<prompt> True statement about widal test in typhoid is:Widal test is confirmative in endemic areasAntibiotic treatment does not alter widal test resultsPrevious infection alters widal testWidal test does not alter with prior vaccination  <response>: Ans. is c i.e., Previous infection alters widal test Ref: Ananthanarayan, 9the, p. 298 and 9the, p. 296-297People 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:Antibiotic Chloramphenicol treated cases may show a poor agglutinin response.Other than a positive culture, no specific laboratory test is diagnostic. QBoth prior vaccination immunization or infection can alter the widal test. 