A Dominant Clone of Leptospira interrogans Associated with an Outbreak of Human Leptospirosis in Thailand

Abstract

BackgroundA sustained outbreak of leptospirosis occurred in northeast Thailand between 1999 and 2003, the basis for which was unknown.Methods and FindingsA prospective study was conducted between 2000 and 2005 to identify patients with leptospirosis presenting to Udon Thani Hospital in northeast Thailand, and to isolate the causative organisms from blood. A multilocus sequence typing scheme was developed to genotype these pathogenic Leptospira. Additional typing was performed for Leptospira isolated from human cases in other Thai provinces over the same period, and from rodents captured in the northeast during 2004. Sequence types (STs) were compared with those of Leptospira drawn from a reference collection. Twelve STs were identified among 101 isolates from patients in Udon Thani. One of these (ST34) accounted for 77 (76%) of isolates. ST34 was Leptospira interrogans, serovar Autumnalis. 86% of human Leptospira isolates from Udon Thani corresponded to ST34 in 2000/2001, but this figure fell to 56% by 2005 as the outbreak waned (p = 0.01). ST34 represented 17/24 (71%) of human isolates from other Thai provinces, and 7/8 (88%) rodent isolates. By contrast, 59 STs were found among 76 reference strains, indicating a much more diverse population genetic structure; ST34 was not identified in this collection.ConclusionsDevelopment of an MLST scheme for Leptospira interrogans revealed that a single ecologically successful pathogenic clone of L. interrogans predominated in the rodent population, and was associated with a sustained outbreak of human leptospirosis in Thailand.

Multiple-locus variable-number tandem repeat analysis and clinical characterization of Leptospira interrogans canine isolates

“…Infection with serovar Icterohaemorrhagiae or Pomona is commonly associated with severe hepatic dysfunction, whereas serovar Canicola tends to cause acute interstitial nephritis (Wohl, 1996;Langston & Heuter, 2003). Although an association of specific genotypes and enhanced virulence has been suggested in human leptospirosis (Gouveia et al, 2008;Thaipadungpanit et al, 2007), differences in the virulence of Leptospira genotypes in canine leptospirosis remain unknown.…”

“…All isolates were identified as the species L. interrogans by DNA sequencing of the flaB gene (data not shown). MLST for the isolates was performed as described by Thaipadungpanit et al (2007), and sequence types were assigned based on the MLST database (http://leptospira.mlst.net/).…”

Viability of Leptospira Isolates from a Human Outbreak in Thailand in Various Water Types, pH, and Temperature Conditions

“…3,4 Blood culture isolates of Leptospira spp. from 2000 to 2005 were typed using multilocus sequence typing (MLST).…”

Progress on research on rodents and rodent-borne zoonoses in South-east Asia

“…All these viruses can be transmitted directly between rodent hosts, although transmission of hantaviruses and LCMV likely also occurs through exposure to aerosolised infectious excretions (Monath 1975;Armstrong et al 1995). Among the bacteria, three genera in particular have been a major focus: Leptospira spp., agents of leptospirosis (Thaipadungpanit et al 2007;Ivanova et al 2012;Cosson et al 2014); Bartonella spp., agents of bartonellosis (Castle et al 2004;Saisongkorh et al 2009;Jiyipong et al 2012Jiyipong et al , 2015; and Orientia tsutsugamushi (Coleman et al 2003), the agent of scrub typhus. Bartonella spp.…”