Leptospira

Leptospira is a genus of slender, spiral-shaped spirochete bacteria with hooked ends. They are weakly Gram-negative and require silver stain techniques for visualization. Pathogenic species cause leptospirosis, a globally distributed zoonosis, especially common in warm, humid climates.

Clinical Features

Leptospirosis typically progresses in two phases:

Initial (leptospiremic) phase:

• Sudden fever
• Severe headache
• Muscle pain (notably in calves and lower back)
• Nausea, vomiting, diarrhea
• Dry cough
• Non-purulent conjunctivitis

Immune phase (more severe):

• Jaundice
• Liver and kidney failure (Weil’s disease)
• Pulmonary hemorrhage
• Aseptic meningitis
• Myocarditis

Risk factors: contact with contaminated water/soil (animal urine), exposure during agriculture, recreational water activities, veterinary work, urban rodent exposure.

Diagnosis

Diagnosis includes:

• Serologic testing (MAT or ELISA)
• PCR (early-stage detection)
• Culture (blood, urine)
• Supportive labs:
  • CBC (leukocytosis, thrombocytopenia)
  • Elevated liver enzymes
  • Elevated creatine kinase
  • Urinalysis (proteinuria, hematuria)

Treatment

Antibiotic therapy:

• Doxycycline (mild cases)
• Penicillin G or ampicillin (moderate cases)
• Ceftriaxone or azithromycin (alternative options)

Severe cases require:

• Hospitalization
• ICU care
• Supportive treatment for kidney, liver, or lung complications

Doxycycline prophylaxis may be considered in high-risk situations.