Occurrence of Escherichia coli in Brassica rapa L. chinensis irrigated with low quality water in urban areas of Morogoro, Tanzania

Academic Journal Vol. 15(49), pp. 2772-2777,Low quality water has become valuable resource with restricted or unrestricted use in food production depending on its quality. This study has quantified the occurrence of Escherichia coli in Brassica rapa L. chinensis (Chinese cabbage) vegetables and low quality irrigation water. A total of 106 samples including Chinese cabbage (69) and water (37) were collected. The E. coli were cultured in petri film selective E. coli plates at 44°C. The Chinese cabbage irrigated with river water at Fungafunga area indicated significantly (P<0.001) high prevalence 86% (n=21, 0.00-4.10 log cfu/g) of E. coli than those irrigated with treated wastewater at Mazimbu 10% (n=48, 0.00-1.36 log cfu/g). The mean counts of E. coli in untreated wastewater ranged from 4.59 to 5.56 log cfu/mL, while in treated wastewater was from 0.54 to 1.05 log cfu/mL and in river water it was 2.40 log cfu/mL. Treated wastewater of the quality found in this study could be used for food production

Molecular identification versus local people’s information for accurate estimates of bushmeat utilization from the Serengeti ecosystem, Tanzania

Sustainable wildlife management assumes thorough knowledge of the factors of importance for species population dynamics. In this study, we examined the diversity of wildlife species that are illegally harvested in the Serengeti ecosystem, Tanzania. A total of 124 bushmeat samples were obtained from hunters, middlemen and consumers in 79 sub-villages adjacent to the protected areas in western Serengeti. The species identity was verified in 118 bushmeat samples through molecular sequencing of the cytochrome oxidase subunit I (COI) and phylogenetic assignments to established reference sequences of the respective species. The species diversity among the bushmeat samples was high with 15 identified species altogether. Wildebeest (Connochaetes taurinus) was clearly the most common species (n = 52), but also buffalo (Syncerus caffer, n = 15), eland (Tragelaphus oryx, n = 11), zebra (Equus burchelli, n = 10), topi (Damaliscus lunatus, n = 8) and impala (Aepyceros melampus, n = 7) were relatively frequently identified. The correctness of the species identification given by the bushmeat providers was relatively low (59%) with error rates higher in consumers than in hunters and middlemen. This high error rate suggests that care should be taken in relying on local peoples’ information for accurate estimates of biodiversity of bushmeat utilization.Key words: Bushmeat, illegal hunting, species identification, cytochrome oxidase subunit I (COI) sequencing, western Serengeti

Removal of Escherichia coli in treated wastewater used for food production in Morogoro, Tanzania

Acadmic Journal Vol. 10(33), pp. 1344-1350The aim of this study was to assess the removal efficiency of Escherichia coli at Mafisa and Mzumbe domestic wastewater treatment ponds in Morogoro, Tanzania. The study was done from October, 2013 to April, 2014. A total of 125 water samples from inlets and subsequent anaerobic, facultative and maturation ponds as well as treated wastewater were collected and analysed for E. coli. The estimated retention times of the wastewater treatment units were 19 and 22 days in Mafisa and Mzumbe ponds, respectively. The concentration of E. coli ranged from 4.70 to 5.60 log cfu/mL in untreated wastewater and was reduced to <1.00 to 2.00 log cfu/mL in the treated wastewater. During rainy and cold seasons, the effluent discharged out at Mafisa during August 2013; and March and April, 2014 was about 2 log cfu/mL while at Mzumbe E. coli concentration in effluent discharged out was up to 1.23 log cfu/mL. The concentration of E. coli in untreated and treated wastewater from the two wastewater treatment ponds study sites were comparable (P<0.05). Reduction of E. coli concentration in wastewater treatment ponds study sites was significant with less reduction seen at Mafisa, during rainy and cold seasons in March, April and August. To conclude, the simple wastewater treatment ponds in the study sites were effective and demonstrated potential for reduction of public health risks associated with use of treated wastewater in agricultural irrigation and aquaculture

Genome-Based Analysis of Extended-Spectrum β-Lactamase-Producing Escherichia coli in the Aquatic Environment and Nile Perch (<i>Lates niloticus</i>) of Lake Victoria, Tanzania

Extended-spectrum β-lactamase (ESBL)-producing bacteria constitute an emerging global health issue with food products being vehicles of transmission and the aquatic environments serving as potential reservoirs. This study aimed to characterize ESBL-producing Escherichia coli in Nile perch and water from Lake Victoria in Tanzania. A total of 180 samples of Nile perch and 60 water samples were screened for ESBL-producing E. coli on MacConkey agar supplemented with 2 μg/ml of cefotaxime and confirmed by blaCTX–M and blaTEM PCR. Antimicrobial resistance was determined by the disk diffusion method, and the ESBL-producing isolates were whole genome sequencing (WGS). ESBL-producing E. coli were detected in eight of the 180 analyzed Nile perch samples, and only one water sample was positive (1.7%, n = 60). Isolates were resistant to sulfamethoxazole–trimethoprim (100%), ampicillin/cloxacillin (100%), erythromycin 72.7% (8/11), tetracycline 90.9% (10/11), and nalidixic acid 63.6% (7/11). This mostly corroborates the resistance genes that they carried for sulfonamides (sul1 and sul2), trimethoprim (dfrA and dfrB), aminoglycosides [aac(3)-IId, strA, and strB], tetracycline [tet(B) and tet(D)], and fluoroquinolones (qepA4). They harbored plasmid replicon types IncF, IncX, IncQ, and Col and carried blaCTX–M–15 and blaTEM–1B genes generally found on the same contigs as the IncF plasmid replicon. Although epidemiologically unrelated, the strains formed three separate sequence type–phylogroup–serotype-specific clusters: C1, C2, and C3. Cluster C1 included five strains (3 to 13 SNPs) belonging to ST167, phylogroup A, and serotype O9:H21; the two C2 strains (11 SNPs) belong to ST156, phylogroup B1, and serotype ONT:H28; and C3 was made up of four strains (SNPs ranged from 4 to 17) of ST636, phylogroup B2, and serotype O45:H7. The common virulence gene gad was reported in all strains. In addition, strains in C2 and C3 possessed iss, lpfA, and nfaE virulence genes, and the vat gene was found only in C3. The present study reports the occurrence of multidrug-resistant ESBL-producing E. coli carrying plasmid-mediated ESBL genes in offshore water and Nile perch in Lake Victoria. Strains formed three clonal clusters of unknown origin. This study reveals that the Lake may serve as reservoir for ESBL-producing bacteria that can be transmitted by fish as a food chain hazard of One-Health concern.Published versio

Cholera hotspots and surveillance constraints contributing to recurrent epidemics in Tanzania

Objective: We described the dynamics of cholera in Tanzania between 2007 and 2017 and assessed the weaknesses of the current surveillance system in providing necessary data in achieving the global roadmap to 2030 for cholera control. Results: The Poisson-based spatial scan identifed cholera hotspots in mainland Tanzania. A zero-infated Poisson regression investigated the relationship between the incidence of cholera and available demographic, socio-economic and climatic exposure variables. Four cholera hotspots were detected covering 17 regions, home to 28 million people, including the central regions and those surrounding the Lakes Victoria, Tanganyika and Nyaza. The risk of experiencing cholera in these regions was up to 2.9 times higher than elsewhere in the country. Regression analyses revealed that every 100 km of water perimeter in a region increased the cholera incidence by 1.5%. Due to the compilation of surveillance data at regional level rather than at district, we were unable to reliably identify any other signifcant risk factors and specifc hotspots. Cholera high-risk populations in Tanzania include those living near lakes and central regions. Successful surveillance require disaggregated data available weekly and at district levels in order to serve as data for action to support the roadmap for cholera control.Published versio

Detection and Quantification of Oestrogenic Endocrine Disruptors in Water in Mwanza Gulf in the Lake Victoria Basin, Tanzania

The aim of this study was to detect the presence and quantify the total oestrogens (estriol (E1), estradiol (E2), and estrone (E3)) in Lake Victoria water with a view of assessing their contribution to the health status of fish. A total of 27 water samples; three from each of the nine sampling sites were collected in Mwanza gulf in the city in May 2012. Solvent extraction procedures were used to obtain extracts of pollutants that were further analysed using the competitive Enzyme- Linked Immunosorbent Assay (ELISA) technique to detect and quantify the total oestrogens. Overall, the concentration of total oestrogens was low and ranged from 10 – 200 pg/L. Concentrations of these chemicals decreased along the gradient, being highest (107±81.4 pg/L) in rivers before entering into the lake and lowest (19±5.4 pg/L) in water samples collected in the lake at about 100 meters from inshore (intermediate sampling points). Levels of total oestrogens were significantly different between categories of water sources (P = 0.009). Two most polluted rivers were Butimba and Nyakurunduma with concentrations at 150 pg/L and 200 pg/L respectively. Dumping of wastes in rivers without treatment was the most likely source of the pollutants. Findings from this study have revealed the existence of oestrogens with endocrine disrupting properties at different concentrations, and that rivers are the main sources of oestrogenic endocrine disruptors in Lake Victoria water near Mwanza City.Keywords: ELISA, endocrine disruptors, oestrogens, pollutio

Current State of Modern Biotechnological-Based Vaccines for Aquaculture: A Systematic Review.

This research article published by Hindawi, 2019This systematic review describes what "the cutting edge vaccines for are". The focus is on types of high tech biotechnological based vaccines, target gene or antigen in developing these vaccines, and challenge model fish species used in vaccines efficacy testing. Vaccines delivery methods, immune response, and their efficacy, adjuvant or carrier systems used, and the overall experimental setup or design of the vaccines under investigation are also described. The search for the original papers published between 2009 and 2018 was conducted in June of 2018, using the PubMed and Google scholar electronic database. Twenty-three (23/4386) studies were included in the final assembly using PRISMA guidelines (Protocol not registered). Recombinant protein vaccines were the highly experimented type of the modern biotechnological based vaccines identified in the selected studies (16/23; 70%). Outer membrane proteins (OMPs) of different -barrels were shown to be a potential antigenic entity for vaccines (57%). Intraperitoneal route with conventional carries or adjuvants was the highly applied delivery system while very few studies used herbal based vaccine adjuvants and nanomaterial as a vaccine carrier. Variation was observed in terms of protection levels in the selected studies. The experimental designs partly contributed to the observed variation. Therefore, recombinant vaccines that use new carrier system technologies and delivered through oral route in feeds would have been of great value for use in the prevention and control of infections in fish. Despite the usefulness as academic tools to identify what is important in pathogenicity of the etiological agent to the host fish, these vaccines are only economically viable in very high-value animals. Therefore, if vaccination is a good option for group, then simple autogenous vaccines based on accurate typing and evidence-based definition of the epidemiological unit for their use would be the most viable approach in terms of both efficacy and economic feasibility especially in low and middle-income countries (LMIC)

Present status of aquaculture and the challenge of bacterial diseases in freshwater farmed fish in Tanzania; A call for sustainable strategies

This research article published by Elsevier, 2020Aquaculture provides significant contributions to household food security, as the capture of wild fish from lakes, dams, and oceans do not meet the current demand for animal protein in Tanzania. Sustainable aquaculture requires well-established regulatory systems and extension services for good pond management practices and maintaining fish health by fish farmers. Fish farming is practiced widely in Tanzania, from small-to large-scale ponds and these farming systems are moving from extensive normal operations (low input demand) to intensive farming (high input demand). However, the industry is largely still operating at a subsistence level with low production. Bacterial infections have been occurring in these fish farms and will continue to be an issue of concern into the future. This review highlights the current challenges, successes, and prospects towards a sustainable aquaculture industry in Tanzania, including: limited extension services mirroring the limited knowledge by farmers regarding pond management practices; the inadequacy of funds to carry out fish disease research or implement a surveillance system; little expertise in fish disease diagnosis and treatment; and poor management options. To minimize disease outbreaks and optimize production in the future, we suggest a strengthening of extension services, augmented with on-farm knowledge transfer. Emphasis should be on pond management practices and fish disease management; the creation of a well-functioning fish disease surveillance system; and strengthening collaborative research on aquaculture between the government research institutions and academia. Establishing small cooperative fish farmer groups within the Aquaculture Association of Tanzania (AAT) for easy access to information is also recommended

Virulence pattern of circulating aeromonads isolated from farmed Nile tilapia in Tanzania and novel antibiotic free attenuation of Aeromonas hydrophila strain TZR7-2018

This research article published by Elsevier B.V., 2020Aeromonads are gram-negative, rod-shaped, facultative anaerobes bacteria known to cause motile aeromonads septicemia diseases (MAS) in warm freshwater farmed fish. Outbreaks are associated with pathogenicity of aeromonads in fish which is partly contributed by virulence characteristics of the etiological agent. The objective of this study was to assess the virulence characteristics of the previously isolated and identified aeromonads, and attenuate potential Aeromonas hydrophila strain TZR7-2018 to serve as local vaccine candidate. Six virulence genes and other virulence characteristics were molecularly and phenotypically assessed both using in-vitro and in-vivo approaches. Attenuation of A. hydrophila parent strain TZR7-2018+ was performed by passaging through thermal continuous sub-culturing 40 times in Tryptic soy agar (TSA). Bacterin was prepared by formalin inactivation from the same parent strain. Humoral responses were assayed using quantitative serological agglutination test (qSAT) while protective efficacy was measured through relative percent survival (RPS). A total 240 Nile tilapia fingerlings with an average weight of 8.1 ± 0.4 g were used in all in-vivo studies. The presence of aerolysin (aer), cytotoxic enterotoxin (act), elastase (ahy), haemolysin (hly), serine (ser) and polar flagella (fla) genes were determined using PCR. Out of 201 isolates, 75.1 % (151/201) of the aeromonads possessed virulence genes (120=A. hydrophila and 31=Aeromonas veronii). The virulence gene pattern of aer/hly/fla was the most prominent with the prevalence of 12.6 %. The attenuated strain TZR7-2018− showed reduced: colon size, multiplication rate, cell size and loss in; haemolysis, motility and capsule. Humoral responses increased gradually and reached maximum at day 28 in both attenuated and bacterin formulation given through intraperitoneal (IP) injection and immersion (IM). A RPS of 82.3 %, 71.4 % and 85.1 %, were recorded to the attenuated vaccine given through IP and IM and bacterin provided through IP respectively. Therefore the attenuated strain TZR7-2018− obtained through thermal continuous subculture technique and the bacterin proved to be efficacious and can serve as vaccine candidate

Phenotypic and molecular detection of Aeromonads infection in farmed Nile tilapia in Southern highland and Northern Tanzania

This research article published by Elsevier Ltd., 201