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