Papers by Edwin Rutalebwa
Tanzania Journal of Science
In Tanzania, poor retention rates among pregnant and breastfeeding mothers continue to be a probl... more In Tanzania, poor retention rates among pregnant and breastfeeding mothers continue to be a problem, contributing to a mother-to-child HIV transmission rate of 11% in 2019, compared to a global target of 5%. The goal of this study was to determine the influence of retention on clinical outcomes and identifying predictors of attrition among HIV-positive pregnant and breastfeeding women from follow-up care in Dar es Salaam. A retrospective cohort study included HIV-positive women who engaged in PMTCT services in public and private health facilities between January 2016 and December 2019. Secondary data were extracted from databases used for routine follow-up in care and treatment clinics (CTCs). The estimates of cumulative incidences of poor retention from date of enrollment or ART initiation were assessed using Kaplan–Meier method. The Cox regression model was used to identify the predictors of attrition. Among 20,225 HIV-infected pregnant and lactating women enrolled in PMTCT servic...
Extreme rainfall events due to heavy rainfall can vary greatly. This variability can be explained... more Extreme rainfall events due to heavy rainfall can vary greatly. This variability can be explained by different factors such as season of the year, temperature and local topography, among others. Statistical models using Extreme Value Theory have been used to model extreme weather events which assume stationarity of rainfall process. However, the stationarity requirement is not met in reality for rainfall data because rainfall time series usually exhibit seasonality. A stochastic model based on a nonhomogeneous Poisson Process (NHPP) charactezised by a time-dependent intensity of rainfall occurrence, is employed in to study the seasonal and trend effects on extreme events modelling of daily rainfalls exceeding prefixed threshold value. Dataset from 14 Tanzania rainfall stations over the period 1981–2014 was used. The Akaike information criterion and likelihood ratio test methods were used to select NHPP model that best fits the data. The results showed a good fit for time–varying int...
Despite Tanzania's efforts and substantial progress in PMTCT, about 11% new infections were recor... more Despite Tanzania's efforts and substantial progress in PMTCT, about 11% new infections were recorded among Tanzanian children in 2019 (UNAIDS 2020a). The objective of this study was to determine the rate of HIV transmission and to identify its risk factors among HIV exposed infants born to HIV-positive mothers in Dar es Salaam, Tanzania. A cross-sectional study was conducted using retrospective data collected from HIV-positive mothers and their exposed babies who were followed and registered in health facilities in four administrative districts (Ilala, Temeke, Kinondoni, and Ubungo) in Dar es Salaam between January 2016 and December 2019. To identify risk factors for MTCT, univariate and multivariate Cox Proportional hazard regression analyses were employed. Out of 18705 registered children exposed to HIV, 586 (3.1%) were positive during the study period, while 18119 (96.9%) were negative. In this study, the following factors were increasing the risks of MTCT of HIV infections, not receiving ARV prophylaxis right at birth (
A series of rainfall data over 31 years in the period 1961-2014 and 1984-2014 recorded at fourtee... more A series of rainfall data over 31 years in the period 1961-2014 and 1984-2014 recorded at fourteen different stations in Tanzania is modelled using Extreme Value Theory. In order to reduce destruction and loss of life and property, it is necessary to make proper inference about extreme rainfall. The main goal of this study was to determine the best fitting distribution to the extreme daily rainfall based for each station, while considering b o t h s t a t i o n a r y and non-stationary processes. The model parameters were estimated and predicted the extreme rainfall return periods and their confidence intervals. The evidences of non-stationary for Dar es Salaam region and stationary for the remaining stat ions were found. The model fit suggest that, the Gumbel distribution provides the most appropriate model for the annual maximums of daily rainfall and the Exponential distribution gives the reasonable model for the daily rainfall data over the threshold value of 99\% for all statio...
A 54 years dataset (1961 -2014) of recordings of the maximum daily (24 h) rainfall in the Dar Es ... more A 54 years dataset (1961 -2014) of recordings of the maximum daily (24 h) rainfall in the Dar Es Salaam area, Tanzania is analyzed using Extreme Value Theory with Bayesian framework. Prior distributions are constructed using quantiles approach. Experts in the field are normally used to elicit distribution of quantiles. With scarcity of data, these experts may not exist. In this paper a different approach in eliciting prior distribution is proposed. In this proposal the quantiles for prior construction are obtained from the Weather Research Forecasting (WRF) model. For the case of Dar es Salaam, WRF outputs are generated based on the physical conditions around 20 December 2011, a day when Dar es Salaam experienced the extreme rainfall which has never been experienced for more than 50 years. A combination of these two data sets, through Bayesian framework, has improved the reliability of forecasting of extreme events. The point estimates for both Maximum Likelihood and Bayesian estima...
54 year datasets (1961 -2014) of recordings of the maximum and minimum daily (24 h) temperature i... more 54 year datasets (1961 -2014) of recordings of the maximum and minimum daily (24 h) temperature in the coastal zone of Tanzania are analysed to test whether there is any significant (in statistical sense) trends in variability of daily temperature. In recent studies it has been reported that there are trends in mean temperature and other climate indices over Tanzania and many other countries worldwide. However, in Tanzania it is not clear whether there is also a trend in variability of daily temperature. In this study 3 meteorological stations (Dar es Salaam, Mtwara, Tanga) have been analysed for trends in variability using F-ratio test, least square method and Mann-Kendall trend test. The results indicate that the observed increasing/decreasing trends in variability of the maximum temperature are statistically non-significant at the level of 5% while the trends are statistically significant for minimum temperatures. Daily minimum temperatures for Dar es Salaam and Mtwara show an in...
Journal of Geoscience and Environment Protection
This paper evaluates the skills of physical Parameterization schemes in simulating extreme rainfa... more This paper evaluates the skills of physical Parameterization schemes in simulating extreme rainfall events over Dar es Salaam Region, Tanzania using the Weather Research and Forecasting (WRF) model. The model skill is determined during the 21 December 2011 flooding event. Ten sensitivity experiments have been conducted using Cumulus, Convective and Planetary boundary layer schemes to find the best combination and optimize the WRF model for the study area for heavy rainfall events. Model simulation results were verified against observed data using standard statistical tests. The model simulations show encouraging and better statistical results with the combination of Kain-Fritsch cumulus parameterization scheme, Lin microphysics scheme and Asymmetric Convection Model 2 (ACM2) planetary boundary scheme than any other combinations of physical parameterization schemes over Dar es Salaam region.
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Papers by Edwin Rutalebwa