More than 100 cases have been reported in recent weeks among populations not typically vulnerable to the disease.
The rare monkeypox virus, usually confined mostly to Central and West Africa, has spread in unusual ways this year, and among populations that have not been vulnerable in the past.
President Biden has said that “everybody should be concerned about” the rise in cases. But while the transmissions have created some alarm among officials and infectious disease experts, and while a Covid-weary world is on high alert for new outbreaks, there are several reasons monkeypox is not being treated with the same level of concern as the coronavirus.
There have been more than 100 confirmed cases outside Africa in the current outbreak, and none of the infected people have died. Here’s what to know about monkeypox and the risks it poses.
What is monkeypox?
Monkeypox is a virus endemic in parts of Central and West Africa. It is a more benign version of smallpox.
It was discovered in 1958, after outbreaks occurred in monkeys kept for research, according to the Centers for Disease Control and Prevention.
What are the symptoms of monkeypox?
Monkeypox creates a rash that starts with flat red marks that become raised and filled with pus. Infected people will also have a fever and body aches.
Symptoms typically appear in six to 13 days but can take as long as three weeks after exposure. They can last for two to four weeks, with severe cases occurring more commonly among children, according to the World Health Organization.
The C.D.C. says there is “no proven, safe treatment” for monkeypox but the Food and Drug Administration has approved the use of smallpox vaccines and antiviral treatments to control outbreaks.
How infectious is it?
Typically it does not lead to major outbreaks — in most years there are just a handful of cases outside Africa, if any. The most severe outbreak in the United States came in 2003, when dozens of cases were linked to exposure to infected prairie dogs and other pets. It was the first time there had been a monkeypox outbreak outside of Africa, according to the World Health Organization.
Within Africa, 11 countries have reported cases since 1970, when the first human case was identified in a 9-year-old boy in the Democratic Republic of Congo. Nigeria has experienced a large outbreak, with more than 500 suspected cases and 200 confirmed cases since 2017, the W.H.O. said.
The virus can spread via body fluids, skin contact and respiratory droplets. The majority of cases this year have been in young men, many of whom self-identified as men who have sex with men.
“Most cases presented with lesions on the genitalia or peri-genital area, indicating that transmission likely occurs during close physical contact during sexual activities,” the European Center for Disease Prevention and Control said in May.
How many cases have there been this year, and where have they been?
By late May, cases had been identified in 12 countries outside of the African nations where it is endemic, according to the World Health Organization.
In the United States, the first case was diagnosed in Massachusetts on May 18. The man had recently traveled to Canada, which has had fewer than five cases this year but suspects 11 to 20 more.
Public health officials in Florida said they had identified one presumptive case of monkeypox in Broward County in a person who had recently traveled internationally. And public health officials in New York City said that they had tested two patients who were under investigation for possible monkeypox.
Europe has been hit much harder. Portugal and Spain reported between 20 and 30 cases each, according to the World Health Organization. In Britain, the U.K. Health Security Agency said it had detected 56 cases of monkeypox in England.
Fewer than five cases were reported in Belgium, France, Germany, Italy, the Netherlands and Sweden.
Australia has also reported two cases in men who had traveled to Britain.
How is the current outbreak different?
This is the first time that chains of transmission were reported in Europe without links to West or Central Africa, according to the European Center for Disease Prevention and Control. The agency also said this year’s cases included the first that have been reported among men who have sex with men.
Should I be worried?
The likelihood of the virus being spread during sexual contact is high, but the risk of transmission from other forms of close contact is low, the European Center for Disease Prevention and Control said.
The symptoms are typically mild, and most people recover within weeks, but the virus has had a fatality rate of about 3.3 percent in Nigeria, with children, young adults and immunocompromised people most susceptible.