Leptospiral uveitis- "Transition 'from epidemic to endemic form" difficulties in laboratory confirmations

Abstract

Purpose: Leptospirosis is a waterborne zoonotic disease that primarily causes systemic illness, followed by uveitis. After heavy flooding in Madurai district, an epidemic outbreak of systemic and ocular leptospirosis occurred in 1994. Our data shows a transition to endemicity after each epidemic.

Aim: The aim of this study is to report the clinical signs, epidemic outbreaks, and persistent endemicity of leptospiral uveitis, as well as the diagnostic dilemmas associated with it.

Methods: A retrospective analysis of clinical signs was conducted using medical records of leptospiral uveitis patients over a period of 27 years (1994-2020) in a tertiary care eye hospital. The clinical workup of uveitis included a detailed clinical history, systemic, and ophthalmic examination. Microagglutination tests (MATs) was done at the Centers for Disease Control and Prevention (CDC) in Atlanta and later in our regional laboratory. Serum samples were collected from human systemic leptospirosis cases and a small group of animals in and around Madurai.

Results: The first epidemic outbreak resulted in 200 seropositive patients. Subsequent epidemic outbreaks occurred in 1997, 1998, 2001, 2005, and 2012, with Madurai experiencing multiple outbreaks. However, the disease remained endemic, with 25-50 patients being observed per year in between the peaks. Ocular examination revealed acute non-granulomatous uveitis (94.9%), pan uveitis (59.8%), vitreous inflammatory reaction (55.4%), retinal vasculitis (29.5%), disc hyperemia (20.9%), and hypopyon. (16.2%). New serovars emerged every year, resulting in decreased sensitivity of the MAT. Over time, the MAT started to miss diagnoses.

Conclusion: The persistent endemicity of leptospiral uveitis emphasizes the need for accessible diagnostic tests. The low performance of the MAT can be attributable to the use of an older panel. The incorporation of new isolates in the MAT by a national laboratory will improve the accuracy of diagnosis.

Keywords: Endemic; leptospiral uveitis; leptospirosis and eye; microagglutination test; ocular leptospirosis.

Figure 1

Various ocular manifestations of leptospirosis. (a and b) Bilateral free floating vitreous membrane in a young farmer. (c) Patchy retinal vasculitis of superior temporal vein. (d) string of pearl-like vitreous precipitates with floating vitreous membrane. (e) Dense vitreous membrane attached to the hyperemic disc. (f) Disc hyperemia. (g) Pearl-like mature cortical cataract with hypopyon. (h) Unilateral cataract with clear lens in the other eye

Figure 2

From 1994 to 1999 all cases clinically diagnosed as leptospiral uveitis were all positive by MAT done at CDC Atlanta, however next three epidemics in 2000, 2006, and 2010 had different serovars negative cases were more than positive cases. 2012 again positive cases were more than negative