Analysis of Kudoa septempunctata as a cause of foodborne illness and its associated differential diagnosis

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Epidemiol Health. 2017;39.e2017037
Publication date (electronic) : 2017 August 21
doi : https://doi.org/10.4178/epih.e2017037
Department of Preventive Medicine, Dongguk University College of Medicine, Gyeongju, Korea
Correspondence: Ji-Hyuk Park  Department of Preventive Medicine, Dongguk University College of Medicine, 123 Dongdae-ro, Gyeongju 38066, Korea  E-mail: skeyd@naver.com

Dear Editor,

With great interest, I read the paper entitled, “Analysis of Kudoa septempunctata as a cause of foodborne illness and its associated differential diagnosis”, written by Lee [1], which was published in Epidemiology and Health in March 2017. The pathogenicity of K. septempunctata was advocated for in an article written by Kawai et al. [2] in Japan, but this proposal was argued against in 2 studies conducted by Ahn et al. [3] and Jang et al. [4] in South Korea (here-after Korea) using suckling mice. However, there are a few differences among these studies that should be noted.

First, the study by Kawai et al. [2] used K. septempunctata spores isolated from the cases of foodborne illness outbreaks, while the other studies [3,4] used K. septempunctata spores collected from commercial fish farms. Second, the genotypes of K. septempunctata can be classified as sequence type1 (ST1), ST2, and ST3. The ST1 and ST2 genotypes are mostly found in Japan, while the ST3 genotype is most commonly found in Korea [5]. No information was provided about the genotype of K. septempunctata in the study performed in Japan [2]. The 2 studies performed in Korea [3,4] assessed the pathogenicity of the ST3 genotype. Thus, these findings do not demonstrate the lack of pathogenicity of the ST1 and ST2 genotypes.

According to the study by Lee [1] in Korea, 11 foodborne outbreaks in 2015 provide support for the possibility of K. septempunctata pathogenicity. However, there are limitations to this argument because those outbreak investigations were case series studies, not case-control studies or retrospective cohort studies. In Japan, among 24 foodborne outbreaks with unknown causes, 4 outbreaks were significantly associated with the consumption of olive flounder (Paralichthys olivaceus). Among those 4 outbreaks, K. septempunctata was isolated from at least 1 foodborne outbreak [2].

In Korea, K. septempunctata has not been included as a causative agent of foodborne outbreaks in the 2016 guidelines for water and foodborne diseases prevention and control [6]. However, K. septempunctata was included as a causative agent of food poisoning in the 2017 food safety administrative guidelines [7]. To obtain more epidemiological evidence of pathogenicity, further efforts are needed to perform a case-control study or cohort study of foodborne outbreaks relating to the consumption of olive flounder. Moreover, more stringent traceback investigations are needed to determine the production and distribution chain of olive flounder.

Notes

The author has no conflicts of interest to declare for this study.

References

1. Lee SU. Analysis of Kudoa septempunctata as a cause of foodborne illness and its associated differential diagnosis. Epidemiol Health 2017;39e2017014.
2. Kawai T, Sekizuka T, Yahata Y, Kuroda M, Kumeda Y, Iijima Y, et al. Identification of Kudoa septempunctata as the causative agent of novel food poisoning outbreaks in Japan by consumption of Paralichthys olivaceus in raw fish. Clin Infect Dis 2012;54:1046–1052.
3. Ahn M, Woo H, Kang B, Jang Y, Shin T. Effect of oral administration of Kudoa septempunctata genotype ST3 in adult BALB/c mice. Parasite 2015;22:35.
4. Jang Y, Ahn M, Bang H, Kang B. Effects of Kudoa septempunctata genotype ST3 isolate from Korea on ddY suckling mice. Parasite 2016;23:18.
5. Takeuchi F, Ogasawara Y, Kato K, Sekizuka T, Nozaki T, SugitaKonishi Y, et al. Genetic variants of Kudoa septempunctata (Myxozoa: Multivalvulida), a flounder parasite causing foodborne disease. J Fish Dis 2016;39:667–672.
6. Korea Centers for Disease Control and Prevention. Guideline for water and foodborne diseases prevention and control, 2016. 2017. [cited 2017 Jul 11]. Available from: http://cdc.go.kr/CDC/notice/CdcKrTogether0302.jsp?menuIds=HOME001-MNU1154-MNU-0005-MNU0088&cid=69022 (Korean).
7. Ministry of Food and Drug Safety. Food safety administrative guideline, 2017. 2017. [cited 2017 Jul 11]. Available from: http://www.mfds.go.kr/index.do?mid=695&pageNo=1&seq=25549&cmd=v (Korean).

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