Molecular epidemiology of Vibrio cholerae O1 in northern Vietnam (2007–2009), using multilocus variable-number tandem repeat analysis

Abstract

Cholera is an infectious disease of major concern in Vietnam and other Asian countries. In 2009, there was a large outbreak of cholera in northern Vietnam. To investigate relationships among isolates of the causative pathogen Vibrio cholerae in this region since 2007, we carried out a multilocus variable-number tandem repeat analysis (MLVA) of 170 isolates collected between 2007 and 2009. A total of 24 MLVA types were identified using seven loci. Five clones (1-5) were identified using five loci of the large V. cholerae chromosome; clones 1 and 2 were major, and the others were minor. Clone 1 isolates were responsible for the 2009 outbreak. A shift in the predominant clone occurred between 2007 and 2009, with clone 1 likely derived from clone 2. Moreover, the former was less diverse than the latter, suggesting a single source of cholera dissemination. Epidemiological data indicated a wavelet prior to the large outbreak, suggesting that drinking water source or food chain became contaminated during dissemination. Our results reveal the utility of MLVA for analysis of V. cholerae isolates within a relatively short period and broaden our understanding of its transmission and response to cholera.

Fine‐scale geographic clustering pattern of human T‐cell leukemia virus type 1 infection among blood donors in Kyushu‐Okinawa, Japan

“…To visualize the age‐ and sex‐specific seroprevalence of HTLV‐1 (%) at the municipal level, we used a free Geographic Information System software package, MANDARA (version 9.45, Japan) (http://ktgis.net/mandara/). MANDARA has been used in several geographic distribution studies …”

Molecular characterization of Vibrio cholerae O1 isolates obtained from outbreaks in the Philippines, 2015–2016

“…The MLVA profiles are shown in Table S2. Because the two VNTR loci in the small chromosome are hypervariable, grouping of MLVA results based on those of the large chromosome was applied [10, 17, 18]. We identified 14 types based on the VNTR loci of the large chromosome (large chromosome type, LCT).…”

“…The Yemeni strains (2017Yemen) [6] formed a complex in the bottom part of the MST. The epidemic strains from Southeast Asia in 2007–2010 [18, 27–29] were located on an edge in the bottom part of the MST. All were distinct from the isolates in this study.…”

“…A minimum spanning tree was created via the MST algorithm with a categorical coefficient using BioNumerics software. Because the two small chromosomal loci are highly variable [10, 17], the MLVA types were designated as a combination of allele profiles of the five large chromosome-derived loci (MLVA5) [18] and all seven loci (MLVA7), such as A-01. The former types are called large-chromosome types (LCTs) here.…”