Cause and Pathogenesis
Symptoms and Signs
Investigations and Diagnosis
Treatment and Prognosis
Leptospirosis is a disease caused by a type of bacteria and is associated with animals. It is more common in the tropical countries. The disease is also known as canefield fever, canicola fever, field fever, mud fever, seven day fever and swineherd disease.
Leptospirosis is caused by different strains of bacteria of the genus Leptospira. Of all the varieties that cause disease, Leptospira icterohaemorrhagiae is the most serious type.
If not treated properly, it could lead to serious complications.
Cause and Pathogenesis
Leptospirosis is a disease of animals that can spread to humans. Rats are the most common reservoirs. Contact with soil contaminated with urine of infected animals can also transmit the disease. Persons exposed to cattle urine, rat urine or to foetal fluids from cattle are at increased risk. Sewage workers, agricultural workers, butchers, meat inspectors, workers in contact with contaminated waters and veterinarians are at risk.
Person to person transmission is not possible. Spread of leptospires can occur due to contact with urine, blood or tissues from infected persons. The organisms enter the body through the breaks in the skin or through mucous membranes. The organisms can also be acquired by drinking contaminated water. Infection is commonly acquired by bathing in contaminated water. The organisms multiply in the blood and tissues of the body.
Though the organism can affect any organ of the body, the kidney and liver are commonly involved. The incubation period is usually 10 days. It may vary from 2-20 days.
Symptoms and Signs
In mild forms the disease mimics influenza or ‘flu’. In severe types jaundice, bleeding and abnormal kidney function can result.
Anicteric leptospirosis (Leptospirosis without jaundice): This is a mild form of the disease, which occurs in two phases. The first phase is the septicaemic phase which is characterised by fever, chills, severe headache, nausea, vomiting, abdominal pain and muscle pain. Cough, sore throat, anaemia and rash can also occur. Conjunctival suffusion or redness of the conjunctiva is common. Symptoms last for a few days or may persist for weeks. After this the patient seems to recover but falls ill again. The second phase is characterised by absence of fever. A small number of patients can develop meningitis, rash, or uveitis.
Icteric leptospirosis (Leptospirosis with jaundice _ also called Weil’s disease): This is the most severe form of the disease with jaundice, bleeding and deranged kidney function, hypotension, alteration in the conscious level. If not treated kidney damage, meningitis, liver failure, respiratory distress and death (though rarely) can occur.
Diagnosis is usually made by blood or urine tests in the laboratory. However, it might take anywhere between 1-6 weeks for these tests to show positive results. Diagnosis can also be made by observing rising antibody titres in the Microscopic Agglutination Test (MAT). Tests like Ig M ELISA and PCR are useful to diagnose the disease very early. Elevated WBC count, presence of protein, casts and blood in the urine are other associated findings.
Rapid semi quantitative Latex Agglutination Test (LAT) can be done to detect the presence of leptospira antibodies in the serum. Though ELISA is more sensitive than LAT, the latter can be used as an effective screening test for detecting leptospira antibodies.
Antibiotics like penicillin G, amoxicillin, ampicillin, erythromycin, tetracycline, doxycycline and cephalosporins are effective against leptospirosis. There are several strains of the organism. Infection with one strain usually produces immunity to that organism but not to the other strains.
Prognosis: Most patients recover. Mortality is high in old people and pregnant women. The common complications are myocarditis, aseptic meningitis and renal failure.
Good sanitation, rodent control, and protective measures like wearing boots and gloves can help to prevent exposure. Direct contact with potentially contaminated waters by swimming and wading should be avoided. Individuals, who are occupationally at risk, should cover all cuts and broken skin with waterproof plasters before and during work. Wearing protective clothing and washing hands (after handling animals and always before eating) are important in preventing exposure.
Dr. V.Ramasubramaniam MBBS, MD, MRCP.
Dr.V.Ramasubramaniam is an Assistant Professor of Medicine and heads the Division of Infectious Diseases at the Sri Ramachandra Medical College and Research Institute
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