An outbreak of hepatitis A has spread over the past year among gay men in Europe, the United States and Chile, and upcoming gay pride events and a vaccine shortage could worsen the situation, the World Health Organization said on Wednesday.

The WHO said the rise in cases was "of particular concern from a public health perspective because of the current limited availability of hepatitis A vaccine worldwide", and most of the affected countries had routinely recommended vaccination for gay men. The virus is mainly spread by ingesting food or water contaminated by the faeces of an infected person, but for gay men the main risk is sexual transmission, particularly oral-anal sexual contact.

The WHO said up to 2 million international guests were expected to attend the LGBT World Pride Festival in Madrid between 23 June and 2 July, with "moderate to high" risk of person-to-person sexual transmission of hepatitis A. People attending the Madrid festival should seek advice from healthcare providers on hepatitis A vaccination before traveling, and should take preventive measures while in Madrid to reduce the risk of infection, it said. Read more via Reuters