Primate Conservation 2018 (32): 123-132 Assessment of Health Risks Posed by Tourists Visiting Mountain Gorillas in Bwindi Impenetrable National Park, Uganda Allison C. Hanes1,3, Gladys Kalema-Zikusoka2, Magdalena S. Svensson3, and Catherine M. Hill3 1One Health Productions, Brooklyn, New York, NY, USA 2Conservation Through Public Health, Entebbe, Kampala, Uganda 3Anthropology Centre for Conservation, Environment and Development, Department of Social Sciences, Oxford Brookes University, Oxford, UK Abstract: The mountain gorilla, Gorilla beringei beringei, is listed by the International Union for Conservation of Nature (IUCN) as Endangered. About 1000 individuals remain in the wild, and the loss of even a single animal has implications for the viability of their two populations. Poaching, political instability and risk of anthropozoonotic disease transmission are potential threats to this species’ recovery. Consequently, reducing the risk of infectious disease transmission by humans to the approximately 400 mountain gorillas of Bwindi Impenetrable National Park, Uganda, must be a priority for conservationists, tourists and the Uganda Wildlife Authority (UWA). Tourist revenue from gorilla trekking is significant and vital to the local communities and the UWA, and for the total gross revenue of Uganda. Data collected through a questionnaire survey (N = 136) and semi-structured inter- views (N = 25) were used to (i) document tourists’ self-reported health status, (ii) explore risk of disease transmission to gorillas, and (iii) assess tourists’ reported willingness to wear disposable face masks during gorilla trekking. Results show that tourists pose a health risk to gorillas—contact and proximity to gorillas while trekking has increased compared to previous studies, and most respondents reported an average viewing distance of 5 m or less. Twenty-five percent of respondents indicated they might trek if sick, especially when symptoms were not severe and even when aware of regulations forbidding they do so. However, tourists are willing to adapt to new protocols, especially the use of face masks (51%). The introduction of face masks for tourists and guides during gorilla trekking is unlikely to reduce tourism revenue by reducing tourist numbers or reducing their willingness to pay. There is a need for improved access to information regarding potential risks of tourist-gorilla disease transmission in order to encourage responsible health-related behavior in tourists. Key Words: Conservation, disease transmission, great apes, health, primates, veterinary medicine Introduction Humans share more than 98% of genes with great apes, allowing for the transmission of many pathogens between Bwindi Impenetrable National Park (BINP), Uganda, them (Wallis and Lee 1999; Daszak et al. 2000; Hacia 2001; has approximately 400 of the world’s 1,004 mountain goril- Gilardi et al. 2015). Disease transmission from habituated las (Gorilla beringei beringei), recently down-listed to primates to humans (zoonotic) and from humans to primates Endangered on the International Union for Conservation of (anthropozoonotic) has been documented since the 1960s. Nature (IUCN) Red List (Hickey et al. 2018a, 2018b). This In 1966, a polio-like virus was recorded in a population of extremely small population is susceptible to various anthro- chimpanzees habituated for research at Gombe National Park pogenic threats, including disease, small-scale encroach- (Goodall 1986; Kormos et al. 2003). Since then other chim- ment and deforestation, conflict from humans when ranging panzee and gorilla research and tourism sites have experi- in community land, and civil unrest (Woodford et al. 2002; enced the devastating impact that infectious diseases can have McNeilage et al. 2006; Plumptre et al. 2016). Disease, par- on small populations. Köndgen et al. (2008) found habitu- ticularly respiratory illnesses, is a common cause of mortal- ated chimpanzees in Taï National Park (Ivory Coast) dying ity in mountain gorillas, second only to trauma (Gilardi et al. after being infected by two common human paramyxoviruses, 2015). Outbreaks of respiratory diseases are prevalent among and Hanamura et al. (2008) reported that chimpanzees in gorilla families as well as the conservation personnel during the Mahale Mountains National Park (Tanzania) were dying the rainy season (Cranfield 2008). from an influenza-like disease. Scabies Sarcoptes( scabiei), 123 Hanes et al. Figure 1. Location of the Bwindi Impenetrable National Park, Uganda, and the distribution of the mountain gorilla (Gorilla gorilla beringei). Map created using IUCN shape files (Plumptre et al. 2016). intestinal parasites, yaws, various respiratory infections, and as a national park in 1991 with the Ugandan Parks Act of measles (suspected) are examples of infections recorded in 1952, allowing for higher protection status against threats great apes, all believed to be of human origin (Hastings et that would compromise the integrity of its forest (Castro and al. 1991; Kalema et al. 1998; Mudakikwa et al. 1998; Pusey Nielsen 2003; Nolan et al. 2017). The park, of 32,092 ha, 1998; Adams et al. 2001). is located on the eastern edge of the Albertine Rift Valley Over time, human and animal populations build immu- sharing a border with the Democratic Republic of Congo nities when exposed to pathogens and viruses, but there can (DRC). It has a wet and mild climate with a mean tempera- be considerable morbidity and mortality when confronting ture range of 11–23°C with no dry season, and provides hab- new diseases or strains (Cranfield 2008). Between August itats ranging from 1160 to 2706 m above sea level (Nolan and December 1996, scabies affected all members of a BINP et al. 2017). Renowned as a biodiversity hotspot, the park gorilla group habituated for tourism. An infant was the most contains more than 163 species of tree, 104 species of fern, severely affected, dying before it could be treated (Kalema- 202 butterfly species, 350 species of bird and 120 mammal, Zikusoka et al. 2002). The source of the outbreak was traced including 11 primates (Butynski and Kalina 1993; Nolan et to a local human community (Graczyk et al. 2001; G. Kalema- al. 2017; UNESCO 2017). It is home to many endangered Zikusoka, pers. obs.). Two wild Rwandan mountain gorillas and threatened species including the African green broadbill died of human metapneumovirus (HMPV) during a series of (Pseudocalyptomena graueri), Grauer's rush warbler (Brad- respiratory outbreaks in 2009 (Palacios et al. 2011). Post- ypterus graueri), cream-banded swallowtail (Papilio leuco- mortem analysis of HMPV samples from the female and her taenia), African elephant (Loxodonta Africana), chimpanzee infant exhibited a close relationship to South African human (Pan troglodytes), l’Hoest’s monkey (Allochrocebus lhoesti), isolates, leading many experts to believe the outbreak source and the mountain gorilla (UNESCO 2017). Afromontane was a tourist (Palacios et al. 2011; G. Kalema-Zikusoka, pers. endemic species of the Rift Valley and almost half the world’s obs.). population of mountain gorillas increase the conservation sig- Bwindi Impenetrable National Park is regarded as one of nificance of the area (Butynski and Kalina 1993) and have the most biologically diverse parks in Africa. It was gazetted resulted in BINP becoming a UNESCO World Heritage Site. 124 Health risks posed by tourists visiting mountain gorillas The park is surrounded by some of the highest and most during trekking. Interviews were piloted at the start of the steadily increasing human population densities in Africa, study with eight participants and were subsequently refined. with 200–700 people/km2, increasing the likelihood of con- We completed a maximum of two interviews for each tourist, tact between humans and gorillas (Plumptre et al. 2016; either at the briefing point following a trek, or scheduled for a Nolan et al. 2017). The growing need for land fosters aggres- later time at the tourist’s lodge. The interviews were recorded sive human encroachment, threatening the gorilla population using a tape recorder and/or video recorder with the permis- and compromising conservation goals (Guerrera, et al. 2003; sion of the interviewee. Twenty-five SSIs were completed, Plumptre et al. 2016; Nolan et al. 2017). Despite extensive conducted by AH. Because questionnaires were completed and sustained management, and support from local and inter- anonymously, it was not possible to link an individual’s ques- national non-governmental organizations (NGOs), goril- tionnaire responses to their interview responses (not all par- las remain vulnerable in this volatile region, and especially ticipants completed both). to disease transmission (Gilardi et al. 2015). Appropriate Quantitative data were coded and analyzed using SPSS research and rigorous preventive measures need, therefore, to (version 25.0). Kolmogorov-Smirnov tests revealed data be implemented in Uganda to protect the existing population were not normally distributed and so non-parametric tests from disease transmission risks that exposure to increasing were applied. Descriptive statistics were run on all ques- numbers of travelers might impose (Wallis and Lee 1999; tionnaire data, including the mean and median ages of par- Cranfield 2008; Macfie and Williamson 2010; Russon and ticipants. Pearson’s chi-square and Fisher exact tests were Wallis 2014). used to compare categorical data (Kranzler 2007). Statistical This study of the potential risk of anthropozoonotic dis-