductive behavior and physiology of female insects. In natural populations of the malaria mosquito Anopheles gambiae, blood-fed females direct nutritional resources towards oogenesis only when inseminated. Here we show that the mating-dependent pathway of egg development in these mosquitoes is regulated by the interaction between the steroid hormone 20-hydroxy-ecdysone (20E) transferred by males during copulation and a female Mating-Induced Stimulator of Oogenesis (MISO) protein. RNAi silencing of MISO abolishes the increase in oogenesis caused by mating in blood-fed females, causes a delay in oocyte development, and impairs the function of male-transferred 20E. Co-immunoprecipitation experiments show that MISO and 20E interact in the female reproductive tract. Moreover MISO expression after mating is induced by 20E via the Ecdysone Receptor, demonstrating a close cooperation between the two factors. Male-transferred 20E therefore acts as a mating signal that females translate into an increased investment in egg development via a MISO-dependent pathway. The identification of this male–female reproductive interaction offers novel opportunities for the control of mosquito populations that transmit malaria