In short
Leptospirosis is a bacterial infection picked up from water or soil contaminated by animal urine — classically after wading through floods. It starts like flu, but a small proportion progress to jaundice and kidney failure, and early antibiotics change the course.
Emergency if: Yellowing of the skin or eyes, very little urine, coughing up blood, severe breathlessness, confusion or a stiff neck after a feverish illness — go to emergency care.
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WBC / Total Leukocyte Count, Absolute Neutrophil Count, Platelet Count, Creatinine +3 more
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01
How People Catch It
Leptospira bacteria live in the kidneys of infected animals — rats above all, but also dogs, cattle and pigs — and are shed in their urine. In warm, wet conditions the bacteria survive for weeks in water and mud. People become infected when contaminated water or soil touches broken skin, or splashes into the eyes, nose or mouth.
Risk spikes after heavy rain and flooding, when urban runoff mixes with rodent-contaminated water and people wade through it. Farmers, sewer and sanitation workers, veterinarians, and people who swim, kayak or fish in fresh water are also at higher risk. It does not spread from person to person.
02
Two Phases of Illness
Symptoms begin 5 to 14 days after exposure (range 2 to 30) and, in the first phase, are indistinguishable from flu or dengue: sudden high fever, chills, headache, severe muscle pain — characteristically in the calves and lower back — nausea, and sometimes a rash. Red, painful eyes without discharge (conjunctival suffusion) are a distinctive clue when present.
Most people recover at this point. In some, symptoms return after a brief lull as the immune phase begins, and in roughly 5–10% of cases the illness is severe (Weil's disease): jaundice, kidney failure, bleeding — including into the lungs — and sometimes meningitis. Severe disease carries a significant death rate, which is why early treatment matters.
03
What the Tests Show
Blood tests in leptospirosis often show a raised white cell count with neutrophils predominating (dengue more often lowers it), a low platelet count, raised CRP and, in more severe disease, rising creatinine and urea from kidney involvement and a raised bilirubin with only modestly elevated liver enzymes — a pattern that distinguishes it from viral hepatitis. Creatine kinase is often high because of muscle inflammation.
Confirmation is by PCR early in the illness or antibody tests (MAT or IgM ELISA) from the second week. Because results can take days, treatment is usually started on clinical suspicion when the exposure history fits.
04
Treatment
Mild leptospirosis is treated with oral doxycycline or amoxicillin, and starting within the first few days shortens the illness and reduces the chance of progression. Severe disease needs hospital care with intravenous penicillin or ceftriaxone, fluids, and dialysis if the kidneys fail — kidney function usually recovers fully with support.
For people with an unavoidable high-risk exposure, such as relief workers in flooded areas, a weekly dose of doxycycline is sometimes used as prevention; discuss this with a doctor before the exposure rather than after.
05
Protecting Yourself in the Wet Season
Avoid wading or swimming in flood water, and if you must, wear waterproof boots and gloves and cover any cuts with waterproof dressings. Wash thoroughly with soap afterwards, and don't drink untreated surface water. Control rodents around the home and keep food covered.
If you develop fever with muscle pain, red eyes or dark urine within two weeks of contact with flood water or fresh water, tell the doctor about the exposure — it changes what they test for and lets them start antibiotics early.
When to act
Emergency — act now
Yellowing of the skin or eyes, very little urine, coughing up blood, severe breathlessness, confusion or a stiff neck after a feverish illness — go to emergency care.
Same-day — call promptly
Fever with severe muscle pain, headache or red eyes within two weeks of contact with flood water, fresh water or animals.
Routine — see a doctor
A flu-like illness that seems to be settling but you had a recent water exposure — mention it; a test and a short antibiotic course may still be worthwhile.
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Sources
- Leptospirosis — CDCcdc.gov
- Leptospirosis — NHSnhs.uk
- Leptospirosis — MedlinePlusmedlineplus.gov
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