You are in: eMedicine Specialties > Infectious Diseases > MEDICAL TOPICS LeptospirosisArticle Last Updated: Aug 11, 2008AUTHOR AND EDITOR INFORMATIONAuthor: Sandra G Gompf, MD, FACP, FIDSA, Associate Professor of Infectious Diseases and International Medicine, University of South Florida College of Medicine; Chief of Infectious Diseases Section, Director, Occupational Health and Infection Control Programs, James A Haley Veterans Hospital Sandra G Gompf is a member of the following medical societies: American College of Physicians and Infectious Diseases Society of America Coauthor(s): Ana Paula Velez, MD, Assistant Professor of Medicine, Division of Infectious Diseases, University of South Florida College of Medicine and James A Haley Veterans Affairs Medical Center Editors: Maria D Mileno, MD, Assistant Professor, Department of Internal Medicine, Division of Infectious Diseases, Brown University; Francisco Talavera, PharmD, PhD, Senior Pharmacy Editor, eMedicine; Charles V Sanders, MD, Edgar Hull Professor and Chairman, Department of Internal Medicine, Professor of Microbiology, Immunology and Parasitology, Louisiana State University School of Medicine at New Orleans; Medical Director, Medicine Hospital Center, Charity Hospital and Medical Center of Louisiana at New Orleans; Consulting Staff, Ochsner Medical Center; Eleftherios Mylonakis, MD, Clinical and Research Fellow, Department of Internal Medicine, Division of Infectious Diseases, Massachusetts General Hospital; Burke A Cunha, MD, Professor of Medicine, State University of New York School of Medicine at Stony Brook; Chief, Infectious Disease Division, Winthrop-University Hospital Author and Editor Disclosure Synonyms and related keywords: leptospirosis, Leptospira infection, Leptospira interrogans, L interrogans, Leptospira biflexa, L biflexa, anicteric leptospirosis, autumnal fever, 7-day fever, seven-day fever, canefield fever, swineherd's disease, swamp fever, mud fever, Fort Bragg fever, Weil disease, canicola fever, rice-field fever, cane-cutter fever, hemorrhagic jaundice, Stuttgart disease, nanukayami fever, leptospiremia, leptospiruria, zoonosis, bilious typhoid, Spirochaeta interrogans, S interrogans INTRODUCTIONBackgroundLeptospirosis is a disease that is caused by pathogenic spirochetes of the genus Leptospira. It is considered the most common zoonosis in the world. Leptospirosis has recently been recognized as a re-emerging infectious disease among animals and humans1 and has the potential to become even more prevalent with anticipated global warming. Leptospirosis is distributed worldwide (sparing the polar regions) but is most common in the tropics. Human leptospirosis is often acquired via contact with fresh water contaminated by bovine, rat, or canine urine as part of occupational contact with these animals. The disease is also acquired during adventure travel or vacations that involve water sports or hiking, or even as a consequence of flooding. The burgeoning exotic-pet trade further increases the likelihood of transmission. In 2005, leptospirosis was transmitted from southern flying squirrels imported from Miami, Florida, to two Japanese animal handlers employed by an importer of exotic pets. Endemic canine leptospirosis is becoming more common in the United States, and California has seen a re-emergence of disease since 2000. Leptospirosis in humans is characterized by an acute febrile illness followed by mild self-limiting sequelae or an even more severe, and often fatal, multiorgan involvement. The disease was first described by Larrey in 1812 of fièvre jaune among Napoleon's troops at the siege of Cairo. It was initially believed to be related to the plague but not as contagious. Throughout the remainder of the 19th century, the illness was known in Europe as bilious typhoid. A little over 100 years ago, Adolph Weil published his historic paper describing the most severe form of infection that would be later known as Weil disease. In 1907, special staining techniques were used to confirm that a spirochete was responsible for this illness. A postmortem examination of the kidney of a person with Weil disease contained a spiral organism with hooked ends, which was first named Spirochaeta interrogans. PathophysiologyThe leptospires are thin, coiled, gram-negative, aerobic organisms 6-20 µm in length. They are motile, with hooked ends and paired axial flagella (one on each end), enabling them to burrow into tissue. Motion is marked by continual spinning on the long axis. They are unique among the spirochetes in that they can be isolated on artificial media. Leptospires belong to the order Spirochaetales and the family Leptospiraceae. Traditionally, the organisms are classified based on antigenic differences in the lipopolysaccharide envelopes that surround the cell wall. Serologic detection of these differences, therefore, is based on identifying serovars within each species. Based on this system, the genus Leptospira contains two species—the pathogenic Leptospira interrogans, with at least 218 serovars, and the nonpathogenic, free-living, saprophytic Leptospira biflexa, which has at least 60 serovars. Current studies that classify the organisms based on DNA relatedness identify at least 7 pathogenic species of leptospires. However, organisms that are identical serologically may be different genetically, and organisms with the same genetic makeup may differ serologically. Therefore, some authors feel that the traditional serologic system is the most useful from a diagnostic and epidemiologic standpoint. Although not fully understood, leptospires are believed to enter the host through abrasions in healthy skin, through sodden and waterlogged skin, directly through intact mucus membranes or conjunctiva, through the nasal mucosa and cribriform plate, through the lungs (after inhalation of aerosolized body fluid), or through the placenta during pregnancy. Virulent organisms in a susceptible host gain rapid access to the bloodstream through the lymphatics, resulting in leptospiremia and spread to all organs. The incubation period is usually 5-14 days but has been described from 72 hours to a month or more. If the host survives the acute infection, septicemia and multiplication of the organism persist until the development of opsonizing immunoglobulin in the plasma, followed by rapid immune clearance. However, after clearance from the blood, leptospires remain in immunologically privileged sites, including the renal tubules, brain, and anterior chamber of the eye, for weeks to months. In humans, leptospires in the renal tubules and resulting leptospiruria rarely persist longer than 60 days. During acute infection, leptospires are thought to multiply in the small blood vessel endothelium, resulting in damage and vasculitis. The major clinical manifestations of the disease are believed to be secondary to this mechanism, which can affect nearly any organ system.
Clinical manifestations of leptospirosis after the acute infection are the result of the inflammatory response, as well as action of the remaining organisms in the aqueous humor. FrequencyUnited StatesLeptospirosis is a ubiquitous disease found throughout the world. Leptospirosis is no longer a reportable disease in the InternationalUp to 80% of individuals in tropical areas are estimated to have positive seroconversion rates, indicating either past or present infection. Mortality/MorbidityThe mortality rate in severe leptospirosis has been described as ranging from 5-40%. The mild form of the illness is rarely fatal, and an estimated 90% of cases fall into this category. Elderly and immunocompromised people are at the highest risk of mortality overall. Subclinical infection is controversial. Evidence from limited population studies during epidemics have indicated agglutination titers are elevated in more people than are clinically infected with the disease. SexAlthough leptospirosis is rare in pregnancy, acute infection without fever may mimic the clinical pattern of HELLP (hemolytic anemia, elevated liver enzymes, low platelet count) syndrome or acute fatty liver of pregnancy, and the diagnosis may be a challenge.4 AgeNo evidence suggests that leptospirosis affects persons of various races, ages, or sexes differently. However, because occupational exposure constitutes a major risk for development of disease, a disproportionate number of working-aged males seem to be affected. CLINICALHistoryA good clinical history is often the key to accurate diagnosis in leptospirosis. Important features include a plausible exposure history and a clinical picture consistent with the disease. Leptospirosis occurs worldwide wherever risk of contact with the urine, kidneys, or conception products of infected animals exists. Typically, rodents, dogs, cattle, and pigs are considered reservoirs for this organism; however, increasing diversity of travel and exotic-pet trade are expanding the list. The leptospires may live for years in the renal tubules of animals and are excreted in the urine into standing water or soil. This explains sources of both direct infection (eg, body fluids or organs of infected animals) and indirect infection (eg, inoculated soil or water). In 2004, cases were linked to flood water in urban endemic regions of Hawaii. In tropical settings, leptospirosis is becoming more prevalent among travelers and residents. For example, recreational activities in rivers (eg, white-water rafting) may be a significant risk factor for infection with leptospires. Leptospires can live outside the body for several weeks. They enter the body through disrupted skin or mucosal barriers, such as abrasions or waterlogged skin. Other means of infection have been documented, including inhalation of aerosolized leptospires and direct infection across intact mucus membranes or conjunctivae. After an incubation period of 2-30 days (typically 5-14 d), clinical symptoms ensue. A plausible history of possible exposure must precede clinical symptoms in order to consider the diagnosis of leptospirosis. Expert consensus is that leptospirosis occurs as two recognizable clinical syndromes. A third syndrome of asymptomatic infection is more controversial. Anicteric leptospirosis is a self-limited disease similar to a mild flulike illness. Icteric leptospirosis, also known as Weil disease, is a severe illness characterized by multiorgan involvement or even failure. Two distinct phases of illness are observed in the mild form—the septicemic (acute) phase and the immune (delayed) phase. In icteric leptospirosis, the 2 phases of illness are often continuous and indistinguishable. At disease onset, clinically predicting the severity of disease is not possible. Subsequent sequelae depend on the serovar involved and the health, nutritional status, and age of the patient, as well as the rapidity of definitive and supportive treatment. An acute illness follows any infection with any serovar of leptospirosis. Most of the following symptoms develop in varying degrees: high temperature (38-40°C), rigors, sudden headache, nausea and vomiting, anorexia, diarrhea, cough, pharyngitis, nonpruritic skin rash, and muscle pain. Muscle pains are typically localized to the calf and lumbar areas. This phase of illness lasts 5-7 days and either regresses to a relatively asymptomatic period or progresses to a more severe illness. In anicteric leptospirosis, the acute illness is followed by 1-3 days without fever and then progresses to 4-30 days of the immune (delayed) phase of the illness. PhysicalThe physical examination findings differ depending on the severity of disease and the time from onset of symptoms. Patients may appear mildly ill or toxic. Early in the disease, temperatures as high as 40°C and tachycardia are common. Hypotension, oliguria, and abnormal chest auscultation at presentation may portend severe illness. When fever is severe and prolonged, hypotension and shock due to volume depletion may also occur. The fever typically subsides within 7 days. Early in the disease, the skin is warm and flushed. Additional skin findings include a transient petechial eruption that can involve the palate. Later in severe disease, jaundice and purpura can develop. The classic ocular finding of conjunctival suffusion occurs early irrespective of disease severity. Conjunctival suffusion is characterized by redness of the conjunctiva that resembles conjunctivitis but that does not involve inflammatory exudates. Uveitis is a common feature following acute leptospirosis; however, patients who receive antibiotics during the acute phase of illness may develop only mild uveitis.6 Lung examination results may be normal in early or mild illness. In severe illness, signs of consolidation due to alveolar hemorrhage may be found. In patients with cardiac-related pulmonary edema, rales and wheezes can be heard. Abdominal examination may reveal liver enlargement and tenderness due to hepatitis. Acalculous cholecystitis, which may be suggested by a positive Murphy sign, is a finding of profound systemic illness. Pancreatitis has also been described in severe cases.9 DIFFERENTIALSInfluenza
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| Drug Name | Penicillin G (Pfizerpen, Permapen) |
|---|---|
| Description | First-line antibiotic therapy. Interferes with synthesis of cell wall mucopeptide during active multiplication, resulting in bactericidal activity against susceptible microorganisms. |
| Adult Dose | 20-24 million U/d IV divided q4-6h for severe infection in hospitalized patients |
| Pediatric Dose | Not established |
| Contraindications | Documented hypersensitivity |
| Interactions | Probenecid can increase effects of penicillin; coadministration of tetracyclines can decrease effects of penicillin |
| Pregnancy | B - Fetal risk not confirmed in studies in humans but has been shown in some studies in animals |
| Precautions | Caution in impaired renal function; as is observed in the treatment of syphilis, the Jarisch-Herxheimer reaction is a possible complication of therapy that occurs more often in patients with a high spirochete burden; antibiotic therapy can result in a massive killing of bacteria and subsequent release of bacterial antigens that fuel this immune-mediated reaction; therapy should not be discontinued as a result of this complication; supportive therapy may be necessary if hemodynamic instability occurs |
| Drug Name | Doxycycline (Vibramycin, Doryx) |
|---|---|
| Description | Inhibits protein synthesis, and thus bacterial growth, by binding to 30S and possibly 50S ribosomal subunits of susceptible bacteria. |
| Adult Dose | 100 mg IV q12h 100 mg PO bid for outpatient oral therapy of less severe infection |
| Pediatric Dose | <8 years: Not recommended >8 years: Not established |
| Contraindications | Documented hypersensitivity; severe hepatic dysfunction |
| Interactions | Bioavailability is slightly decreased with antacids containing aluminum, calcium, magnesium, iron, or bismuth subsalicylate; tetracyclines can increase hypoprothrombinemic effects of anticoagulants; tetracyclines can decrease effects of oral contraceptives, causing breakthrough bleeding and increased risk of pregnancy |
| Pregnancy | D - Fetal risk shown in humans; use only if benefits outweigh risk to fetus |
| Precautions | Photosensitivity rarely may occur; tetracycline use during tooth development (last one-half of pregnancy through age 8 y) can cause permanent discoloration of teeth |
| Drug Name | Erythromycin (E.E.S., E-Mycin, Eryc) |
|---|---|
| Description | In pregnant patients who are allergic to penicillin, erythromycin is the therapy of choice. Inhibits bacterial growth, possibly by blocking dissociation of peptidyl tRNA from ribosomes, causing RNA-dependent protein synthesis to arrest. |
| Adult Dose | 500 mg IV q6h 500 mg PO qid |
| Pediatric Dose | Not established |
| Contraindications | Documented hypersensitivity; hepatic impairment |
| Interactions | Coadministration may increase toxicity of theophylline, digoxin, carbamazepine, and cyclosporine; may potentiate anticoagulant effects of warfarin; coadministration with lovastatin and simvastatin increases risk of rhabdomyolysis |
| Pregnancy | B - Fetal risk not confirmed in studies in humans but has been shown in some studies in animals |
| Precautions | Caution in liver disease; estolate formulation may cause cholestatic jaundice; GI adverse effects are common (administer doses pc); discontinue use if nausea, vomiting, malaise, abdominal colic, or fever occur |
| Drug Name | Amoxicillin (Amoxil, Trimox) |
|---|---|
| Description | Alternative therapy. Interferes with synthesis of cell wall mucopeptides during active multiplication, resulting in bactericidal activity against susceptible bacteria. |
| Adult Dose | 0.5-1 g PO q8h |
| Pediatric Dose | Not established |
| Contraindications | Documented hypersensitivity |
| Interactions | Reduces the efficacy of oral contraceptives |
| Pregnancy | B - Fetal risk not confirmed in studies in humans but has been shown in some studies in animals |
| Precautions | Adjust dose in renal impairment; may enhance chance of candidiasis |
| Drug Name | Cefotaxime (Claforan) |
|---|---|
| Description | Third-generation cephalosporin with broad gram-negative spectrum, lower efficacy against gram-positive organisms, and higher efficacy against resistant organisms. Arrests bacterial cell wall synthesis by binding to one or more of the penicillin-binding proteins, which in turn inhibits bacterial growth. Used for septicemia and treatment of gynecologic infections caused by susceptible organisms. |
| Adult Dose | 1 g IV q6h |
| Pediatric Dose | Not established |
| Contraindications | Documented hypersensitivity |
| Interactions | Probenecid may increase cefotaxime levels; coadministration with furosemide and aminoglycosides may increase nephrotoxicity |
| Pregnancy | B - Fetal risk not confirmed in studies in humans but has been shown in some studies in animals |
| Precautions | Adjust dose in severe renal insufficiency (high doses may cause CNS toxicity); superinfections and promotion of nonsusceptible organisms may occur with prolonged use or repeated therapy; has been associated with severe colitis |
| Drug Name | Ceftriaxone (Rocephin) |
|---|---|
| Description | Third-generation cephalosporin with broad-spectrum, gram-negative activity; lower efficacy against gram-positive organisms; higher efficacy against resistant organisms. Bactericidal activity results from inhibiting cell wall synthesis by binding to one or more penicillin-binding proteins. Exerts antimicrobial effect by interfering with synthesis of peptidoglycan, a major structural component of bacterial cell wall. Bacteria eventually lyse owing to the ongoing activity of cell wall autolytic enzymes while cell wall assembly is arrested. Highly stable in presence of beta-lactamases, both penicillinase and cephalosporinase, of gram-negative and gram-positive bacteria. Approximately 33-67% of dose excreted unchanged in urine, and remainder secreted in bile and ultimately in feces as microbiologically inactive compounds. Reversibly binds to human plasma proteins, and binding have been reported to decrease from 95% bound at plasma concentrations <25 mcg/mL to 85% bound at 300 mcg/mL. |
| Adult Dose | 1 g IV q24h |
| Pediatric Dose | Not established |
| Contraindications | Documented hypersensitivity; hyperbilirubinemic neonates, particularly those who are premature |
| Interactions | Probenecid may increase ceftriaxone levels; coadministration with ethacrynic acid, furosemide, and aminoglycosides may increase nephrotoxicity |
| Pregnancy | B - Fetal risk not confirmed in studies in humans but has been shown in some studies in animals |
| Precautions | Adjust dose in severe renal insufficiency (high doses may cause CNS toxicity); superinfections and promotion of nonsusceptible organisms may occur with prolonged use or repeated therapy; caution in breastfeeding women; may displace bilirubin from albumin-binding sites, increasing the risk of kernicterus; caution in gallbladder, biliary tract, liver, or pancreatic disease or in patients with history of colitis or penicillin hypersensitivity |
The authors and editors of eMedicine gratefully acknowledge the contributions of previous coauthors Juan D Diaz, DO; Matthew R Jezior, MD; Cecily K Peterson, MD; and Joseph T Morris, MD, to the development and writing of this article.
| Media file 1: A scanning electron micrograph depicting Leptospira atop a 0.1-µm polycarbonate filter. (This image is in the public domain and thus free of any copyright restrictions. Courtesy of the Centers for Disease Control/Rob Weyant) | |
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| Media file 2: Darkfield microscopy of leptospiral microscopic agglutination test. (This image is in the public domain and thus free of any copyright restrictions. Courtesy of the Centers for Disease Control/Mrs. M. Gatton) | |
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| Media file 3: Silver stain, liver, fatal human leptospirosis. (This image is in the public domain and thus free of any copyright restrictions. Courtesy of the Centers for Disease Control/Dr. Martin Hicklin) | |
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Article Last Updated: Aug 11, 2008