He may have monkeypox, according to a 61-year-old man from northern Greece.
Only a few symptoms are exhibited by the patient, who had been isolated in a Thessaloniki medical unit.
Friday is expected to be the day that Aristotle University of Thessaloniki releases test results.
The individual is said to have travelled from Morocco to Greece through Istanbul, according to reports.
More than 300 cases of monkeypox were reported in Europe in May. Smallpox-like symptoms are seen in monkeypox, an animal-to-human virus.