"After the weekend, we will give an update on any new infections that have become known," said researchers from the National Institute for Public Health and the Environment.

"In recent days it was already known that several people in Europe tested positive for this disease," said the institute, noting there are cases in Portugal, Britain and Belgium, among others.

Monkeypox is a poxvirus, which primarily occurs in countries in West Africa and Central Africa. The virus is common in wild animals like rodents and primates, but humans can also get the virus.

Symptoms include fever, headache, muscle ache, backache, swollen lymph nodes, chills and exhaustion. A rash typically develops. The rash eventually forms a scab, which later falls off, indicating that the person is no longer infectious. ■