Leptospirosis

Epidemiology

  • 300,000-500,000 cases per year

  • Age distribution?? children??

Taxonomy

  • Phylum: spirochaetae

  • Genus: Leptospira

  • Species: 22, 15 infective (L.interrogans, etc), 7 non-pathogenic

  • Serogroup: a group of antigenically related serovars; defined by microscopic agglutination test using reference antisera, 26 serogroups in pathogenic Leptospira spp.

  • Serovar: defined by cross agglutination absorption test (MAT using reference antisera and antiserum for the isolate to be defined), more than 250 pathogenic serovars

Transmission

  • Pathogenic Leptospira spp. can survive but not proliferate in environments (e.g. soil 74 days, water 7-14 days)

  • Asymptomatic 60-70%

  • Symptomatic: mild, 90%, (fever, headache, myalgia, vomiting, conjunctival suffusion); severe 10% (jaundice, haemorrhage, renal failure, death)

Diagnosis

Mild elevated ALT/AST

Culture & MAT are gold-standard diagnostic tests

  • Culture

  • Molecular methods

  • Serology methods: require paired samples

Clinical features

  • 60-70% asymptomatic

  • 30% symptoms e.g. fever, myalgia, conjunctival suffusion

10% severe:

  • Acute kidney injury

  • Jaundice: proportion??

  • Pulmonary haemorrhage

Treatment

Antibiotics

  • Doxycycline (or azithromycin)

  • Intravenous penicillin (severe case), or cephalosporins (ceftriaxone, cefotaxime)

  • Corticosteroids

Prevention

Chemoprophylaxis

  • Doxycycline, 100-200mg orally per week

Vaccination

  • Inactivated whole-cell vaccine, serovar specific effectiveness

Robin, below: