Monkeypox, the rare virus usually contracted in Africa, is continuing to spread internationally, with several European countries confirming new cases of the disease on Friday.
U.K. Health Minister Sajid Javid said Friday that 11 new cases of monkeypox had been identified in Britain - meaning the country's total number of confirmed cases had more than doubled from 9 to 20 in just two days.
Javid said the U.K. government was following the United States' lead by acquiring doses of vaccines that are effective against monkeypox. He did not elaborate on how many doses the U.K. had procured.
The update from Britain comes as health officials across Europe are confirming more cases of monkeypox by the day.
Spain's Ministry of Health said in a statement on Friday that as of May 19, 30 patients' samples had been analyzed by the country's National Microbiology Center.
Seven had been confirmed as monkeypox, and the remaining samples were identified as viruses of the same family that were awaiting sequencing to give a final diagnosis of monkeypox.
All of the patients were based in Madrid.
Carolina Darias, Spain's health minister, said the infections were mild and had not required treatment.
Spanish news outlet La Vanguardia reported on Friday that the country was also investigating a further 19 suspected cases, making Spain the country with the most monkeypox cases in the world.
Meanwhile, French health authorities announced Friday that they had identified a single case of monkeypox in the Paris region. The patient, a 29-year-old man, had no history of travel to a country where the virus is circulating, officials said.
Andrew Preston, a professor of microbial pathogenicity at the University of Bath, told Fortune on Thursday that it was concerning to see that many of the identified cases had no links to one another.
"That would suggest there are other contacts forming the connections between those cases," he explained. "That's the worrying thing: The epidemiology would suggest there are other unrecognized cases at the moment. There have to be other cases in the community."
On Thursday, Italian health officials confirmed that one patient was being treated for monkeypox in Rome's Lazzaro Spallanzani hospital. The individual was a young man who had recently returned from Spain's Canary Islands.
The hospital said two more suspected cases were being investigated.
Earlier this week, Portugal reported five confirmed monkeypox cases and more than 20 suspected cases, while Sweden's Ministry of Health confirmed on Thursday that a single case had been identified in Stockholm.
According to Britain's National Health Service, the first symptoms of monkeypox include fever, headaches, muscle aches, exhaustion, and swollen glands.
A rash appears one to five days after the first symptoms, often beginning on the face before spreading to other parts of the body.
EXPLAINED: What is monkeypox? Everything you need to know
This story was originally featured on Fortune.com