Leptospirosis is an infection of worldwide distribution caused by spirochaetes of the genus Leptospira, which infect many species of both wild and domestic animals.
- Leptospires are naturally aquatic organisms and are found in fresh water, damp soil, vegetation, and mud. Flooding may spread the organism because, as water saturates the soil, leptospires pass directly into surface waters.
- The principal source of human infection is the rat but other sources include dogs, cattle, pigs, and other wild animals.
- Infected animals carry the bacteria in their kidneys, often without becoming unwell. They can excrete leptospires in their urine for some time. The spirochaetes are shed from the urine and can survive in the environment for several months in moist, warm conditions.
- Disease is acquired through contact with contaminated water or soil, or through contact with urine or tissues of infected animals.
- They enter the bloodstream through abraded skin or the mucosa from contaminated water or soil.
- Water-borne transmission has also been documented.
- Infection occurs as two syndromes: anicteric (which is self-limiting) and icteric leptospirosis (Weil's disease).
- Reported to be the most widespread zoonosis in the world (having an incidence greater in warm-climate areas than in temperate regions).
- Leptospirosis is uncommon in the UK. There are usually fewer than 40 cases each year in England and Wales.
- A large proportion of the population is antibody-positive in areas such as rural Belize and Vietnam. Leptospirosis is a significant human disease in eastern and southern Europe, Australia and New Zealand.
- It most often affects teenagers and adults and is more common in men.
- Risk factors include sewage workers, travellers (eg swimming in contaminated water), farmers, veterinarians, abattoir workers, rodent control workers, and other occupations with animals.
- The incubation period is usually 7-14 days but can range from 2-30 days. Onset is usually abrupt.
- Many infections are mild with fever, headache, myalgia, anorexia, nausea and vomiting, dry cough and lethargy. Affected patients may not seek medical attention.
- The anicteric form may cause pneumonitis, arthritis, orchitis, cholecystitis, myocarditis, coronary arteritis, aortitis, aseptic meningitis and uveitis.
The flu-like illness may resolve without treatment but, in some cases, an immune phase follows with a return of fever, jaundice, red eyes, abdominal pain, diarrhoea, or a rash. In more severe cases, there may be organ failure, eg the kidneys, or meningitis.
- Approximately 10% of those infected become jaundiced (with hepatocellular necrosis) and have a severe and rapidly progressive form of the disease with liver failure and renal failure.
- The jaundice appears during days 5-9 of illness and is most intense 4-5 days later, continuing for about 1 month.
- The degree of jaundice itself is not indicative of prognosis but leptospirosis without jaundice is very rarely fatal.
- Purpura, petechiae, epistaxis, minor haemoptysis and other signs of bleeding are common.
- Other symptoms include fever, vomiting, abdominal pain, skin rashes, conjunctival haemorrhage, and uveitis. There is often a severe headache, retro-orbital pain, and photophobia. A severe myalgia (lower back, and legs) is common. Leptospirosis may present as aseptic meningitis.
- Pulmonary symptoms vary from cough, dyspnoea, and haemoptysis to adult respiratory distress syndrome and massive pulmonary haemorrhage.
- Hepatomegaly: hepatic percussion tenderness is a useful indicator of continuing disease activity.
- Kidney dysfunction (leptospiral nephropathy) is usual, sometimes with life-threatening renal failure with signs of uraemia and disturbance of consciousness.
Possible alternative diagnoses to consider will include:
- Viral hepatitis
- Typhoid fever
- Yellow fever
- Relapsing fever
- Scrub typhus
- Dengue fever
- Legionnaires' disease
- Toxic shock syndrome
- Liver function tests: increased serum bilirubin, transaminases.
- Prolonged prothrombin time (coagulation times may be elevated in patients with hepatic dysfunction and/or disseminated intravascular coagulation).
- FBC: thrombocytopenia, leukocytosis and anaemia.
- Renal function and electrolytes (renal failure); serum amylase levels are raised in acute renal failure.
- Raised creatine kinase (muscle involvement, rhabdomyolysis).
- MSU usually shows sediment and proteinuria.
- CXR: may be normal or show patchy shadowing in alveolar haemorrhage.
- Diagnostic tests:
- Diagnosis can be confirmed by serology (paired), either using microscopic slide agglutination test or new rapid sero-diagnostic kits.
- Enzyme-linked immunosorbent assay (ELISA); has greater sensitivity and comparable specificity to microscopic slide agglutination test.
- First-choice drug is oral doxycycline, starting within 48 hours of illness (starting antibiotics can lead to a Jarisch-Herxheimer reaction).
- Oral amoxicillin, ampicillin and doxycycline are effective in mild-to-moderate infections.
- Intravenous penicillin G is the drug of choice for severely ill patients.
- A recent clinical trial showed that third-generation cephalosporins are as effective as doxycycline and penicillin in the treatment of acute disease.
- Chloramphenicol is also active against Leptospira but should be reserved for critically ill patients.
- Supportive care and treatment of the hypotension, haemorrhage, renal failure and liver failure.
- Vitamin K should be administered for hypoprothrombinaemia.
- Immunity to leptospirosis is incomplete and so patients should be advised to adopt lifestyle changes to avoid re-exposure if possible.
- Spontaneous abortion in pregnant women.
- Acute renal failure.
- Liver failure.
- Disseminated intravascular coagulation.
- Gastrointestinal haemorrhage.
- Pulmonary haemorrhage.
- Eye problems, eg chronic or recurrent uveitis, iridocyclitis, chorioretinitis.
- Adult respiratory distress syndrome.
- Hypotension; vascular collapse may develop abruptly and can be fatal in the absence of aggressive supportive care.
- Cerebrovascular accident, subarachnoid haemorrhage, cerebral arteritis.
- Kawasaki's disease.
- Erythema nodosum.
- Congestive heart failure is rare but nonspecific ECG changes are common.
Complete recovery is the usual outcome, with no long-term effects. However, two to three people in England and Wales die every year from leptospirosis.
- Leptospirosis is usually self-limiting. Most cases recover fully within two to six weeks but some may take up to three months.
- Liver and renal dysfunction are usually reversible, with resolution over 1-2 months.
- Leptospirosis with jaundice is fatal in 5-15%. Death is often caused by gastrointestinal and pulmonary haemorrhage, renal failure and adult respiratory distress syndrome.
- Mortality is increased in the elderly.
- After infection, immunity develops against the infecting strain, but this may not fully protect against infection with unrelated strains.
- There is no available human vaccine effective against leptospirosis.
- For people who may be at high risk for short periods (eg occupational risk, high-risk water sports activities in known endemic areas or living or working in areas after natural disasters), taking doxycycline (200 mg weekly) may be effective.
- Immunisation of animals with Leptospira vaccines: an animal vaccine is available, and immunising and treating infected animals is worthwhile.
- Reduce rodent populations, eg by clearing rubbish and preventing rodent access into buildings.
- The risk of infection can be greatly reduced by not swimming or wading in water that might be contaminated with animal urine.
- If there is contact with fresh, surface waters, eg canals, ponds or rivers, or with rats, then advise the person to:
- Cover cuts, scratches or sores with a waterproof plaster and thoroughly clean any cuts or abrasions caused during the water activity.
- Wear appropriate protective clothing, gloves or protective footwear.
- Wash or shower promptly after water sports.
- Avoid capsize drill or rolling in stagnant or slow-moving water.
- Wear thick gloves when handling rats.
- Wash hands after handling any animal, and before eating.
Further reading & references
- Leptospirosis, Health Protection Agency
- Levett PN; Leptospirosis. Clin Microbiol Rev. 2001 Apr;14(2):296-326.
- Leblebicioglu H, Sencan I, Sunbul M, et al; Weil's disease: report of 12 cases. Scand J Infect Dis. 1996;28(6):637-9.
- Gompf SG et al, Leptospirosis, Medscape, Mar 2011
|Original Author: Dr Colin Tidy||Current Version: Dr Colin Tidy|
|Last Checked: 20/12/2010||Document ID: 686 Version: 25||© EMIS|
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