THE HAGUE, May 23 (Xinhua) -- The number of monkeypox cases in humans rose to six in the Netherlands, the National Institute for Public Health and the Environment (RIVM) announced on Monday.

       The first human case of monkeypox in the Netherlands was confirmed last Friday. The RIVM and the Erasmus University Medical Center are analyzing new samples to ensure rapid detection of any new cases and to reduce the chances of further spread.

       "Some of the people infected attended the Darkland festival in Belgium," the RIVM said. "All cases involve men who have sex with men, though this does not mean that the virus can, or can only, be spread through sexual contact or that the virus cannot spread beyond this group of people."

       The RIVM asks high-risk contacts, such as sexual contacts or housemates, with whom an infected person has had skin-to-skin contact, to self-isolate. Vaccination will only be offered at the Municipal Health Service (GGD) to people with a high risk of infection.