Leptospirosis: also known as Weil’s Disease

Organism

Spirochaete bacterium called Leptospira spp
incubation: 7-14 days

Transmission

  • Via the urine of an infected animal (contagious as long as it is still moist)
  • Rats, mice, and moles are important primary hosts
  • Humans become infected through contact with water, food, or soil containing urine (ingestion/skin contact)
  • Incidence related to rainfall – seasonal in temperate climates and year-round in tropical climates.

Epidemiology

  • Uncommon in the UK (fewer than 40 cases/yr in England and Wales, approx. 2-3 of these die from the disease/yr)
  • Significant number affected by disease in eastern and southern Europe, Australia and New Zealand.
  • Those at risk include sewage workers, travellers (i.e. swimming in contaminated water), farmers, vets, abattoir workers, rodent control workers, among others.

 

Pathogenesis

  • Leptospires enter through broken skin/ mucous membranes/ inhalation
  • The motile organisms  disseminate throughout the body
  • Multiply in small blood vessel endothelium
  • Release products which cause damage and vasculitis affecting almost any organ
  • Capillary leak.
  • Organism multiply and septicaemia persists until host develops targeted immunoglobulin
  • Rapid clearance from bloodstream but leptospires remain in immunologically privelidges sites (i.e. renal tubules)

 

Clinical features

Infection can be asymptomatic, cause a mild flu-like illness, or severe, life-threatening illness.
Disease is usually self-limiting( Most recover fully within 2-6 weeks)

Disease usually  presents in 2 phases:
ACUTE/SEPTICAEMIC phase:

IMMUNE phase: (follows 5-7 days later)
Associated with antibody production and excretion of the organism in urine
Patients suffer from severe systemic manifestations i.e. renal failure/ hepatic failure/pulmonary haemorrhages..

*Liver and renal dysfunction are usually reversible, with resolution over 1-2 months.
*immunity develops following infection, but may not fully protect against infection with other strains.

Complications

 

Diagnosis

(leptospires can be found in blood and CSF for the first 7 -10 days and then moves to the kidneys)

  • ELISA and PCR
  • Culture (blood/CSF/Kidney biopsy)
  • Microscopy of fresh urine (after 7-10 days)

 

Treatment

Antibiotics

  • Cefotaxime/doxycycline/penicillin
  • Supportive measures (i.e.some patients require dialysis)

Prevention

  • Prophylaxis (i.e. high risk occupations/activities for short period) can be given, usually Doxycycline
  • No human vaccine available; (animal vaccines exist)
  • Reduction of rodent populations, e.g. by clearing rubbish and preventing rodent access into buildings.
  • Avoidance of swimming/wading in water that might be contaminated with animal urine.

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