On July 15, the U.S. Centers for Disease Control and Prevention (CDC) confirmed the first known case of monkeypox in Texas. The patient, a resident of Dallas, had recently traveled to and from Nigeria. In the days since, the CDC announced that it is working with state and federal agencies in 27 states to monitor more than 200 individuals who may have been exposed.
This announcement struck with more resonance than usual. The COVID-19 pandemic still looms large over much of the world — for many, the idea of another global disease outbreak might feel both terrifying and all too possible.
But before you start stocking up on toilet paper again, let's take a moment to break down what monkeypox is, how it spreads and how much risk it poses.
What Is Monkeypox?
Monkeypox is a viral infection that first presents with a basic suite of flu-like symptoms: fever, chills and body aches (sound familiar?). It may also cause fatigue and swollen lymph nodes. But its most distinct symptom by far is a pimple-like rash that can cover the entire body — including the palms and soles of feet of the person infected. The illness usually lasts for two to three weeks, and monkeypox has an incubation period of five to 12 days.
The monkeypox virus is a member of the Orthopoxvirus family, which includes both the smallpox and cowpox viruses. While all these viruses are serious, monkeypox is significantly less virulent than smallpox, despite causing similar symptoms.
"Monkeypox has so far about 11 percent mortality in individuals who do not have prior smallpox vaccination," says Dr. Andrea McCollum, an epidemiologist at the CDC, "but smallpox could have, you know, upward of 80 or 90 percent mortality."
Smallpox has the distinction of being the first disease to be eradicated by a modern vaccine. The World Health Organization (WHO) launched an intense vaccination program in 1967. The last known infection was in Somalia in 1977, and by 1980, the virus was declared functionally eliminated.
Monkeypox, however, has not been eradicated. In fact, cases have been on the rise over the last few decades. But where does monkeypox come from, and how does it spread?
How Does Monkeypox Spread?
Contrary to its name, monkeypox is not usually spread by monkeys; it was given the moniker after it was first isolated from a monkey colony in 1958. The virus is typically spread by small rodents such as dormice, rats, and tree and rope squirrels. Scientists still haven't pinned down which species is the natural reservoir for the disease, though some kind of rodent seems likely.
In 1970, the first case of monkeypox in humans was recorded in the Democratic Republic of the Congo. To this day, the DRC and other Central and West African countries, including Nigeria, see the vast majority of monkeypox outbreaks. Cases usually crop up in heavily forested, rural areas. "These are populations that are routinely hunting wild animals or have close contact with wild animals in the forest," McCollum says.
Once a human contracts monkeypox, they can pass it to other humans via respiratory droplets or contact with skin lesions. It is much less contagious than COVID-19 or other respiratory viruses when spread through the air, but it can linger on surfaces. Typically, close family members or caregivers of people with monkeypox are at the highest risk of becoming infected. Animal-to-human transmission also can occur when someone is bitten or scratched by an infected animal or if they eat infected bush meat.
So how likely is monkeypox to become a pandemic? In short, it's highly unlikely. But we should continue to be cautious.
"In the United States, we have actually dealt with monkeypox," McCollum says. In 2003, monkeypox was accidentally imported into the U.S. along with several small West African mammals as part of the "pocket pet" industry. The mammals, which included Gambian giant pouched rats, were housed alongside a pack of prairie dogs also destined for the pet trade.
Prairie dogs (and their fleas) are notorious for transmitting zoonotic diseases, including bubonic plague — the little rodents picked up the monkeypox virus easily. The infected prairie dogs were then sold to a Wisconsin family from a company called Phil's Pocket Pets in Villa Park, Illinois.
In the end, more than 45 people across six states contracted the virus. The spread prompted the CDC to bust out a few reserve smallpox vaccines that the U.S. government had stockpiled in case of a bioterrorism attack. The smallpox and monkeypox viruses' similar physiology means that a dose of the smallpox vaccine can confer some immunity.
Fortunately, there were no fatalities from the 2003 outbreak. However, the incident did lead to a ban on the sale of Gambian giant pouched rats and other West African rodents.
Is There a Monkeypox Vaccine?
Today, the U.S. wouldn't necessarily need to dip into its smallpox vaccine stores to fight a monkeypox outbreak. In 2019, the Federal Drug Administration approved Jynneos, its first-ever monkeypox vaccine. Like the smallpox vaccine, it uses a weakened — or attenuated — version of the vaccinia virus (a related pox virus) to stimulate an immune response. The one-shot vaccine is available for anyone 18 and older and also provides protection against smallpox. Jynneos is available as part of the Strategic National Stockpile (SNS) supply of life-saving pharmaceuticals, which are for use in a public health emergency, or for anyone determined to be at high risk of either smallpox or monkeypox infection.
As for the current monkeypox case in Texas, McCollum says that swift action on the part of both the patient and medical experts likely limited the spread. The patient wore a facial mask on their flight back to the United States as required by the Federal Aviation Administration (FAA) due to the COVID-19 pandemic. That alone reduced the risk of transmission to fellow passengers, and the infected patient went into isolation and reported their symptoms as soon as they became apparent.
But the CDC is working with the airlines and state and local health officials to monitor the risks to other passengers and anyone else who may have been in contact with the patient during two flights, including one from Lagos, Nigeria, to Atlanta July 8, and a second from Atlanta to Dallas July 9.
That said, the United States is not alone in recent monkeypox cases. Since 2017, six cases of monkeypox have been reported in the U.K., one in Singapore and one in Israel, all connected to individuals traveling back from West Africa. And in the Democratic Republic of the Congo, where the disease is endemic, more than 1,000 individuals are infected annually.
We live in a highly interconnected world, where a local epidemic in one corner can easily to spill over to another. "It's a good example of how diseases don't have borders," says McCollum.