A 35-year-old farmer from Kerala presents with fever, conjunctival suffusion (hyperaemia without discharge), myalgia particularly in calf muscles, and jaundice with renal failure (Weil's disease). Serology confirms leptospirosis. Which Leptospira serogroup is classically associated with Weil's disease?

• A Leptospira interrogans serogroup Icterohaemorrhagiae ✓
• B Leptospira interrogans serogroup Canicola
• C Leptospira interrogans serogroup Pomona
• D Leptospira biflexa (saprophytic)

Explanation

Weil's disease (severe leptospirosis with jaundice, renal failure, and haemorrhage) is classically associated with Leptospira interrogans serogroup Icterohaemorrhagiae, typically carried by rats (Rattus norvegicus). Conjunctival suffusion (bilateral hyperaemia without discharge — a relatively specific early sign) plus calf muscle tenderness and fever suggests leptospirosis. Serogroup Canicola is associated with dogs as reservoir and causes primarily nephritis. Serogroup Pomona is associated with cattle/pigs and causes anicteric disease. L. biflexa is non-pathogenic. The MAT test with Icterohaemorrhagiae antigen showing highest titre confirms the serogroup.

Reference: Ananthanarayan & Paniker's Textbook of Microbiology, 11th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.