Objectives
Kudoa septempunctata 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 K. septempunctata-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 K. septempunctata testing and genotyping—were analyzed in detail. Results: Diarrhea (88.8%) and vomiting (61.2%) were the most common symptoms. The detection rate of K. septempunctata 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 K. septempunctata. Conclusion: Since 2020, the proportion of reported outbreaks associated with Kudoa has increased, indicating its continued public health relevance. The timing of specimen collection is a key determinant of K. septempunctata 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
Anopheles sinensis is a predominant malaria vector found throughout the Republic of Korea (ROK). Population genetic analysis can provide insights into the origins and migration patterns of malaria vectors by assessing genetic variation and distribution among populations. Methods: In this study, we examined the population genetic structure of An. sinensis in the ROK using mitochondrial cytochrome c oxidase subunit I (COI) marker. Results: A total of 903 specimens of An. sinensis were collected from 9 sampling regions, including malaria-endemic and non-endemic areas. All populations displayed characteristics typical of migrant populations, with high haplotype diversity (Hd) and low nucleotide diversity (Pi). Network analysis identified 124 haplotypes grouped into 2 clusters. Both clusters included haplotypes from malaria-endemic and non-endemic areas. Cluster I shared its most recent common ancestry with Chinese reference sequences, while cluster II had related with Japanese reference sequences. Pairwise genetic distance (FST) analysis indicated generally low genetic differentiation among populations. Furthermore, FST values tended to increase proportionally with geographical distance between regions. Analysis of molecular variance confirmed that individual mosquitoes within the population had a large effect on the overall variation. Neutrality tests using 4 methods (Tajima’s D, Fu’s Fs, Fu and Li’s D, and Fu and Li’s F) yielded negative values, suggesting that An. sinensis populations are expanding in all studied regions. Conclusion: This study characterizes the genetic attributes of An. sinensis in the ROK, providing valuable insights into the biology of this important malaria vector and contributing useful data for malaria control strategies.