Regional Differences of Leptospirosis in Sri Lanka: Observations from a Flood-Associated Outbreak in 2011

Abstract

Leptospirosis is known to be an important cause of weather disaster-related infectious disease epidemics. In 2011, an outbreak of leptospirosis occurred in the relatively dry district of Anuradhapura, Sri Lanka where diagnosis was resisted by local practitioners because leptospirosis was not known in the area and the clinical presentation was considered atypical. To identify the causative Leptospira associated with this outbreak, we carried out a cross-sectional study. Consecutive clinically suspected cases in this district were studied during a two-and-a-half-month period. Of 96 clinically suspected cases, 32 (33.3%) were confirmed by qPCR, of which the etiological cause in 26 cases was identified using 16S rDNA sequencing to the species level. Median bacterial load was 4.1×102/mL (inter-quartile range 3.1–6.1×102/mL). In contrast to a 2008 Sri Lankan leptospirosis outbreak in the districts of Kegalle, Kandy, and Matale, in which a predominance of Leptospira interrogans serovars Lai and Geyaweera was found, most cases in the 2011 outbreak were caused by Leptospira kirschneri. Seven (21.9%) confirmed cases had acute renal failure; five (15.6%) had myocarditis; severe thrombocytopenia (<20,000/uL) was seen in five (15.6%) cases. This outbreak of leptospirosis in the relatively dry zone of Sri Lanka due primarily to L. kirschneri was characterized by markedly different clinical presentations and low leptospiremia. These observations and data demonstrate the public health relevance of molecular diagnostics in such settings, possibly related to the microgeographic variations of different Leptospira species, but of particular value to public health intervention in what appears to have been a regionally neglected tropical disease.

Redefining Gold Standard Testing for Diagnosing Leptospirosis: Further Evidence from a Well-Characterized, Flood-Related Outbreak in Sri Lanka

“…Control of this outbreak and treatment were a challenge to all clinicians due to two reasons; first the clinical presentation was unusual and the classical "Weil's disease" was not observed among these patients; second, diagnostic facilities were not available routinely for early diagnosis. We previously reported preliminary confirmation of the etiology of this outbreak using molecular methods, 13 which showed that there were dengue and hantavirus infections mimicking leptospirosis during this outbreak as well. 18 The purpose of the this study was to describe the clinical and biochemical features of this post-flood leptospirosis outbreak, with a particular focus on identifying the most useful laboratory methods to provide definitive, actionable diagnosis.…”

“…13 Briefly, this cross-sectional descriptive study was carried out in the Teaching Hospital Anuradhapura (THA), Sri Lanka. The study was carried out from February to May, 2011, during an outbreak of leptospirosis related to unusual heavy rains and floods.…”

“…Procedure of DNA extraction, qPCR primers, and conditions have been previously described. 13 Two different ELISA tests and standard MAT tests were carried out in the Federal Institute for Risk Assessment, Berlin. For the in-house ELISA (ELISA-BfR), protein was extracted from 1-2 × 10 8 Leptospira kirschneri serovar Grippotyphosa/mL.…”

“…[13][14][15][16][17] In 2011, a major outbreak of leptospirosis was reported from Anuradhapura, a district located in a dry area in North Central part of the country. Control of this outbreak and treatment were a challenge to all clinicians due to two reasons; first the clinical presentation was unusual and the classical "Weil's disease" was not observed among these patients; second, diagnostic facilities were not available routinely for early diagnosis.…”

Spatial and seasonal analysis of human leptospirosis in the District of Gampaha, Sri Lanka

“…4 Scientifically sound data and scientific publications are lacking in Sri Lanka due to lack of laboratory diagnostic facilities and baseline data on transmission of leptospirosis. 5 Laboratory confirmation of patients with leptospirosis is important for preventing severe complications and death. 1 Most feral and domestic mammals may serve as major reservoir hosts for Leptospira.…”