Leptospirosis is a globally important zoonotic disease caused by spirochetes of
the genus
Leptospira. Leptospires are tightly and regularly coiled, with characteristic hooked ends
(hence the species name
interrogans), and are highly motile, spinning
around their longitudinal axis and darting back and forth.
Cause/Mode of Transmission:
Human-to-human transmission does not occur. The most important sources of transmission to humans are rats, dogs, cattle, and
pigs. Factors that facilitate human infection are those that bring susceptible persons
into indirect contact with contaminated animal urine through surface waters,
moist soil, or other wet environments or into direct contact with urine and
other excreta (e.g., products of parturition, placenta) of infected animals. Leptospires infect humans through the mucosa (usually conjunctival and possibly
oral or tonsillar) or through macerated, punctured, or abraded skin.
Signs/Symptoms:
Leptospirosis is classically described as biphasic. Acute fever in
the initial leptospiremic phase lasts for 3–10 days, during which period the
organism may be cultured from blood. In a later immune phase, fever is not
responsive to antibiotic therapy but leptospires can be isolated from urine. Physical examination may include any of the following
findings, none of which is pathognomonic for leptospirosis: conjunctival
suffusion (dilated conjunctival blood vessels in the absence of discharge);
pharyngeal erythema without exudate; muscle tenderness; rales on lung
auscultation or dullness on chest percussion over areas of pleural hemorrhage;
rash (which may be macular, maculopapular, erythematous, petechial, or
ecchymotic); jaundice; meningismus; and hypo- or areflexia, particularly in the
legs.
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| conjunctival suffusion
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Weil's disease is characterized by variable combinations of jaundice, acute
kidney injury, hypotension, and hemorrhage—mostcommonly involving the lungs but also potentially affecting the gastrointestinal tract,
retroperitoneum, pericardium, and brain. Other syndromes include aseptic
meningitis, uveitis, cholecystitis, acute abdomen, and pancreatitis (with hypo-
or hyperglycemia).
Diagnostics:
The organisms cannot be seen by direct light microscopy. To visualize the
spirochetes directly in culture or in clinical specimens, dark-field or
phase-contrast microscopy must be used.
Treatment:
Mild leptospirosis often is not specifically identified and typically resolves
without antibiotic treatment. Mild disease should be treated with
oral antibiotics—in particular, doxycycline, especially where rickettsial
infections (including scrub typhus) are coendemic. severe leptospirosis frequently requires empirical initiation of
broad-spectrum parenteral therapy before the diagnosis can be confirmed.
Prevention
No vaccine is available for human leptospirosis. Preventive
strategies, including prophylaxis with doxycycline, have been variably effective
in different settings. General sanitation
approaches (e.g., rodent control) and avoidance of swimming in potentially
contaminated places (e.g., for recreational use) are recommended, but these
measures are difficult to apply consistently.
Leptospirosis guidelines from PCP and PSMID
Resources:
Harrison's Principle of Internal Medicine 18th ed
Philippinr College of Physician
