What Is Monkeypox (Mpox)? Symptoms, Causes, Diagnosis, Treatment, and Prevention

Monkeypox (also known as mpox) is a highly infectious disease caused by the monkeypox virus.

The monkeypox virus is closely related to the smallpox virus, but is far less dangerous. Still, infection can be painful and leave scars. In rare cases, monkeypox can be fatal.

As with other pox diseases, the hallmark symptom of monkeypox is a rash that develops into pus-filled lesions.

On July 23, 2022, the World Health Organization (WHO) declared the rapidly spreading monkeypox outbreak to be a public health emergency of international concern.

Outbreaks of Monkeypox

Monkeypox was first discovered in 1958 when two outbreaks occurred in colonies of monkeys used for scientific research. (The WHO has announced that it will decide on a new and more appropriate name for the disease soon.)

Scientists documented the first human case of monkeypox in 1970 in the Democratic Republic of the Congo as health officials were ramping up efforts to eradicate smallpox. “During this period, anybody who had a rash-like illness that looked like smallpox was investigated very heavily to see if what they had was, indeed, smallpox. As they were scrutinizing every case, they found monkeypox in humans for the first time,” says Amesh Adalja, MD, senior scholar at the Johns Hopkins Center for Health Security at the Bloomberg School of Public Health in Baltimore.

Since that time, monkeypox cases have been reported in other central and western African countries — areas where the disease is endemic (consistently present).

Prior to 2022, monkeypox cases outside Africa typically involved people who had traveled internationally from Africa or animals imported from Africa. But since May 13, 2022, countries around the world where monkeypox is not usually found have been reporting an alarming rise in cases to the WHO.

It appears the virus infected a person traveling from one of the endemic countries to Europe, then began to spread in a social-sexual network of men who have sex with men, says Dr. Adalja. “As is typically the case, it originated with someone who travelled to one of the endemic countries, but what makes this outbreak different is that it ended up in a network where it has been able to spread,” he says.

Though most cases in the current outbreak involve men who have sex with men, anyone can contract monkeypox through close contact with infected skin and other modes of transmission.

Monkeypox infection goes through different stages:

Incubation Period

The monkeypox incubation period (the time between infection and first symptoms) is usually 7 to 14 days but can range from 5 to 21 days.

A Rash Appears

According to the Centers for Disease Control and Prevention (CDC), some people who are infected with monkeypox may experience a rash as the only early symptom. Others may develop a rash along with symptoms such as fever, headache, muscle aches, respiratory issues (sore throat, nasal congestion, cough), exhaustion, and swollen lymph nodes. Backache and chills can also occur.

The rash often begins on the face, then spreads to other parts of the body. It then turns into lesions (sores) that are sometimes located on or near the genitals or anus, but can also appear in other areas such as the hands, feet, chest, or face, including inside the mouth. 

The lesions go through several stages. At first, they are flat, then raised and firm; later they fill with clear fluid, like a blister.

Lesions Fill With Pus

After about a week, the fluid in the lesions turns yellowish, and the pustules feel firm to the touch. This stage can last five to seven more days until the sores begin to crust over into scabs before eventually scabbing over.

Scabs Fall Off

Within a week or so, the scabs fall off (scarring can occur). At this point, the person is no longer contagious.

Monkeypox spreads in a variety of ways.

Contrary to what the name might suggest, monkeys are not a main source of transmission, according to Yale School of Medicine. Past outbreaks in the United States involved pet prairie dogs that were infected after being housed near small mammals imported as pets from Ghana.

The current outbreak mainly involves person-to-person transmission through direct contact with the infectious rash, scabs, or body fluids, although this is not the only way monkeypox spreads.

Infections have been clustering in men who have sex with men, but the virus can infect anybody, says Adalja, and sexual contact does not have to occur for the virus to pass from person to person.

“If a person with monkeypox had lesions on their skin and their skin rubs against someone else’s skin, that can transmit the disease. The closer the contact and the longer the duration of the contact, the more likely it is that transmission would occur — it’s usually not something that’s transmitted casually,” says Adalja.

Touching items such as clothing or bedding that were previously in contact with an infectious rash or body fluids is another way to contract monkeypox.

The virus is not considered to be airborne: “It is not known to linger in the air and is not transmitted during short periods of shared airspace,” said the CDC in a media statement.

Research is underway to see if monkeypox can spread through fluids such as semen, or whether people who are asymptomatic can be contagious.

Does Monkeypox Spread by Coughing?

Researchers are still gathering information about how monkeypox spreads. Prior studies of the disease suggest that although the virus can spread from respiratory secretions that travel through the air via coughing, sneezing, or breathing, it’s not very common.

"While we do not know with certainty what role direct physical contact has versus the role of respiratory secretions, in instances where people who have monkeypox have traveled on airplanes, no known cases of monkeypox occurred in people seated around them, even on long international flights,” said the CDC in a media statement.

The CDC recommends that people with a confirmed case of monkeypox wear a well-fitting mask if they must be close to others in the home or a healthcare setting.

Who Is at Highest Risk for Severe Monkeypox?

The WHO notes that newborns babies, children, and people with underlying immune deficiencies may be at greater risk of more serious symptoms and death from monkeypox.

It is possible for a pregnant person to transmit the virus to a fetus.

People who suspect they have monkeypox should contact their healthcare provider right away for testing and care, notes Yale School of Medicine. Diagnosis relies on PCR lab testing of material in the skin lesions, says Adalja.

The CDC is urging healthcare providers in the United States to be alert for patients who have rash illnesses consistent with monkeypox.

If someone has close contact with a person or animal confirmed to have monkeypox, a healthcare provider should monitor them for symptoms for three weeks after their exposure, according to the CDC. If a fever or rash develops, the person’s close contacts should isolate and get in touch immediately with their local or state health department.

CDC Director Rochelle Walensky, MD, MPH, said doctors should not rule out a monkeypox diagnosis if a patient appears to have symptoms of a sexually transmitted infection (STI).

"It's important to be aware that monkeypox cases may present similar to some sexually transmitted infections and could be mistaken for other diagnoses," she said in a media call in June. “Healthcare providers should not rule out monkeypox just because a patient has another diagnosis or another STI."

According to the CDC, a number of people confirmed to have monkeypox in the United States also received a diagnosis of herpes, gonorrhea, or chlamydia at the same time.

Prognosis of Monkeypox

In most cases, monkeypox resolves on its own without treatment, says Adalja.

In Africa, monkeypox has been shown to cause death in as many as 1 in 10 people who contract the disease.

But as of July 23, only five people have died out of more than 16,000 reported cases worldwide in the current outbreak, the WHO reports.

Monkeypox typically lasts for two to four weeks, per the CDC. Once the lesions crust over and new skin appears, the virus has been cleared from the body and the person is no longer contagious, says Adalja.

Currently there is no treatment specifically approved for monkeypox. But antiviral drugs and vaccines developed to protect against other illnesses can be used to treat and prevent monkeypox.

The currently available treatments include:

Tecovirimat (TPOXX) is an antiviral medication that is approved for the treatment of smallpox in adults and children.

Cidofovir (Vistide) is an antiviral medication that is approved for the treatment of cytomegalovirus (CMV) infections in people with AIDS (acquired immunodeficiency syndrome) and transplant recipients.

Vaccinia immune globulin intravenous (VIGIV) are antibodies obtained from pooled human plasma of people who have been immunized with the smallpox vaccine. These usually wouldn’t be used in an average case of monkeypox, but would typically be reserved for people who are severely ill with monkeypox, says Adalja.

If you’re in an endemic area, you want to avoid close contact with anyone with monkeypox or any close contact with an animal that may be harboring monkeypox; that's the standard prevention, says Adalja.

“In this current outbreak, men who have sex with men should be aware that this virus is spreading in that social group and to be very wary of having close, intimate contact with anybody who has lesions that look like monkeypox or any kind of skin lesions,” he says.

People who have been exposed should contact their local health department to get vaccinated to avoid getting monkeypox, says Adalja. The U.S. government has stockpiles of two smallpox vaccines — JYNNEOS and ACAM2000 — that can prevent monkeypox in people who have been exposed to the virus. (As of yet, ACAM2000 is not being distributed in the United States.)

“If people who have been exposed to monkeypox get one of these vaccines during the incubation period, it can keep the infection from occurring,” he says.

The CDC currently recommends vaccination for people who’ve been in close contact with someone who has monkeypox. That includes individuals who are aware that one of their sexual partners in the past two weeks has been diagnosed with monkeypox, or people who had multiple sexual partners in the past two weeks in an area where monkeypox is spreading.

According to the WHO, complications of monkeypox can include the following:

• Secondary infection, which may occur during or after monkeypox treatment
• Bronchopneumonia, or inflammation of the lungs
• Sepsis, which is a life-threatening emergency that can rapidly lead to tissue damage, organ failure, and death
• Encephalitis, inflammation of the brain that can have several causes, including viral infection
• Infection of the cornea, which can cause loss of vision
• Scarring can result from the skin lesions, says Adalja
• Death

The CDC website operates a 2022 Monkeypox Outbreak Global Map with the latest statistics on how many monkeypox cases have been diagnosed around the world, and in which countries.

As of July 25, 2022 there were over 18,000 confirmed cases of monkeypox in 75 countries.

Although monkeypox is caused by a virus originating from West Africa, the current outbreak in the West involves countries with predominately white populations. The Foreign Press Association, Africa condemned monkeypox coverage as perpetuating negative stereotypes because most of the images initially shown on the news were of the disease on Black skin.

Disproportionally showing monkeypox on darker skin not only has a stigmatizing effect, it may give people who are white the false impression that monkeypox doesn’t impact them.

Smallpox Historians believe that smallpox may have started as long as 3,000 years ago. Symptoms included fever, headache, severe fatigue, severe muscle aches, vomiting, and a rash or blisters.

At one time, smallpox killed an average of 3 in every 10 adults who got it and was even more deadly in babies and young children. In the early 1800, scientists developed a smallpox vaccine — the first successful vaccine in history.

In 1959, the WHO launched a plan to eradicate smallpox. The campaign took nearly two decades to succeed due to a lack of funding and support. No one outside a laboratory has had smallpox since 1975, and the World Health Assembly declared the world free of smallpox on May 8, 1980, according to the CDC.

Centers for Disease Control and Prevention (CDC)

The government agency provides information for both healthcare providers and the public, including information about monkeypox and the current outbreak.

World Health Organization (WHO)

This organization focuses on improving health around the world. They provide guidance, resources, case counts, and recommendations about many different diseases, including monkeypox.