The coronavirus pandemic shows what can happen when diseases (known as zoonoses) spill over from animals to humans. It is a two-way street, though records of us spreading viruses to animals are rare.
Being closely related, great apes are most at risk, which is why mountain gorilla ecotourism was suspended. Fifteen years ago, a fatal outbreak of respiratory disease in Tanzania’s chimpanzees is thought to have come from the tourists who visited them.
But other species, including livestock and pets, can also catch our viral, bacterial, parasitic and fungal diseases. In April, a tiger at New York’s Bronx Zoo tested positive for COVID-19, having caught it from an infected zookeeper.
Similarly in 2009, captive cheetahs in California caught the human flu known as H1N1. Meanwhile, in Namibia, African painted dogs often carry the diarrhoea-causing parasitic micro-organism Giardia duodenalis, which they pick up from human faeces.
