Mountain gorillas in Uganda and Rwanda, an endangered species, are dying from respiratory illnesses, according to study published on Wednesday.
Poaching is the biggest killer of the gorillas but new research shows that a quarter of 100 gorilla deaths dating back to 1968 were due to illnesses such as influenza and other viruses.
"In a bid to cut the risk of people passing these diseases on, eco-tourists who trek to see the gorillas in the wild already have to stay at least 7 metres (yards) away, and keep their visit to no more than an hour," New Scientist magazine noted on Wednesday.
The Mountain Gorilla Veterinary Project in Ruhengeri, Rwanda, which carried out the research, said 40 deaths were due to trauma which is usually due to poaching. But respiratory illnesses came a surprising second.