Leptospirosis - Causes, Symptoms and Treatment

Definition:

First isolated in 1916 by a team of Japanese researchers, Leptospirosis is a group of bacterial diseases caused by antigenically distinct members of the bacteria Leptospira interogans. It is also known as Red Water Disease in cattle, and Swineherd's disease in humans. It is primarily an animal pathogen, affecting both domestic and wild animals, and causes significant losses in the livestock industry. In humans, leptospirosis causes a flu-like illness ranging in severity from asymptomatic to fatal. Leptospirosis is the most widespread zoonotic disease in the world. In the United States, approximately 100 to 200 cases are identified annually; of these, 50% occur in Hawaii. The disease tends to occur most often in the summer and early autumn months. Those most likely to suffer infection include farmers, sewer workers, veterinarians, commercial fishery workers, dairy and pig farmers, military personnel, slaughterhouse workers, and meat inspectors. Campers and those who particiratc ill outdoor sports, particularly if water is involved, are also at risk in contaminated areas.

Causes of Leptospirosis

Leptospire organisms tend to thrive in the kidneys and are released through urination, resulting in transmission of the microbes to humans and animals. Human exposure to leptospirosis occurs primarily through recreational swimming in urine contaminated water and by occupational exposure to infected animal urine. The mucous membranes of the eye, nose, and mouth, as well as abraded skin, serve as portals of entry. Leptospires can survive several weeks outside the body in moist, alkaline soil and in stagnant or slow-moving, slightly alkaline water.

Signs and Symptoms of Leptospirosis

The time between exposure and manifestation of clinical symptoms varies from two days to four weeks. Initial symptoms include abrupt onset of fever, headache, muscle aches, vomiting, conjunctivitis, and weakness. Diarrhea, abdominal pain, jaundice, and hemorrhagic rash may also be present. Symptoms typically last four to seven days, though some patients may be asymptomatic. The disease is often biphasic. If a second phase occurs it is more severe; kidney or liver failure, vasculitis, or meningitis complicates recovery. This phase, known as Weil's disease, accounts for approximately 10% of leptospirosis cases and can be fatal. Illness may last three or more weeks with treatment and several months without treatment.

Diagnosis for Leptospirosis

Diagnosis is based upon a combination of clinical signs and laboratory tests. Microscopically, leptospirosis is an aerobic, gram-negative spirochete tightly coiled around an axial filament. These motile spirochetes are often bent at one or both ends, producing a hook-like appearance. Examination of body fluids and tissues under dark-field microscoPY, utilizing Warthin-Starry or Geimsa stains,will reveal the leptospire spirochete. Fluorescent antibody and microscopic and macroscopic agglutination tests are serologic methods of detection. Blood, cerebrospinal fluid, urine, or tissues can be successfully cultured during, or immediately after, the acute phase of the disease. Differential diagnoses include influenza, malaria, rickettsial disease, dengue, viral gastroenteritis, bacterial enteritis, or nephritis; aseptic, viral, or bacterial meningitis; and hepatitis. The variability of the signs and symptoms and the biphasic nature of the disease may complicate the differential diagnosis.

Treatment for Leptospirosis

Pharmacological treatment is accomplished with antibiotics such as doxycycline, penicillin, and streptomycin during the acute phase of the illness. For severe cases, I.V. penicillin is the recommended treatment. Fluid therapy to prevent dehydration and electrolyte imbalances may be required. In severe cases, dialysis and life-support measures may be instituted. prophylactic therapy consists of doxycycline 200 mg once weekly, beginning one week prior to anticipated exposure.

Special Considerations and Prevention Tips for Leptospirosis

• Warn domestic pet owners to contain their pets away from pools, marshes, and streams. Advise them to consult their veterinarians regarding immunizing pets against leptospire infection in areas where the spirochete is present.
• Although human-to-human transmission has not been documented, gloves should be worn when handling body fluids, particularly urine. Teach the patient to thoroughly wash hands after toileting.
• Intake and output should be accurately monitored and adequate hydration maintained.
• Monitor laboratory test results, such as blood urea nitrogen, creatinine, liver function tests, and bleeding times.
• Nationally, leptospirosis is not currently a reportable disease, although several states, including Hawaii, do require the reporting of suspected cases for surveillance purposes. Contact your state department of health for updates involving reportable diseases. An emerging trend is the association of leptospirosis with flooding and urbanization.
• Recovery from leptospirosis confers immunity to that particular serovar; however, Leptospirosis serovars number 183.
• Good personal hygiene, with particular attention to the faces of those with beards or mustaches, should be practiced. Advise those at risk for infection via recreational exposure to avoid swimming in stock ponds or slow-moving streams frequented by domestic or wild animals.
• Patients who have been infected with leptospirosis should not donate blood for at least twelve months after recovery.
• Advise persons at risk for occupational exposure to prevent infection by using water proof aprons, gloves, and boots.
• Additionally, any breaks in the skin should be sealed with waterproof dressings; the dressing should be replaced after known or suspected contamination.