Two rare but potentially lethal illnesses with "monkey" in the name are leading to confusion.

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Two rare viruses with the phrase "monkey" in their name are making headlines right now. Monkeypox turned heads at the end of last week, after the Centers for Disease Control and Prevention (CDC) revealed that an American who had recently traveled to Nigeria was diagnosed with the potentially serious virus. The patient traveled on two flights—one from Lagos, Nigeria, to Atlanta on July 8, and the other from Atlanta to Dallas on July 9. CDC officials are currently trying to track down those who came into contact with the patient. The patient, who has not been publicly identified, is currently hospitalized in Dallas.

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Credit: Getty Images

Monkey B virus is also in the news after the Chinese Centers for Disease Control and Prevention revealed that a 53-year-old biomedical researcher has died from the virus. The researcher dissected two dead monkeys on March 4 and March 6, 2021, and then developed nausea, vomiting, and a fever "with neurological symptoms" a month later. He died on May 27.

While both of these viruses contain the word "monkey," they're not the same. They're "totally different viruses," David Cennimo, MD, associate professor of medicine, adult and pediatric infectious diseases, at the Rutgers New Jersey Medical School, tells Health. Here's what you need to know about these rare viruses that are suddenly being mentioned everywhere, and if you could be at risk.

Monkeypox and monkey B virus have completely different causes

Monkeypox is caused by the monkeypox virus, which is in the same genus as the variola virus, the cause of smallpox. The monkey B virus is a form of herpes B virus, Richard Watkins, MD, an infectious disease physician and professor of internal medicine at the Northeast Ohio Medical University, tells Health. It's worth noting, according to Dr. Cennimo: "Monkeys are not the primary host. It is rodents."

Monkey B virus infections in people are usually caused by macaque monkeys, the CDC says. While chimpanzees and capuchin monkeys can catch the B virus, they usually die from the infection.

"Monkeypox and herpes B are two totally distinct viruses," infectious disease expert Amesh A. Adalja, MD, senior scholar at the Johns Hopkins Center for Health Security in Maryland, tells Health.

Monkeypox and monkey B virus are both rare

Monkeypox is a rare disease that's even more rare in the US, according to the CDC. The virus is most common in the Democratic Republic of Congo, according to CDC data, but it has appeared in the US in the past. An outbreak of the virus in 2003 in America caused 47 cases.

Monkey B virus infections in people are also rare, with only 50 documented infections ever identified, the CDC says. Most people were infected after getting bit or scratched by a monkey, or when tissue or fluids from an infected monkey got on their broken skin, such as via a needle stick or cut. "Herpes B is primarily a threat to workers who work with Old World monkeys," Dr. Adalja says. (Old World monkeys are found in Africa and Asia.) "Facilities have protocols in place for exposures."

There are some overlapping symptoms between monkeypox and monkey B virus

According to the CDC, monkeypox symptoms include:

  • Fever
  • Headache
  • Muscle aches
  • Backache
  • Swollen lymph nodes
  • Chills
  • Exhaustion

These symptoms are followed by bumps that progress through five separate stages, ending in scabs that fall off. The illness usually lasts from two to four weeks, according to the CDC.

Monkey B virus is "severe," Dr. Cennimo says. The CDC says that the first symptoms are usually flu-like, including:

  • Fever and chills
  • Muscle aches
  • Fatigue
  • Headache

After that, you may develop small blisters on the area of your body that had contact with the monkey, along with these symptoms:

If the disease progresses, the virus will spread and cause swelling of the brain and spinal cord, resulting in symptoms like:

  • Pain, numbness, and itching near the infection site
  • Problems with muscle coordination
  • Brain damage and severe damage to the nervous system

People can also develop breathing issues and subsequently die from the infection, usually one day to three weeks after they first have symptoms.

Both monkeypox and monkey B virus can be deadly

According to the CDC, one in 10 people in Africa who catch monkeypox die from the virus. Of the 50 documented cases of people who have contracted monkey B virus, 21 have died, the CDC says.

Should you worry about contracting monkey B virus or monkeypox?

"I do not think people should be concerned about this virus," Dr. Cennimo says about monkeypox. As for monkey B virus, Dr. Adalja points out that documented cases have happened in laboratory researchers who specifically work on monkeys. If that doesn't describe you, he says, the virus is unlikely to be a risk.

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