You are a helpful, respectful, and honest assistant. Always answer as helpfully as possible, while being safe. Your answers should not include any harmful, unethical, racist, sexist, toxic, dangerous, or illegal content. Please ensure that your responses are socially unbiased and positive in nature. If a question does not make any sense or is not factually coherent, explain why instead of answering something not correct. If you don't know the answer to a question, please don't share false information.
What is All are true regarding point-source epidemic except? and explain in detail?
Ans. is b i.e., Children are most commonly involved o The main aim of descriptive epidemiology is to study the distribution of disease in time, place and person. Time distribution o There are three kinds of time trends or fluctuations in disease occurence :? A. Sho term fluctuations epidemics B. Secular trends or long term fluctuations C. Periodic fluctuation Sho term fluctuation o The best known sho - term fluctuation in the occurence of a disease is an epidemic. o There are three major types of epidemics ? 1) Common - source epidemics a) Single exposure or point source epidemics b) Continuous or multiple exposure epidemics 2) Propagated epidemics 3) Slow (modern) epidemics Common source epidemics q As name suggests, the source of disease agent is common for all cases. q It is of two types. a) Single exposure or point source epidemics o The exposure to the disease agent is brief and essentially simultaneous --> single exposure. Because disease agent enters into all exposed persons at same time --> the resultant cases all develop within one incubation period of the disease. The epidemic curve rises and falls rapidly. Because exposure is single (simultaneous) with no fuher exposure ---> No secondary wave (no secondary case). Epidemic tends to be explosive, there is clustering of cases within a narrow interval of time. o Point source epidemics are mostly (not always) due to exposure to an infectious agent. Examples --> Food poisoning, Bhopal gas tragedy, Minamata disease in Japan, Chernobyl tragedy. b) Continous or multiple exposure epidemics o Exposure from the common (same) source is prolonged - continous, repeated or intermittent. o Exposure is not at the same time or place. o For examle, a prostitute may be a common source in a gonorrhea outbreak, but since she will infect her clients over a period of time there may be no explosive rise in number of case. Because disease agent enters into exposed person at different time --> outbreaks continues over more than one incubation period. o Example --> Outbreak of legionnaire's disease (respiratory illness) in 1976 in Philadelphia (USA).