Water quality modelling and quantitative microbial risk assessment for uMsunduzi River in South Africa

South African rivers generally receive waste from inadequate wastewater infrastructure, mines, and farming activities, among others. The uMsunduzi River in KwaZulu-Natal, South Africa, is among these recipients with recorded poor to very poor water quality. To identify parts of the uMsunduzi River that are polluted by Cryptosporidium and Escherichia coli (E. coli), this study mapped out pollutants emanating from point and non-point sources using the Soil and Water Assessment Tool (SWAT). Streamflow calibration in the upper and lower reaches of the catchment showed good performance with R-2 of 0.64 and 0.58, respectively. SWAT water quality output data were combined with a Quantitative Microbial Risk Assessment (QMRA) to understand the microbial health implications for people using river water for drinking, recreational swimming, and non-competitive canoeing. QMRA results for Cryptosporidium and pathogenic E. coli showed that the probability of infection for most users exceeds the acceptable level for drinking and recreation as outlined in the South African water quality guidelines, and by the World Health Organisation (WHO). The results of this study can be used as a baseline to assess the economic and health implications of different management plans, resulting in better-informed, cost-effective, and impactful decision-making

Quantitative microbial risk assessment of wastewater and faecal sludge reuse in Ghana

The probabilistic health risks of rotavirus and Ascaris infections associated with different scenarios of diluted wastewater and faecal sludge agricultural reuse in Ghana were estimated based on the Quantitative Microbial Risk Assessment (QMRA) approach. The annual risks of rotavirus and Ascaris infections associated with diluted wastewater reuse scenarios were 10-2 and 10-3 to 10-4 respectively compared with the WHO tolerable health risk of 10-4 per person per year. The risk of Ascaris infection for the different scenarios of faecal sludge reuse ranged from 10-4 to 10-2 while it was <10-14 to 10-1 for rotavirus infections per single exposure. The treatment of faecal sludge significantly reduced the risk of rotavirus infections but had less effect on the reduction of Ascaris infections. It is stressed that the estimated risks of infection need to be validated against follow-up data obtained from epidemiological investigations coupled with studies on different health risk barriers

Distribución espacial de Aedes aegypti (Diptera: Culicidae) en el área rural de dos municipios de Cundinamarca, Colombia

Introduction: It is difficult to adapt or create new strategies for dengue control in rural areas due to the dispersion of homes and the lack of knowledge about the presence and behavior of the vector in these areas. Spatial data analysis could help understand time and space dynamics related to the transmission of vector-borne diseases in rural areas and, thus, contribute to the prevention and control of dengue.Objective: To determine the probability of the presence of the dengue vector Aedes aegypti in the rural area of the municipalities of Anapoima and La Mesa, in the central area of Colombia.Materials and methods: The probability of the presence or absence of the vector in the study area was determined by means of the kriging spatial interpolation method.Results: The region with the highest probability of the presence of the vector was located in the central part, close to the urban centers of both municipalities.Conclusion: This study shows the importance of geostatistics for the surveillance of vector-borne diseases and the analysis of time and space dynamics of vector insects and of diseases transmitted by them.Introducción. Es difícil adaptar o formular nuevas estrategias para el control del dengue en las áreas rurales debido a la dispersión de los hogares y a la falta de conocimiento sobre la presencia y el comportamiento del vector en estas áreas. El análisis de los datos espaciales podría ayudar a comprender las dinámicas temporales y espaciales relacionadas con la transmisión de enfermedades transmitidas por vectores en las zonas rurales y, por lo tanto, contribuir a la prevención y el control del dengue.Objetivo. Determinar la probabilidad de la presencia del vector del dengue, Aedes aegypti, en el área rural de los municipios de Anapoima y La Mesa, Cundinamarca, Colombia.Materiales y métodos. Se visitaron 102 viviendas del área rural, se inspeccionaron los criaderos potenciales del mosquito A. aegypti y se capturaron las formas adultas encontradas en su interior. La probabilidad de la presencia o la ausencia del vector en el área de estudio, se estableció mediante el método de interpolación espacial kriging.Resultados. La región con mayor probabilidad para la presencia del vector se encontró en la parte central, cerca de los centros urbanos de los dos municipios.Conclusión. Los análisis de las dinámicas espacio-temporales de los vectores de enfermedades pueden utilizarse en los sistemas para su vigilancia, con el fin de complementar los métodos usados actualmente, optimizar la determinación de las áreas de intervención de control vectorial y ahorrar recursos

Dengue-like illness surveillance: a two-year longitudinal survey in suburban and rural communities in the Lao People’s Democratic Republic and in Thailand.

Objective: This study aimed to determine the incidences of dengue-like illness (DLI), dengue virus (DENV) infection, and serotypes and to identify socio-demographical and entomological risk factors of DLI in selected suburban and rural communities in the Lao People’s Democratic Republic and in Thailand. Methods: A two-year longitudinal study was conducted in four villages during the inter-epidemic period between 2011 and 2013. Entomological surveys, semi-structured interviews of household heads and observations were conducted. Occurrences of DLI were recorded weekly using the World Health Organization’s dengue definition along with blood samples; results were compared with national surveillance dengue data. Risk factors of DLI were assessed using logistic regression. Results: Among the 2007 people in the study, 83 DLI cases were reported: 69 in suburban Lao People’s Democratic Republic, 11 in rural Thailand, three in rural Lao People’s Democratic Republic and none in suburban Thailand. Four were confirmed DENV: two from suburban Lao People’s Democratic Republic (both DENV-1) and two from rural Thailand (both DENV-2). Although the number of detected DLIs during the study period was low, DLI incidence was higher in the study compared to the dengue surveillance data in both countries. DLI in suburban Lao People’s Democratic Republic was associated with age and occupation, but not with the number of pupae per person. Discussion: This study highlights the importance of continuous clinical and vector surveillance for dengue to improve early detection of dengue and other mosquito-borne diseases in the region

Dengue-like illness surveillance: a two-year longitudinal survey in suburban and rural communities in the Lao People’s Democratic Republic and in Thailand.

Objective: This study aimed to determine the incidences of dengue-like illness (DLI), dengue virus (DENV) infection, and serotypes and to identify socio-demographical and entomological risk factors of DLI in selected suburban and rural communities in the Lao People’s Democratic Republic and in Thailand. Methods: A two-year longitudinal study was conducted in four villages during the inter-epidemic period between 2011 and 2013. Entomological surveys, semi-structured interviews of household heads and observations were conducted. Occurrences of DLI were recorded weekly using the World Health Organization’s dengue definition along with blood samples; results were compared with national surveillance dengue data. Risk factors of DLI were assessed using logistic regression. Results: Among the 2007 people in the study, 83 DLI cases were reported: 69 in suburban Lao People’s Democratic Republic, 11 in rural Thailand, three in rural Lao People’s Democratic Republic and none in suburban Thailand. Four were confirmed DENV: two from suburban Lao People’s Democratic Republic (both DENV-1) and two from rural Thailand (both DENV-2). Although the number of detected DLIs during the study period was low, DLI incidence was higher in the study compared to the dengue surveillance data in both countries. DLI in suburban Lao People’s Democratic Republic was associated with age and occupation, but not with the number of pupae per person. Discussion: This study highlights the importance of continuous clinical and vector surveillance for dengue to improve early detection of dengue and other mosquito-borne diseases in the region

Spatial distribution of Aedes aegypti (Diptera: Culicidae) in the rural area of two municipalities of Cundinamarca, Colombia

Introduction: It is difficult to adapt or create new strategies for dengue control in rural areas due to the dispersion of homes and the lack of knowledge about the presence and behavior of the vector in these areas. Spatial data analysis could help understand time and space dynamics related to the transmission of vector-borne diseases in rural areas and, thus, contribute to the prevention and control of dengue. Objective: To determine the probability of the presence of the dengue vector Aedes aegypti in the rural area of the municipalities of Anapoima and La Mesa, in the central area of Colombia. Materials and methods: The probability of the presence or absence of the vector in the study area was determined by means of the kriging spatial interpolation method. Results: The region with the highest probability of the presence of the vector was located in the central part, close to the urban centers of both municipalities. Conclusion: This study shows the importance of geostatistics for the surveillance of vector-borne diseases and the analysis of time and space dynamics of vector insects and of diseases transmitted by them