leptospirosis: the “other” spirochete unm marine and tropical medicine april, 2005
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LEPTOSPIROSIS: LEPTOSPIROSIS: The “Other” SpirocheteThe “Other” Spirochete
UNM Marine and Tropical MedicineApril, 2005
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Lecture OverviewLecture Overview
• Epidemiology and Vectors of Lepto
• Clinical and Laboratory Findings
• Weil’s Disease
• Making the Diagnosis
• Prevention and Treatment
• Morbidity and Mortality
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Learning ObjectivesLearning 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.
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Lepto: World Wide Lepto: World Wide EpidemiologyEpidemiology
• 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
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Lepto: Hawaiian EpidemiologyLepto: 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
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Hawaii: all the right conditionsHawaii: 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
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Hawaii: the reservoir (dogs)Hawaii: the reservoir (dogs)
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Animal VectorsAnimal Vectors
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Leptospirosis in the UrineLeptospirosis 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.
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Hawaiian Risk FactorsHawaiian Risk Factors
• Rainwater catchment systems
• Contact with cattle
• Handling of animal tissue
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Hawaii: a familiar signHawaii: a familiar sign
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Making the diagnosisMaking 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
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Clinical FeaturesClinical 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
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Clinical FindingsClinical Findings
• Suffusion- peripheral engorgement of conjunctival vessels.
• Icterus
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Laboratory FeaturesLaboratory Features
• 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
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Typical CXRTypical CXR
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Making the DiagnosisMaking 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.
• It’s a clinical diagnosis
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Differential DiagnosisDifferential Diagnosis
• An infectious disease expert’s smorgasbord of favorites…
• Dengue fever• Hanta virus• Viral hemorrhagic
fevers (Ebola, Marburg)
• Influenza• Typhoid fever• Rickettsial diseases• Brucellosis
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PathophysiologyPathophysiology
• 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.
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The Severe Form: The Severe Form: Weil’s Disease Weil’s Disease
• Renal Failure – may require dialysis
• Liver dysfunction – rarely progresses to liver failure
• Thrombocytopenia -> DIC
• Pulmonary hemorrhage and ARDS
• Myocarditis -> CHF
• Encephalitis
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CXR in Weil’s DiseaseCXR in Weil’s Disease
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Predicting Severe DiseasePredicting Severe Disease
• It appears to be impossible to predict whose illness will progress to a fulminate course vs. a self limited illness.
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MortalityMortality
• 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)
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PreventionPrevention
• 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.
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TreatmentTreatment
• 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.
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Lepto: Reportable 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.