"Leptospirosis" - what is it, definition of the term
Leptospirosis is a bacterial zoonotic disease caused by pathogenic spirochetes of the genus Leptospira; the organisms colonize the kidneys of carrier mammals—most notably rats and mice—and are expelled in urine, contaminating water, soil, or food, where they can penetrate human skin or mucous membranes, producing an acute febrile illness that may progress to renal, hepatic, or pulmonary dysfunction.
Detailed information
Leptospirosis, a bacterial zoonosis caused by spirochetes of the genus Leptospira, is closely linked to rodent populations, particularly rats and mice. These mammals serve as primary reservoirs, maintaining the pathogen in the environment through chronic renal colonization and prolonged urinary shedding.
Transmission occurs when contaminated urine contacts broken skin, mucous membranes, or is ingested. Water or soil polluted by rodent excreta presents the highest risk, especially in tropical regions, flood‑prone areas, and settings with inadequate sanitation.
In rodents, infection is typically subclinical. Key characteristics include:
- Persistent colonization of renal tubules
- Continuous excretion of organisms in urine for months
- Minimal overt illness, allowing long‑term carrier status
Human disease manifests after an incubation period of 5–14 days and progresses through two phases:
- Acute (septicemic) phase
- High fever, chills, myalgia, headache
- Conjunctival suffusion, nausea, vomiting
- Immune (organ‑specific) phase
- Jaundice, renal dysfunction, hemorrhagic manifestations
- Pulmonary involvement, meningitis, myocarditis in severe cases
Laboratory diagnosis relies on:
- Microscopic agglutination test (MAT) for serologic confirmation
- Polymerase chain reaction (PCR) detecting leptospiral DNA in blood, urine, or CSF
- Culture of organisms from blood (early) or urine (later), though time‑consuming
Effective treatment uses early administration of doxycycline or penicillin G. Intravenous ceftriaxone is recommended for severe presentations involving multiple organ systems.
Control measures focus on interrupting rodent‑human transmission:
- Rodent population management through trapping and baiting
- Environmental sanitation to eliminate standing water and contaminated soil
- Protective equipment (gloves, boots) for personnel handling potentially infected materials
- Pre‑exposure prophylaxis with a single dose of doxycycline for high‑risk groups during outbreaks
Vaccination of livestock and, where available, human pre‑exposure vaccines reduce disease incidence in endemic regions, but no universal vaccine exists for the rodent reservoir. Continuous surveillance of rodent populations and environmental testing for leptospiral shedding remain essential components of public‑health strategies.