WHO warns Pakistan 's growing refugee population at risk of polio . The number of displaced could reach 600,000 in the northwest . North Waziristan , where the army is targeting militants , has the most cases . Score: 6
WHO warns Pakistan 's growing refugee population at risk of polio . The number of displaced could reach 600,000 in the northwest . North Waziristan , where the army is targeting militants , has the most cases . Polio is highly infectious and ca n't be cured , but is preventable with a vaccine .