The health ministry is planning an emergency mop-up operation that will vaccinate three lakh children living in and around Kirti Nagar against polio to contain further spread of the deadly P1 strain of the virus in Delhi. The decision was taken after the country's first PI strain of wild polio virus sprung up this year from Darbangia Colony in Kirti Nagar. Since this is the first P1 polio case in Delhi after August 2006, which had made officials declare the city free of the virus last year, shocked state polio eradication experts have now identified 2,500 high risk clusters, mostly occupied by migrants from Uttar Pradesh and Bihar