What is Leptospirosis (Weil’s disease/syndrome; Icterohemorrhagic fever)

Leptospirosis is a rare, severe, and contagious bacterial infection caused by several species of the genus Leptospira, a spiral-shaped microorganism (spirochete).
Leptospirosis often is referred to as swineherd’s disease, swamp fever, or mud fever. The organism enters the body when mucous membranes or abraded skin comes in contact with contaminated environmental sources. The infection causes a systemic illness that can quite often lead to renal and hepatic dysfunction and possible failure.

Statistics on Leptospirosis (Weil’s disease/syndrome; Icterohemorrhagic fever)

Leptospirosis is a zoonosis (animal borne) infection with a worldwide distribution and incidence. The incidence varies from sporadic in temperate zones to endemic in a few tropical countries.
The disease has a seasonal incidence. Most cases occur during the rainy season in the tropics and, in Western countries, during the late summer or early fall, when the soil is moist and alkaline.
Leptospirosis generally is associated with tropical countries and heavy rainfall, but the majority of cases actually occur in temperate climates, probably because of underreporting in some countries.

Risk Factors for Leptospirosis (Weil’s disease/syndrome; Icterohemorrhagic fever)

Direct exposre to the microorganism is the method in which the disease is contracted.

  • Occupational exposure: farmers, abattoir workers, trappers, veterinarians, loggers, sewer workers, rice field workers, and military personnel.
  • Recreational activities: fresh water swimming, canoeing, kayaking, and mountain biking in warm areas.
  • Household exposure: pet dogs, domesticated live stock, rainwater catchment systems, and infestation by infected rodents.

Progression of Leptospirosis (Weil’s disease/syndrome; Icterohemorrhagic fever)

Leptospirosis infection has a number of manifestations. As a result, it is frequently misdiagnosed.

  • Approximately 15-40% of patients who are exposed but do not become ill show serologic (of blood/urine/saliva) evidence of an existing past infection. This statistic includes 15% of abattoir workers, packinghouse workers, and veterinarians.
  • The incubation period is usually between 7-12 days, with a range of 2-20 days.
  • Approximately 90% of patients manifest a mild form of the disease, and approximately 5-10% have the severe form with jaundice, otherwise known as Weil disease.
  • The natural course of leptospirosis falls into 2 quite distinct phases, septicemic and immune. During a brief period of 1-3 days between the 1st and 2nd phase, the patient shows some improvement.

How is Leptospirosis (Weil’s disease/syndrome; Icterohemorrhagic fever) Diagnosed?

  • 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.

Prognosis of Leptospirosis (Weil’s disease/syndrome; Icterohemorrhagic fever)

Generally the prognosis related to this disease is good, usually with full recovery following infection. More severe systemic infections (Weil’s disease), can lead to renal (kidney) and hepatic (liver) failure, myocarditis (heart muscle inflammation), and can be potentially fatal.

How is Leptospirosis (Weil’s disease/syndrome; Icterohemorrhagic fever) Treated?

Penicillins, tetracyclines, chloramphenicol, and erythromycin can be given to treat leptospirosis. Supportive care needs to be provided in cases involving complications.
Vaccines are offered to high-risk workers in some European and Asian countries (eg, rice workers in Italy). Vaccines are not used in the US.

Leptospirosis (Weil’s disease/syndrome; Icterohemorrhagic fever) References

  1. Cohen R, LaDou J, eds: Occupational Infections. In: Occupational Environmental Medicine. Connecticut: Appleton & Lange; 1997.
  2. Cole DJ, Hill VR, Humenik FJ: Health, safety, and environmental concerns of farm animal waste. Occup Med 1999 Apr-Jun; 14(2): 423-48[Medline].
  4. MEDLINE Plus.