Monkeypox… More Than Just an Excellent Name for a Band

by Raywat Deonandan, PhD
Epidemiologist & Associate Professor
University of Ottawa

(I add my credentials to these COVID-19 blog posts in case they get shared. I want readers to know that my opinion is supposedly an educated and informed one… But wait! This is not a COVID-19 post.  And yet…. the credentials still remain relevant here. Sigh.)

As the title suggests, today’s topic is monkeypox. My inbox is blazing hot with dozens of media requests to come on-air and talk about this disease. So I thought I’d get ahead a bit and write what I know first, as I am certainly not a monkeypox researcher or expert.

I remember when I first gave monkeypox more than a passing thought. It was when reading a paper listing the likely candidates for a world-stopping global pandemic. The paper was written before the COVID pandemic. I wish I could find it now!

As of today, there are 36 suspected cases in Europe (UK, Portugal, and Spain), one in the USA, and a whopping 13 in Canada. (UPDATE: since I wrote this sentence a few hours ago, the disease has spread to Italy and Sweden.)

So, what is this disease, and should we be worried?  Let’s break it down.

1. What Is Monkeypox?

Other than being my secret hip-hop name, monkeypox is a viral disease caused by a member of the orthopoxvirus family, which currently has 83 members, including its close relatives smallpox, rabbitpox, camelpox, and cowpox. It does not include chickenpox, despite the seductive name. Yes, I said seductive. Don’t judge me.

Do recall that smallpox has been a scourge of humanity for millennia. That is, until scientists rendered that monster officially eradicated in 1980. Thus is the power of vaccines and epidemiology. Sometimes we gotta strut.

(Eradicated does not mean extinct. Samples of smallpox exist in labs around the world still.)

Monkeypox was first identified in the 1950s Copenhagen among captive lab monkeys, hence its name. Yet it is believed to circulate most commonly among certain rodents (some species of rats, dormice, and squirrels) in Africa. I say “believed” because, frankly, the disease has not been as deeply studied as some of its cousins. So there are some things we still don’t know about it, like its base natural reservoir (the preferred host species to which it retreats). But I think that that will change soon, as more of the world’s attention turns to this “new” pathogenic threat, at least for now.

In short, monkeypox looks a lot like its cousin smallpox, but is less deadly and less transmissible. Frankly, camelpox is probably more serious to humans, as it is more closely related to our ancient (defeated) foe, smallpox.


2. Who Gets Monkeypox?

First, it seems that most people are at least susceptible to getting it. But until now, close to 100% of cases were in central or West Africa. In 2003, there was an outbreak in the USA that was traced to imported pets from Ghana. At least 71 people were infected then, with no fatalities. Those were the first known cases to have occurred outside of Africa.

It’s important to note that all of the 2003 US cases were contracted from contact with animals. No one got it from another human being. But some of the UK cases seem to be the result of sexual contact, something not before observed with this disease.

This may end up qualifying monkeypox as an STI (sexually transmitted infection). But that can be misleading. Remember that Ebola and Zika virus have been found in sexual fluids and can therefore be transmitted sexually. But no one thinks of those diseases as innately sexual in nature. We shouldn’t think of monkeypox that way, either.


3. What are the Symptoms of Monkeypox?

Monkeypox typically presents clinically with fever, rash and swollen lymph nodes. The incubation period is typically 1-2 weeks, but sometimes stretches to 3.

Within 1-3 days of contracting a fever, the rash makes itself known, very often concentrated in the face and extremities and very much resembling smallpox. They can range from a few to several thousand circular forms. After a few days, some will erupt with pus. Fun? Wow!

The good news is that these symptoms are usually self-limiting and will resolve in 2-4 weeks. The scabs can leave scars, but rarely do.


4. How is Monkeypox Transmitted?

As per the CDC, “The virus enters the body through broken skin (even if not visible), respiratory tract, or the mucous membranes (eyes, nose, or mouth).” Human-to-human transmission, though, is thought to occur primarily through large respiratory droplets, the type that fall harmlessly to the ground over a distance of 1-2 metres. So staring longingly into the eyes of an infected person is not advised.

However, just to scare you a bit, at least one study has shown that aerosolized monkeypox particles can be detected 90 hours later, suggesting at least the possibility of airborne transmission. But that has not been observed to any great extent in places where the disease is more common.

It’s important to note that unlike COVID, monkeypox only becomes transmitted once symptoms arise. So it’s much more easily controlled with simple public health measures… like staying the frack away from other people once you develop symptoms.

So, in short, we think you get monkeypox from touching infected people’s (or animals’) body fluids, their infected sores, and from getting breathed on or bitten by them. You can get it by touching something that touched their fluids or sores. Sharing bedsheets is a good example of something you should not do with someone infected with monkeypox. So it’s really not surprising that sexual contact might be driving some of the current transmission.


5. How Contagious is Monkeypox?

Because this is 2022 everyone is now an armchair epidemiologist with at least cursory understanding of indicators like the “reproduction number”, which is the average number of people that a single infected person will infect during the course of their infection. The “base reproduction number”, or r0 (pronounced “R-naught”), is the reproduction number computed in the context of a fully susceptible population in which no one is immune. We use r0 for a variety of purposes, including helping us compare the infectiousness of different diseases.

Famously, the r0 for the Omicron variant of SARS-CoV2 could be as high as 8-12. Whereas, chickenpox probably has an r0 of 10-12, and measles 16-18.

The r0 for monkeypox has been modelled to likely be 2.13, which is lower than smallpox (which had an r0 of about 3) but critically above unity, suggesting that it would experience exponential growth in a naive population that has not put into place appropriate mitigation strategies.

A 1988 study of monkeypox secondary attack rates (the proportion of household contacts who get infected from an index case) concluded that, “The inefficient spread from person to person, even in conditions of maximum exposure, supports the concept that monkeypox virus is poorly adapted for sustained transmission between humans and that such transmission does not pose a significant health problem.” Note, however, that this was at a time when many people were still getting freshly vaccinated for smallpox, and the study notes that these attack rates were kept low by people who had been previously jabbed against smallpox.

Best estimate, though, is that about 11% of household contacts become infected.


6. How Dangerous is Monkeypox?

There are at least two circulating “clades” of the virus, one more serious than the other. The West African version is less serious than the Congo version, which moves more easily from person to person. Thankfully, the clade that seems to be making its way out of Africa is the less serious West African version.

The Congo clade has a CFR (case fatality ratio) of about 10%, meaning that 1 in every 10 people who contracted it was observed to die of the disease. Whereas the West African clade has a CFR of about 1%… and that’s the one we’re dealing with in the West. Mortality is higher among children and, of course, immunocompromised people.

Compare this to COVID, which has an IFR hovering around 1% in an unvaccinated population.

Do keep in mind that CFR is very sensitive to health care systems. So the high rates seen in Africa are unlikely to be repeated in North America or Europe where health care systems are profoundly better. The 2003 outbreak resulted in zero deaths, after all.


7. Should I Be Worried About Monkeypox?

The short answer is no, you shouldn’t be worried about it. Not yet. Public health managers should probably be a little worried because they now have a more work to do, though, and can’t afford to mess it up. The fact that there are unrelated clusters simultaneously in several countries distant from each other suggests that there are chains of transmission yet to be identified. So that signals that there is some sleuthing work to be done.

The UK lists monkeypox as an “HCID“, or “high consequence infectious disease.” And an r0 of 2.13 is nothing to sneeze at (pun intended). However, we have many advantages over monkeypox that we did not have over COVID.

(a) Public health works!

First, is that we have experience with this disease. As noted, the 2003 outbreak in the USA was contained and quashed using standard public health methods. Toronto Epidemiologist Diego Bassani says it this way:

Using droplet, aerosol, and fomite precautions –like many do for the flu and COVID– is highly effective in containing and preventing monkeypox infection.

As noted, infectious monkeypox carriers are easily identified: they have symptoms. There are probably no stealth carriers among us (except for those people who don’t notice or acknowledge their fevers).  And you really can’t miss that rash.

(b) We already have a vaccine!

Immunity from smallpox confers some immunity against monkeypox, since the two diseases are so closely related. I’m old enough to have received a smallpox vaccine in my youth. But its power has surely waned in the intervening decades. In fact, if your smallpox jab was more than 3-5 years ago (as almost everyone’s was), then I believe you would need a booster for proper protection against monkeypox.

But looky looky here! As recently as 2019, the US FDA approved a “new” non-replicating live smallpox vaccine specifically for use in preventing both smallpox and monkeypox. (While smallpox has been eradicated (yay!) there are still some scientists and technicians who work with preserved samples for research purposes; so they need to be jabbed.) The vaccines are about 85% effective in preventing monkeypox infection.

In fact, close contacts of known monkeypox infections in the current outbreaks are being vaccinated as we speak. So transmission is being blunted appreciably.

Do note that while the COVID mRNA vaccines are overwhelmingly safe, the live smallpox/monkeypox vaccines carry substantial risk for a segment of the population. The immunocompromised are at risk for very bad outcomes from live virus vaccines.

(c) We already have treatments!

The vaccine can be used as a kind of treatment, if it’s given promptly after exposure.  In general, vaccination within 4 days of exposure can result in the reduction or avoidance of symptoms altogether.

The antiviral tecovirimat has also been approved for use against many poxes, including monkeypox. The USA has millions of doses in its strategic reserve, and Canada appears to have approved its use just a few months ago.


8. So What’s Going to Happen?

Public health will continue to investigate the transmission chains of these outbreaks and interrupt them if possible. While COVID restrictions are being lifted in many places, enough are being maintained that the pox will have a less easy time finding purchase than if it had made its move in 2019 or earlier.

I do not foresee a mass public smallpox vaccination campaign. Perhaps in some select communities where the disease has a troubling presence, it might be recommended. But nowhere near the scale of COVID global jabbery. But we always have that option in our back pocket if the need arises.

What is likely is that we will be asked to be on alert for monkeypox symptoms for a few months, and to avoid some behaviours (like randomly licking strangers’ pustules) if we can.

But it’s still early days. As more information comes in, so will the prognosis for this disease and its pandemic potential.


8. Conclusion

Monkeypox is a known quantity, at least when compared with COVID. Ironically, because of COVID, the public health systems in wealthy nations –not to mention the public itself– are actually in a good place to control any monkeypox outbreaks that might appear. In other words, we have the tools, the knowledge, and the forewarning to nip this one in the bud. So I’m not overly concerned at this point. However, people do have a way of making stupid decisions when their lives depend on it. So don’t hold me to any of this!