Wild mouse on grass
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Naming a new virus or disease after a location is now generally frowned upon because of the potential stigma it can create, so we’ll see if the name “Alaskapox” actually sticks to this relatively new poxvirus that was first reported in 2015 in a person in Alaska, and has now been reported for a second time in August 2020.
The first case was in a woman in Fairbanks, Alaska, who went to a physician because of a suspected spider bite. She also had fatigue, fever, malaise and some tender lymph nodes. She had some small skin lesions, including a couple of vesicles (i.e. little fluid-filled bumps). As is often the case, the key role was played by an astute or curious primary care practitioner, who in this case decided to collect a sample from a vesicle and submit it for viral testing. That’s how the “Alaskapox” virus was first detected. None of the patient’s human contacts were sick or had similar skin lesions, apart from a social contact who reported a transient rash within a week of an earlier contact with the patient. Neither that person nor any of her other contacts (including family members) developed antibodies to the virus, supporting the conclusion that the index patient was the only infected person. The patient reported contact with rodents (which are hosts for many poxviruses), but the virus wasn’t identified in any rodents that were trapped in the area.
A genetic analysis of the Alaskapox virus showed it’s a member of the Orthopoxvirus genus, which includes a wide range of poxviruses such as smallpox, monkeypox and cowpox. Some poxviruses are very host-specific, meaning they only infect one species, like smallpox which infects only people. Some are more promiscuous, living in a reservoir species but spilling over into other species, as we see with coxpox and monkeypox that infect both animals and people.
That was the end of the story until another case of Alaskapox was identified in August 2020. It was pretty similar story to the first case: a person in Fairbanks went to their doctor because of a strange skin lesion, along with fatigue and fever, and Alaskapox was once again identified. As before, there was no apparent transmission to human contacts, and her infection resolved by itself after about a month. The patient didn’t report any direct contact with rodents this time, but said her cats captured and killed small rodents and that she’d spent time outside.
Why has this virus only been found in the past few years?
Emerging disease always “emerg” for one of a few reasons:
- The disease was already there but was not previously identified, because no one looked for it or testing methods weren’t good enough to detect it. With mild disease, lack of curiosity or lack of access to testing, it’s easy to overlook something like this.
- OR the disease has been around but controlled, so it’s rarely evident. With this virus, it’s possible that smallpox vaccination was cross-protective and historically kept it under control. Now that smallpox vaccination isn’t being done (since smallpox has been eradicated), Alaskapox virus might have more opportunity to cause disease.
- OR the disease is truly something new and we’re actually detecting the first few occurrences in real time.
From where did Alaskapox come?
That’s still unclear. Since the majority of emerging infectious diseases are zoonotic, it’s a safe bet to assume the source was an animal of some kind. The very limited information that’s available seems to indicate that it’s not highly (or at all) transmissible between people, since contacts of the infected patients were not infected. Also, genetically the virus seems to have recombined (i.e. swapped DNA) with ectromelia virus (a mouse poxvirus) at some point in the past. All these factors suggest that an animal, most likely a rodent, is the reservoir, and that people are sporadically infected from direct or indirect contact with infected rodents.
In the grand scheme of emerging diseases, a rodent-associated virus that causes rare and mild infection in people isn’t a big deal. However, it’s a reminder of the many unknown threats that are lurking in the animal kingdom, and the need to continue to study emerging diseases.
(Reprinted with permission from Worms and Germs Blog)
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