Monkeypox has now been detected in Portugal and Spain in what could be the first global outbreak of the disease.
Spain is monitoring eight men who it believes are infected, with tests being carried out to confirm the virus.
All of the men are believed to be gay or bisexual, according to local media, and most were detected at sexual health clinics in Madrid. But it is not yet clear how they caught the virus.
Five men in Portugal have tested positive and more than a dozen more are under investigation, health officials there said today.
Experts fear it is spreading far wide after seven Britons were diagnosed in the past fortnight.
Six of them appear to have been infected in the UK and the majority are not linked, which suggests more cases are going undetected.
Officials say the pattern of transmission is ‘highly suggestive of spread in sexual networks’.
Dr Simon Clarke, a microbiologist at the University of Reading, told MailOnline he suspects UK case numbers are already ‘in the tens’. But he insisted the disease will not spread like Covid, adding: ‘I would be surprised if we ever got to more than 100 cases [in Britain]’.
Regions across Spain have been put on alert following the announcement of eight suspected cases in Madrid.
The country’s top public health doctor, Fernando Simón, said ‘it is not likely that monkeypox will generate a significant transmission but it cannot be ruled out.’
It claims most of the cases were detected at the Sandoval Health Centre in the capital, an STI clinic.
The Spanish broadcaster RTVE said all eight of the patients were men who had homosexual relationships.
The men are said to be ‘stable’ and all suffering from ‘ulcerative lesions’, one of the tell-tale signs of the virus.
Portugal’s health ministry has issued a warning urging people with lesions and rashes to see a doctor.
When these symptoms appear, ‘direct physical contact’ should be avoided, officials added.
Health experts investigating the monkeypox outbreak in Britain, believe the virus may be transmitting sexually for the first time.