Kolkata, June 16 : Six pockets in Kolkata are under constant monitoring following the recent detection of the polio virus in sewage water. Officials of the Word Health Organization's (WHO) eastern regional office and Kolkata Municipal Corporation (KMC) are monitoring the six pockets on the basis of certain parameters like improper gutter sewerage facilities and high rate of open defecation tendencies, among others. Besides the Metiabruz, where the virus was detected, the five other areas are Shyamlal Lane, World Vision School area, Dhapa Lockgate, Maheshtala and Narkeldanga. Apart from that, the KMC authorities have decided to adopt additional measures to identify whether there are any polio-affected victims in the areas. The councillors of the all 144 wards under KMC have been instructed to use their own infrastructure to identify polio victims. Similar instructions have been sent to the officers-in-charge of the police stations under the KMC area. Meanwhile, the state health department has also identified certain districts where special polio-vaccination drives will be carried out from June 19 Some of these districts are Howrah, Hooghly, South 24 Parganas, North 24 Parganas, North Dinajpur, Malda and Murshidabad. Meanwhile, all the state-run medical colleges and hospitals have been instructed to conduct stool tests of all immunity deficit children admitted there. Initial observations indicate two possibilities behind the existence of polio virus in the sewage waters. The first is the possibility of the stool of any polio-affected child getting mixed with the gutter water. The second is the possibility of the polio vaccine getting mixed with the same water. The last polio-affected child in West Bengal was detected from Kolkata in 2011. In 2014, the WHO declared India as a polio-free nation. /IANS