Seven cases of yellow fever have been confirmed and another four suspected in Paraguay, following an outbreak in nearby Brazil, the World Health Organisation announced Wednesday.
Seven people in the jungle of Paraguay's San Pedro region have contracted the virus, while another four in the town of Lorenzo, near Asuncion, may also be infected, the WHO said in a statement quoting Paraguay's health ministry.
The government has rolled out a massive vaccination campaign, dispatched health and epidemiological experts and stepped up surveillance of the affected areas.
Countries in the region are also sending yellow fever vaccines to Paraguay, the WHO said.
Authorities in neighbouring Brazil reported in January that at least 11 people have died from yellow fever in jungle areas; the country claims to have eradicated the virus from urban areas since 1942.
A viral disease that causes fever, muscle aches, loss of appetite and nausea, yellow fever is transmitted by infected mosquitoes. It is found only in parts of South America and Africa.