| dc.description.abstract | Introduction: Filoviruses pose significant threats to both human and animal populations in Africa, particularly in Uganda, which ranks among the most affected by Ebola and Marburg virus outbreaks. These viruses are closely linked to bats, especially those in the Pteropodidae family. The 2022 outbreak of Sudan virus (Orthoebolavirus sudanense) in Uganda, reported 164 cases and 55 confirmed deaths before containment which underscores the ongoing risk of pathogen outbreak and spillover in the region.
This is coupled with the prevailing traditional knowledge and systems with varying norms and beliefs that increase the bat-human interaction. The social epidemiological and ecological role of bats living in locales such as caves remains complex and largely unknown. Therefore, this study aimed to assess the relationship aspects of bat ecology and social epidemiology of filoviruses in central and western, Uganda. Materials and Methods: The study utilized a mixed methods approach to comprehensively assess bat ecology and social epidemiology of filoviruses in Uganda. This study utilized various methods including systematic review, quantitative surveys, participatory epidemiology, qualitative methods; focus group discussion (FGDs), key informant interviews (KIIs), and in-depth interviews (IDIs), bat fecal sample collection, respective laboratory-based techniques and mathematical modeling. The investigation consisted of five sub-studies each representing a study objective: Study 1: This was a systematic review adhering to PRISMA-P guidelines, examining relevant studies regarding bat ecological and behavioural factors as well as human actions that increase susceptibility to bat-borne pathogens. Data from published articles in different databases and grey literature were qualitatively analyzed, with key findings processed for reflexive thematic analysis in Excel to create themes. The themes generated were combined with Z-scores in R software for statistical analysis to create a Principal Component Analysis (PCA), cluster dendrogram and Pearson correlation for the variables within each theme. Study 2: To achieve this, the study utilized a mixed-methods approach involving surveys (n = 384) and FGDs with participants residing near bat caves in Bundibugyo district (western Uganda). Quantitively, the study assessed the knowledge aspects, perception and risk factors associated with bat
exposure among persons living near bat roosting sites and analysed using descriptive statistics. Proportional piling through ranking was done using 10 FGDs (6–8 participants for each group) to explore community perceptions of activities associated with bat exposure and risk of bat-borne disease transmission. Study 3: This study was carried out in western Uganda i.e. Mubende and Kassanda districts which were known to have had Ebola cases. Qualitative data was collected through FGDs; n=4, IDIs; n=12,
KIIs; n=12, and participatory landscape mapping to explore perceived drivers of the Ebola virus disease outbreak in the study areas. Thematic analysis using a deductive approach guided by social ecological model and epidemiological model in NVivo 12
pro software. Study 4: This study aimed to investigate the presence of filoviruses and characteristics of Kasokero (Masaka district, central region) and python caves (Rubirizi district, western region). To achieve this, 115 environmental bat fecal swab samples
were collected and analysed using nested Reverse Transcriptase Polymerase Chain Reaction (RT-PCR). Additionally, the ecological characteristics were assessed through observation checklists. Study 5: This study developed and analyzed a stochastic model considering the bat-human-environment interface to assess the impacts on disease outbreak extinction and persistence. Using a multitype branching process, the model assessed transmission dynamics involving bats, humans, and environmental
contamination. Parameters were based on existing data, incorporating bat excretions and human exposure behaviors. Numerical simulations of both deterministic and stochastic models depicted a major outbreak and persistence of the virus. Results: Study 1: Five key themes i.e. pathogen spillover from bats to humans, anthropogenic influences, pathways to spillover, seasonal and climate variability, and drivers of bat abundance and viral dynamics were identified related to bat and human leading to pathogen spillover. Among these, influence of anthropogenic activities and seasonal changes had a more significant role on transmission dynamics. The PCA highlighted strong correlations between bat abundance, viral dynamics, and environmental factors. Study 2: In total, 214/384 respondents (55.7%) had a history of bat exposure. Increased exposure to bats was associated with being male (OR = 1.6; 95% CI: 1.0, 2.4), staying in urban areas (OR=1.9; 95% CI: 1.2, 3.1), hunting (OR = 10.9; 95% CI: 1.4 to 87.6), and positive perception to bat guano being safe as fertiliser (OR= 2.5; 95% CI: 1.0, 5.9) and hunting was ranked as the major risk factor. Based on the provided data, the adjusted odds ratio of 0.7 for the good measures (95%CI: 0.4, 1.1), suggests a potential protective effect on the risk of bat exposure. Study 3: Five themes were identified as perceived drivers of Ebola virus outbreaks: (1) Individual factors (knowledge of EVD and fear from deaths of suspected cases); (2) Interpersonal factors (ecological, anthropogenic, environmental, and cultural sources of spillover); (3) Community impact (economic loss and lack of government support for survivors); (4) Organizational challenges (delayed lab results, inadequate reporting systems, and poor surveillance); and (5) Policy recommendations (One Health approach and ongoing public sensitization). Study 4: The study compared Kasokero and Python Caves, both home to fruit bats (Rousettus aegyptiacus). Python cave, with its larger colony size and water sources, supports greater bat populations. Kasokero cave features cultural practices at its entrance. No active viral shedding was revealed at the time of sampling despite the presence of large bat colonies. Despite verified RNA quality, the findings indicate a maximum filovirus prevalence of less than 0.02 at a 95% confidence level. Study 5: Through a multitype branching process approximation, it was demonstrated that both bats and humans can significantly increase the likelihood of disease outbreaks persisting. Managing environmental contamination alone is inadequate for controlling viral transmission without addressing infected hosts. The findings emphasize the need for a One Health approach, involving collaboration across public health, veterinary, wildlife, and environmental sectors, applicable to Marburg virus control. Conclusion: This thesis investigated the complex interactions between bats, humans, and the environment in Uganda regarding filovirus transmission. Through five studies, it highlights that spillover risks driven by human activities, viral dynamics, ecological and environmental factors, cultural norms, and seasonal changes along with bat exposure from hunting, gender roles, and geographical location, are crucial to transmission dynamics. The findings highlight that spillover is not solely due to ecological and environmental factors but is intensified by human behavior and socio-
cultural practices, such as hunting, farming, and bat consumption, which increase bat-human interactions and amplify transmission. Understanding the ecology of bats alongside the associated social epidemiological dynamics is important for designing filovirus preparedness plans as well as heightening prevention and control of related outbreaks. | en_US |
