European and American health authorities in recent days have identified a number of cases of monkeypox, mostly in young men. It is an amazing outbreak of a disease that rarely appears outside of Africa.
Health officials around the world are watching the new cases because it seems to be the first time the disease has spread among people who have not traveled to Africa. They emphasize, however, that the risk to the general population is low.
What is monkeypox?
Monkeypox is a virus that originates in wild animals such as rodents and primates, and occasionally spreads to humans. Most human cases have been in central and West Africa, where the disease is endemic.
The disease was first identified by scientists in 1958, when there were two outbreaks of “smallpox” disease in research monkeys – hence the name monkeys. The first known human infection occurred in 1970 in a 9-year-old boy in a remote part of the Congo.
What are the symptoms and how is it treated?
Smallpox belongs to the same family of viruses as smallpox, but causes milder symptoms.
Most patients experience only fever, body aches, chills and fatigue. People with more serious illnesses can develop rashes and lesions on the face and hands that can spread to other parts of the body.
The incubation period is five days to three weeks. Most people recover in about two to four weeks without the need for hospitalization.
Smallpox in monkeys can be fatal to one in 10 people and is considered more severe in children.
People who have been exposed to the virus are often given one of several smallpox vaccines that have proven effective against monkeypox. Antiviral drugs are also being developed.
On Thursday, the European Center for Disease Prevention and Control recommended isolating all suspected cases and offering high-risk vaccines to people at high risk.
How common is monkeypox?
The World Health Organization estimates that thousands of monkeys are infected in about a dozen African countries each year. Most in the Congo, where 6,000 cases are reported annually, and in Nigeria with about 3,000 cases per year.
Immediate health monitoring systems mean many infected people are likely to be missed, experts say.
Isolated cases of monkeypox are sometimes found outside of Africa, including the United States and the United Kingdom. The cases are usually related to trips to Africa or contact with animals from areas where the disease is more common.
In 2003, 47 people in six U.S. states had confirmed or probable cases. They picked up the virus from domestic meadow dogs kept near small mammals imported from Ghana.
How are these cases different?
This is the first time that monkeypox has spread among people who have not traveled to Africa. In most cases, these are men who have had sex with men.
In Europe, the infection has been reported in the UK, Italy, Portugal, Spain and Sweden.
The UK Health Agency has said that not all of its cases are related, suggesting that there are several transmission chains. Infections in Portugal were discovered at a sexual health clinic where men sought help because of genital lesions.
On Wednesday, U.S. officials reported a case of monkey infestation in a man who recently traveled to Canada, where authorities are investigating suspected infections in the Montreal area.
Is monkeypox transmitted through sex?
It is possible, but not yet clear.
It has not previously been documented that monkeypox is sexually transmitted, but it can be transmitted through close contact with infected people, their body fluids, clothing or sheets.
Michael Skinner, a virologist at Imperial College London, said it was too early to determine how the men were infected in the UK.
“By its nature, sexual activity includes intimate contact, which is to be expected to increase the likelihood of transmission, regardless of a person’s sexual orientation and regardless of the mode of transmission,” Skinner said.
Francois Balu of University College London said monkeypox qualifies as the type of close contact needed to transmit the disease.
The cases in the UK “do not necessarily mean recent changes in the way the virus is transmitted,” Balu said.