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Leptospirosis medical comic

This comic introduces Leptospira interrogans, the hooked spirochete that spreads from rat urine to people wading through rice fields, sewers and floodwater. It explains the two phases of illness, the severe form known as Weil's disease, which sample and test to use in each week, and treatment — ending with an exam-style clinical case.

For MBBS, NEET-PG, FMGE, NEXT and USMLE revision.

Leptospirosis: what the comic covers

High-yield points

  • Leptospira interrogans is a thin, tightly coiled, aerobic spirochete with hooked ends.
  • It lives in the kidneys of reservoir animals — rodents, cattle and dogs — and is shed in urine.
  • People catch it through cuts or mucosa after contact with contaminated water or soil: farmers in rice fields, sewer workers and people in monsoon floods are at risk.
  • Illness is biphasic: a first week of bacteraemia with fever, myalgia (especially calves) and conjunctival suffusion, then an immune phase when organisms appear in urine.
  • Weil's disease is the severe form, with jaundice, acute kidney injury and bleeding; the kidney damage is tubulointerstitial nephritis, often with low potassium.
  • Choose the test by the week: blood culture or PCR in the first week; urine and serology (IgM ELISA, microscopic agglutination test) from the second week.
  • Leptospires can be seen by dark-ground microscopy or silver staining.
  • Early antibiotics shorten illness and help prevent Weil's disease: doxycycline for mild cases, IV penicillin or ceftriaxone for severe disease; watch for a Jarisch–Herxheimer reaction.

Mnemonics from the comic

  • Which sample when: Week 1: catch it in the blood. Week 2 onwards: catch it in the urine and the antibodies.

Quick questions

What is Weil's disease?

Severe leptospirosis with the triad of jaundice, acute kidney injury and bleeding, sometimes with lung haemorrhage and myocarditis.

Which test is used to diagnose leptospirosis?

It depends on timing. In the first week, blood culture or PCR detect the organism. From the second week, urine testing and serology, such as IgM ELISA and the microscopic agglutination test (MAT), are used.

What is the drug of choice for leptospirosis?

Doxycycline for mild disease. Severe disease is treated with intravenous penicillin or ceftriaxone. Doxycycline is also used as prophylaxis for people at high risk of exposure.

Is this comic free to read?

The first pages are free to preview. Members read the full comic, and you can sign up free to read one comic in full.

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Topic map: Leptospirosis in 7 branches

  1. The organism
    • Leptospira interrogans
    • Thin, tightly coiled, hooked
    • Too thin for Gram stain
    • Slow culture
  2. Reservoir and spread
  3. Two phases
  4. Weil's disease
  5. Diagnosis by week
  6. Treatment
  7. Prevention

39 points, each linked to its comic page. Guests open the first branch; a free account opens two; Hero and Superhero members open the whole map.

Practice MCQs (8 questions, NEET-PG and USMLE style)

Question 1 (NEET-PG style)

Leptospira interrogans in a clinical sample is best seen by:

  1. Gram stain
  2. Dark-field microscopy
  3. Ziehl–Neelsen stain
  4. India ink preparation

Answer: B. Dark-field microscopy

Leptospires are very thin (about 0.1 µm wide), tightly coiled spirochaetes with hooked ends like a question mark (hence 'interrogans'). They are too thin to be seen on Gram stain, so they are viewed live by dark-field microscopy, where they spin and move with a corkscrew motion driven by periplasmic flagella (endoflagella), or in tissue by silver impregnation. Ziehl–Neelsen is for acid-fast organisms; India ink shows the capsule of Cryptococcus. Comic hook: ice-tongs and question marks, seen best on dark-field and silver stain.

Question 2 (USMLE style)

A 32-year-old rice farmer develops high fever, headache and severe muscle pain 10 days after working barefoot in fields flooded by monsoon rains. He has small cuts on both feet. No one else in his family is ill. Which of the following is the most likely source of his infection?

  1. Bite of an infected mosquito
  2. Water contaminated with the urine of infected rodents
  3. Undercooked pork
  4. Respiratory droplets from an infected person
  5. Bite of an infected tick

Answer: B. Water contaminated with the urine of infected rodents

Leptospirosis is a zoonosis. Rodents, cattle and dogs carry leptospires in their renal tubules without illness and shed them in urine, contaminating water and soil. People are infected through abraded skin or intact mucous membranes, including the conjunctiva, during floods, farming (rice fields), sewer work or water sports. There is no human-to-human spread, which fits no one else in his family being ill. Comic mnemonic: the 3 Rs — Rodents, Rainfall/Rice fields, Risky occupation or recreation.

Practice questions written by Q World Medical Comics. Not affiliated with NBEMS, NBME or the USMLE program.

High-yield flash cards (17 cards)

Causative organism of leptospirosis
*Leptospira interrogans* (pathogenic leptospires), a thin, tightly coiled spirochaete with hooked ends — Think 'question-mark' or 'hooked' ends on dark-field microscopy.
How do humans usually acquire leptospirosis?
Contact of abraded skin or mucous membranes with water or soil contaminated by the urine of infected animals (classically rats); also direct contact with animal urine — Rice-paddy workers, sewer workers, floods and monsoon are the exam settings.
Fill in the blank: The severe icteric form of leptospirosis with jaundice, renal failure and haemorrhage is called ______.
Weil disease — Triad: jaundice + acute kidney injury + haemorrhage (often pulmonary).

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