Pakistan, June 24 -- Punjab Chief Minister Maryam Nawaz Sharif on Tuesday welcomed a major breakthrough in the province's anti-polio campaign after the World Health Organisation (WHO) confirmed that 31 environmental samples collected from 19 districts of Punjab had tested negative for poliovirus.

Chairing a special meeting to review polio eradication measures, the chief minister was informed that environmental samples collected from Lahore, Multan, Faisalabad, Attock, Bahawalpur, Bahawalnagar, Dera Ghazi Khan, Gujranwala, Gujrat, Jhang, Khanewal, Mianwali, Okara, Rajanpur, Rawalpindi, Rahim Yar Khan, Sahiwal, Sargodha and Sialkot were found free of the virus.

Describing the development as a historic achievement, CM Maryam Nawaz said tha...