How is leptospirosis diagnosed and treated?

From the Guidelines

Leptospirosis diagnosis is primarily confirmed through serological tests, with an IgM titre >1 in 320 considered suggestive of the disease, and treatment should begin as soon as suspected, with antibiotics such as doxycycline or penicillin G, due to the potential for severe complications and improved outcomes with early intervention. The diagnosis of leptospirosis involves initial investigations that are non-specific, including urinalysis, which may show proteinuria and haematuria, and blood tests that may indicate a polymorphonuclear leucocytosis, thrombocytopenia, and anaemia 1. Key points to consider in the diagnosis and treatment of leptospirosis include:

• Confirmation of the diagnosis is most commonly serological, with the earliest positives appearing 6-10 days after onset of symptoms 1
• An IgM titre >1 in 320 is considered suggestive of leptospirosis, while a titre of 1 in 80 to 1 in 160 is consistent with early infection but may be due to cross-reactions 1
• Convalescent serology, >10 days after symptom onset, should be sent for IgM ELISA and microscopic agglutination test (MAT) to confirm the diagnosis 1
• Treatment should be initiated upon suspicion, given the non-specific nature of initial investigations, and early mild disease is generally self-limiting, with penicillin and tetracycline antibiotics thought to be effective during the bacteraemic phase 1
• Patients presenting with classical symptoms and signs of Weils disease, such as jaundice, can become very unwell despite therapy and may require renal or liver support 1
• Supportive care is essential, including hydration, fever management, and monitoring for complications like kidney or liver failure, and in severe cases, dialysis or respiratory support may be necessary.

From the Research

Diagnosis of Leptospirosis

• Leptospirosis is diagnosed using specific laboratory tests, as its clinical manifestations are nonspecific and diverse, making clinical diagnosis difficult 2.
• The diagnosis of leptospirosis depends on the stage of the disease, requiring the combination of diagnostic tests using appropriate specimens at each disease stage 2.
• Suitable laboratory diagnostic tests include:
  • Microscopic agglutination test (MAT) as the reference serological test, which requires significant expertise 3.
  • Immunochromatographic tests, such as the Leptocheck test, which can be used for rapid diagnosis and can provide results consistent with MAT in most cases 3.
  • Polymerase chain reaction (PCR) and Leptospira isolation, which can be used to confirm the results, although they have low sensitivity compared to serological tests 3, 4.

Treatment of Leptospirosis

• The optimal antimicrobial treatment for leptospirosis has not been established, but several options are available, including:
  • Penicillin, which has long been considered the treatment of choice 5.
  • Doxycycline, which is a reasonable alternative, but concerns exist regarding its use in all patients 5, 4.
  • Cefotaxime and ceftriaxone, which have been shown to be effective and may be preferred agents due to their ease of use 5, 6.
  • Azithromycin, which appears promising for the treatment of less severe disease 5.
  • Fluoroquinolone antimicrobials, which may be used in combination with standard therapy in certain cases, although adequate human trials are lacking to fully support their use 5, 4.