Security for polio health workers in Pakistan

The number of cases of polio in Pakistan has topped 200 for the first time in nearly 15 years.

Pakistan is the only country where the virus is spreading fast - showing up in sewage samples all over Karachi.

The Taliban imposed a ban on the vaccine in 2012 which has meant nearly 300,000 children have not been vaccinated for two years. Security personnel escort workers as they administer the vaccine.

Shaimaa Khalil reports from Karachi.