Serological diagosis is made in -

Ans. is 'c' i.e., Syphilis . Most common method used for diagnosis of syphilis is serological diagnosis. " Q fever: Laboratory diagnosis is by serology, by complement fixation or indirect immunofluroscent assay." " Gonococcus: Serological test may be of value in some chronic cases or from patients with metastatic lesions such as ahritis" " Immunodiagnosis for T B. : Serological tests are not useful in diagnosis, though antibodies to many bacillary antigens have been demonstrated in the sera of the patients" " The diagnosis of actinomycosis is rarely considered. All too often, the first mention of actinomycosis is by the pathologist after extensive surgery. The diagnosis is most commonly made by microscopic identification of sulfur granules ( an in vivo matrix of bacteria, calcium phosphate and host material) in pus or tissues"