Action: Ensure that researchers/tourists are up-to-date with vaccinations and healthy
Key messagesRead our guidance on Key messages before continuing
- One controlled study in Malaysia found that a population of reintroduced orangutans decreased by 33% over 33 years despite staff and volunteers having received medical checks, alongside other interventions.
- One before-and-after study in Rwanda, Uganda and Congo found that mountain gorilla numbers increased by 168% over 41 years while sick/unwell researchers and visitors were not allowed to visit gorillas, alongside other interventions.
Several studies have demonstrated that a significant proportion of travellers at wildlife sanctuaries/ecotourism sites may be ill, potentially infectious and not protected against vaccine-preventable illnesses, creating unnecessary risk of pathogen transmission to the primates that are housed/live there (Muehlenbein et al. 2008, Muehlenbein et al. 2010). This intervention aims to prevent the spread of viral and bacterial diseases from humans to primates and can be implemented in situations where humans regularly come into close contact with primates, such as when researchers or tourists observe habituated primates in their natural habitat.
Other means of preventing the spread of bacterial and viral diseases from researchers/tourists/managers to primates are discussed under ‘Wear face-masks to avoid transmission of viral and bacterial diseases to primates’, ‘Keep safety distance to habituated animals’, ‘Limit time that researchers/tourists are allowed to spend with habituated animals’, ‘Implement quarantine for people arriving at, and leaving the site’, ‘Regularly disinfect clothes, boots etc.’, and ‘Wear gloves when handling primate food, tool items, etc.’.
Muehlenbein M.P., Martinez L.A., Lemke A.A., Ambu L., Nathan S., Alsisto S., Andau P. & Sakong R. (2008) Perceived vaccination status in ecotourists and risks of anthropozoonoses. EcoHealth, 5, 371–378.
Muehlenbein M.P., Martinez L.A., Lemke A.A., Ambu L., Nathan S., Alsisto S. & Sakong R. (2010) Unhealthy travelers present challenges to sustainable primate ecotourism. Travel Medicine and Infectious Disease, 8, 169–175.
Supporting evidence from individual studies
A controlled study in 1967-2004 in tropical forest in Kabili-Sepilok Forest Reserve, Malaysia found that rehabilitated and reintroduced orangutans Pongo pygmaeus morio decreased by 33% over 33 years (1964-1997), although staff and volunteers received medical checks to avoid disease transmission alongside eight other interventions. In addition, infant mortality (57%) was higher than in other wild and captive populations, and the sex ratio at birth was strongly biased towards females (proportion males=0.11) compared to other wild and captive populations. Inter-birth-interval (6.1 years) was similar to wild populations of the same subspecies. Mean age at first reproduction (11.6 years) was lower than in other wild and captive populations. Orangutans were daily provided supplementary food from 2-7 feeding platforms. Individuals underwent in-depth veterinary checks and were kept in quarantine for 90 days before release into the reserve, in which other rehabilitated orangutans lived. Sick or injured individuals were captured and treated. Tourists had to keep safety distances (>5 m) at all times. The study does not distinguish between the effects of the different interventions mentioned above.
A controlled, before-and-after study in 1967-2008 in tropical montane forest in Volcanoes-, Mgahinga-, and Virunga National Parks in Rwanda, Uganda, and the Democratic Republic of Congo found that the mountain gorilla Gorilla beringei beringei population that was regularly visited by healthy tourists and researchers alongside ten other interventions, increased in size over time. Annual population growth was 4.1%, resulting in an overall population increase of 168% over 41 years. No statistical tests were carried out to determine whether this increase was significant. Visitors/researchers were asked to report if they were not feeling well and were not allowed to visit the gorillas if they felt sick. As part of the ecotourism- and research programmes, gorillas were habituated to human presence, where visitors/researchers had to follow strict health procedures; these included keeping a safety distance to the gorillas, wearing face-masks, spending only a limited amount of time with gorilla groups, disinfecting visitor’s/researcher’s clothes, boots etc. The population was continuously monitored by vets and individuals received medical treatment if necessary. When gorillas died, their cause of death was examined. The study only tests for the effect of veterinary interventions, but does not distinguish between the effects of the other interventions mentioned above.
- Kuze N., Sipangkui S., Malim T.P., Bernard H., Ambu L.N. & Kohshima S. (2008) Reproductive parameters over a 37-year period of free-ranging female Borneo orangutans at Sepilok Orangutan Rehabilitation Centre. Primates, 49, 126-134
- Robbins M.M., Gray M., Fawcett K.A., Nutter F.B., Uwingeli P., Mburanumwe I., Kagoda E., Basabose A., Stoinski T.S., Cranfield M.R. & Byamukama J. (2011) Extreme conservation leads to recovery of the Virunga mountain gorillas. PLoS ONE, 6