12 Novel clonal groups of Leptospira infecting humans in multiple contrasting epidemiological contexts in Sri Lanka

Abstract

Leptospirosis is a ubiquitous zoonotic disease and a major clinical challenge owing to the multitude of clinical presentations and manifestations that are possibly attributable to the diversity of Leptospira, the understanding of which is key to study the epidemiology of this emerging global disease threat. Sri Lanka is a hotspot for leptospirosis with high levels of endemicity as well as annual epidemics. We carried out a prospective study of Leptospira diversity in Sri Lanka, covering the full range of climatic zones, geography, and clinical severity. Samples were collected for leptospiral culture from 1,192 patients from 15 of 25 districts in Sri Lanka over two and half years. Twenty-five isolates belonging to four pathogenic Leptospira species were identified: L. interrogans, L. borgpetersenii, L. weilii, and L. kirschneri. At least six serogroups were identified among the isolates: Autumnalis (6), Pyrogenes (4), Icterohaemorrhagiae (2), Celledoni (1), Grippotyphosa (2) and Bataviae (1). Seven isolates did not agglutinate using available antisera panels, suggesting new serogroups. Isolates were sequenced using an Illumina platform. These data add 25 new core genome sequence types and were clustered in 15 clonal groups, including 12 new clonal groups. L. borgpetersenii was found only in the dry zone and L. weilii only in the wet zone. Acute kidney injury and cardiovascular involvement were seen only with L. interrogans infections. Thrombocytopenia and liver impairment were seen in both L. interrogans and L. borgpetersenii infections. The inadequate sensitivity of culture isolation to identify infecting Leptospira species underscores the need for culture-independent typing methods for Leptospira.

Time series models for prediction of leptospirosis in different climate zones in Sri Lanka

“…Another possibility is that the soil was not retaining water due to steep slope in the highlands as compared with the lower-elevation dry zone, making it difficult for Leptospira to survive for a longer period. The survival of Leptospira in different climate zones has not yet been thoroughly studied, which makes further explanation of these findings difficult [ 33 ]. A recently published study revealed that virulence of Leptospira interrogans is maintained for more than one year, even with prolonged starvation [ 34 ].…”

“…been thoroughly studied, which makes further explanation of these findings difficult [33]. A recently published study revealed that virulence of Leptospira interrogans is maintained for more than one year, even with prolonged starvation [34].…”

Optimizing the microscopic agglutination test (MAT) panel for the diagnosis of Leptospirosis in a low resource, hyper-endemic setting with varied microgeographic variation in reactivity

“…Inclusion of an adequate number of currently circulating Leptospira isolates in the MAT panel and a re-evaluation procedure is required before committing to the use of new isolates. The on-going studies in Sri Lanka with recently recovered isolates will provide adequate new strains for this purpose[ 50 ]…”

“…on-going studies in Sri Lanka with recently recovered isolates will provide adequate new strains for this purpose [50] A relatively low reactivity was observed with the saprophytic non-pathogenic serovar Patoc (16%). Usually the saprophytic species L. biflexa is considered to have a broader reactivity and is therefore recommended to be included in MAT panels [11].…”

Estimating the burden of leptospirosis: global lessons from Sri Lanka

“… 13 Although the studies are limited, available evidence indicates a similar pattern among humans. 14 Serogroups are predominantly reservoir specific, and environmental survival depends on diverse factors in different geographical regions. 14 While the seasonal variation in leptospirosis is well known, 9 the differences in leptospirosis by climatic zones within countries need further exploration, especially with the observed macrogeographical changes in leptospirosis.…”