Leptospirosis

OVERVIEW

  • Leptospirosis is an infection caused by the spirochaete genus of Leptospira
  • It is an emerging infectious disease with a worldwide distribution, it is prevalent in tropical areas such as South East Asia and Northern Australia
  • Severe forms may result in critical illness, including Weil disease and severe pulmonary haemorrhage

CAUSE

Leptospira species

  • 20 species, 9 are pathogenic with over 200 serovars
  • 8 serovars cause most of the infections in Australia
  • transmitted by animal vectors and survives in contaminated soil and water

Vectors

  • numerous
  • livestock (e.g. cows, pigs, and sheep)
  • rodents (e.g. rats and mice)
  • bats
  • marsupials (e.g. bandicoot, possum and kangaroo)

Pathophysiology

  • Leptospira enter the body via abrasions or mucous membranes
  • incubation period of 2–20 days
  • biphasic disease
  • acute spiraemic phase (~1 week)
  • subsequent immunogenic phase
  • systemic illness results from widespread vasculitis and endothelial damage causing multiorgan dysfunction

RISK FACTORS

  • occupational activities (e.g. cattle farming, banana cultivation)
  • direct contact with vectors (e.g. handling carcasses)
  • indirect contact with vectors (e.g. exposure to contaminated urine)
  • recreational exposure (e.g. bushwalking, hunting, swimming, camping, and adventure sports such as white water rafting and kayaking)
  • travel to endemic regions, especially those with high rainfall and temperatures

CLINICAL FEATURES

Assess for risk factors

Features of acute spiremic phase (~1 week)

  • may resemble a flu-like illness
  • typical symptoms include: fever, headaches, myalgia, rigors, arthralgia, nausea, vomiting and jaundice
  • Less common signs include hepato-splenomegaly and lymphadenopathy

Features of immunogenic phase

  • acute renal failure
  • hepatic failure
  • aseptic meningitis
  • severe pulmonary hemorrhage syndrome
  • conjunctival suffusion or haemorrhages (diagnostic clue)
  • myositis, rhabdomyolysis
  • myocarditis
  • coagulopathy and purpura

INVESTIGATIONS

  • culture: blood, urine, CSF (use Ellinghausen McCullough Johnson harris (EMJh) media containing 0.5% agar ); organisms may be seen on dark field microscopy at 1-2 weeks, may take 1 month for positive cultures
  • Leptospira PCR testing (96.4% sensitivity and 99.5% specificity)
  • serology: microscopic agglutination test (MAT) is the gold standard

DIAGNOSTIC CRITERIA

Definitive criteria

  • Isolation of pathogenic Leptospira sp., or
  • Fourfold or greater increase in Leptospira MAT titre, or
  • A single high Leptospira MAT titre greater than or equal to 400 against a pathogenic species

Suggestive criteria

  • Detection of pathogenic Leptospira sp. by nucleic acid test (NAT), or
  • A positive Leptospira (EIA) IgM result

DIFFERENTIAL DIAGNOSIS

Infectious diseases

  • malaria
  • viral — dengue, cytomegalovirus, Epstein-Barr virus, influenza, coronavirus, hepatitis, Ross River virus, Barmah Forest virus, Murray Valley encephalitis virus and Japanese encephalitis virus, viral haemorrhagic fever
  • bacterial — typhoid, typhus, Q-fever, brucellosis
  • overwhelming sepsis of any cause

Other

  • hematological disorders such as leukemia
  • other causes of pulmonary haemorrhage, aseptic meningitis, rhabdomyolysis, myocarditis, liver and renal failure

MANAGEMENT

Resuscitation

Specific therapy

  • Doxycycline 100 mg bd po
  • Ceftriaxone 1 g IV once daily
  • Cefotaxmine 1 g IV q6h
  • Benzylpenicillin 1.2 g IV q6h

Supportive care and monitoring

Prevention

Notifiable disease

Consult infectious diseases specialist


Journal articles


CCC 700 6

Critical Care

Compendium

Chris is an Intensivist and ECMO specialist at The Alfred ICU, where he is Deputy Director (Education). He is a Clinical Adjunct Associate Professor at Monash University, the Lead for the  Clinician Educator Incubator programme, and a CICM First Part Examiner.

He is an internationally recognised Clinician Educator with a passion for helping clinicians learn and for improving the clinical performance of individuals and collectives. He was one of the founders of the FOAM movement (Free Open-Access Medical education) has been recognised for his contributions to education with awards from ANZICS, ANZAHPE, and ACEM.

His one great achievement is being the father of three amazing children.

On Bluesky, he is @precordialthump.bsky.social and on the site that Elon has screwed up, he is @precordialthump.

| INTENSIVE | RAGE | Resuscitology | SMACC

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