Leptospirosis is a zoonotic infection with a worldwide distribution. It occurs most frequently in tropical and subtropical regions and is caused by the gram-negative spirochete Leptospira interrogans. The natural reservoirs for Leptospira organisms include livestock, horses, dogs, and rodents, which excrete the organism in their urine. Humans contract the disease upon exposure to contaminated soil or water; thus, groups at risk include agricultural workers, sewer workers, veterinarians, fishery and slaughterhouse workers, and military personnel, as well as swimmers, triathletes, and whitewater rafters. The disease is not known to spread from person to person, but maternal–fetal transmission might occur infrequently. It is very rare in the United States, with 100–150 cases being identified annually, half of them in Puerto Rico. Globally, 1 million people are estimated to be infected each year, with almost 60,000 deaths. Since 2013, leptospirosis has been reinstated as a nationally notifiable disease in the United States.
Leptospirosis is frequently a biphasic disease, with the initial, or leptospiremic, phase following an incubation period of 2–4 weeks heralded by the abrupt onset of fever, chills, headache, myalgias, vomiting, and diarrhea. Severe septicemic leptospirosis, also known as Weil disease, is characterized by renal and hepatocellular dysfunction; it is rare (occurs in 10%) but can be fatal in 30%. Leptospires may be isolated from the blood and CSF but are cleared rapidly as the disease progresses to the second, or immune, phase of the illness, which is characterized by meningitis, leptospiruria, cranial nerve palsies, myelitis, and uveitis. The organism may persist for longer periods of time in immunologically privileged sites such as the brain and the eye.
Centers for Disease Control and Prevention. Leptospirosis. Atlanta: US Department of Health and Human Services; 2018. Available at www.cdc.gov/leptospirosis/health_care_workers/index.html. Accessed September 12, 2018.
Rathinam SR. Ocular manifestations of leptospirosis. J Postgrad Med. 2005;51(3):189–194.
Ocular involvement can occur in both the leptospiremic and immune phases, but there is frequently a prolonged interval between systemic and ocular disease. Circumcorneal conjunctival hyperemia is the earliest and most common sign of ocular leptospirosis. The development of intraocular inflammation, which can range from mild anterior uveitis to panuveitis with retinal vasculitis (in 10%–44% of patients), is the more serious, potentially vision-threatening complication.
Excerpted from BCSC 2020-2021 series: Section 9 - Uveitis and Ocular Inflammation. For more information and to purchase the entire series, please visit https://www.aao.org/bcsc.