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The aim of this study was to assess the prevalence of anemia and its determinants among children aged 6–59 months in Zanzibar, Tanzania, from 2005 to 2015. We used secondary data from the Tanzania Demographic and Health Surveys from three different periods: 2005, 2010, and 2015. A sample of 3502 child-mother pairs from three survey datasets was used to analyze the overall prevalence of anemia and reveal its determinants. Hierarchical logistic regression was used to demonstrate the prevalence odds ratio of factors, both from the mothers and children, for anemia prevalence. The study indicated a significant decrease in anemia prevalence from 76.1% in 2005 to 65.4% in 2015 (p < 0.001). Hierarchical logistic regression between variables and anemia showed a significant association (p = 0.02) with households that improperly disposed of stool, children with minimum dietary diversity (p = 0.041), children in low age quartiles (p = < 0.001), and underweight children (p = 0.025). Maternal, household characteristics, and child factors were associated with childhood anemia in Zanzibar, Tanzania. Despite the significant decrease of anemia in Zanzibar, the overall prevalence rate is still a significant public health concern. Designing and strengthening comprehensive interventions to address anemia in the general population and different categories should be given special consideration.

Anthropogenic activities are increasingly catalyzing natural climatic factors that drive land cover change at different spatial scales. Available land cover data of the Mara River basin however give a broader picture of the entire basin regardless of the heterogeneity that exists at the sub-catchment level. This study sought to establish sub-catchment specific information on land cover changes through examination of satellite images of four Mara River sub-catchments (Amala, Nyangores, Talek and Sand River) for the period 1987-2017. The relationship between temperature, rainfall and land cover was also computed. In addition, a household survey and focus group discussions were conducted in each sub-catchments to establish the socio-economic impacts of land cover change on the community’s wellbeing. Forest cover was dominant in Amala (39.8%) and Nyangores (43.7%) sub-catchments in 1987 but by 2017 crop lands had surpassed forest cover in the two sub-catchments, accounting for 53.2% and 45.7%, respectively. However, in Talek (52.8%) and Sand River (47.4%) sub-catchments, grassland was the dominant land cover type in 1987 and after the 30 year period, grasslands remained dominant in Sand River, while shrub land became dominant in Talek sub-catchment. A weak positive correlation was observed between rainfall and forest cover, shrub land and cropland, while a negative correlation was observed between rainfall and bare land. Average temperature showed a positive moderate correlation with bare land and built up areas. Analysis of survey data revealed that livestock keeping, temperature increase, type of trees, education level of household head and weak environmental laws were the main drivers of land cover change (P ?0.587), beans (r = ?0.5459), sorghum (r = ?0.351), cow peas (r = ?0.544), and pigeon peas (r = ?0.337). Focus group discussions participants were supportive of environmental protective measures to reverse negative land cover changes, while planting drought resistant trees, crop diversification and awareness creation among community members were recommended as the most ideal environmental management strategies.

Anthropogenic activities, including replacing natural forests with human settlements and increased agricultural activities have environmental impacts. The activities can contaminate aquatic ecosystems including spring waters that are sources of major rivers like the Amala and Nyangores, tributaries of Mara River in Mau Complex. In the complex, forestlands have been converted to human settlements and agricultural lands. Although residents of the Mara River Basin use the spring waters for domestic and animal watering purposes, evaluation of the impact the activities have on the spring water quality has not been done. This study evaluated the site and seasonal variations of zinc, copper, selenium, manganese, chromium, cadmium and lead concentrations in spring waters within the Mau Complex where forests have been cleared and converted to anthropogenic activities. The study covered areas along Amala and Nyangores rivers. There were variations (p≤0.05) in the heavy metals levels with sites and seasons. Except for Mn, Cu and Cd which were lower, the levels of the other heavy metals in water from the control points (undisturbed forest areas) were higher in downstream areas that had undergone massive anthropogenic activities. Although there were seasonal variations (p≤0.05), the pattern was not clear. Some heavy metals levels were higher in wet seasons while others were higher in dry season. But the heavy metals levels were within the recommended international standards for domestic/animal use. These results demonstrate that the anthropogenic activities were not yet causing pollution of the spring waters. Maintaining the anthropogenic activities at present levels is recommended. However, periodic monitoring to ascertain the quality of the spring water is necessary to mitigate increase to detrimental levels with time. These results contribute knowledge helping regulatory agencies and management of Lake Victoria basin to formulate monitoring polices to curb water quality deterioration. Key words: Anthropogenic activities, heavy metals, spring water, River Mara, Mau Complex.

Multilingual abstracts in the six official working languages of the United Nations. (PDF 673Â kb)

Human-induced changes to natural landscapes have been identified as some of the greatest threats to freshwater resources. The change from natural forest cover to agricultural and pastoral activities is rampant especially in the upper Mara River catchment (water tower), as well as along the course of the Mara River. The objective of this study was to determine the effect of land use change on the physico-chemical properties of soil (bulk density, carbon, nitrogen, phosphorus and pH) along the course of the Mara River. Five major land uses (agricultural lands, livestock/pastoral lands, forested lands, conservancy/game reserves, and natural wetland) were explored. Results revealed that the mean soil bulk density was 0.956 g/cm3 and differed significantly between sites (p < 0.001). Live biomass values differed significantly between sampling sites (land use types) within the Mara River Basin (F(4, 147) = 8.57, p < 0.001). The mean infiltration over a period of 150 minutes differed, not only among sampling sites, but also between different sides of the river (left and right) within the same sampling site. Soil pH was generally acidic across the five sites and varied significantly (F(4, 63) = 19.26, p < 0.0001) between sites along the Mara River Basin. The mean percentage soil nitrogen across all sampling blocks was 4.87%, with significant differences observed in percentage soil nitrogen (F (4, 63) = 3.26, p < 0.006) between sampling sites. The results indicated that the five land use types affected land degradation differently along the Mara River, while adjacent land degradation affected water physico-chemical properties. These results point to the need to have focused policies on integrated land and water resource management strategies in the Mara River Basin.

Background Vector-borne diseases are increasingly becoming a major health problem among communities living along the major rivers of Africa. Although larger water bodies such as lakes and dams have been extensively researched, rivers and their tributaries have largely been ignored. This study sought to establish the spatial distribution of mosquito species during the dry season and further characterize their habitats along the Mara River and its tributaries. Methods In this cross-sectional survey, mosquito larvae were sampled along the Mara River, its two perennial tributaries (Amala and Nyangores), drying streams, and adjacent aquatic habitats (e.g. swamps, puddles that receive direct sunlight [open sunlit puddles], rock pools, hippo and livestock hoof prints, and vegetated pools). Each habitat was dipped 20 times using a standard dipper. Distance between breeding sites and human habitation was determined using global positioning system coordinates. The collected mosquito larvae were identified using standard taxonomic keys. Water physico-chemical parameters were measured in situ using a multiparameter meter. Mean mosquito larvae per habitat type were compared using analysis of variance and chi-square tests, while the relationship between mosquito larvae and physico-chemical parameters was evaluated using a generalized linear mixed model. The Cox-Stuart test was used to detect trends of mosquito larvae distribution. The test allowed for verification of monotonic tendency (rejection of null hypothesis of trend absence) and its variability. Results A total of 4001 mosquito larvae were collected, of which 2712 (67.8%) were collected from river/stream edge habitats and 1289 (32.2%) were sampled from aquatic habitats located in the terrestrial ecosystem about 50 m away from the main river/streams. Anopheles gambiae s.s, An. arabiensis, and An. funestus group, the three most potent vectors of malaria in Sub-Saharan Africa, together with other anopheline mosquitoes, were the most dominant mosquito species (70.3%), followed by Culex quinquefasciatus and Cx. pipiens complex combined (29.5%). Drying streams accounted for the highest number of larvae captured compared to the other habitat types. A stronger relationship between mosquito larvae abundance and dissolved oxygen (Z = 7.37, P ≤ 0.001), temperature (Z = 7.65, P ≤ 0.001), turbidity (Z = −5.25, P ≤ 0.001), and distance to the nearest human habitation (Z = 4.57, P ≤ 0.001), was observed. Conclusions Presence of malaria and non-malaria mosquito larvae within the Mara River basin calls for immediate action to curtail the insurgence of vector-borne diseases within the basin. A vector control program should be conducted during the dry period, targeting drying streams shown to produce the highest number of larval mosquitoes. Electronic supplementary material The online version of this article (10.1186/s40249-017-0385-0) contains supplementary material, which is available to authorized users.

Background: A number of factors impact negatively on natural surface water resources across the world. Although sources of surface water pollution are numerous, anthropogenic activities have been singled out as among the most important and of great concern. The aim of this study was to assess the influence of anthropogenic activities on nutrients and microbial levels along the Amala and Nyangores tributaries of the Mara River in Kenya. Materials and Methods: Four sampling sites along each tributary were specifically selected from which water samples were collected and analyzed for nutrients by use of spectrophotometric techniques, and coliform bacterial presence by a multiple tube fermentation technique. Results: Higher levels of total phosphorus were recorded along the Nyangores than the Amala tributary (P= 0.02). Significant differences in phosphorus levels were recorded between different sites along the Nyangores tributary (P= However, total nitrogen levels varied only within sites along the Nyangores tributary (P Conclusions: The findings imply that the health of local communities who depend on this water for domestic use might be compromised. As such, regular monitoring, strict enforcement of environmental protection laws, public education and proper sewage disposal is recommended.

Intermediate host snails of schistosomiasis were surveyed in this study to determine their abundance and distribution in the lake and land aquatic habitats of Lake Victoria basin of Kenya. Several sites were sampled at eight locations, both in the lake and on the land. The habitat and/or vegetation type (i.e. open water, hippo grass, hyacinth, ambatch trees, other vegetation, stream, swamp, pond, dam) of the sampled aquatic sites within the locations were also differentiated, water physicochemical parameters were determined, and the abundance of different species or taxa of phytoplankton and zooplankton were enumerated and correlated with the abundance of schistosomiasis snails in the sites. The results indicated significantly more Biomphalaria sudanica snails than Bulinus africanus snails in different physical habitats on land (Student’s t-test, P < 0.05), as well as in different locations on land (Student’s t-test, P = 0.026). Regression analyses revealed that several physicochemical parameters, including dissolved oxygen (R 2 = � 0.659; n = 8; P = 0.014), pH (R 2 = 0.728; n = 8; P = 0.007) and turbulence (R 2 = � 0.616; n = 8; P = 0.02), were predictive of Biomphalaria spp. abundance, while pH (R 2 = 0.610; n = 8; P = 0.02) and turbulence (R 2 = � 0.578; n = 8; P = 0.028) were predictive of Bulinus spp. abundance in different locations in the lake. Cyanobacteria (R 2 = 0.638; n = 8; P = 0.02) and chlorophyceae (R 2 = � 0.50; n = 8; P = 0.05) were shown to be predictive of both Biomphalaria spp. and Bulinus spp. abundance in different locations in the lake. Zooplankton abundance varied significantly between different locations in the lake (One-way ANOVA, P < 0.001). Bosmina spp. were found to be predictive of both Biomphalaria spp. (R 2 = � 0.627; n = 8; P = 0.01) and Bulinus spp. (R 2 = � 0.50; n = 8; P = 0.05) in different locations in the lake. The results from this study will help inform policy regarding control measures for schistosomias and intermediate snail hosts in Lake Victoria waters, as well as in adjacent terrestrial aquatic habitats and even beyond.

This study was conducted from September to December 2008 to investigate the relative abundance of malaria vectors and schistosomiasis host snails associated with aquatic weeds in Nyanza Gulf (Lake Victoria). Larval and adult’s stages of mosquitoes, lakeflies and snails were collected and identified with standard entomological and malacological techniques. The relative species composition and abundance of fish associated with macrophytes were also determined. Physicochemical parameters were determined with standard analytical methods. Community-based surveys were also conducted, using standard questionnaires, focused group discussions and direct observations. The results of this study indicated that the abundance of malaria-causing mosquitoes was low, accounting for only 0.4% of the total number of mosquitoes and lake flies collected from the gulf. Lake flies (Chaoborus and Chironomus spp.) were the most abundant flying insects associated with aquatic macrophytes (84.2%), followed by Culicines Culex spp. (12.2%) and Aedes spp. mosquitoes (3.2%). Biomphalaria sudanica and Bulinus africanus, the two most common hosts for schistosomiasis in the gulf, were detected in both types of macrophytes, but were most significantly attached to water hyacinth (P < 0.0001) and hippo grass (P = 0.0003). There were significantly fewer snails attached to the hippo grass, compared with those unattached in the open water (P < 0.05, GENMOD). Different habitats exhibited low Secchi disc transparency values, but elevated total phosphorous (TP), total nitrogen (TN), chlorophyll-a concentrations, as well as algal cell counts. Furthermore, Oreochromis niloticus and Haplochromine fishes were more abundant in water hyacinth mats compared with hippo grass mats and open-water habitats. The low mosquito abundance indicated that the sampled habitats were unsuitable for mosquito breeding, likely attributable to water turbulence and ⁄ or predation by larvivorous fish. The strong association between B. sudanica and B. africanus and aquatic macrophytes, and the observation that local communities perform many lakeshore-related activities that bring them into contact with water, can potentially lead to a higher prevalence of schistosomiasis in the Nyanza Gulf region.

The effects of land use types on levels of microbial contamination based on total coliforms and E. coli (faecal coliform) levels was investigated in the Mara River system, Kenya and Tanzania. Water samples were taken from five sampling sites with different land uses and the Most Probable Number (MPN) method used to determine the total coliforms. A biochemical test was done and the proportions of E. coli bacteria given per study site. The mean concentration of total coliforms was lowest at Silibwet Bridge and highest at Kirumi Bridge. However, counts of E. coli were highest at an urban site (Bomet Bridge) and lowest at a swamp site (Kirumi Bridge). Overall, the proportion (40.9%) of Eosin Methylene Blue (EMB) broth plates that produced E. coli in the study sites was higher than the WHO recommended standards of 0% per 100 ml in potable water. The results show that sections of the river with most human activity and inappropriate types of land-use contributed to high levels of coliform bacteria, particularly E. coli. This may indicate the existence of point sources of faecal contamination along the Mara River and corrective measures should be taken to control them.Keywords: E. coli, faecal coliform bacteria, land use type, most probable number, Mara River.

Among all the malaria controlling measures, biological control of mosquito larvae may be the cheapest and easiest to implement. This study investigated baseline predation of immature mosquitoes by macroinvertebrate predators along the Mara River, determined the diversity of predators and mosquito larvae habitats and the range of their adaptive capacity to water physico-chemical parameters. Between July and August 2011, sampling sites (n=39) along the Mara River were selected and investigated for the presence of macroinvertebrate predators and mosquito larvae. The selected sampling sites were geocoded and each dipped 20 times using standard mosquito larvae dipper to sample mosquito larvae, while a D-frame dip net was used to capture the macroinvertebrate predators. Water physico-chemical parameters (dissolved oxygen, temperature, pH, conductivity, salinity and turbidity) were taken in situ at access points, while hardness and alkalinity were measured titrimetically. The influence of macroinvertebrate predator occurrence was correlated with mosquito larvae and water quality parameters using Generalized Linear Model (GLM). Predators (n=297) belonging to 3 orders of Hemiptera (54.2%), Odonata (22.9%) and Coleoptera (22.9%), and mosquito larvae (n=4001) belonging to 10 species, which included An.gambiae s.l (44.9%), Culex spp. (34.8%) and An. coustani complex (13.8%), An. maculipalpis (3.6%), An. phaorensis (1.2%), An. funestus group (0.5%), An. azaniae (0.4%), An. hamoni (0.3%), An. christyi (0.3%), An. ardensis (0.08%), An. faini (0.07%), An. sergentii (0.05%) and 0.05% of Aedes mosquito larvae which were not identified to species level, due to lack of an appropriate key, were captured from different habitats along the Mara river. It was established that invasion of habitats by the macroinvertebrate predators were partially driven by the presence of mosquito larvae (p < 0.001), and the prevailing water physico-chemical parameters (DO, temperature, and turbidity, p

We purposively selected 39 sampling sites along the Mara River and its two perennial tributaries of Amala and Nyangores and sampled snails. In addition, water physicochemical parameters (temperature, turbidity, dissolved oxygen, conductivity, alkalinity, salinity and pH) were taken to establish their influence on the snail abundance and habitat preference. Out of the 39 sites sampled, 10 (25.6%) had snails. The snail species encountered included Biomphalaria pfeifferi Krauss – the intermediate host of Schistosoma mansoni Sambon, Bulinus africanus – the intermediate host of Schistosoma haematobium , and Lymnaea natalensis Krauss – the intermediate host of both Fasciola gigantica and F. hepatica Cobbold. Ceratophallus spp ., a non-vector snail was also encountered. Most (61.0%) of the snails were encountered in streamside pools. Schistosomiasis-transmitting host snails, B. pfeifferi and B. africanus , were fewer than fascioliasis-transmitting Lymnaea species. All the four different snail species were found to be attached to different aquatic weeds, with B. pfeifferi accounting for over half (61.1%) of the snails attached to the sedge, followed by B. africanus and Lymnaea spp . , accounting for 22.2 and 16.7%, respectively. Ceratophallus spp. were non-existent in sedge. The results from this preliminary study show that snails intermediate hosts of schistosomiasis and fascioliasis exists in different habitats, in few areas along the Mara River, though their densities are still low to have any noticeable impacts on disease transmission in case they are infected. The mere presence of the vector snails in these focal regions calls for their immediate control and institution of proper regulations, management, and education among the locals that can help curtail the spread of the snails and also schistosomiasis and fascioliasis within the Mara River basin. Keywords : Fascioliasis; Habitat preference; Mara River; Schistosomiasis; Vector snails Citation: Infection Ecology and Epidemiology 2014, 4 : 24281 - http://dx.doi.org/10.3402/iee.v4.24281 Responsible Editor: Mare Lohmus, Uppsala University, Sweden.

This study, conducted in Nyanza Gulf of Lake Victoria, assessed ecological succession and dynamic status of water hyacinth. Results show that water hyacinth is the genesis of macrophyte succession. On establishment, water hyacinth mats are first invaded by native emergent macrophytes,Ipomoea aquaticaForsk., andEnydra fluctuansLour., during early stages of succession. This is followed by hippo grassVossia cuspidata(Roxb.) Griff. in mid- and late stages whose population peaks during climax stages of succession with concomitant decrease in water hyacinth biomass. Hippo grass depends on water hyacinth for buoyancy, anchorage, and nutrients. The study concludes that macrophyte succession alters aquatic biodiversity and that, since water hyacinth infestation and attendant succession are a symptom of broader watershed management and pollution problems, aquatic macrophyte control should include reduction of nutrient loads and implementing multifaceted approach that incorporates biological agents, mechanical/manual control with utilization of harvested weed for cottage industry by local communities.

Climate variability has a strong influence on disease prevalence and subsequently on economic wellbeing of the affected households. In this study, six regions were selected and clustered into three groups based on their climatic conditions as follows: areas prone to droughts, floods and those with relatively good weather. Respondents were interviewed and the effects of prevailing climatic conditions on the prevalence of diseases established. Malaria, respiratory tract infection, typhoid, pneumonia and diarrhoea were the major diseases among the Lake Victoria basin residents. The annual disease frequency per household was highest in Budalang'li, a flood prone region; and lowest in Bomet, a region with relatively good weather. The findings reveal the often unseen subtle effects of adverse climatic conditions on economically vulnerable communities in the Lake Victoria basin (LVB) and elsewhere, and recommends flood/drought prevention and mitigation strategies and awareness creation to better cope with the adverse climatic events.