Worshippers attending Dublin's Phoenix Park this month for the Papal visit run the risk of contracting infectious diseases, health experts have warned.

Temporary morgues are already planned for the event over fears that a small percentage of the 500,000 strong crowd will die of natural causes, given the age profile of the attendees.

Organisers believe it will be the largest single event the country has hosted since Pope John Paul II visited in 1979.

Now the Irish health service's Health Protection Surveillance Centre (HPSC) has said that preparations for the Pope's visit need to be more than just a "wing and a prayer".

Dr Mary O'Riordan, specialist in Public Health Medicine at the HPSC, said mass gatherings of this nature pose "unique health risks to attendants" and public health resources.

Dr O'Riordan highlighted a 2016 review which found disease outbreaks after mass gatherings are generally rare, outside of the Islamic Hajj and Umrah pilgrimages. But outbreaks have occurred at Muslim, Christian and Hindu religious events, at sports events, and at large-scale open air festivals in the past.

"When they occur, they most commonly involve vaccine preventable diseases such as measles, influenza, mumps and hepatitis.

"Other reported outbreaks are mainly of gastrointestinal infections caused by a number of different pathogens," Dr O'Riordan said.

"Given the nature of this historic papal visit, a large number of young children and elderly visitors are expected to attend the final mass, including many international visitors.

"In the current context of ongoing measles spread in Europe, it is highly advisable that all attendants, especially young children, ensure that they are up to date with their vaccinations," Dr O'Riordan added.

According to the European Centre for Disease Prevention and Control, the measles outbreak is continuing across Europe, with more than 30 deaths reported in 2018.

The Papal visit is expected to attract 15,000 overseas visitors and the final mass will draw a crowd of around 500,000 people.

The World Health Organisation (WHO) defines a mass gathering as "a planned or spontaneous event where the number of people attending is sufficient to strain the planning and response resources of the community, state or nation hosting the event".

Dr Jack Lambert, specialist in infectious diseases at the Mater Hospital, Dublin, said the reality is people risk contracting diseases during mass gatherings.

"There are real outbreaks, as with the Hajj in Saudi Arabia in the past… but most of the population in Ireland are protected against diseases like measles," Dr Lambert said. "But, in saying that, if one person with measles is walking around 15,000 people and coughs, some individuals might get it."

He cautioned, however, that while infectious disease spread is not impossible during the Papal visit, it is "highly unlikely" and the risk is "minimal".

Pope Francis will attend the 'Festival of Families' in Croke Park on August 25 and a final mass in Phoenix Park on August 26. A significant policing plan has been put in place, along with major traffic diversions.

Irish Rail will provide capacity for up to 250,000 journeys for those travelling to the Papal Mass. Extra bus and rail services will be provided by Translink for people travelling from Northern Ireland to Dublin for the visit.

Buses will be run across both days by Translink, with additional services from Belfast, Banbridge, Newry and Londonderry for the Saturday.

On the Sunday, as well as the destinations listed, additional services will run from Larne, Dungannon, Downpatrick, Limavady, Dungiven, Magherafelt and Newtownards. Additional rail services will also run across both days.

Belfast Telegraph