Leptospirosis
Leptospirosis is a potentially serious illness caused by species of the spirochete Leptospira.
Leptospirosis occurs in many wild and domestic animals. Some animals act as carriers and pass the bacteria in their urine; others become ill and die. People acquire these infections through contact with infected animals, their urine, or soil and water contaminated by infected urine.
Although leptospirosis is an occupational disease of farmers and sewer and slaughterhouse workers, most people become infected while engaging in outdoor activities such as swimming or wading in contaminated water. The 40 to 100 infections reported every year in the United States occur mainly in the late summer and early fall. Because mild leptospirosis typically causes vague, flu-like symptoms, many infections probably go unreported.
Symptoms and Diagnosis
Leptospirosis causes mild disease in about 90% of infected people, whereas 10% have severe, potentially fatal, disease that affects many organs. The first phase starts 2 to 20 days after infection with Leptospira. Symptoms begin abruptly with a fever, headache, severe muscle aches, and chills. The eyes usually become very red on the third or fourth day. Nausea and vomiting are common. Symptoms involving the lungs (including the coughing up of blood) occur in 10 to 15% of infected people. Episodes of chills and fever, which often reaches 102° F, continue for 4 to 9 days.
The fever clears for a few days, marking the beginning of the second phase. During this phase, the body's immune reaction against the bacteria causes inflammation, producing many symptoms. The fever returns, and there is often inflammation of the tissues covering the brain (meningitis), causing a stiff neck, headache, and sometimes stupor and coma. In the severe form of the infection, people may also have inflammation of the liver, kidneys, and lungs, resulting in jaundice, kidney failure, and bloody cough. Sometimes the heart is inflamed, causing palpitations and dangerously low blood pressure (shock). A pregnant woman who develops leptospirosis may miscarry.
Weil's syndrome is a severe form of leptospirosis that causes a continuous fever, stupor, and a reduction in the blood's ability to clot, which leads to bleeding within tissues. Blood tests reveal anemia. By the third to sixth day, signs of kidney damage and liver injury appear. Kidney abnormalities may cause blood in the urine and painful urination. Liver injury tends to be mild and usually heals completely.
A doctor can confirm the diagnosis of leptospirosis by identifying Leptospira in cultures of blood, urine, or cerebrospinal fluid samples or, more commonly, by detecting antibodies against the bacteria in the blood.
Prognosis and Treatment
Infected people who do not develop jaundice usually recover. Jaundice indicates liver damage and increases the death rate to 10% or higher in people older than 60.
The antibiotic doxycycline can prevent the disease and is given to people who were exposed to the same source as an infected person. Penicillin, ampicillin, or similar antibiotics are given to treat the disease. In severe infections, antibiotics may be given intravenously. People with the disease do not have to be isolated, but care must be taken when handling and disposing of their urine.
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