The owner of an animal rescue shelter in Wierden, her colleague, and her husband all tested positive for cowpox, a viral infection that is rare in humans. The namesake behind Jolanda Kittens Wierden told RTL that she likely contracted the virus from a kitten who had probably been infected by a mouse.

“Cowpox-I had never heard of it,” said the 57-year-old woman. “A very shy kitten called Rox was brought in. I could see something was wrong, so I took it to the vet.”

The vet diagnosed a respiratory infection and prescribed antibiotics, but a week later, Rox developed a swelling under an eyelid. Another round of antibiotics was prescribed for the cat. which antibiotics were also prescribed.

Soon after, Jolanda discovered a lesion on her skin and contacted a physician. The doctor initially thought the cause was related to a fungus, but a dermatologist examining photos of the lesion suspected cowpox to be the cause.

“Wild rodents carry the virus,” said Dutch public health institute RIVM. “They do not get sick from it, but they can pass it on to other animals and people.” Cats, on the other hand, can become sick. Aside from lesions, they can also develop fever and lethargy.

The virus almost never happens in people, according to the RIVM. When it does, a human develops localized lesions as pox and blisters. “It is important that we cover the spot well to prevent further infection,” Jolanda said.