At a recent gathering of the European Society for Pediatric Dermatology in London – and as spotted by BBC News – researchers made a rather surprising announcement: Three months ago, a teenage boy in Wales was diagnosed with cowpox.

Lesions, which have since healed, developed on his limbs. Reports suggest that this unfortunate teenage boy developed the itchy, pus-filled marks shortly after he was bitten by the calves he was feeding. He was taken to a clinical practitioner, and the boy was genuinely taken aback when his infection was identified as cowpox.

Cowpox isn’t really dangerous, nor anything to be hugely worried about. It's essentially a disease of history; although still in existence in the wild in both Europe and Asia, it is not diagnosed in humans at any significant rate.

In Wales, for example, the last known case occurred between 10 and 15 years ago. The industrialization of farming means that very few people milk cows by hand, and so the virus can’t be transmitted from cow-to-person so easily. Sometimes it crops up in veterinarians and zoo workers, but that’s about it.

As noted by the European Centre for Disease Prevention and Control, it goes away by itself in people with healthy immune systems, and there’s no evidence of human-to-human transmission of the virus either, which renders it somewhat unthreatening.

It’s most likely to be seen in feral cats that have been inadvertently infected with it via rodents, but otherwise it’s not really on any public health professional’s radar. This new case isn’t the start of some new epidemic or anything, so don’t worry – but as the researchers speaking at the conference note, it’s worth keeping an eye on simply because such diagnoses are so rare these days.

One of the last times it made headlines in this way was back in 2011: According to a case report by the US Centers for Disease Control and Prevention, a student laboratory worker at the University of Illinois, Urbana-Champaign, accidentally contracted it due to lab contamination.

Cowpox is best known not for what harm it may do but what good it did in the hands of one Edward Jenner. Back in the late-18th century, this English physician noticed that the far deadlier viral cousin, smallpox, was less prevalent in milk maids, who tended to contract cowpox.

Using fluid from a cowpox lesion, he created the first prototypical vaccine, which immunized people from smallpox. He wasn’t the first to suggest this plan, nor was he to attempt it, but he is regarded nevertheless as the founder of immunization science.

The last naturally occurring case was in Somalia in 1977, and in 1980, the World Health Organization declared that it was officially eradicated in the wild.