Leptospirosis

Disease Description (Causes and Symptoms)

• Cause: A zoonotic infection caused by bacteria of the genus Leptospira. Infected animals (especially rodents, dogs, and livestock) excrete the bacteria in their urine, contaminating soil, water, and polluted environments; infection occurs when the bacteria enter the human body through wounds or mucous membranes.
• Pathophysiology: The bacteria enter through mucous membranes or damaged skin → spread through the bloodstream (leptospiremic phase) → infiltrate multiple organs (liver, kidneys, lungs, and central nervous system) → immune-phase symptoms subsequently appear as antibodies form.
• Incubation period: Usually 1–2 weeks (range: several days to several weeks).
• Main symptoms: Acute fever, chills, headache, muscle pain (especially in the calves), conjunctival suffusion, jaundice, nausea and vomiting, urinary and renal dysfunction (acute renal failure), meningeal irritation symptoms (neck stiffness), and pulmonary hemorrhage or difficulty breathing (in severe cases).
• Clinical spectrum: The disease may range from asymptomatic infection or mild flu-like symptoms to severe liver and renal failure, pulmonary hemorrhage, meningitis, and shock.
• Disease characteristics (seasonal and exposure-related): Risk increases after heavy rain or flooding and with exposure to contaminated water or soil during agricultural work, disaster recovery, water-related activities, and similar situations (in Korea, mainly from late summer to fall).

Treatment Methods

• Antibiotics
  • Mild cases: Oral doxycycline is recommended. Early treatment is effective in shortening the duration of symptoms.
  • Severe cases: IV penicillin G or cephalosporins (e.g., ceftriaxone, cefotaxime) are used. The choice of antibiotic is determined according to clinical severity and whether the patient has allergies.
  • The earlier treatment is started (as soon as possible after symptom onset), the more effective it is; administration within 5 days after disease onset can shorten the hospital stay and duration of fever.
• Supportive treatment
  • Fluid and electrolyte correction, and hemodynamic stabilization.
  • If acute renal failure is present, hemodialysis (or continuous renal replacement therapy).
  • If pulmonary hemorrhage or ARDS develops, mechanical ventilation and hemorrhage management (requiring intensive care treatment).
  • If meningitis is also present, hospitalization and observation, as well as symptom-specific treatment, may be provided as needed.
• Precautions (including self-care)
  • Use caution with nephrotoxic drugs (e.g., some NSAIDs and aminoglycosides).
  • Be attentive to dehydration and electrolyte imbalance, and get sufficient rest and fluids.
  • Immediate emergency treatment is required if severe symptoms occur (difficulty breathing, decreased consciousness, hematuria or hemoptysis, severe jaundice, anuria, etc.).
• Preventive antibiotics (in cases of high-risk exposure)
  • In situations involving high-risk work or exposure (such as flood recovery work), prophylaxis with doxycycline 200 mg taken at 1-week intervals may be used.
• Vaccines
  • Broad-spectrum vaccines for human use are limited and are not widely used as a general preventive measure (there are differences by country and region).

Checklist Before an Outpatient Visit (Including Example Questions)

Items/information to prepare

• The date symptoms recently began (including the first day of fever) and a record of symptom progression
• Changes in urine or stool, whether hemoptysis has occurred, and urine volume (anuria or decreased output)
• A list of medications currently being taken (including prescription drugs, over-the-counter medicines, and supplements)
• Allergy history (especially antibiotic allergies)
• Recent exposure history: work in flooded or inundated areas, rice paddy or outdoor work, contact with rats or wild animals, water-related activities, and whether wounds or mucous membranes were exposed
• Existing underlying conditions (kidney or liver disease, and whether pregnant)
• Previous test results, if available (blood tests, liver and kidney function tests, urinalysis, chest X-ray, etc.) Examples of questions that healthcare professionals may ask during an outpatient visit
• "When did your symptoms start?"
• "Have you recently had contact with contaminated water, such as from a flood, rice paddy, river, or stream?"
• "Have you recently had contact with rats or wild animals?"
• "How has your urine output changed compared with usual? Do you have blood in your urine, or are you unable to urinate at all at night?"
• "Do you have severe symptoms such as difficulty breathing, hemoptysis, severe abdominal pain, or changes in consciousness?"

Examples of General Questions to Ask the Doctor

• "Which antibiotic is right for me, and how long should I take it?"
• "How high is my risk of complications from this disease, such as renal failure or pulmonary hemorrhage?"
• "How do you determine whether I need inpatient treatment or can be treated as an outpatient?"
• "Are there any medications (e.g., nephrotoxic drugs) or foods I should avoid during treatment?"
• "When is it safe to resume activities after recovery, such as work or agricultural work?"

Examples of Disease-Specific Questions

• "I have had a fever and muscle pain for about a week after being exposed during flood recovery work, and leptospirosis is suspected. Which test should I have first, the antibody test (MAT) or PCR?"
• "My kidney function appears to be impaired (decreased urine output and elevated creatinine). What is the likelihood that I will need renal replacement therapy (dialysis) if I am hospitalized? What signs require immediate dialysis?"

(If necessary: Diagnostic tests may include serologic testing (MAT), IgM ELISA, culture, and PCR (when available). Antibodies usually begin to be detectable at the end of the first week after disease onset and reach their highest levels at 3–4 weeks, so comparing acute-phase and convalescent-phase sera can help with diagnosis.)