May 16 (UPI) -- The Papua New Guinea National Department of Health announced early Friday that a polio outbreak has struck there. The nation's government said it is "stepping up its response after the poliovirus was detected in wastewater samples and in two healthy children in Lae, Morobe Province." The World Health Organization has reported that less than 50% of the country's population have been immunized against the disease, which is caused virally via contact with an infected person's feces