Coughs and colds spread quickly within wild mountain gorillas but keeping a distance appears to stop illness spreading between neighbouring groups, a study suggests.
Respiratory infection is one of the biggest threats to ape conservation, and the animals can catch many of the same diseases as humans.
While respiratory infections can be relatively mild in humans, they can have major consequences in apes like gorillas and chimpanzees.
In these animals a case of the common cold or flu can be lethal, experts say.
Scientists from the Dian Fossey Gorilla Fund studied 15 respiratory outbreaks across the last 17 years to understand how diseases transmitted through a population of mountain gorillas in the Volcanoes National Park, Rwanda.
They found that the close contact and strong social relationships within gorilla groups meant respiratory diseases spread rapidly between group members.
Gorilla groups interact fairly infrequently, and when they do they tend to keep their distance, rarely approaching to within that crucial one to two-metre distanceYvonne Mushimiyimana, co-author
The research also found that patterns of transmission could not be predicted by a group’s social network.
In one outbreak, it took only three days for 45 out of 46 group members to begin coughing.
However, according to the study, opportunities for infections to spread between neighbouring groups were limited.
Yvonne Mushimiyimana, a co-author on the project, said: “The outbreaks we investigated all appeared to stay within a single group rather than spreading through the wider population.
“Gorilla groups interact fairly infrequently, and when they do they tend to keep their distance, rarely approaching to within that crucial one to two-metre distance.”
Researchers suggest this aloofness towards neighbouring groups might help protect the wider population by limiting broader transmission of infections.
Previous research has found that respiratory outbreaks are almost exclusively caused by pathogens of human origin.
Dr Robin Morrison, lead author of the study, said: “If we can better understand how diseases have spread in the past, we can better prepare for and respond to outbreaks in the future.
“Our best guess is that these infections in mountain gorillas are coming from humans.
“It really highlights the importance of ongoing efforts to minimise wild great ape exposure to human diseases during activities like research, tourism and protection.
“Vaccination, mask wearing and maintaining adequate distance are all more important than ever in the midst of a global pandemic.”
Dr Tara Stoinski, president and chief scientific officer of the Fossey Fund, said: “The findings from this study suggest that since respiratory diseases transmit quickly within gorilla groups and transmission between groups is much less common, strategies that prevent initial transmission into a group may be most effective.
“For Covid-19 and other human respiratory pathogens, that means preventing that first introduction of a disease from a human to a gorilla.”
The research is published in the Scientific Reports journal.