LEPTOSPIROSIS: The “Other” Spirochete UNM Marine and Tropical Medicine April, 2005

Lecture Overview 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 Suffusion- peripheral engorgement of conjunctival vessels. Icterus

Laboratory 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 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. 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 3 rd 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 3 rd 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.