Criteria for defining polio epidemic are all except ?
Ans. is 'd' i.e., Cases occuring during 6 month period o An epidemic of polio is defined as 2 or more local cases caused by same virus type in any 4 week period. So, it has following features - i) 2 or more cases of polio ii) Caused by same virus type iii) Within 4 week period
2 or more cases
Cases should occur in same locality
Caused by same virus type
Cases occurring during 6 month period