"Between mid-January and mid-February 2009, 33 human cases of cowpox were reportedly diagnosed in France (15 cases, 14 of which were in the north) and Germany (18 cases, 12 of which were in North-Rhine-Westphalia and six in Bavaria."
As we know, cowpox doesn't really constitute a particularly high public health risk for humans, but it's still interesting to see a zoonotic emergence, especially one with such a rich history in infectious diseases. The infected persons were mostly children, and the zoonotic source was shown to be pet rats. Rodents are just one of the main hosts of the cowpox virus- cows and cats also have endemic cowpox numbers in their populations. Other accidental hosts for cowpox include big cats, elephants, and anteaters.
Most past human infections of cowpox have occurred from contact with infected domesticated cats, and while there seems to be no serious heatlh risks in immunocompetent hosts, there are severe and occasionally fatal risks for immunocompromised patients.