Mountain gorilla trekking in the mountains of the Democratic Republic of Congo, Rwanda and Uganda, when tourists visits groups of wild gorillas, has become popular in recent years. Trekking generates considerable revenues and it plays an important role in the conservation of these threatened primates and their forest habitat. One downside of gorilla trekking, however, is that it might enable the spread of diseases from humans to gorillas. As human, we share over 98% of our DNA with gorillas, which makes them susceptible to some of the diseases we carry, and there are several cases where human diseases have caused death in gorillas and other great apes. Airborne diseases represent a huge risk in gorilla ecotourism, and keeping a safe distance between visitors and gorillas is therefore crucial. Our study looks at these risks by focusing on the proximity of visitors and gorillas and investigates if set guidelines are followed.
We used 858 Instagram photographs of tourists posing with gorillas (gorilla selfies) to analyse how close tourists get to gorillas in the wild, and what the potential was for disease transmission. The average distance during encounters was 2.96 m, and nine out of ten photographs showed tourists within four metres of the gorillas, a distance small enough for airborne diseases to spread. Disease carrying droplets can travel over 6 metres when sneezing occurs, and this is without considering the effect of wind. Photos of female tourists with immature gorillas had the smallest average distance between the two. Face masks were used in DRC but not in Rwanda or Uganda. Our research suggests that regulations that are in place to ensure appropriate social distancing between tourists and gorillas are inadequately enforced. The widespread global use of facemasks as to prevent the spread of Covid-19 may offers an opportunity to introduce face mask wearing as a compulsory element of gorilla trekking.