Human infection usually results from exposure to animal urine in contaminated water or soil. Leptospirosis is prevalent among people who spend a lot of time around water sources (e.g. surfers, sewer workers, and farmers) particularly in tropical areas (e.g. Hawaii).
Portals of entry for Leptospira include cuts or abraded skin, mucous membranes, or conjunctivae. This is especially common in people who spend a lot of time around contaminated water sources.
The genus Leptospira contains 22 species among which 10 are considered pathogenic. L. interrogans is the most common organism causing leptospirosis.
Leptospirosis is caused by pathogenic spirochetes of the genus Leptospira. Spirochetes are a group of spiral-shaped bacteria.
Leptospira can be distinguished morphologically from other spirochetes by their unique "question mark" hook at the end of the bacterium.
Leptospirosis presents with flu-like symptoms such as myalgias (classically of calves), fever, photophobia, headache, and gastrointestinal distress.
Conjunctival suffusion is conjunctival erythema without the classic exudates seen in conjunctivitis. In leptospirosis, conjunctival suffusion is commonly bilateral and diffuse.
Photophobia is a common symptom in patients with leptospirosis. They may also complain of retro-orbital pain.
Weil's disease or icterohemorrhagic leptospirosis is a severe form of leptospirosis that can progress to acute liver and kidney failure. Clinical features are due to systemic spread and multiorgan involvement.
Involvement of the liver causes hepatitis which can result in jaundice. Although the exact pathomechanism is not well understood, it is thought that Leptospira invades intercellular junctions between hepatocytes causing bile to leak. Other features of acute liver failure may be evident.
Patients with Weil’s disease are at increased risk of bleeding events. Several mechanisms have been implicated such as increased vascular permeability, complement activation, and immune-mediated damage to cells. Pulmonary hemorrhage can result in hemoptysis and is a major cause of death in these patients.
Anemia can be attributed to widespread hemorrhage. Consider blood transfusions for precipitous drops in hemoglobin.
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