Leptospirosis Flashcards
A globally important zoonotic disease, reemerging globally, caused by pathogenic Leptospira species
Leptospirosis
What are the symptoms of mild leptospirosis?
Nonspecific symptoms like fever, headache, and myalgia
Weil’s syndrome
Jaundice, renal dysfunction, hemorrhagic diathesis
What is an important presentation of severe leptospirosis?
Severe pulmonary hemorrhage, with or without jaundice.
What are the characteristics of Leptospires?
Coiled, thin, highly motile, with hooked ends and two periplasmic flagella. 6–20 μm long, ~0.1 μm in diameter.
How can Leptospires be observed?
Stain poorly but visible by dark-field examination and after silver impregnation staining of tissues.
The most important reservoirs for leptospirosis?
Rodents, especially rats, though other wild and domestic animals can also harbor these microorganisms.
How do leptospires persist in hosts?
Establish symbiotic relationship
How is leptospirosis transmitted?
Direct contact with urine, blood, or tissue of infected animals, or environmental contamination
What is the severity of most human leptospirosis infections?
Mild
Which occupational groups are at high risk for leptospirosis?
Veterinarians, agricultural workers, sewage workers, slaughter-house employees, fishing industry workers.
Leptospires can be isolated from the bloodstream
Leptospiremic phase
Appearance of antibodies coincides with the disappearance of leptospires from the blood
Immune phase
What is the incubation period for leptospirosis?
Usually 1–2 weeks, but ranges from 2 to 30 days
Fever of 3–10 days, organism can be cultured from blood and detected by PCR.
Leptospiremic phase
Resolution of symptoms may coincide with the appearance of antibodies, leptospires can be cultured from urine
Immune phase
What is the characteristic muscle pain in mild leptospirosis?
Intense muscle pain, particularly affecting calves, back, and abdomen.
How is the headache in mild leptospirosis described?
Intense, frontal or retroorbital, sometimes with photophobia, resembling dengue
What is the natural course of mild leptospirosis?
Spontaneous resolution within 7–10 days, but persistent symptoms can occur.
What factors are associated with higher mortality in severe leptospirosis?
Age >40 years, altered mental status, acute renal failure, respiratory insufficiency, hypotension, arrhythmias.
Typical electrolyte abnormalities in severe leptospirosis
hypokalemia
hyponatremia
Loss of ___ in the urine is uniquely associated with leptospiral nephropathy
Magnesium
What cardiac findings are considered poor prognostic factors
Repolarization abnormalities and arrythmias
What radiographic abnormalities are observed in severe leptospirosis?
Patchy bilateral alveolar pattern, pleura-based densities, diffuse ground-glass attenuation typical of ARDS.
What does CSF examination reveal in leptospirosis with meningitis symptoms?
CSF shows pleocytosis that can range from a few cells to >1000 cells/μL, with a predominance of lymphocytes
What is required for a definitive diagnosis of leptospirosis?
Isolation of the organism
positive PCR result
seroconversion, or
a rise in antibody titer.
What antibody titer indicates leptospirosis in the MAT?
A single antibody titer of 1:200–1:800 in the MAT, depending on endemic area, or a fourfold rise in titer between acute- and convalescent-phase serum specimens.
When do antibodies typically become detectable in leptospirosis?
Usually not until the second week of illness.
What are the standard serologic procedures for leptospirosis?
microscopic agglutination test (MAT)
enzyme-linked immunosorbent assay (ELISA).
What is the limitation of serologic testing in early acute leptospirosis?
Lacks sensitivity in the early acute phase (up to day 5)
What is the advantage of PCR in diagnosing leptospirosis?
PCR, especially real-time PCR, can confirm diagnosis with high accuracy during the first 5 days of illness.
What is the recommended initial treatment for severe leptospirosis?
What is the recommended oral treatment for mild leptospirosis?
Doxycycline, azithromycin, ampicillin, or amoxicillin.
What should be considered with regards to treatment in regions with coendemic rickettsial diseases?
Doxycycline or azithromycin as the drug of choice.
What rare reaction may develop after starting antimicrobial therapy?
Jarisch-Herxheimer reaction
What is crucial in the supportive care for leptospirosis with nonoliguric renal dysfunction
Aggressive fluid and electrolyte resuscitation