leptospirosis: the “other” spirochete

LEPTOSPIROSIS: LEPTOSPIROSIS: The “Other” SpirocheteThe “Other” Spirochete

UNM Marine and Tropical MedicineApril, 2005

Lecture OverviewLecture Overview

• Epidemiology and Vectors of Lepto

• Clinical and Laboratory Findings

• Weil’s Disease

• Making the Diagnosis

• Prevention and Treatment

• Morbidity and Mortality

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.

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

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

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

Hawaii: the reservoir (dogs)Hawaii: the reservoir (dogs)

Animal VectorsAnimal Vectors

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.

Hawaiian Risk FactorsHawaiian Risk Factors

• Rainwater catchment systems

• Contact with cattle

• Handling of animal tissue

Hawaii: a familiar signHawaii: a familiar sign

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

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

Clinical FindingsClinical Findings

• Suffusion- peripheral engorgement of conjunctival vessels.

• Icterus

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

Typical CXRTypical CXR

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

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

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.

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

CXR in Weil’s DiseaseCXR in Weil’s Disease

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.

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)

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.

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.

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.