Leptospirosis

Leptospirosis is a zoonotic systemic infection caused by Leptospira interrogans serovars. Diagnosis is usually based on serology, but seroconversion is sometimes delayed for several weeks. Leptospirosis-specific blood culture and nucleic acid amplification testing (eg polymerase chain reaction [PCR]) can identify the serovar if positive.

Leptospirosis is often self-limited so may not require antimicrobial therapy. If the diagnosis is made after clinical recovery and antibiotics have not been given, then they are not required.

If leptospirosis is suspected clinically, start antimicrobial therapy before the diagnosis is confirmed. Use:

1 doxycycline orally, 12-hourly for 7 days¹ leptospirosis doxycycline

adult: 100 mg

child less than 21 kg: 2.2 mg/kg²

child 21 to less than 26 kg: 50 mg

child 26 to 35 kg: 75 mg

child more than 35 kg: 100 mg

OR

2 benzylpenicillin 1.2 g (child: 50 mg/kg up to 1.2 g) intravenously, 6-hourly for 7 days. For dosage adjustment in adults with kidney impairment, see benzylpenicillin dosage adjustment leptospirosis benzylpenicillin

OR

3 ceftriaxone 2 g (child 1 month or older: 50 mg/kg up to 2 g) intravenously, daily for 7 days. leptospirosis ceftriaxone

Doxycycline is preferred for empirical therapy because it also treats rickettsial infections, which have a similar presentation to leptospirosis.

¹ An oral liquid formulation of doxycycline is not marketed in Australia but is available via the Special Access Scheme. For formulation options for children or people with swallowing difficulties, see the Don't Rush to Crush Handbook, which is available for purchase from The Society of Hospital Pharmacists of Australia website or through eMIMs.Return

² When used short term (eg less than 21 days), doxycycline has not been associated with tooth discolouration, enamel hypoplasia or bone deposition so can be used in children of all ages.Return