This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Concept of health and disease, Subject name: Social & Preventive Medicine
Which of the following is characteristic of a single exposure common vehicle outbreak 
Select and explain. 
A. Explosive, B. Frequent secondary cases, C. Severity increases with increasing age, D. Cases occur continuously beyond the longest incubation period
A: Explosive
Answer: A: Explosive 
Explanation: In Point Source Epidemics, the exposure to the disease agent is brief and essentially simultaneous and the resultant cases all develop within one incubation period of the disease. A vehicle-borne transmission means the transmission of infectious agents through the agency of water, food or other biological products. If the dose of contamination is heavy, the outbreak may be explosive as in the case of cholera epidemics. *Since in the question it is given a single exposure, they develop within one incubation period. Ex: Food poisoning at an event. Ref : Park 23rd edition Pgno : 100