Other Names:Weil’s disease, canicola fever, canefield fever, nanukayami fever, 7-day fever and many more
Definition:Leptospirosis is an infectious disease caused by a particular type of bacteria called a spirochete. Leptospirosis can be transmitted by many animals such as rats, skunks, opossums, raccoons, foxes, and other vermin.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, eyes or with the mucous membranes. Outside of tropical areas, leptospirosis cases have a relatively distinct seasonality with most of them occurring August-September/February-March. The soil or water is contaminated with the waste products of an infected animal. People contract the disease by either ingesting contaminated food or water or by broken skin and mucous membrane (eyes, nose, sinuses, mouth) contact with the contaminated water or soil.
Though being recognised among the world’s most common zoonoses, leptospirosis is a relatively rare bacterial infection in humans.
Leptospirosis occurs worldwide, but it is most commonly acquired in the tropics. The U.S. Centers for Disease Control and Prevention states 100-200 cases of leptospirosis are reported each year in the United States, with about 50% of cases occurring in Hawaii.
Leptospirosis is caused by a spirochaete bacterium called Leptospira spp. that has at 5 different serovars of importance in the United States causing disease (icterohaemorrhagiae, canicola, pomona, grippotyphosa, and bratislava). 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 seemingly 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. Although rats, mice and voles are important primary hosts, a wide range of other mammals including dogs, deer, rabbits, hedgehogs, cows, sheep, raccoons, possums, skunks, and even certain marine mammals are also able to carry and transmit the disease as secondary hosts. Dogs may lick the urine of an infected animal off the grass or soil, or drink from an infected puddle. There have been reports of “house dogs” contracting leptospirosis apparently from licking the urine of infected mice that entered the house. The type of habitats most likely to carry infective bacteria are muddy riverbanks, ditches, gulleys and muddy livestock rearing areas where there is regular passage of either wild or farm mammals. 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.
Leptospirosis is also transmitted by the semen of infected animals. Abattoir workers can contract the disease through contact with infected blood or body fluids.
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 specific areas as prolonged immersion in water is known to promote the entry of the bacteria. Occupational risk factors include veterinarians, slaughter house workers, farmers, sewer workers, and architects and other building workers working on derelict buildings. An outbreak in an inner city environment has been linked to contact with rat urine.
In humans, leptospiral infection causes a wide range of symptoms, and some infected persons may have no symptoms at all. Leptospirosis is a biphasic disease that begins with flu-like symptoms (fever, chills, myalgias, intense headache). The first phase resolves and the patient is asymptomatic briefly before the second phase begins that is characterized by meningitis, liver damage (causing jaundice), and renal failure. 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 vomiting, and may include jaundice, red eyes, abdominal pain, diarrhea, and/or a rash. The symptoms in humans appear after a 4-14 day incubation period.
Leptospirosis symptoms begin from two to 25 days after initial direct exposure to the urine or tissue of an infected animal. This can even occur via contaminated soil or water. Veterinarians, pet shop owners, sewage workers, and farm employees are at particularly high risk. People participating in outdoor sporting activities like canoeing, rafting, hiking, and camping can also come into contact with contaminated water or soil.
The illness typically progresses through two phases:
The first phase of nonspecific flulike symptoms includes headaches, muscle aches, eye pain with bright lights, followed by chills and fever. Watering and redness of the eyes occurs and symptoms seem to improve by the fifth to ninth day.
The second phase begins after a few days of feeling well. The initial symptoms recur with fever and aching with stiffness of the neck. Some patients develop serious inflammation of the nerves to the eyes, brain, spinal column (meningitis), or other nerves. Right upper area abdominal pain may occur. Less common symptoms relate to disease of the liver, lungs, kidneys, and heart.
Leptospirosis associated with liver and kidney disease is called Weil’s syndrome and is characterized by yellowing of the eyes (jaundice). Patients with Weil’s syndrome can also develop kidney disease and have more serious involvement of the organs affected.
The diagnosis of leptospirosis is made by culture of the bacterial organism Leptospira from infected blood, spinal fluid, or urine. However, many doctors must rely upon rising Leptospira antibody levels in the blood in order to make the diagnosis, as the technique required to perform the culturing is delicate and difficult.
Differential diagnosis list for leptospirosis is very large due to diverse symptomatics. For forms with middle to high severity, the list includes dengue fever and other hemorrhagic fevers, 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).
Leptospira can be cultured in Ellinghausen-McCullough-Johnson-Harris medium, which is incubated at 28 to 30°C. The median time to positivity is three weeks with a maximum of 3 months. This makes culture techniques useless for diagnostic purposes, but is commonly used in research.
Can my pets get leptospirosis?
According to the CDC, your pets (especially dogs, less commonly cats) can contract leptospirosis. Your pet can contract it in the same ways you can (ingesting contaminated soil, water or through skin wounds). Your pet may exhibit vomiting, refusal to eat, weight loss, decreased activity, muscle pains, or stiffness.
If you suspect your pet is ill, take them to a veterinarian for testing and treatment. Early antibiotic treatment often can limit or prevent organ damage.
If your pet is diagnosed with leptospirosis, you must be careful to try to prevent exposure to yourself or other household members. Remember to wash your hands frequently with soap and water after cleaning up waste from your pet. If possible, use latex or rubber gloves to do the job of clean up. Use a diluted (1:10 parts) bleach solution to clean surfaces where pet wastes may have contaminated. And make sure your pet receives the full course of antibiotic treatment that is prescribed by your vet. Discuss other pet-care issues directly with your vet should you have any other questions regarding the disease.
Leptospirosis treatment is a relatively complicated process comprising two main components – suppressing the causative agent and fighting possible complications. Aetiotropic drugs are antibiotics, such as cefotaxime, doxycycline, penicillin, ampicillin, and amoxicillin (doxycycline can also be used as a prophylaxis). There are no human vaccines; animal vaccines are only for a few strains, and are only effective for a few months. Human therapeutic dosage of drugs is as follows: doxycycline 100 mg orally every 12 hours for 1 week or penicillin 1-1.5 MU every 4 hours for 1 week. Doxycycline 200-250 mg once a week is administered as a prophylaxis. 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). Corticosteroids 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.
Disclaimer: This information is not meant to be a substitute for professional medical advise or help. It is always best to consult with a Physician about serious health concerns. This information is in no way intended to diagnose or prescribe remedies.This is purely for educational purpose.
Leptospirosis: a zoonotic disease of global importance. Lancet Infect Dis. 2003 Dec;3(12):757-71 Bharti AR, Nally JE, Ricaldi JN, Matthias MA, Diaz MM, Lovett MA, Levett PN, Gilman RH, Willig MR, Gotuzzo E, Vinetz JM; Peru-United States Leptospirosis Consortium.
In the past decade, leptospirosis has emerged as a globally important infectious disease. It occurs in urban environments of industrialised and developing countries, as well as in rural regions worldwide. Mortality remains significant, related both to delays in diagnosis due to lack of infrastructure and adequate clinical suspicion, and to other poorly understood reasons that may include inherent pathogenicity of some leptospiral strains or genetically determined host immunopathological responses. Pulmonary haemorrhage is recognised increasingly as a major, often lethal, manifestation of leptospirosis, the pathogenesis of which remains unclear. The completion of the genome sequence of Leptospira interrogans serovar lai, and other continuing leptospiral genome sequencing projects, promise to guide future work on the disease. Mainstays of treatment are still tetracyclines and beta-lactam/cephalosporins. No vaccine is available. Prevention is largely dependent on sanitation measures that may be difficult to implement, especially in developing countries.
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.
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