Reilly T. Jackson1*, Tamika J. Lunn1, Isabella K. DeAnglis1, Joseph G. Ogola2, Paul W. Webala3, Kristian M. Forbes1Department of Biological Sciences, University of Arkansas, Fayetteville, Arkansas, USADepartment of Medical Microbiology, University of Nairobi, Nairobi, KenyaDepartment of Forestry and Wildlife Management, Maasai Mara University, Narok, Kenya*Correspondence author: rtj006@uark.eduABSTRACTSimultaneous use of domestic spaces by humans and wildlife is little understood, despite global ubiquity, and can create an interface for human exposure to wildlife pathogens. Bats are associated with several pathogens that can spillover and cause disease in humans and, due to loss of natural habitat and urbanization, are increasingly using anthropogenic structures for roosting. The purpose of this study was to characterize human interactions with bats in shared buildings to assess potential for exposure risk to bat pathogens.We surveyed 102 people living and working in buildings used as bat roots in rural Kenya between 2021 and 2023. Based on responses, we characterized and quantified the timing, intensity, and frequency of human-bat interactions occurring in this common domestic setting.Survey respondents reported living with bats in buildings year-round, with cohabitation occurring for at least 10 years in 38% of cases. Human contact with bats occurred through direct and indirect routes, including exposure to excrement (90% of respondents), and direct touching of bats (39% of respondents). Indirect contacts most often occurred daily and direct contacts most often occurred yearly. Domestic animal consumption of bats was also reported (16% respondents).Synthesis and applications : We demonstrate that shared building use by bats and humans in rural Kenya leads to prolonged, frequent, and sometimes intense interactions between bats and humans, consistent with exposure interfaces that can facilitate pathogen spillover. Identifying and understanding the settings and practices that may lead to zoonotic pathogen spillover is of great global importance for developing countermeasures, and this study establishes bat roosts in anthropogenic structures as such a setting.KEYWORDSAfrica, Chiroptera, emerging infectious disease, human-wildlife interaction, spillover, wildlife conflict, zoonosisINTRODUCTIONEmerging infectious diseases (EIDs) are a significant threat to global health and security, as demonstrated by the recent COVID-19 pandemic and Mpox disease outbreak (Morens and Fauci 2013, Wang et al. 2022, Zumla et al. 2022). Most EIDs have zoonotic origins and emerge in humans via spillover of pathogens from animals, often wildlife (Jones et al. 2008). These risks are exacerbated by growing human populations and conversion of natural lands to anthropogenic regions, which increase human contacts with wildlife and exposure to their pathogens (Woolhouse and Gowtage-Sequeria 2005, Jones et al. 2008, Gottdenker et al. 2014).Settings and practices that lead to pathogen spillover are little understood but of great importance for informing outbreak mitigation strategies. In lieu of direct knowledge on pathogen exposure, which is extremely difficult to identify from wild animals, characterization of human-wildlife contact can be used to infer exposure risk. Identifying exposure settings has primarily focused on direct contact between humans and wildlife, largely in the form of wildlife hunting and markets for the sale of live animals (Karesh et al. 2005, Mossoun et al. 2015, Keatts et al. 2021, Nawtaisong et al. 2022). For example, wildlife consumption and associated handling and butchering creates human contact with wildlife viscera and bodily fluids, which can facilitate spillover of their pathogens (Wolfe et al. 2005). However, contacts between humans and wildlife occur across numerous settings outside of wildlife trade and consumption and can result in human exposure to wildlife pathogens (Plowright et al. 2017). Other settings and practices that promote contact between wildlife and humans have received far less focus despite the importance of their characterization to mitigating zoonotic pathogen spillover.Wildlife often share spaces with humans and domestic animals, especially in the Global South, where humans and wildlife coexist closely in developing landscapes and EID risk is high (Seoraj-Pillai and Pillai 2016, Allen et al. 2017). Studies have reported many communities struggling to manage small mammal incursion into buildings (Salmon-Mulanovich et al. 2016, Doty et al. 2017, Balčiauskas and Balčiauskiene 2020). The presence of mammals in these spaces can create opportunities for human and domestic animal contact with wildlife and their excreta, potentially exposing them to wildlife-borne pathogens (Ogola et al. 2021). Despite the risk, characterization and quantification of contacts within buildings, where people may spend significant portions of their lives, is lacking.Bats can harbor zoonotic pathogens that may be shed in excreta and bodily fluids (eg., feces, urine, saliva, blood, etc.; Mildenstein et al. 2016, Waruhiu et al. 2017). Several bat-borne viruses have emerged in humans after transmission from bats via indirect contact with bat excreta or direct contact with bat bodily fluids (Belotto et al. 2005, Epstein et al. 2006, Towner et al. 2009, Eby et al. 2023). Domestic animals can also be exposed to these pathogens after contact with bats excreta and fluids (Marsh and Wang 2004). In developing settings, anthropogenic structures, like family homes, places of worship, and schools, can be highly permeable to bats, and with ongoing habitat loss bats are increasingly using these buildings as roosts (Russo and Ancillotto 2015, Voigt et al. 2016). Few options exist for people to safely manage bat use of their buildings, and this provides numerous opportunities for human-bat contact and conflict. However, detailed characterization of how humans contact bats and their excreta in relation to pathogen exposure risk in shared spaces is lacking and requires attention.We investigated human-bat interactions in anthropogenic structures in rural south-eastern Kenya to characterize and quantify forms of contact that could lead to human exposure to bat pathogens. Bats are known to roost frequently in buildings simultaneously used by humans in this region (Musila et al. 2018, Jackson et al. 2023, Lunn et al. 2023) and this area has been forecasted as a hotspot for zoonotic pathogen emergence where surveillance and mitigation efforts are needed (Allen et al. 2017). By understanding these contacts and their potential to facilitate pathogen exposure, we can better identify human health risks in this interface and provide data necessary to mitigate risks.METHODSThis study was conducted in Taita-Taveta County, Kenya. The most recent 2019 population estimate of Taita-Taveta County was 340,671 people in 2019 (Kenya National Bureau of Statistics), with a 1.8% annual increase in population over the preceding 10 years. Almost three-quarters of the population is considered rural, although urbanization and deforestation are increasing substantially in the region (Platts et al. 2011, Nyongesa et al. 2022). This area is characterized by remnant patches of high-elevation cloud forest surrounded by low-elevation grasslands, woodlands, and agriculture (Abera et al. 2022).We surveyed people in Taita-Taveta County during 2021 (August – October), 2022 (January – April), and 2023 (May – June) to understand and characterize human and domestic animal interactions with bats living in buildings. Participants were identified via word-of-mouth conversations with community members throughout the study area. We sought out adults who had bats in their homes (permanent and rental properties) or workplaces at the time of the survey, or who had evidence of recent sustained bat use (i.e., urine staining, fecal deposits, dead bats, etc.). Surveys were directed to one individual per property, however additional family members were sometimes present during questioning. Participants were informed about the study and verbal consent was obtained prior to conducting surveys. This research was approved by the National Commission for Science, Technology and Innovation (#NACOSTI/P/21/9267) and University of Arkansas Institutional Review Board (Protocol #2103320918).Surveys were conducted in the local Taita language, Swahili, or English by local Taita assistants and at least one of the authors. Questions were read to respondents by the research team and answers were transcribed by the team. Our survey consisted of short-answer, dichotomous, and categorical questions to characterize resident human and domestic animal demographics of the property, the duration of bat use of the property and its buildings, and human and domestic animal interactions with bats and their excreta (see Supplementary Materials for detailed information on survey questions). Surveys from 2021 (n = 23) included 23 multi-part questions. After this initial data collection, we added one additional question to characterize human and domestic animal contact with dead bats on the property. Therefore, surveys conducted in 2022 and 2023 (n = 79) included 24 multi-part questions.To explore the effect of the number of residents on the property, length of bat building use, and respondent demographics (gender, education, and age) on direct (e.g., touching, scratches, bites, etc.) and indirect (e.g., contact with bat excrement) interactions with bats, we used univariate generalized linear models with a binomial error distribution and logit link function. We used chi-square tests to compare the frequencies of bat interactions, length of time of bat occupation of buildings, exclusion methods, and reasons for exclusion. All analyses were conducted in R (Version 2023.06.2+561) using the stats package (v4.1.3).RESULTSWe surveyed 102 people who lived or worked in buildings used by bats (Table S1). Over 70% of people reported bat use of their buildings for >5 years (n = 72), with bat presence for 5-10 years most commonly reported (χ 2 = 36.52, P< 0.01, Fig. 1). Most properties (88%) had bat presence year-round (n = 90). Survey participants described frequent exposure to bats that would support pathogen transmission through two main routes: direct and indirect (fecal/oral) contact, with indirect contact between bats and people reported more frequently than direct contacts (χ 2 = 24.77, P < 0.01, Fig. 2A).