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: Microbiology
[{'content': 'True statement about widal test in typhoid is-( \nSelect and explain. \nA. Widal test is confirmative in endemic areas, B. Antibiotic treatment does not alter widal test results, C. Previous infection alters widal test, D. Widal test does not alter with prior vaccination', 'role': 'user'}, {'content': "Answer: C \nExplanation: Ans. is 'c' i.e., Previous infection alters widal test . Person who have had prior infection or immunization may develop an anamnestic response during unrelated fever and may show false positive reaction. This may be differentiated by repetition of test after a week. The anamnestic response shows only a transient rise, while in enteric fever the rise is sustained. About other options : . Cases treated with antibiotic (cholermphenicol) may show a poor agglutinin response. . Other than a positive culture, no specific laboratory test is diagnostic - . Both prior vaccination (immunization) or infection can alter the widal test (see above).", 'role': 'assistant'}]