In 2003, 47 people across six Midwestern states caught monkeypox from pet prairie dogs that were infected after they were housed with rodents imported from Ghana, Africa. Today’s outbreak, which has already infected more than 14,100 people in the U.S. and more than 41,000 across the globe, is spreading mostly through close human contact among gay and bisexual men.

But scientists reported the first presumed human-to-pet transmission in a dog in France this month, prompting U.S. and global health officials to step up warnings to ensure the virus doesn’t spread to other pets and animals. The recommendation stems from concerns that monkeypox could spill into wildlife or rodent populations as the human outbreak grows, allowing the virus to pass back-and-forth between humans and animals and giving the virus a permanent foothold in countries where it hasn’t historically circulated.

Prior to the global outbreak this year, monkeypox spread primarily in remote parts of West and Central Africa where people caught the virus after exposure to infected animals. The 2003 outbreak, which was contained, was the first documented case of humans catching the virus outside Africa.

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