The Papua New Guinean government has confirmed a third case of polio, giving rise to fears that an outbreak of the crippling disease in the Pacific half-island nation is more widespread than previously thought.
Last month the government announced the first polio case in 18 years after a 6-year-old boy with weak lower limbs from Lae in Morobe province was detected to have contracted the disease.
Health officials also found the virus present in the stool samples of another child from the boy's neighbourhood in July.
The latest victim - a 3-year-old boy - confirmed by government health authorities on Tuesday, is from Mulitaka in Enga province, which is separated from Morobe by two other provinces. It means the outbreak is not confined to just to one area.
"Confirmation of this case in Enga highlights that the outbreak has spread geographically, and this is a concern," Pascoe Kase, Papua New Guinea's secretary of health, said in an emailed statement.
He said the detection of the new case was a result of the government stepping up surveillance since the first outbreak was recorded.
The World Health Organization said there was a high risk that the disease would spread further, given substantial vaccination coverage gaps across the country, with 55 additional suspected polio cases.
The impoverished nation with about 8 million inhabitants had been declared polio-free since 2000. It now joins three other countries in the world battling the virus: Afghanistan, Pakistan and Nigeria.
The contagious and crippling disease mainly affects children under 5 years of age. It cannot be cured, but it can be prevented with vaccinations.