A fatal Alaskapox virus infection in a person in (unsurprisingly) Alaska has once again focused a lot of attention on this rather obscure virus. When I last wrote about Alaskapox virus in 2020, we had a lot of unanswered questions about it, yet today we’re not that much further along, largely because this virus is still really rare. Rare viruses are hard to study since there aren’t many natural infections from which to learn, and they usually don’t attract much funding to allow for in-depth research. That’s particularly true when infections don’t seem to have very serious consequences, as was the case until this latest infection.

Alaskapox virus is a member of the Orthopoxvirus genus, which includes poxviruses such as smallpox, mpox (previously known as monkeypox) and cowpox. Some poxviruses are very host-specific, meaning they only infect one species. For example, smallpox only infected people, but others are more promiscuous, circulating in a reservoir species but also able to spill over into other species, as with mpox.

Based on the genetic makeup of Alaskapox virus, part of its genome seems to come from the ectromelia virus, a mouse poxvirus, suggesting the two viruses are somewhat related. Given what we know about the reservoirs of many poxviruses (which are often rodents), the genetic makeup of Alaskapox virus, and the rarity of human disease (which supports human infections being spillovers from a separate reservoir species), rodents have been assumed to be the natural reservoir. It’s been stated that the virus has been found in a variety of rodent species, including red-backed voles, shrews and red squirrels, although I can’t find actual research papers describing that.

Alaskapox was first identified in 2015, and there have been 7 confirmed human infections to date. Until now, they were all mild and got better on their own. The most recent case has gotten attention both because this is a rare disease, but more importantly because the patient died. That understandably amplifies concerns about the virus, but it’s important to keep things in perspective: There’s no indication that this virus or anything related to it has changed. It seems this is simply another rare spillover infection, but it unfortunately occurred in a person with a compromised immune system, and therefore had much more dire consequences.

The affected individual was undergoing cancer treatment, putting him at much greater risk of acquiring infections and developing serious illness from things that would normally make a person significantly sick. The patient first developed signs of Alaskapox in September, starting with a tender lesion around his armpit. It gradually got worse, probably because his cancer treatment impact his body’s ability to eliminate what would normally be a pretty mild infection. He continued to deteriorate and died in January, with a variety of problems including kidney and respiratory failure.

How the person got infected has generated a lot of discussion, and some overreach. Since this is a rodent-associated virus, direct contact with rodents would be a likely source. If there’s no known direct contact with rodents, then we have to think about environmental exposure (e.g. contact with rodent feces) or, more likely, contact through an infected intermediary. Cats jump to the top of that list, as they can have a lot of contact with rodents and people. Cats are susceptible to some rodent poxviruses, like cowpox, so the concern is that a cat could have caught an infected rodent, become infected (with signs of disease or not), and then passed the virus on to a person.

It’s a logical thought process, but it’s just a thought process at this point.

Two common factors are present in human Alaskapox infections: the people lived in wooded areas, and they had contact with dogs or cats that could have encountered wildlife. Those are important things to note, but they also probably apply to a pretty large percentage of the population in Alaska. In this case, the infected person lived in a wooded area and cared for a stray cat that hunted small mammals. He had direct contact with the cat, as it would sometimes come in his house and often scratched him. (That’s a whole other issue… cat scratches create risk for various infections, especially in a high-risk person like a cancer patient. There needs to be better awareness of that and discussion of the importance of first aid after cat scratches). Officials in Alaska have taken a reasonable line, saying the cat was a possible source, but not more than that.

We need to understand the role of cats in Alaskapox virus transmission, just like we need to understand the role of animals in various other emerging diseases. Too often, it’s one extreme or the other: either the role of animals is ignored, or people jump to conclusions (e.g. virus infects mice > cats catch mice > cats hang out with people > ergo the human infection is the cat’s fault). We need to consider the role of animals and take reasonable precautions to avoid potential disease transmission, but at the same time, we need to actually investigate those potential routes of transmission, and not stop at “this seems to make sense.”

As I mentioned, rare viruses are hard to study, and it’s really hard to get funding for any infectious disease work with companion animals, but a good start would be testing cats for the presence of antibodies against Alaskapox virus, focusing on cats that have access to rodents. That would give us an idea of how commonly cats get infected, and a starting point for understanding their role (or not) as a bridging host for this virus. For this case, since the potential source cat is known, it would be very useful if it could be caught and tested. If the cat has antibodies against the virus, it provides more support that the cat was the source, but we’d still want to know more about how common exposure to Alaskapox is in the general cat population to put things into better context.

How much time, effort and money to put into a rare disease is always a controversial topic. Some people want to be proactive. Some want a clear business case, which is tougher to make for a rare disease. However, a little effort into more rodent surveillance, testing of cats to see how much spillover occurs into this species, and testing people for antibodies to see how many infections might be occurring under the radar would be a relatively inexpensive but informative start.