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    Last update: October 2022



    Leptospirosis is a zoonosis that affects many domestic and wild animals, mainly rodents (particularly rats) but also dogs and cattle, etc.


    It is transmitted to humans by contact through skin lesions or mucous membranes (e.g. eyes, mouth) with:

    • freshwater or moist soil contaminated with urine of an infected animal (indirect contact);
    • urine, blood and other body fluids or tissues of an infected animal (direct contact).


    It is caused by bacteria (spirochetes) of the genus Leptospira.


    Leptospirosis occurs worldwide, particularly in tropical and subtropical regions. There are often outbreaks after heavy rainfall or flooding.

    Clinical features

    Approximately 90% of cases are asymptomatic or mild with a favourable outcome. 5 to 15% of cases present a severe form with multiple organ dysfunction and a high mortality rate without prompt treatment.

    Mild form 

    • Acute phase (septicaemic): 
      • Sudden onset of high fever with chills, headache, myalgia (especially calf and lumbar pain), photophobia, ocular pain. Bilateral conjunctival suffusion affecting the bulbar conjunctiva (redness without discharge) is a characteristic sign, but not always present.
      • May be associated with: gastrointestinal symptoms (anorexia, abdominal pain, nausea, vomiting), non-productive cough, lymphadenopathy, hepatomegaly, and sometimes, skin rash.
    • Immune phase:
      • The signs of the acute phase regress after 5 to 7 days then reappear for a few days usually in a milder form (milder fever, less severe myalgia) then disappear. 
      • Signs of meningitis (thought to be of immune origin) are however very common during this phase.

    Severe or ictero-haemorrhagic form 

    The onset is the same but a few days later the symptoms worsen: renal disorders (oliguria or polyuria), hepatic disorder (jaundice), widespread haemorrhages (purpura, ecchymoses, epistaxis, haemoptysis, etc.), pulmonary signs (chest pain) or cardiac signs (myocarditis, pericarditis).


    Diagnosis is difficult because of the broad spectrum of clinical manifestations. Patients that present the following should be considered as suspected cases of leptospirosis [1] Citation 1. World Health Organization. Human leptospirosis: guidance for diagnosis, surveillance and control. World Health Organization, 2003.
    https://apps.who.int/iris/bitstream/handle/10665/42667/WHO_CDS_CSR_EPH_2002.23.pdf?%20sequence=1&isAllowed=y [Accessed 5 September 2022]

    • abrupt onset of fever, chills, conjunctival suffusion, headache, myalgia and jaundice


    • one or more risk factors for infection: exposure to contaminated freshwater (e.g. swimming, fishing, rice fields, flooding) or infected animals (e.g. crop and livestock farmers, veterinarians, butchers and slaughterhouse workers).


    Other conditions to consider include a wide range of acute febrile illnesses, e.g.:  



    • Collect pre-treatment specimens and send them to reference laboratory:
      • Acute phase (first week of illness): blood and/or serum for IgM screening, PCR, and acute specimen for microscopic agglutination test (MAT);
      • Immune phase (second week of illness): serum for IgM screening and convalescent specimen for MAT, and urine for PCR.
    • In all cases, rapid test for malaria in endemic regions (and antimalarial treatment if needed, see Malaria, Chapter 6).

    Other investigations

    (if available)

    • Serum creatinine: elevated if renal dysfunction.
    • Full blood count: possible neutrophilia and thrombocytopenia (acute phase), or anaemia secondary to haemorrhage (immune phase).
    • Cerebrospinal fluid (immune phase): features of aseptic meningitis in CSF (see viral meningitis, Chapter 7).
    • Urine: mild proteinuria, leukocyturia, possible microscopic haematuria (acute phase).


    Start empiric antibiotic treatment as soon as leptospirosis suspected, before results of diagnosis tests are available.

    Mild form (outpatients)

    Symptomatic treatment

    • Rest and treatment of pain and fever: paracetamol PO (Chapter 1).
    • Acetylsalicylic acid (aspirin) is contra-indicated (risk of haemorrhage).


    Antibiotic treatment

    • doxycycline PO for 7 days

    Children under 45 kg: 2 to 2.2 mg/kg (max. 100 mg) 2 times daily

    Children 45 kg and over and adults: 100 mg 2 times daily

    or, particularly in pregnant women:

    • azithromycin PO for 3 days

    Children: 10 mg/kg (max. 500 mg) on D1 then 5 mg/kg (max. 250 mg) once daily on D2 and D3

    Adults : 1 g on D1 then 500 mg once daily on D2 and D3 

    or, if not available,

    • amoxicillin PO for 7 days

    Children: 25 mg/kg (max. 1 g) 2 times daily 

    Adults: 1 g 2 times daily


    Antibiotic treatment can trigger a Jarisch-Herxheimer reaction (high fever, chills, fall in blood pressure and sometimes shock). It is recommended to monitor the patient for 2 hours after the first dose of antibiotic for occurrence and management of severe Jarisch-Herxheimer reaction (symptomatic treatment of shock).


    Severe form (inpatients)

    Symptomatic treatment

    • Specific management according to organs affected. Oliguria generally responds to correction of hypovolaemia.
    • Rest and treatment of pain and fever: paracetamol PO (Chapter 1). Avoid or use paracetamol with caution in patients with hepatic involvement.


    Antibiotic treatment

    • ceftriaxone IV for 7 days a Citation a. For IV administration of ceftriaxone, dilute with water for injection only.

    Children: 80 to 100 mg/kg (max. 2 g) once daily

    Adults: 2 g once daily


    • benzylpenicillin IV for 7 days

    Children: 50 000 IU (30 mg)/kg (max. 2 MIU or 1200 mg) every 6 hours

    Adults: 1 to 2 MIU (600 to 1200 mg) every 6 hours


    • Avoid bathing in freshwater in endemic areas.
    • Disinfect laundry and objects soiled by urine of infected animal or patient. 
    • Vaccination and protective clothing (only for professionals at risk of exposure).


    • (a)For IV administration of ceftriaxone, dilute with water for injection only.