: With the detection of polio virus prevalence in the environs of a couple of towns, health workers in the city will undertake their polio eradication efforts during a three-day immunisation drive being launched across the province on Tuesday. About 2,245,243 children will be administered oral polio vaccine in the city, amidst concerns that Karachi is now being considered as a reservoir of polio virus.Sources privy to polio eradication activities in Sindh are of the view that officials should work not only to check the infiltration of the virus but also to eliminate the chances of its spread to other parts of the province. Only a high quality vaccination activity is the way to interrupt the virus circulation, they observe. The sub-national immunisation campaign against polio, which will be the 75th vaccination round since 1994, will benefit over 6.5 million children across the province. About 19,329 mobile and fixed teams are in place to administer M-3 polio vaccine to the children. Although a majority of the country's population, according to a national surveillance cell's report, lives in polio-free areas the low-grade indigenous circulation continues to speckle three identified zones of transmission, including that of Karachi district. Significant changes in polio virus epidemiology include the resurgence of cases during the start of low-transmission season as 15 cases have been reported in the province since November 1, 2007, which reflected that the status of Karachi may also have changed from being an indicator to becoming an intermediate reservoir. Three cases reported in other parts of the province since the year's beginning were genetically related to the virus earlier reported from Karachi in 2006 and 2007. Two of the three cases indicated appearance of wild poliovirus Type 1 in southern Sindh, which is sandwiched between active circulation areas of Karachi and northern Sindh, the report adds. Targeted drives In Karachi, last time a polio case was detected in September 2007, putting the total number of confirmed cases at five in Sindh till then. Sindh reported a total of 12 cases in 2007 from its six polio infected districts, including two in Karachi, one each in Khairpur, Ghotki and Thatta, two in Jacobabad, and five in Kambar, which was a sign of a weak operation in certain districts, said a source. With little improvement in the situation, Sindh is facing growing challenges, which calls for targeted vaccination drives in addition to national and sub-national immunisation campaigns. However, the project director of the Expanded Programme on Immunisation (EPI), Sindh, Dr Salma Kauser Ali, maintained that no case had been reported in the metropolis for the last eight months, which clear indicated that the city with a mixed ethnic population was free of polio. Korangi and Baldia towns, she said, could not be blamed for a spread of the dreaded virus to Hyderabad, Nawabshah or Shikarpur, which reported one case each this year. Kambar, hit by floods in 2007, became prone to epidemics and viruses instead, she said, adding that the district was exporting the virus to other parts of the province. Korangi Town Health Officer Dr Syed Hussain Ahmed claimed that his area was free from polio virus. He said he based his observation on the results of a recent study conducted with a random sampling of children in the town. He said that optimum routine vaccinations against preventable diseases among children and maximum coverage (i.e. up to 98 per cent) of the town's children up to five years for supplementary oral vaccination against polio had been the two key factors in the change of status of Korangi Town. Change in strategies Health experts have, however, suggested for bringing some changes in the existing strategies for communication and fielding of staff to eliminate polio virus in Sindh. There is a need to develop district-specific plans to ensure innovations, bring changes in the attitude of field staffers and their supervisors both at national and international levels, and doing away with the stereotype methods, they observe. Otherwise, they fear, poor sanitation and infiltration of the virus will continue to daunt all polio eradication efforts. According to a foreign expert associated with polio eradication activities, efforts against polio in high-risk areas needed to be stepped up. Sindh should go for an increased access of vaccinators and surveillance staff to children under five in the areas where children missed the polio drops with the support of local and religious leaders and media. Immunisation cost For every polio immunisation campaign in Karachi, about Rs7.3 million is spent as operational cost, in addition to Rs500,000 for orientation of over 6,000 teams, one million rupees for social mobilisation and another one million for mobility support in Karachi.