Australia will limit travel between its islands in the Torres Strait and those of neighbouring Papua New Guinea in a bid to clamp down on a long-running cholera outbreak, officials said Friday.
Health authorities say the water-borne disease is unlikely to spread to the Australian mainland, but they are concerned that the Papua New Guinea outbreak has reached Daru, a town close to the islands of the Torres Strait.
Australian officials said traditional cross-border travel between Australian and Papua New Guinean islands, short journeys for which indigenous inhabitants normally do not require a passport, would be restricted.
"In consultation with PNG authorities in Daru, Australia has as a precaution restricted all cross-border travel under the free-movement provisions of the Torres Strait Treaty," a foreign ministry spokesman said.
"This restriction will remain in place until further notice, but will be subject to ongoing review."
The restrictions will prevent traditional visits to Australia by indigenous inhabitants but the border otherwise remains open for travellers with a valid passport and visa, he said.
Cholera cases have been reported in several Papua New Guinea provinces, including the capital Port Moresby since 2009, Australia said in a travel advisory.
Health experts at Australia's James Cook University said the outbreak had killed 13 people -- all children -- in Daru alone and some 260 people have been treated for the disease in the past three weeks.
Professor Ian Wronski, of the university's medicine faculty, said the mortality rate for cholera was generally around one percent but in impoverished Papua New Guinea appeared to be above 2.5 percent.
"It does appear that the death rates are higher than you would like," he told AFP.
With the distance across the Torres Strait from Australia's Cape York to Papua New Guinea just 150 kilometres (93 miles) at its closest point, some of the islands separated by the international border are only kilometres apart.
Wronski said the cholera outbreak highlighted the risk of the potential for other disease, including dengue fever, tuberculosis and avian influenza, to travel from Papua New Guinea to Australia.
"We are witnessing the re-emergence of tropical infectious disease in Australia. And our response is inadequate," he said.
Cholera is transmitted via contaminated food and water and spreads as a result of poor hygiene.