Objectives
<i><i>Kudoa</i> septempunctata</i> is a marine myxosporean parasite implicated in seafood-borne acute gastroenteritis, predominantly associated with the consumption of raw olive flounder. This study aimed to characterize the molecular and genetic features of <i>K. septempunctata</i>-associated with foodborne outbreaks in the Republic of Korea from 2016 to 2024.
Methods
We reviewed 415 suspected foodborne outbreaks reported through national surveillance between 2016 and 2024. Among these, 37 outbreaks with complete clinical, epidemiological, and laboratory data from 2020 to 2024—including <i>K. septempunctata</i> testing and genotyping—were analyzed in detail.
Results
Diarrhea (88.8%) and vomiting (61.2%) were the most common symptoms. The detection rate of <i>K. septempunctata</i> was significantly higher in specimens collected ≤24 hours after raw fish consumption (69.8%) than in those collected >24 hours after consumption (35.9%). Outbreak occurrence was higher during warmer months (May–October) than during other periods, although this difference was not statistically significant. All sequences obtained from patient specimens belonged to sequence type 3 (ST3) of <i>K. septempunctata</i>.
Conclusion
Since 2020, the proportion of reported outbreaks associated with <i>Kudoa</i> has increased, indicating its continued public health relevance. The timing of specimen collection is a key determinant of <i>K. septempunctata</i> detection, as diagnostic yield declines significantly when specimens are collected more than 24 hours after exposure. These findings highlight the need for standardized rapid investigation protocols and an integrated surveillance system linking clinical data with seafood supply-chain information.

Objectives
The introduction of new rotavirus vaccines into the public sphere makes it necessary to maintain constant surveillance and to heighten public awareness of the appearance of new rotavirus strains. We describe the molecular epidemiology of circulating rotavirus strains after vaccine introduction.
Methods
We collected a total of 1070 stool samples from children with gastroenteritis from January 2013 to June 2013. The antigenic prevalence of rotavirus group A was distinguished using enzyme immunoassay. The G and P genotypes of enzyme immunoassay-positive samples were determined with reverse transcription-polymerase chain reaction and nucleotide sequencing analysis.
Results
Of the 1070 samples collected, 277 (25.9%) tested positive for rotaviruses by enzyme-linked immunoabsorbent assay. The most prevalent circulating genotype G was G1 (51.3%), followed by G2 (34.7%) and G9 (10.8%). The predominant type of genotype P was P[8] (66.1%), followed by P[4] (31.4%). In this study, nine genotypes were found. G1P[8] was the most prevalent (51.8%), followed by G2P[4] (30.5%), G9P[8] (9.9%), and G2P[8] (4.0%). Several unusual combinations (G1P[4], G3P[9], G3P[8], G4P[6], and G9P[4]) were also identified.
Conclusion
Molecular epidemiological knowledge of rotaviruses is critical for the development of effective preventive measures, including vaccines. These data will help us monitor the effectiveness of current rotavirus vaccines.

Objectives
To confirm genotype diversities of clinical isolates of <i>Bordetella pertussis</i> and to evaluate the risk of pertussis outbreak in Korea.
Methods
Seven housekeeping genes and 10 antigenic determinant genes from clinical <i>B. pertussis</i> isolates were analyzed by Multilocus sequence typing (MLST).
Results
More variant pattern was observed in antigenic determinant genes. Especially, <i>PtxS1</i> gene was the most variant gene; five genotypes were observed from eight global genotypes. In the bacterial type, the number of observed sequence types in the isolates was seven and the most frequent form was type 1 (79.6%). This major sequence type also showed a time-dependent transition pattern. Older isolates (1968 and 1975) showed type 1 and 6 in housekeeping genes and antigenic determinant genes, respectively. However, these were changed to type 2 and 1 in isolates 1999–2008. This transition was mainly attributed to genotype change of <i>PtxS1</i> and <i>Fim3</i> gene; the tendency of genotype change was to avoid vaccine-derived genotype. In addition, there was second transition in 2009. In this period, only the sequence type of antigenic determinant genes was changed to type 2. Based Upon Related Sequence Types (BURST) analysis confirmed that there were two clonal complexes (ACCI and ACCII) in the Korean isolates. Moreover, the recently increased sequence type was revealed as AST2 derived from AST 3 in ACCI.
Conclusions
Genotype changes in Korean distributing strains are still progressing and there was a specific driving force in antigenic determinant genes. Therefore continuous surveillance of genotype change of the distributing strains should be performed to confirm interrelationship of genotype change with vaccine immunity.