Population structure and transmission modes of indigenous typhoid in Taiwan
Abstract Background Indigenous typhoid fever was continuing to be identified in Taiwan which has not been endemic for the enteric fever for more than 20 years. The source and transmission by which the local patients acquired typhoid and the population structure of the indigenous typhoid strains rema...
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| Format: | Article |
| Language: | English |
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BMC
2019-09-01
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| Series: | BMC Medical Genomics |
| Subjects: | |
| Online Access: | http://link.springer.com/article/10.1186/s12920-019-0576-6 |
| _version_ | 1830198583443324928 |
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| author | Kai-Yu Wang De-Jen Lee Shian-Sen Shie Chih-Jung Chen |
| author_facet | Kai-Yu Wang De-Jen Lee Shian-Sen Shie Chih-Jung Chen |
| author_sort | Kai-Yu Wang |
| collection | DOAJ |
| description | Abstract Background Indigenous typhoid fever was continuing to be identified in Taiwan which has not been endemic for the enteric fever for more than 20 years. The source and transmission by which the local patients acquired typhoid and the population structure of the indigenous typhoid strains remain not well characterized. Methods During 2001 and 2014, non-duplicated clinical Salmonella enterica serovar Typhi isolates in a hospital were analyzed by whole-genome sequencing (WGS) and determined for pulsotypes. Maximum likelihood phylogeny was constructed by nucleotide alterations in core genomes and compared to the framework of global typhoid strains. Potential source and transmission were traced by correlating the phylogeny and the temporal relationship between isolates. Results A total of 43 S. Typhi isolates from indigenous cases were analyzed and a majority (39, 90.7%) of them were belonged to six WGS-defined genotypes prevailing mainly in Southeast Asia. Genotype 3.4.0 and a multidrug-resistant type 4.3.1 (also known as pandemic H58 haplotype) were associated respectively with two solitary small-scale outbreaks, implying a transmission mode of importation followed by outbreak. Twelve isolates with nearly identical core genomes were belonged to genotype 3.2.1 but were categorized into three different pulsotypes. The 3.2.1 isolates were identified across 13 years and involved in three clusters and a sporadic case, indicating sustained local transmission of the same strain. The remaining indigenous isolates belonging to three genotypes (2.1, 3.1.2, and 3.0.0) were of substantial genetic diversity and isolated at different time points, indicating independent event of each case. Conclusions Indigenous typhoid in Taiwan occurred mainly with the forms of small-scale outbreaks or sporadic events likely by contracting imported strains which prevailed in Southeast Asia. Sustained local transmission of certain strain was also evident by WGS analysis, but not by conventional pulsotyping, highlighting the importance of continuing molecular surveillance of typhoid fever with adequate tools in the non-endemic region. |
| first_indexed | 2024-12-18T01:56:41Z |
| format | Article |
| id | doaj.art-4bc5ce849d9046849defb874086d6379 |
| institution | Directory Open Access Journal |
| issn | 1755-8794 |
| language | English |
| last_indexed | 2024-12-18T01:56:41Z |
| publishDate | 2019-09-01 |
| publisher | BMC |
| record_format | Article |
| series | BMC Medical Genomics |
| spelling | doaj.art-4bc5ce849d9046849defb874086d63792022-12-21T21:24:53ZengBMCBMC Medical Genomics1755-87942019-09-011211810.1186/s12920-019-0576-6Population structure and transmission modes of indigenous typhoid in TaiwanKai-Yu Wang0De-Jen Lee1Shian-Sen Shie2Chih-Jung Chen3School of medicine, College of Medicine, Chang Gung UniversityPhysical Education Office, Chang Gung UniversitySchool of medicine, College of Medicine, Chang Gung UniversitySchool of medicine, College of Medicine, Chang Gung UniversityAbstract Background Indigenous typhoid fever was continuing to be identified in Taiwan which has not been endemic for the enteric fever for more than 20 years. The source and transmission by which the local patients acquired typhoid and the population structure of the indigenous typhoid strains remain not well characterized. Methods During 2001 and 2014, non-duplicated clinical Salmonella enterica serovar Typhi isolates in a hospital were analyzed by whole-genome sequencing (WGS) and determined for pulsotypes. Maximum likelihood phylogeny was constructed by nucleotide alterations in core genomes and compared to the framework of global typhoid strains. Potential source and transmission were traced by correlating the phylogeny and the temporal relationship between isolates. Results A total of 43 S. Typhi isolates from indigenous cases were analyzed and a majority (39, 90.7%) of them were belonged to six WGS-defined genotypes prevailing mainly in Southeast Asia. Genotype 3.4.0 and a multidrug-resistant type 4.3.1 (also known as pandemic H58 haplotype) were associated respectively with two solitary small-scale outbreaks, implying a transmission mode of importation followed by outbreak. Twelve isolates with nearly identical core genomes were belonged to genotype 3.2.1 but were categorized into three different pulsotypes. The 3.2.1 isolates were identified across 13 years and involved in three clusters and a sporadic case, indicating sustained local transmission of the same strain. The remaining indigenous isolates belonging to three genotypes (2.1, 3.1.2, and 3.0.0) were of substantial genetic diversity and isolated at different time points, indicating independent event of each case. Conclusions Indigenous typhoid in Taiwan occurred mainly with the forms of small-scale outbreaks or sporadic events likely by contracting imported strains which prevailed in Southeast Asia. Sustained local transmission of certain strain was also evident by WGS analysis, but not by conventional pulsotyping, highlighting the importance of continuing molecular surveillance of typhoid fever with adequate tools in the non-endemic region.http://link.springer.com/article/10.1186/s12920-019-0576-6Typhoid feverWhole-genome sequencingPulsed-field gel electrophoresisTransmission modeTaiwan |
| spellingShingle | Kai-Yu Wang De-Jen Lee Shian-Sen Shie Chih-Jung Chen Population structure and transmission modes of indigenous typhoid in Taiwan BMC Medical Genomics Typhoid fever Whole-genome sequencing Pulsed-field gel electrophoresis Transmission mode Taiwan |
| title | Population structure and transmission modes of indigenous typhoid in Taiwan |
| title_full | Population structure and transmission modes of indigenous typhoid in Taiwan |
| title_fullStr | Population structure and transmission modes of indigenous typhoid in Taiwan |
| title_full_unstemmed | Population structure and transmission modes of indigenous typhoid in Taiwan |
| title_short | Population structure and transmission modes of indigenous typhoid in Taiwan |
| title_sort | population structure and transmission modes of indigenous typhoid in taiwan |
| topic | Typhoid fever Whole-genome sequencing Pulsed-field gel electrophoresis Transmission mode Taiwan |
| url | http://link.springer.com/article/10.1186/s12920-019-0576-6 |
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