Transcript LEPTOSPIROSIS - Travel and Emergency Medicine

LEPTOSPIROSIS:
The “Other” Spirochete
UNM Marine and Tropical Medicine
April, 2005
Lecture Overview
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Epidemiology and Vectors of Lepto
Clinical and Laboratory Findings
Weil’s Disease
Making the Diagnosis
Prevention and Treatment
Morbidity and Mortality
Learning Objectives
• Know the risk factors associated with
Leptospirosis.
• Know the common clinical and
laboratory findings associated with
Lepto.
• Know the prevention and treatment
options for Lepto.
Lepto: World Wide
Epidemiology
• Most common illness transmitted by
animals. (zoonosis)
• Occurs everywhere except the polar
regions. Most common in the tropics
• Hot spots: Belize, Tahiti, Thailand,
Vietnam.
• In the US: sporadic epidemics, usually
recreation related
Lepto: Hawaiian Epidemiology
• Hawaii: Endemic. Highest prevalence
in the US with incidence ~ 128/100,000
annually
• Population of the Big Island in 2002:
148,677
• We would expect ~190 symptomatic
cases per year on the island
Hawaii: all the right conditions
• The spirochete prefers warm moist
environments and a rodent reservoir
• The two hot spots on the islands are
Kauai and the East side of the Big
Island
Hawaii: the reservoir (dogs)
Animal Vectors
Leptospirosis in the Urine
• Infected animals can shed spirochetes
in their urine for years. Lepto remains
in the renal tubules.
• Infected humans can shed spirochetes
in their urine for up to 60 days. We are
considered accidental hosts.
Hawaiian Risk Factors
• Rainwater catchment systems
• Contact with cattle
• Handling of animal tissue
Hawaii: a familiar sign
Making the diagnosis
• Maintaining an index of suspicion:
– Practicing in an endemic area
– Patient with travel to an endemic area
• Maintaining an index of suspicion in
the face of nonspecific clinical findings
and test results
Clinical Features
• Sudden onset (high) fever
• Dry cough, severe headache, sore
throat
• Myalgias
• Most cases are probably self limited
(~90%) and many people do not seek
treatment
Clinical Findings
• Suffusionperipheral
engorgement of
conjunctival
vessels.
• Icterus
Laboratory Features
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Mild leukocytosis
Mild to moderate thrombocytopenia
ESR elevated >50 mm/hr
Mild elevations of LFTs, lipase
Elevated CPKs
Proteinuria
CSF: similar to aseptic meningitis
CXR: B/L nonlobar peripheral consolidations
Typical CXR
Making the Diagnosis
• UCxs are the most likely to become positive.
• Blood/tissue cultures can be difficult: lepto
requires a special medium and can take
months to become positive.
• ELISA and MAT (microscopic agglutination)
are used, but can give false negatives early
on in disease course.
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It’s a clinical diagnosis
Differential Diagnosis
• An infectious
disease expert’s
smorgasbord of
favorites…
• Dengue fever
• Hanta virus
• Viral hemorrhagic
fevers (Ebola,
Marburg)
• Influenza
• Typhoid fever
• Rickettsial diseases
• Brucellosis
Pathophysiology
• The spirochetes are thought to multiply
within capillary endothelium causing a
vasculitis.
• This occurs in almost any and all
tissues.
• Kidneys, lung, muscle, liver, brain,
heart etc.
The Severe Form:
Weil’s Disease
• Renal Failure – may require dialysis
• Liver dysfunction – rarely progresses
to liver failure
• Thrombocytopenia -> DIC
• Pulmonary hemorrhage and ARDS
• Myocarditis -> CHF
• Encephalitis
CXR in Weil’s Disease
Predicting Severe Disease
• It appears to be impossible to predict
whose illness will progress to a
fulminate course vs. a self limited
illness.
Mortality
• Mortality rates are reported as 5-40%
worldwide. Hawaii has the lowest
mortality rate even for severe forms of
the disease.
• Most of the deaths are in areas that
lack critical care capabilities (the 3rd
World)
Prevention
• High risk travelers can take prophylactic
doxycycline (covers malaria, too.
• A vaccine is available in SE Asia and Europe.
• Vaccine has uncertain efficacy and safety.
• Consider for people in high risk jobs: rice
paddy workers, sugar cane & banana
plantation workers, folks working with
animals in endemic areas.
Treatment
• PCN – Jarisch-Herxheimer reaction has
been reported
• Doxycycline
• 3rd generation Cephalosporin
• Because the diagnosis may not be
certain early on, starting with broad
spectrum coverage is reasonable.
• Efficacy of steroids has not been
established.
Lepto: Reportable
• Although the feds don’t require
reporting of lepto, every state DOH I
checked does…CA, HI, NM, PA, MN
• It is probably underreported because of
the difficulty in confirming the
diagnosis.