Paper I
Question
Laboratory diagnosis of leptospirosis
Answer
Laboratory diagnosis of leptospirosis (Leptospira interrogans):
- Direct demonstration (first week, leptospiraemic phase): dark-field microscopy of blood/CSF for the characteristic hook-ended spirochete; culture on Fletcher’s or EMJH semisolid medium (slow-growing, up to 4–6 weeks, rarely useful for immediate management); PCR — most sensitive method in the early phase, before antibodies appear.
- Serology (from the second week, leptospiuric phase): Microscopic Agglutination Test (MAT) — the gold standard, using live leptospiral antigens against paired sera to demonstrate a rising titre, technically demanding, available only in reference laboratories; IgM-ELISA — rapid, widely used screening test.
- Supportive findings: deranged LFTs (raised bilirubin with only mildly raised transaminases), raised renal parameters, urine microscopy showing microalbuminuria/casts, thrombocytopenia, raised CPK (reflecting myositis).