PhD - Dissertations

Effects of Climate Change on Agrochemical Use and Health of Fresh Produce Farmers in Nakuru County, Kenya

2025-01-01T00:00:00Z

Effects of Climate Change on Agrochemical Use and Health of Fresh Produce Farmers in Nakuru County, Kenya Kirongo, David Kihara Global surface temperature has risen by ~0.2°C per decade over the past 30 years. In Kenya, mean annual temperature has increased by ~1.0°C since the 1960s (~0.21°Cper decade). Nakuru County has experienced shifts in both temperature and rainfall, with average daily highs rising by 1.5–2.0°C (23.3°C to 27.8°C) and lows by 1–2°C (11.1°Cto 12.8°C). Annual rainfall has declined by ~5–10% compared to early 2010s levels, with increasing variability in the onset and cessation of rains. These changes contribute to greater reliance on agrochemicals, driven by pest resistance and climate variability. Although Africa accounts for only 2–4% of global pesticide use, the continent faces disproportionately high exposure risks. Overuse and misuse of agrochemicals undermine environmental integrity, human health, and agricultural sustainability. This study investigated the effects of climate change on agrochemical use and the health of fresh produce farmers in Nakuru County. Specifically, it examined farmers’ socio-economic status, agrochemical use practices, occupational safety measures, the association between climate change and agrochemical use, and proposed health and safety interventions. A community-based cross-sectional design targeted rural fresh produce farmers routinely exposed to agrochemicals. A two-stage sampling technique was applied: random selection of sub-counties using probability proportional to size, followed by random household selection within clusters. The study accessed a sample size of 388. Quantitative data were collected using structured questionnaires, while key informant interviews (KII), focus group discussions (FGD), and observations provided qualitative data. Data were collected using Kobo Toolbox, exported to Excel, coded, and analyzed in SPSS version 28. Chi-square tested associations between categorical variables, while binomial regression measured statistical significance. Findings showed that agrochemical exposure undermines the health of farmers. Risk factors included financial constraints, years of farming experience, household income, farmer group membership, and type of farming. Farmers with more than 15 years of agrochemical use were 1.3 times more likely to develop adverse health effects compared to those with fewer years (p=0.006). Financially constrained farmers were five times more likely to develop health problems than those without constraints (p<0.01). Regression analysis established a statistically significant association between changes in weather patterns and agrochemical use decisions (p=0.005). Farmers noticing extreme weather were 1.2 times more likely to rely on expert advice or previous experience when making agrochemical use decisions. Overall, farmers with long term agrochemical use and financial challenges faced heightened health risks. 64.2%offarmers expressed willingness to adopt new technologies, shift towards organic farming, andreduce reliance on traditional agrochemicals. The study recommends targeted interventions by Nakuru County’s agriculture department to address financial barriers, such as promoting cooperative membership through agricultural extension services. A multisectoral approach, including the health department, should target experienced farmers for regular health screenings, refresher training, capacity building, and sensitization to enhances afeagrochemical use and strengthen occupational health and safety practices.

Modeling Pulmonary Tuberculosis and Pneumonia Co-Infection Incorporating an Asymptomatic Component and Natural Immunity

2025-01-01T00:00:00Z

Modeling Pulmonary Tuberculosis and Pneumonia Co-Infection Incorporating an Asymptomatic Component and Natural Immunity Kirimi, Erick Mutwiri Pulmonary tuberculosis is one of the leading infectious diseases causing mortality worldwide, and its impact is exacerbated by opportunistic infections such as pneumonia. The lethal synergism between pulmonary tuberculosis and pneumonia contributes to increased mortality in endemic regions. Existing models of pulmonary tuberculosis do not incorporate the screening of asymptomatic infectious individuals, despite their significant contribution to disease transmission within the population. Additionally, these models do not account for the impact of natural immunity in controlling or reducing the spread of infections. The aim of this study was to model pulmonary tuberculosis and pneumonia co-infection, incorporating an asymptomatic infectious component and natural immunity. The study objectives included: formulating a pulmonary tuberculosis model that incorporates an asymptomatic infectious component and natural immunity; formulating a coinfection model that also incorporates an asymptomatic infectious component and natural immunity; determining the reproduction numbers for analyzing the formulated models; and investigating the effects of varying model parameters on the control of pulmonary tuberculosis. A population-based compartmental approach was employed to formulate the models, from which differential equations were derived. The progression from latent infection to pulmonary tuberculosis disease was modeled using Holling’s saturation term to account for natural immunity. The Next-Generation Matrix method was used to determine reproduction numbers, while stability was analyzed using the Routh–Hurwitz criteria, the Castillo–Chávez method, and Lyapunov functions. Sensitivity analyses of the reproduction numbers in relation to the model parameters were conducted using the normalized sensitivity index method. The model equations were solved numerically using fourth- and fifth-order Runge-Kutta methods in MATLAB software to identify effective intervention strategies for significantly reducing disease transmission. Secondary data from National Tuberculosis, Leprosy, and Lung Disease Program (NTLLDP) in Kenya were utilized to perform numerical simulations, with 2022 data serving as the initial conditions. The co-infection model was fitted to NTLLDP prevalence data from 2012 to 2022 using the fminsearch algorithm in MATLAB software to estimate specific parameters. The results predicted that combining vaccination, screening, and treatment for all forms of pulmonary tuberculosis is the most effective intervention for reducing transmission. Enhancing natural immunity, increasing screening rates for latently infected individuals, and improving vaccine efficacy were also shown to reduce the co-infected population. Specifically, a 10% increase in vaccine efficacy was predicted to reduce co-infections by 6.67%, while the same increase in the screening rate for latent infections reduced them by 6.73%. Furthermore, doubling the screening rate for individuals with asymptomatic infectious pulmonary tuberculosis was shown to reduce the population with severe co-infections and those undergoing treatment for severe conditions by 53.2%. These findings offer valuable guidance to healthcare officials in making informed decisions about screening latently infected and asymptomatic infectious tuberculosis patients, thereby contributing to the fight against epidemics of this disease. The results also underscore the importance of accurate diagnosis and effective treatment of tuberculosis and pneumonia co-infections, which contribute to reducing infection transmission. Lastly, the study emphasizes the need to enhance the natural immunity of latently infected individuals to reduce disease progression and transmission.

Extent of Disaster Risk Preparedness in Informal Settlements of Nyeri Town, Nyeri County, Kenya

2025-01-01T00:00:00Z

Extent of Disaster Risk Preparedness in Informal Settlements of Nyeri Town, Nyeri County, Kenya Muriuki, Zachary K. Informal settlements are growing in the world everyday due to poverty and inadequate land to settle. Most informal settlements are faced with a myriad of problems ranging from inadequate infrastructure, poor sanitation, water and noise pollution among others. This study sort to determine the extent of disaster risk preparedness in the informal settlements of Nyeri town, Nyeri County. The specific objectives of the study were to assess the level of awareness on the types of disasters and existing policies to address them, to establish disaster mitigation measures in place, to identify the role of stakeholders in disaster management, to identify the challenges encountered during disaster risk reduction initiatives. The study targeted residents of informal settlements in Majengo Witemere Ngangarithi kwa Mwaura, Mathari “transformer”, and Ruring’u Muslim village. This research applied descriptive cross-sectional study design. A sample of 384 residents was selected among the residents. Data was collected by use of questionnaires and key informant interview guide. Data analysis was done using SPSS version 21. Univariate analysis for each variable was done so as to yield descriptive statistics that was used to analyze the variables. Presentation of the findings was done through prose, tables and figures. The results indicated that there was a significant association between the area of residence and the level of compliance of policy rules concerned with disaster risk reduction [X2 (3) = 11.446, p-value =0.010<0.05]. However, there was no significant association between the area of residence and level of awareness of the disasters that could affect them [X2 (3) = 2.99, p-value =0.393>0.05], and neither was there significant association between the area of residence and level of awareness of any policy rule concerned with disaster risk reduction [X2 (3) =7.026, p-value =0.071>0.05]. Key informants interview was administered to 10 key informants within Nyeri County, these included each Managers and supervisors of Ministry of Health Nyeri County, County Government of Nyeri department disaster Management, Nationals interior and coordination office Nyeri, Kenya Red Cross Society Nyeri office and County National Disaster Management Authority Nyeri office. It was concluded that Risk assessment as a step for successful disaster reduction measures will ensure that the community members are aware of the possible hazards. National and County government should incorporate the national and international guidelines in their policy. Lessons learnt from previous disasters that have affected other informal settlements and other parts of the country should inform the formulation of mitigation measures for disaster management. The researcher further recommends to the scholars to consider research on disaster risk preparedness as the strategy of counties development agenda and Social and economic potentials that the County Governments can tap in informal settlements.

Integrated QOS Management Technique for Internet Protocols Storage Area Network

2022-01-01T00:00:00Z

Integrated QOS Management Technique for Internet Protocols Storage Area Network Kithinji, Joseph The increasing number of Information Technology Users around the world has led to tremendous increase in the amount of data that requires storage. In response to this challenge, new storage area network architectures based on Ethernet (IP) have evolved. With the coexistence of storage traffic with other types of traffic in the same IP network, it is important to offer storage traffic QOS guarantees to prevent performance degradation for storage users. Regrettably, the storage device itself does not provide any capability of guaranteeing storage QOS. QOS is a vital issue in environment of mixed works like IP SANS. The main aim of the study was to analyses the QOS techniques used in IP networks, design, develop and validate an Integrated QOS management technique for IP SANS. The study first analyzed the various techniques for achieving QOS in IP Networks. By decomposing QOS problem into an integration of four techniques of performance isolation, bandwidth management and burst handling the study designed and developed IQMIS, an integrated quality of service management technique for IP SANS. The study adopted experimental research design. Simulations were used as the source of data where Park dale tool was used for simulating reads and writes to the targets. The study generated quantitative results which were analyzed using descriptive statistics and results presented in tables and charts. Empirical results show that IQMIS enables users to fairly share the aggregate system throughput even in environment of contention of resources with a small implementation cost of 6%. In the implementation of bandwidth management and burst handling, IQMIS was found to be work conserving and quickly adopts to network changes with a convergence time of 10 seconds. Further the results show that IQMIS can provide strong performance isolation, superior latency, throughput and jitter compared to best effort. Ultimately, IQMIS can be used to provide end-to-end QOS management in IPSANS and at the same time provide building blocks for providing QOS in IPSANS to a tremendous increase in the amount of data that requires storage.