All are true for Point source epidemic except: (A) Epidemic curve rises and falls sharply, (B) Clustering of cases within a short period of time, (C) Person-to-person transmission, (D) All cases usually develop within one incubation period
Answer is C. EPIDEMIC:
• Definitions of epidemic:
– Occurrence of no. of cases of a disease ‘clearly in excess of normal expectancy (NE)’
1. Normal expectancy is derived by looking at average of no. of cases of the disease in previous 3 – 5 years in that geographical area
2. If NE = zero, ‘even one case is considered epidemic’