The Papua New Guinea pilgrim was staying at Aquinas College, Menai.

More than 80 pilgrims were hit with the flu last week at various World Youth Day (WYD) accommodation sites in other areas of Sydney.

The vomiting and diarrhoea-causing infectious bug was detected in 23 pilgrims staying at a school in Denistone, near Ryde.

Viral gastroenteritis had been on the rise in St George before WYD, with 255 people going to St George Hospital with the bug between March and May this year. The figure was 91 for the same period at Sutherland Hospital.

On June 11, about 20 residents at a St George nursing home came down with viral gastroenteritis, which is common within group settings.

The Leader received a report on Thursday that residents at another St George nursing home had the bug and that families were being asked to keep away to prevent its spread.

Viral gastroenteritis is caused by several viruses, such as rotavirus and norovirus, and is spread by the vomit or faeces of an infected person through contaminated objects, food or drink and touching.

A spokeswoman for the South Eastern Sydney and Illawarra Area Health Service said three pilgrims had gone to Sutherland Hospital last week and a pilgrim had gone to St George Hospital for a dental problem and a fall.