Presentation of leptospirosis in the emergency department – an analysis of different pattern of clinical features during an outbreak

Introduction
Typically, doctors consider a diagnosis of probable leptospirosis when there is a history of fever with kidney or liver involvement and an elevated serum creatine phosphokinase level. However, there are increasing numbers of cases with atypical presentation, which renders the diagnosis challenging.The aim of this study is to determine the presentation patterns of leptospirosis during an outbreak, in order to increase the understanding of this potentially complex disease.

Material and methods
This is a retrospective, observational study of an outbreak that occurred in an army camp in 2012. The data were collected by retrieving the patients’ medical records, including signs and symptoms, laboratory findings, and outcomes.

Results
There were 47 cases of leptospirosis confirmed by a microscopic agglutination test (MAT). Of these, only 50% had a positive point-of-care serology test result at initial encounter in the emergency department. The majority (58%) presented with mild upper respiratory tract and gastrointestinal symptoms and 64% had no fever on presentation. Only five patients had leukocytosis (12%); 86% were within the normal range. Half of the patients (50%) had a normal platelet count and 60% had normal renal function. However, 74% had a creatine phosphokinase level over 200.

Conclusions
Leptospirosis is difficult to diagnose due to its ambiguous clinical presentation. Most of the laboratory findings can be unhelpful in excluding the diagnosis. The point-of-care serology test done in the primary setting should not be relied on in highly suspicious cases. In a cluster where leptospirosis is endemic, the MAT might be warranted; otherwise, empirical antibiotics may be considered, even for mild symptoms.