Snapshot A 40-year-old man presents to the emergency room for fevers, myalgias, jaundice, and some photophobia. He recently returned from a trip to Hawaii, where he spent the majority of his days surfing. He denies having had any mosquito bites. His past medical history includes diabetes mellitus and hypertension. On physical exam, his conjunctivae are erythematous without any exudate. His skin is jaundiced and there are petechiae on his legs. On laboratory testing, he has elevated liver enzymes and creatinine. Introduction Classification Leptospira interrogans a spirochete (spiral-shaped bacteria) with hook-shaped ends (question-marked shaped) does not gram-stain well due to thin cell walls found in water contaminated with animal excretion clinical syndromes leptospirosis Weil disease (icterohemorrhagic leptospirosis) a severe form of leptospirosis with liver failure (jaundice), kidney failure, and pulmonary hemorrhage transmission direct exposure to infected animals direct exposure to contaminated water Epidemiology incidence common in humid tropical areas endemic in South America, South-East Asia, and Hawaii risk factors surfing occupational exposure water sports travel to tropical areas, especially during the rainy season unsanitary living conditions Pathogenesis the spirochete survives in renal tubules of infected animals and ends up in their urine it enters the human body via breaches in skin, mucosal membranes, or ingestion of contaminated water it hematogenously spreads to affect the blood vessels, liver, and kidneys Prognosis severity ranges from asymptomatic to severe (Weil disease) most infections cause a nonspecific febrile illness Presentation Symptoms rapid onset flu-like illness myalgias, especially of the calves photophobia Physical exam fever jaundice renal failure petechiae or ecchymoses may have a rash in the pretibial areas of the legs (rare) conjunctival suffusion injection without exudate Studies Labs microscopic agglutination test gold standard for diagnosis detection of immunoglobulin M via enzyme-linked immunosorbent assay (ELISA) dark-field microscopy can be hard to visualize cultures from blood, urine, or cerebrospinal fluid must also evaluate for liver and kidney dysfunction Making the diagnosis based on clinical presentation and laboratory studies Differential Dengue virus infection distinguishing factors also presents with jaundice but often also presents with a widespread rash and hemorrhage in the mucosa associated with mosquito bites Treatment Medical doxycycline indication mild disease penicillin indication severe disease ceftriaxone indication severe disease Complications Jarisch-Herxheimer reaction Acute respiratory distress syndrome