Epidemic of polio is due to -
Poliovirus tyoe 1 is responsible for most epidemics of paralytic poliomyelitis. Type 3 also causes but to a lesser extent. REF:ANANTHANARAYAN AND PANIKER'S TEXTBOOK OF MICROBIOLOGY 9TH EDITION PAGE NO:490
Type I virus
Type II virus
Type III virus
Combine type II and III virus
Virology