Leptospirosis is an infectious disease caused by spiral-shaped bacteria known as spirochaetes of the genus Leptospira. These organisms include many related strains and species (Leptospira spp.) that can colonize a wide range of hosts. The infection affects humans and numerous animals, notably mammals, birds, amphibians, and reptiles. In humans the disease is often called Weil's disease when severe; several other historical names exist and reflect different local presentations.

Overview and clinical features

Illness ranges from a mild, flu-like syndrome to a serious systemic infection involving liver, kidneys, lungs, or heart. Classic severe signs include enlargement of the spleen, jaundice, and nephritis, features first emphasized by Adolf Weil in 1886 (Adolf Weil). Many cases present with fever, headache, muscle pain, conjunctival redness and sometimes a rash. Without timely treatment, severe leptospirosis can progress to renal failure, liver dysfunction, pulmonary hemorrhage, or cardiac complications.

Transmission and reservoirs

Leptospira are maintained in nature by chronically infected carrier animals. Human infection most commonly occurs when skin, skin, eyes or mucous membranes contact water or soil contaminated with animal urine. Fresh or stagnant fresh water exposed to infected animals is a frequent source. Urban rats are well-known reservoirs (rats), and domestic livestock or companion animals may also contribute.

Diagnosis, treatment and outlook

Leptospirosis is a relatively rare diagnosis in many regions but should be suspected after compatible exposure. Laboratory confirmation commonly uses serologic testing, blood culture in early disease, or molecular methods such as PCR. Prompt antibiotic therapy (for example doxycycline or penicillin-class agents) reduces the risk of complications; supportive care addresses organ dysfunction. The causative pathogen, members of the Leptospira-genus, was isolated from human tissue in the early 20th century (1907) from a post-mortem kidney specimen.

Prevention and public health

  • Avoid swimming or wading in potentially contaminated waters after flooding or in endemic areas.
  • Use protective clothing for occupational exposures and practice good hand hygiene.
  • Control rodent populations and vaccinate livestock or pets where vaccines are available.
  • Post-exposure prophylaxis may be recommended for high-risk contacts in some settings.

Geographically, leptospirosis is more common in tropical and subtropical regions and often follows heavy rainfall or flooding. In temperate zones cases can be seasonal; older reports note peaks in late summer months in the Northern Hemisphere. Because it is a zoonosis with environmental transmission, vigilance among clinicians, public health authorities, and people with relevant exposures is important to reduce illness and prevent outbreaks.