Angola has reported its first case of polio in four years, and the crippling disease has also spread within Indonesia to Sumatra island, the World Health Organisation (WHO) said on Friday, according to Reuters. The paralysis of a baby girl in the Angolan capital Luanda and of a three-year-old girl in Lampung province on Sumatra, Indonesia's 66th case since an outbreak began in May, are fresh blows to its bid to halt the global spread of polio by year-end. Polio, which can cause irreversible paralysis in a matter of hours, re-emerged in May in Indonesia, which had been polio-free since 1995. The first case was near the West Java city of Sukabumi, 100 km (60 miles) south of Jakarta, but the latest case means the virus has jumped westward from the main island Java to Sumatra. A fresh round of immunisation was carried out earlier this week, targeting 6.4 million Indonesian children under the age of five in West Java, Banten and Jakarta provinces. "Lampung and Central Java will be included in the next phase of the large-scale immunisation campaigns which will start from August," the WHO said. Angola is the 17th previously polio-free country to be reinfected since 2003, when the virus began circulating widely in Africa, according to the United Nations health agency. But genetic analysis has shown it was imported from India, also an endemic region, not from Nigeria, where a 10-month ban on vaccination in the northern state of Kano is blamed for the virus spreading across Africa, reaching Saudi Arabia and Yemen. A nationwide polio vaccination campaign is planned for July 29-31 in Angola, where only 45 percent of children are estimated to be vaccinated, according to the WHO statement.