Non-polio Enteroviruses in Karnataka, India: Virological surveillance of acute flaccid paralysis cases (July 1997-2013)

Background and Objectives: Since 1997 National Institute of Virology, Bangalore Unit involved in WHO's Acute flaccid paralysis paediatric cases surveillance programme to isolate and detect polioviruses. Stool samples yielded not only polioviruses but also Non-Polio enteroviruses. This report is an overview of non-polio Enterovirus (NPEV) epidemiology in Karnataka state, India for the period of 16-years and 6 months from July 1997-2013. Methods: A total of 19,410 clinical samples were processed for virus isolation as a part of acute flaccid paralysis (AFP) surveillance for Global Polio Eradication Programme in India at National Polio Laboratory, at Bengaluru. NPEV detection was performed by virus isolation on cell culture according to World Health Organisation recommended protocols. Results: A total of 4152 NPEV isolates were obtained. The NPEV isolation rate varied from year to year but with a total NPEV rate of 21.39%. Conclusion: A seasonal variation was noted with high transmission period between April and October with peaks in June-July. The male to female ratio was 1: 1.2. The isolation of NPEV decreased significantly with the increase in age. Epidemiology of NPEVs from AFP cases in Karnataka is described.