Swineherd's disease
Key points
- Leptospirosis is a rare, severe, and contagious bacterial infection caused by several species of the genus Leptospira, a spiral-shaped microorganism (spirochete).
- Leptospirosis is caused by exposure to the bacteria, which can be found in fresh water contaminated by animal urine.
- Penicillins, tetracyclines, chloramphenicol, and erythromycin can be given to treat leptospirosis.
- Generally good, although deaths do occur in complicated cases if not treated promptly.
Alternative names
Weil disease; Icterohemorrhagic fever; Leptospirosis; Rice-field fever; Cane-cutter fever; Swamp fever; Mud fever; Hemorrhagic jaundice; Stuttgart disease; Canicola fever
Definition
Leptospirosis is a rare, severe, and contagious bacterial infection caused by several species of the genus Leptospira, a spiral-shaped microorganism (spirochete).
Causes, incidence, and risk factors
Leptospirosis is caused by exposure to the bacteria, which can be found in fresh water contaminated by animal urine. It occurs in warmer climates.
Risk factors include:
- Occupational exposure - farmers, ranchers, abattoir workers, trappers, veterinarians, loggers, sewer workers, rice field workers, and military personnel.
- Recreational activities - fresh water swimming, canoeing, kayaking, and trail biking in warm areas.
- Household exposure - pet dogs, domesticated live stock, rainwater catchment systems, and infestation by infected rodents.
The incidence of leptospirosis is low in the continental U.S. Hawaii has the highest number of cases in the U.S.
Symptoms
- Incubation period of 2 to 26 days (average 10 days)
- Abrupt onset of fever, rigors, myalgias, and headache in 75 to 100% of patients
- Dry cough (25-35% of cases)
- Nausea, vomiting, and diarrhea (50% of cases)
- Less common symptoms include joint aches, bone pain, sore throat, and abdominal pain
- Conjunctivitis
- Approximately 7 to 40% of patients may have muscle tenderness, an enlarged spleen or liver, enlarged lymph glands, sore throat, muscle rigidity, abnormal lung sounds, or skin rash
Signs and tests
- White blood cell (WBC) counts are generally less than 10,000.
- Urinalysis frequently is abnormal.
- Elevated creatine kinase is found in approximately 50% of patients.
- About 40% of patients have minimal to moderate elevations of liver enzymes.
- Diagnosis is most frequently made by serologic (antibody) testing.
- Bacteria is best visualized by dark field microscopy, silver stain, or fluorescent microscopy.
Written and revised by
David Cohen, M.D.
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