The Symptoms and Causes of Monkeypox, as Virus Cases Rise Globally

Two confirmed cases of monkeypox have been identified in the U.S.—but the risk of a serious outbreak remains low, according to experts.

Female microbiologist using a microscope. Female biochemist working in high-tech lab.
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Fact checked on May 23, 2022 by Vivianna Shields, a journalist and fact-checker with experience in health and wellness publishing.

Monkeypox cases—both confirmed and suspected—continue to rise in several countries, including in the U.S. where health officials have identified two official cases and one potential case of the virus.

The first positive case in the U.S. was identified last Wednesday in Massachusetts in an adult man who had previously traveled to Canada. Since then, another person tested positive for monkeypox in New York City on Friday, and the Florida Department of Health began investigating a potential third case on Sunday.

Outside of the U.S., monkeypox is being investigated in 11 different countries—Australia, Belgium, Canada, France, Germany, Italy, the Netherlands, Portugal, Spain, Sweden, and the United Kingdom—all areas where the virus is only rarely found.

Though the virus doesn't discriminate—meaning anyone who comes into contact with it can potentially contract the illness—the World Health Organization said Monday that it is specifically looking into transmission between men who have sex with men.

"We are seeing cases in men who identify as gay, bisexual, or from other groups of men who have sex with men in several countries, often linked to travel," Andy Seale, adviser to the WHO Department of Global HIV, Viral Hepatitis and STIs programs, said in a live Q&A session on the agency's social media outlets. But "while…we are seeing some cases amongst men who have sex with men, this is not a gay disease."

Though people in the U.S. are urged to practice caution—not panic—regarding the monkeypox cases, here's what you need to know about the virus, including symptoms, transmission, and treatment or prevention options.

What Is Monkeypox?

Monkeypox is a rare disease, mainly endemic to central and western African countries, Scott Weisenberg, MD, infectious disease specialist and director of the travel medicine program at NYU Langone Health, told Health.

It's caused by an infection with the monkeypox virus, and is what's known as a zoonotic disease, or a disease that can pass from animals to humans. Monkeypox is similar to other poxviruses like the virus that causes smallpox, the virus used in the smallpox vaccine, and the virus that causes cowpox.

The current uptick in cases isn't the first time the virus has been found outside of Africa: In 2003, the U.S saw another monkeypox outbreak due to contact with imported pet prairie dogs. Israel, Singapore, and the U.K., have also seen monkeypox cases in the past.

How Does Monkeypox Spread?

According to Dr. Weisenberg, most monkeypox cases come from "direct animal exposure, such as with infected rodents." That animal-to-human exposure can come from a bite or scratch, meat preparation, or direct or indirect contacts with bodily fluids or wound secretions.

The current case counts, however, are due to human-to-human transmission.

"Human-to-human transmission has been less common, but it is possible from close face-to-face contact or sustained contact with lesions or anything soiled with infectious fluid," Hannah Newman, MPH, director of epidemiology at Lenox Hill Hospital in New York City, told Health. "There are indications that there may be a sexual intercourse component to this out break, but may also be explained close contact in general."

What Are the Signs and Symptoms of Monkeypox?

When a person comes into contact with the monkeypox virus—and if they are exposed enough to become infected—they won't show symptoms right away: The incubation period for the virus (the time from when a person is infected to when they begin to show symptoms) can be anywhere from seven to 21 days.

From there, the symptoms present in stages. According to the Centers for Disease Control, the virus begins with the following initial symptoms:

  • Fever
  • Headache
  • Muscle aches
  • Back ache
  • Swollen lymph nodes
  • Chills
  • Exhaustion

About one to three days after having a fever, the illness can progress to the development of a rash that starts on the face and extends to the rest of the body. Those lesions go through the following stages before eventually falling off:

  • Macules (flat, discolored areas)
  • Papules (solid, raised spots)
  • Vesicles (small, fluid-filled blisters)
  • Pustules (small, inflamed, pus-filled, blister-like sores)
  • Scabs (hardened, dried out spots)

The overall length of the illness can last about two to four weeks. Monkeypox, by nature, is similar to (but milder than) smallpox symptoms.

Is Monkeypox Treatable or Preventable?

There is no monkeypox-specific treatment at this time, however the virus has proven to respond to the smallpox-specific antivirals.

"The smallpox vaccine is roughly 85% effective at preventing monkeypox and can be used for prevention and as post-exposure prophylaxis," said Dr. Newman. "Currently 'ring vaccination' strategies are in place to vaccinate close contacts of confirmed cases to try to cut off transmission. Due to fears of smallpox being used as bioweapons, there is actually a good supply of vaccine available in the U.S., should it be needed."

Implementing some of the other strategies we have been used to incorporating for the past three year due to COVID-19 will come in handy, as well. These include social distancing, masking, increasing ventilation, and staying home if sick. Hand hygiene is also key since this is a virus that can live longer on surfaces.

How Concerned Should the Public Be About Monkeypox Right Now?

Though the world is understandably on edge due to the COVID-19 pandemic, it seems that monkeypox is not yet a high level cause for concern.

"While most people have less severe disease, the severity of the recent cases, as well as risk of death, will hopefully be clear through public health reporting in the days and weeks ahead," said Dr. Weisenberg.

"At this time, it does not appear that we are on the brink of a serious outbreak and the risks to the general public remain very low," added Newman. "That being said, those who experience new or unusual rashes or other symptoms of monkeypox should contact their healthcare provider."

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