Leptospira

Categorization
Cell Wall: Gram Negative Shape: Spirochete
Metabolism: Microaerophilic
Transmission
  • L. interrogans is a widespread zoonotic with natural reservoirs particularly among rodents although both wild and domestic animals may harbor this organism. Leptospira are shed in the body fluids of infected animals, especially their urine, and can survive in watery environments for months. Transmission to humans is through direct contact or ingestion of contaminated animal fluids or water.
Pathogenesis
  • Following inoculation, L. interrogans disseminate widely by a hematogenous route and infect a number of organs, especially the kidneys, liver, and CSF. This leptospiermic phase is responsible for the initial set of symptoms observed following inoculation. Protective humoral immunity generates IgM antibodies which largely eliminate the organism from the body. However, it appears that this protective immune response may initiate an inflammatory reaction, especially in the meninges, which manifests as the second phase of the disease characterized by an Aseptic Meningitis.
Clinical Consequences
  • Overview
    • A large number of infected individuals run a course of completely asymptomatic infection. When clinical consequences are apparent, the disease is most often mild and no jaundice is observed (Anicteric Disease). In about 10% of patients, a severe illness typified by jaundice develops and is termed Icteric Disease or "Weil's Syndrome" .
  • Anicteric Disease
    • Anicteric disease is characterized by rapid onset of constitutional symptoms such as fever, headache, chills, and myalgia. Characteristically, the conjunctiva appear red. This initial phase of disease subsides after about a week and the patient is symptom-free for several days. The second phase of disease is heralded by the return of the previous constitutional symptoms but in milder form together with an aseptic meningitis that is accompanied by CSF pleocytosis. This second phase of disease is correlated with the development of protective antibodies and elimination of organisms. It can last from several days to months.
  • Icteric Disease (Weil's Syndrome)
    • Icteric Disease is characterized by a more severe first, leptospiremic phase in which there is severe dysfunction of the liver and kidneys. Hepatitis leads to hepatic dysfunction resulting in jaundice. Renal dysfunction can precipitate Acute Renal Failure. In addition, widespread hemorrhage is also common.
Treatment
  • Mild cases: Doxycycline
  • Severe cases: IV Penicillin G
  • Rarely, treatment may result in a Jarisch-Herxheimer Reaction