This 2003 electron microscope image made available by the Centers for Disease Control and Prevention shows mature, oval-shaped monkeypox virions, left, and spherical immature virions, right, obtained from a sample of human skin associated with the 2003 prairie dog outbreak. On Wednesday, May 18, 2022, Portuguese health authorities confirmed five cases of monkeypox in young men, marking an unusual outbreak in Europe of a disease typically limited to Africa. Cynthia S. Goldsmith, Russell Regner/CDC via AP

The World Health Organization has declared monkeypox a global health emergency, its highest-level warning, and Biden officials are weighing a similar declaration, as experts worry that the virus may gain a permanent foothold in the United States and other countries where it is not traditionally found.

More than 19,000 cases of monkeypox have been reported in 76 countries this year, most of those in countries that don’t typically see the virus. In the United States, more than 3,500 cases have been confirmed, according to the Centers for Disease Control and Prevention.

Normally, the virus is found mostly in central and western Africa – where it is endemic in some animals that pass it to humans.

What is worrying global health experts about this outbreak is that it is spreading via human-to-human contact, primarily among networks of men who have sex with men. Scientists are trying to figure out whether recent mutations to the virus are helping it spread in ways they don’t yet fully understand.

What are common monkeypox symptoms?

Monkeypox infections typically last two to four weeks, the CDC says, and begin with flu-like symptoms – including fever, headaches, muscle aches and exhaustion. Eventually, fluid-filled bumps – or “pox” – spread across the skin. Health officials have noted that the latest monkeypox cases often involve genital rashes that can be confused with syphilis or herpes.

Monkeypox can be deadly, but two major strains of the virus pose different risks. A Congo Basin strain has been found to be fatal to about 1 in 10 people infected with it, according to the WHO, while a West African strain appears to be less severe, becoming fatal for about 1 in 100 infected people.

That milder strain appears to be the one currently infecting people around the world, including Europe and the United States. Five people have died in this outbreak, all of them in Africa, according to the WHO.

How is monkeypox transmitted?

Monkeypox mainly spreads from human to human through direct contact with infectious rashes, scabs or bodily fluids. It can also be transmitted form respiratory secretions during prolonged face-to-face contact, or during intimate physical contact, such as kissing, cuddling or sex. People can become infected by touching items – such as clothing or bedsheets – previously used by someone who is infectious, the CDC says. Pregnant people can transmit the virus to their fetus.

It’s also possible for people to get monkeypox from infected animals such as rodents or primates, as occurred during a 2003 U.S. outbreak after infected animals from Ghana were shipped to Texas, but that’s not how the virus is currently spreading in the United States and Europe.

Is monkeypox an STD?

Monkeypox is not considered a traditional sexually transmitted disease like syphilis or gonorrhea, but it does spread during sex. And unlike in past outbreaks, transmission during sexual activity is a major driver of the current surge. That’s because the virus spreads through close contact with an infected person, and sex provides opportunity for exposure to rashes or lesions.

But monkeypox can also spread outside of sex, such as skin-to-skin contact while dancing or cuddling, or sharing contaminated clothing or bedding. Respiratory spread is also possible, but usually over prolonged periods of time, such as when a person lives in the same home as an infected person.

Health authorities around the world say cases are overwhelmingly in men who have sex with men – disproportionately in those with multiple sex partners or who attend events where people have sex with strangers, both of which increases opportunities for exposure. WHO Director General Tedros Adhanom Ghebreyesus urged men who have sex with men to consider limiting their number of sexual partners to minimize risk.

A medical laboratory technician picks up from a fridge a reactive to test suspected monkeypox samples at the microbiology laboratory of La Paz Hospital on June 6, 2022, in Madrid, Spain. Pablo Blazquez Dominguez/Getty Images/TNS

How contagious is monkeypox? Could it turn into a pandemic?

Scientists say monkeypox is far less transmissible than the coronavirus that causes COVID-19, which was also placed on the WHO’s highest alert level in January 2020.

Still, David Hayman, a zoonotic diseases expert at New Zealand’s Massey University, said that like COVID-19, the latest monkeypox outbreak “highlights how globally connected the world is, and how humans are encroaching into more wild spaces.”

“We’re spinning the Russian roulette wheel,” he added. “The more transmissions there are, the more opportunity there is for the virus to mutate and evolve, and that is what can lead to more transmissibility – as we have seen with the omicron variant” of the coronavirus.

In addition, Hayman said the monkeypox outbreak has spotlighted big gaps in health care, public health surveillance and diagnostics in the countries where the virus is endemic, “which you could argue [have] been neglected by wealthier countries.”

The WHO’s designation of monkeypox as a global health emergency is intended to pressure countries to address the virus quickly.

The outbreak can be stopped “with the right strategies in the right groups,” said Rosamund Lewis, the WHO’s technical lead on monkeypox, speaking at a news briefing in Geneva. But “time is going by, and we all need to pull together to make that happen,” she added.

Is there a monkeypox vaccine or treatment?

Monkeypox and smallpox come from the same family of viruses, which means that antiviral drugs and vaccines developed and stockpiled for smallpox, which has been largely eradicated, can be used for monkeypox.

The White House is trying to boost the availability of tests, vaccine doses and treatments, but access remains a problem for many.

The Jynneos vaccine, approved by the Food and Drug Administration to treat smallpox and now monkeypox, is about 85% effective, according to the CDC. Supplies are limited, however, and officials in New York and D.C. have said they do not have enough to meet the demand. Nearly 800,000 more doses of the vaccine could be ready for distribution in the United States by the end of July, according to FDA officials.

Another vaccine, ACAM2000, is older and was approved to prevent smallpox. While that vaccine is effective against monkeypox, it can cause significant side effects and cannot be used for people with severely weakened immune systems or eczema, according to the CDC.

Tpoxx, or tecovirimat, is an antiviral approved to treat smallpox that can be used for monkeypox, but doctors have faced hurdles and mountains of paperwork when trying to prescribe it. The CDC, in partnership with the FDA, recently announced a streamlined protocol to make it easier for doctors to get it for their patients.

How can I protect myself and others from monkeypox?

Because the virus spreads from skin to skin, health officials are advising caution in crowded places such as nightclubs where bumping into people may be unavoidable.

The CDC says to avoid sharing utensils, kissing or hugging anyone who has a rash that looks like monkeypox or other possible symptoms. Practicing good hand hygiene is another way to avoid infections, along with not touching the bedding, towels or clothing of a person with monkeypox.

Infected people are being encouraged to self-isolate from other humans as well as pets – and to wear a mask and long clothing over any sores.