The outbreak of COVID-19 could pose a threat to wild mountain gorillas in Rwanda's Volcanoes National Park

According to a modelling study published in Scientific Reports, an outbreak of COVID-19 in wild mountain gorillas in Rwanda's Volcanoes National Park could lead to a collapse of populations. SARS-CoV-2 infection has previously been detected in captive western lowland gorillas, however, the potential risk posed by COVID-19 to wild apes, including endangered mountain gorillas, has been unclear.

Fernando Colchero and colleagues modeled the probability that an outbreak of COVID-19 in a population of mountain gorillas living in Volcanoes National Park could cause that population to collapse. The authors used data from 396 gorillas collected by the Diane Fawce Gorilla Fund between 1967 and 2018, taking into account annual changes in the size and structure of this population. They also considered the epidemiological factors that influence the dynamics of human COVID-19 disease, including the number of individuals infected with the disease (R0) from infected people; the probability of death after infection; the probability of developing immunity; and the duration of immunity.

The authors conducted 2,000 simulations in which the size and structure of the population within the park varied at different rates and found that 71 percent of these simulated populations would collapse within 50 years with similar epidemiological conditions reported in human outbreaks. And the authors argue that because there are fewer treatments for gorillas, the mortality rate in this group may be higher than in humans. When this was taken into account in the model, the proportion of 2,000 simulated populations in the park that collapsed within 50 years increased to 80 percent. While previously found that the average R0 for human COVID-19 was about 2.5, the authors found that when the R0 of a gorillas was at least 1.05, the probability of population collapse increased. This shows the importance of limiting the spread of SARS-CoV-2 within a population.

The authors note that the trend toward natural social distancing between gorilla populations is likely to reduce the risk of SARS-CoV-2 transmission. However, this population has grown in recent years, leading to higher rates of intergroup encounters and possibly increasing the chances of disease transmission.

The findings highlight the risks currently posed by the COVID-19 pandemic to mountain gorilla populations in Volcanoes National Park. The authors recommend continuing measures to limit the spread of SARS-CoV-2 within the park, such as wearing masks and vaccinate park staff and visitors, as well as regular testing for gorillas for possible infection.