(also known as '''Weil's disease''', '''canicola fever''', '''canefield fever''', '''nanukayami fever''' or '''7-day fever''') is a
Bacterial Zoonotic disease caused by
Spirochaete s of the
Genus ''
Leptospira '' that affects
Human s and a wide range of animals, including mammals, birds, amphibians, and reptiles. It was first described by
Adolf Weil in
1886 when he reported an "acute infectious disease with
Enlargement Of Spleen ,
Jaundice and
Nephritis ". The
Pathogen , ''Leptospira''-genus
Bacteria was isolated in
1907 from
Post Mortem Renal Tissue slice.
Though being recognised among the world's most common
Zoonosis , leptospirosis is a relatively rare bacterial
Infection in humans. The infection is commonly transmitted to humans by allowing
Fresh Water that has been contaminated by animal
Urine to come in contact with unhealed breaks in the
Skin ,
Eye s or with the
Mucous Membrane s.
Except for tropic areas, leptospirosis cases have a relatively distinct seasonality with most of them occurring August through September (in the Northern Hemisphere).
of a number of Leptospira sp. bacteria atop a 0.1. µm
Polycarbonate filter]]
Leptospirosis is caused by a spirochaete bacterium called ''
Leptospira interrogans'' that has at least 5 different
Serovar s of importance in the
United States causing disease (icterohaemorrhagiae, canicola, pomona, grippotyphosa, and bratislava).
1 There are other (less common) infectious strains. It should however be noted that genetically different leptospira organisms may be identical serologically and vice versa. Hence, an argument exists on the basis of strain identification. The traditional serologic system is seemingfully more useful from diagnostic and epidemiologic standpoint at the moment (which may change with further development and spread of technologies like
PCR ).
Leptospirosis is transmitted by the urine of an infected animal, and is contagious as long as it is still moist. Deer, rats, raccoons, possums, voles, skunks, mice and even infected dogs may serve as hosts. Dogs may lick the urine of an infected animal off the grass, or drink from an infected puddle. There have even been reports of "house dogs" getting leptospirosis apparently from licking the urine of infected mice that entered the house. There is a direct correlation between the amount of rainfall and the incidence of leptospirosis, making it seasonal in temperate climates and year-round in tropical climates.
Humans become infected through contact with water, food, or soil containing urine from these infected animals. This may happen by swallowing contaminated food or water or through skin contact. The disease is not known to be spread from person to person and cases of bacterial dissemination in convalescence are extremely rare in humans. Leptospirosis is common among watersport enthusiasts in certain areas as prolonged immersion in water is known to promote the entry of the bacteria. Occupational risk factors include
Veterinarian s, slaughter house workers, farmers, and sewer workers. An outbreak in an inner city environment has been linked to contact with rat urine.
2
In animals, the
Incubation Period (time of exposure to first
Symptom s) is anywhere from 2 to 20 days. In dogs, the liver and kidney are most commonly damaged by leptospirosis.
Vasculitis can occur, causing
Edema and potentially
Disseminated Intravascular Coagulation (DIC).
Myocarditis ,
Pericarditis ,
Meningitis , and
Uveitis are also possible sequelae.
3 One should strongly suspect leptospirosis and include it as part of a
Differential Diagnosis if the whites of the dog's eyes appear
Jaundice d (even slightly yellow), but the absence of jaundice does not rule out leptospirosis, and its presence could indicate
Hepatitis or other liver pathology rather than leptospirosis.
Vomit ing, fever, failure to eat, reduced urine output, unusually dark or brown urine, and
Lethargy are also indications of the disease.
In humans, leptospiral infection causes a wide range of
Symptom s, and some infected persons may have no symptoms at all. Because of the wide range of symptoms the infection is often
Wrongly Diagnosed . This leads to a lower registered number of cases than there really are. Symptoms of leptospirosis include high
Fever , severe
Headache , chills, muscle aches, and
Vomit ing, and may include
Jaundice , red eyes,
Abdominal Pain ,
Diarrhea , and/or a
Rash . The symptoms in humans appear after 4-14 day incubation period.
Complications include
Meningitis , respiratory distress and renal interstitial tubular necrosis, which results in
Renal Failure and often
Liver Failure (this severe form of the disease is known as ). Cardiovascular problems are also possible. Approximately 5-50% of severe leptospirosis cases are fatal, however, such cases only constitute about 10% of all registered incidents.
On infection the
Microorganism can be found in
Blood for the first 7 to 10 days (invoking serologically identifiable reactions) and then moving to the kidneys. After 7 to 10 days the microorganism can be found in fresh urine. Hence, early diagnostic efforts include testing a serum or blood sample serologically with a panel of different strains. It is also possible to
Culture the microorganism from blood, serum, fresh urine and possibly fresh kidney biopsy. Kidney function tests (
Blood Urea Nitrogen and
Creatinine ) as well as blood tests for liver ferments are performed. The later reveal a moderate elevation of transaminases.
Diagnosis of leptospirosis is confirmed with tests such as
Enzyme-Linked Immunosorbent Assay (ELISA) and
PCR . Serological testing is laborious and expensive, thus underused in developing countries.
Differential Diagnosis list for leptospirosis is very large due to diverse symptomatics. For forms with middle to high severity, the list includes
Dengue and other hemorrhagic
Fever s,
Hepatitis of various
Etiologies , viral
Meningitis ,
Malaria and
Typhoid Fever . Light forms should be distinguished from
Influenza and other related viral diseases. Specific tests are a must for proper diagnosis of leptospirosis. Under circumstances of limited access (e.g., developing countries) to specific diagnostic means, close attention must be paid to
Anamnesis of the patient. Factors like certain dwelling areas, seasonality, contact with stagnant water (swimming, working on flooded meadows, etc) and/or rodents in the medical history support the leptospirosis hypothesis and serve as indications for specific tests (if available).
Leptospirosis treatment is a relatively complicated process comprising two main components - suppressing the causative agent and fighting possible complications. . In dogs, penicillin is most commonly used to end the leptospiremic phase (infection of the blood), and doxycycline is used to eliminate the
Carrier state.
Supportive therapy measures (esp. in severe cases) include
Detoxication and normalization of the
Hydro-electrolytic Balance . Glucose and salt solution infusions may be administered;
Dialysis is used in serious cases. Elevations of serum potassium are common and if the potassium level gets too high special measures must be taken. Serum phosphorus levels may likewise increase to unacceptable levels due to renal failure. Treatment for hyperphosphatemia consists of treating the underlying disease,
Dialysis where appropriate, or oral administration of
Calcium Carbonate , but not without first checking the serum calcium levels (these two levels are related).
Corticosteroid s administration in gradually reduced doses (e.g.,
Prednisolone starting from 30-60 mg) during 7-10 days is recommended by some specialists in cases of severe haemorrhagic effects.
.
In a study of 38 dogs diagnosed and properly treated for leptospirosis published in the February 2000 issue of the ''Journal of the American Veterinary Association'', the survival rate for the dialysis patients was slightly higher than the ones not put on dialysis, but both were in the 85% range (plus or minus). Of the dogs in this study that did not die, most recovered adequate kidney function, although one had chronic renal problems.
