This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Social & Preventive Medicine
[{'content': 'All are true about epidemiological features of cholera except ? \nSelect and explain. \nA. Epidemic is self limiting, B. Poor sanitation is a cause of epidemic, C. El Tor biotype has decreased endemicity, D. Onset of epidemic is abrupt', 'role': 'user'}, {'content': 'Answer: C \nExplanation: The El Tor biotypes have greater endemic tendency than its classical counterpa in that it causes a higher infection-to-case ratio (i.e. more inapparent infections and mild cases). About other options Cholera epidemic has an abrupt onset. It stas as common source epidemic and often treat an acute health problem. Then it continues as a propagated epidemics as cases become the source for the other persons. Cholera epidemic in a community is self-limiting. This is attributed to the acquisition of temporary immunity, as well as due to the occurrence of a large number of subclinical cases. Poor environmental sanitation is the most impoant predisposing factor for epidemic', 'role': 'assistant'}]