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Call for COVID rules that reduced infections in gorilla parks to remain

  • Respiratory infections recorded among mountain gorillas in Rwanda’s Volcanoes National Park dropped from a pre-pandemic average of 5.4 outbreaks among family groups to just 1.6 per year since the start of the COVID-19 pandemic in March 2020.
  • Conservation group Gorilla Doctors, whose Rwanda team recorded the decrease in infections, says the decline correlates with lower visitor numbers to the park as well as masking requirements and an increase in the distance tourists must stay from habituated apes.
  • In a recent letter in the journal Nature, Gorilla Doctors and the park’s chief warden called for these stricter measures to be kept in place permanently.

Stricter measures implemented to protect endangered mountain gorillas from COVID-19 should be made permanent long after the pandemic has passed, conservationists say, citing a significant drop in respiratory infections among human-habituated gorillas in one major park in Rwanda.

Respiratory infections recorded among mountain gorillas (Gorilla beringei beringei) in Volcanoes National Park (VNP) dropped from an average of 5.4 outbreaks among family groups per year between January 2015 and February 2020, to just 1.6 per year after the start of the pandemic in March 2020, according to veterinarians from Gorilla Doctors. The group works to protect the two subspecies of eastern gorillas — mountain gorillas and eastern lowland gorillas (Gorilla beringei graueri) — in Rwanda, Uganda and the Democratic Republic of Congo.

The drop correlates with the decline in the number of tourists visiting the park, and stricter guidelines for viewing gorillas.

VNP was shut in March 2020 as COVID-19 spread around the globe. When it reopened three months later, tourists had to wear face masks and maintain a distance of at least 10 meters (33 feet) from the gorillas, an increase from 7 m (23 ft) before the pandemic. Wearing a mask was previously not mandatory for tourists visiting the park.

When Volcanoes National Park reopened three months after a lockdown, tourists had to wear face masks and maintain a distance of at least 10 meters (33 feet) from the gorillas. Image by Peter Prokosch/GRID-Arendal via Flickr (CC BY-NC-SA 2.0).

“As the Omicron viral variant surges and tourism returns, we consider it crucial to make these precautionary best practice measures permanent to minimize transmission of human diseases to great apes,” Gorilla Doctors director and chief veterinarian Kirsten Gilardi and VNP chief warden Prosper Uwingeli wrote in a letter published Feb. 10 in the journal Nature.

“We thought it was worth noting in this letter to Nature that even the best practices we use as humans in this pandemic have benefited the gorillas of Volcanoes National Park,” Gilardi told Mongabay. “Because we’re so closely related genetically, great apes are susceptible to human pathogens, and if we’re going to spend time near them in the wild, we’re really obligated to do the basics of disease transmission prevention that we know work.”

Although the SARS-CoV-2 virus that causes COVID-19 has not yet been detected among wild-living mountain gorillas in any of the three range states in East Africa, it has been found to pass from humans to captive and closely related western lowland gorillas (Gorilla gorilla gorilla) in zoos in the United States and the Czech Republic.

Respiratory disease outbreaks, in some cases traced back to humans, are the second leading cause of death in mountain gorillas after “trauma” — the injuries they might sustain from other gorillas or from poachers’ snares.

Human-gorilla transmission of human metapneumovirus was suspected to be behind the deaths of two gorillas during an outbreak in Rwanda in 2009. And a 2020 paper co-authored by Gilardi reported that human viruses were found in fecal samples collected from gorillas suffering from respiratory infections during outbreaks between 2012 and 2013.

The call from Gilardi and Uwingeli echoes that of others working to preserve Africa’s great apes — which include chimpanzees (Pan troglodytes), bonobos (Pan paniscus) and western gorillas — from the humans who come to see them and may unwittingly pass on their germs.

“Wearing of masks should become the new norm for great apes tourism, and maintaining a distance and being healthy when you trek,” Gladys Kalema-Zikusoka, founder and director of Ugandan NGO Conservation Through Public Health, said during a recent webinar on great apes and responsible tourism organized by the African CSOs Biodiversity Alliance.

“There are other diseases, it’s not just COVID. These regulations should remain beyond the pandemic. We don’t know if Omicron is the last variant. There may be another one coming up. But even if Omicron isn’t the last variant, the great apes are highly susceptible to [other] respiratory diseases,” she said.

Bookings with Ugandan tour operators offering gorilla-viewing treks are now ranging between 30 and 50% of full capacity, Kalema-Zikusoka told Mongabay.

As tourism picks up, so does the risk of human-induced infections among gorillas. But Kalema-Zikusoka, who works mostly in Uganda’s Bwindi Impenetrable National Park, home to nearly half the world’s mountain gorillas, said tourists are now more willing to follow stricter great ape viewing guidelines.

A Mountain Gorilla and her baby in Bwindi Impenetrable National Park, Uganda. The increase in gorilla population is thanks in no small part to tourism, which provides the revenue to pay for the protection of the parks and their wild inhabitants. Image by Ralph Earlandson via Flickr (CC BY-NC 2.0).

“The pandemic has enabled them to have a better understanding of how such a disease could easily spread from people to closely related great apes,” she said.

There are an estimated 1,063 mountain gorillas spread between Rwanda, Uganda and the DRC. This figure is up from around 250 in the 1980s. More than 70% of the animals are habituated, or accustomed to being near to humans.

The increase in population is thanks in no small part to tourism, which provides the revenue to pay for the protection of parks and their wildlife.

Gilardi said the acceptance of humans by gorillas also allows her organization’s veterinary teams to do their work.

Sometimes medication has to be given to sick animals by darting them with syringes fired from dart guns, an intervention that requires the team to get close to the animals. That would be a lot harder if mountain gorillas weren’t habituated.

“The veterinary care that we can give to individual gorillas is proven to be a significant factor in the annual population growth rate for the mountain gorillas,” Gilardi said.

“It is a double-edged sword but human habituation and gorilla tourism has saved mountain gorillas from extinction.”

Banner image: A Rwanda mountain gorilla family on the way back into the Virunga Gorilla Reserve. Image by youngrobv via Flickr (CC BY-NC 2.0).


Gilardi, K. V., & Uwingeli, P. (2022). Keep mountain gorillas free from pandemic virus. Nature, 602(7896), 211-211. doi:10.1038/d41586-022-00331-z

Mazet, J. A., Genovese, B. N., Harris, L. A., Cranfield, M., Noheri, J. B., Kinani, J. F., . . . Gilardi, K. V. (2020). Human respiratory syncytial virus detected in mountain gorilla respiratory outbreaks. EcoHealth, 17(4), 449-460. doi:10.1007/s10393-020-01506-8

Palacios, G., Lowenstine, L. J., Cranfield, M. R., Gilardi, K. V., Spelman, L., Lukasik-Braum, M., . . . Lipkin, W. I. (2011). Human metapneumovirus infection in wild mountain gorillas, Rwanda. Emerging Infectious Diseases, 17(4), 711-713. doi:10.3201/eid1704.100883

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