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Leptospirosis 583

Leptospirosis Client Education
Sheet
VetBooks.ir Diseases and Disorders

BASIC INFORMATION
• Those directly exposed to patient urine
should seek medical attention. Those who may be more common than previously
recognized.
Definition are pregnant, planning to become pregnant, • Coagulation abnormalities: petechiae,
Leptospirosis is a zoonotic disease caused by or immunocompromised should avoid all ecchymoses, hematemesis, hematochezia,
thin, motile, gram-negative spirochetes of the contact with the patient and its urine. hemoptysis, melena, epistaxis, and hematuria
genus Leptospira. Leptospira organisms are may be due to liver failure, vasculitis, and/
further classified by serogroups and serovars GEOGRAPHY AND SEASONALITY or disseminated intravascular coagulation
based on lipopolysaccharide antigens. • Worldwide distribution, including much of (DIC).
the United States • Many experimentally infected dogs show
Synonyms • Typically thought of as a disease of the tropics no overt clinical signs. The percentage
Weil disease, Fort Bragg fever, autumnal fever, and subtropics (temperatures ≈80°F-90°F of naturally infected dogs that are sub-
canicola fever (England), swamp fever, mud [30°C], rainfall), it is commonly found in clinical or have only nonspecific signs is
fever, Nanukayami fever, hemorrhagic jaundice, the northeastern United States, and outbreaks unknown.
7-day fever (India), black jaundice, pretibial fever in the Southwest have been confirmed.
• In general, leptospirosis can be found when- Etiology and Pathophysiology
Epidemiology ever there is sufficient rainfall, nonfreezing Leptospires are harbored in the renal tubules of
SPECIES, AGE, SEX temperatures, and exposure to host animals reservoir hosts (deer, opossum, raccoon, rodents,
• Dogs: outdoor intact male working dogs may or urine-contaminated water and soil. skunk, and other wildlife or domestic animals)
be at higher risk for infection. that become infected and then excrete Leptospira
• Cats: despite serologic evidence of expo- Clinical Presentation organisms in urine for long periods, contaminat-
sure, clinical disease has not been clearly DISEASE FORMS/SUBTYPES ing the environment. Although leptospirosis
demonstrated. • Studies have failed to find a definitive is often transmitted directly between reservoir
• Dogs < 6 months of age are more likely to association between specific serovars and hosts through bite wounds, ingestion of infected
be severely affected and have signs of hepatic clinical disease. Currently, no specific disease tissues, and sexual secretions, most pets and
involvement. form/infecting serovars association can be people become infected though indirect contact
made. with contaminated environment. Although
RISK FACTORS • Infection may be subclinical (carrier) or leptospires do not appear to replicate outside
• Suburban or rural environments with manifest as severe illness. Historically, renal, the host, urine-contaminated soil can remain
exposure to wildlife or soil contaminated hepatic, and coagulation abnormalities have infective for months. Swimming in contami-
by their urine been most associated with leptospirosis, nated ponds, lakes, and streams is also a risk.
• Contact with rodents or their urine but pulmonary hemorrhage syndrome and Outbreaks of leptospirosis in dogs have been
• Outdoor activities vasculitis are also important. associated with periods of heavy rainfall and
• Exposure to livestock (potential carriers) flooding.
• Activities involving rivers, lakes, or streams; HISTORY, CHIEF COMPLAINT • Leptospires enter the body by penetrating
leptospires can live in water for months. • Presentation is highly variable, from no mucous membranes or damaged skin.
• Flooding obvious signs to severe systemic illness. • Leptospiremia (7-10 days) causes dissemina-
• Clinical signs in affected dogs often are tion to kidney, liver, spleen, central nervous
CONTAGION AND ZOONOSIS nonspecific: system, eyes, and genital tract.
• Leptospirosis is the most common zoonosis ○ Lethargy • Leptospires cause endothelial damage and
in the world and a common cause of acute ○ Anorexia vasculitis.
kidney injury (AKI) in people. A reportable ○ Vomiting • Renal tubular epithelial cell colonization
disease in people in the United States as of ○ Polyuria occurs in most infected dogs, causing shed-
2013, many states require reporting of canine ○ Increased respiratory effort ding for months to years after infection if
cases. not appropriately treated.
• Those working with patients suspected PHYSICAL EXAM FINDINGS
to have leptospirosis should use personal • Nonspecific signs predominate: lethargy, DIAGNOSIS
protective equipment (PPE), and zoonosis anorexia, vomiting, diarrhea, jaundice,
warning labels should be placed on cages. signs of hypovolemia (e.g., weakness, mental Diagnostic Overview
The placement of a urinary catheter and dullness, weak pulse; may be severe), general- Unexplained renal and/or hepatic insufficiency,
sterile collection system can help avoid ized muscle tenderness, reluctance to move, especially with fever, should prompt consider-
environmental contamination. evidence of abdominal pain ation of leptospirosis. Diagnosis is multimodal;
• Viable organisms may continue to be shed • Kidney: signs consistent with AKI (p. 23). a serum titer alone is rarely sufficient, and a
in urine for 2-3 days after starting antibiotic Quantify urine output because animals combination of history (exposure, clinical
treatment. Urine must be inactivated before may be severely polyuric and at high risk signs), physical exam, routine blood test results,
disposal; this can be performed by mixing for dehydration, and oliguric animals are serologic titers, and organism demonstration (by
urine 1:1 with an aqueous dilution of 10% at high risk for fluid overload and death. polymerase chain reaction [PCR]) contribute
bleach solution. • Liver: signs consistent with acute hepatic to confirming or refuting the clinical diagnosis.
• The patient should be placed in a run or injury (e.g., icterus [p. 442])
bottom cage to avoid contamination. Avoid • Ocular: conjunctivitis, uveitis Differential Diagnosis
using a spray hose to clean contaminated • Respiratory: increased lung sounds, tachy- • Other causes of AKI (e.g., toxin, pyelone-
runs. Use disposable bedding for 3 days after pnea, dyspnea. Acute respiratory distress phritis, heat stroke, shock [p. 23])
starting appropriate antibiotic therapy, and syndrome (p. 27) or leptospiral pulmonary • Other causes of vasculitis (e.g., sepsis,
treat bedding as biomedical waste. hemorrhage syndrome possible; the latter rickettsial disease, pancreatitis)

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