Jpn. J. Infect. Dis., 52, 1999 Laboratory and Epidemiology Communications EpidemiologlCal Studies of an Outbreak of Paratyphoid Fever in the Shima Area of Mie Prefecture Akira Sugiyama*, Yoko Nakan0, Yoshito Iwade, AkinoriYamauchi, Nakao Sakurai, Osamu Nakayama, Yukitaka Yamamotol, Masayuki Nakatsul , Yoko Mori1 , YoshiyaKishidal, Takashi Oidal, Norichika H. Kumazawa2, JunTeraJlma3and Akiko Nakamura3 Mie PrejTectural Institute of Public Health and Environmental Sciences, Sakura-cho 3690-1, Yokkaichi, Mie 512-1211, 1Division offlealth and Welfare, Mie Prefecture Government, Tsu, Mie 514-8570, 2Tropical Biosphelle ReseaTICh CenteTT, UniversityofRyukyu, Nishihara-cho, Okinawa 903-0213 and 3Department of Bacteriology, National Institute of lnjTectious Diseases, Shinjuku, 7Tokyo 162-8640 Communicated by Yutaka Miyazaki (Accepted January I 2, 2000) On 14 December 1993, Mie PrefecturalInstitute of Public consumption. There were 17 patients in Mie, five in Osaka, Health and EnvironmentalSciences was informed by Osaka two in Shizuoka, and one each in Hyogo, Aichiand Yamaguchi Prefecture of four cases of paratyphoid fever. Allthe patients Prefectures (Figs･ I and 2)･ Salmo.nella Paratyphi A was had used the same pension K in the Shima area of Mie isolated in all of the patients. The majority of the isolates was Prefecture･ Then reports of paratyphoid cases came sequen- that of phase type 2 (Fr2). No secondary infections, such as tially･ A totalof 27 paratyphoid cases were reported from the those occumng in family members, were reported･ end of December 1993 to early January 1994. Twenty-four From November to December 1993, 407 persons used patients used pension K and two used pension U. All of the pension K and 140 persons used pension U. All clients of the patients had eaten raw oysters there. One patient was a fisher- two pensions were investigated for possible paratyphoid manwho had never used eitherpension. He retained part of infection. All of them were healthy except patient #9, who his haJVeSt inthe sea near the harbor of the village forpersonal had been diagnosed as having a common coldand who also Fig. 1. Geographicaldis廿ibution of patients. *Corresponding author: Fax: +81 -593129-3∝叫 253 Jpn. J. Infect. Dis., 52, 1999 Date of Ingestion Diagnosis ↓ * : Asymptomatic patients Pension K Pension U @ Fisherman Fig･ 2･ ChronologICaldistribution of illness in patients-dates of food ingestion and final diagnosis･ L 1 2 3 4 5 6 7 8 9 L of all workers in pensions K and U were examined several times･ S･ Paratyphi A was not detected in any of the samples. Foods conserved in refrigerators in both pensions were examined for g. Paratyphi A on 15 and 24 December, and none of the refrigerated samples were positive. All the patients ingested raw oysters. The oysters had been kept ln Sea Water in a harbor about I km away from the village where the two pensions were l∝ated. The water draining Into the harbor or surrounding the oysters kept there was not infected with sewage. Nevertheless, we were able to isolate S. Paratyphi A Fr2 from one in two mud samples collected on 13 January 1994 near the place wherethe causative oysters were kept. The PFGE pattems of the sea water isolate and the other patient-derived isolates (Fig. 3) were identical. Further isolation trials fromthe same or other places wereunsuccessfd. This study demonstrated the power of PFGE in epidemi0- 10gical analysis (I). The data suggest that S. Paratyphi Afirst contaminated the sea water and the mud in the harbor, and then the oysters became contaminated. The phage-type most prevalent in Japan was Frl (2). Fr2, which was associated with the present outbreak, was reported to be more prevalent Fig･ 3･ PFGE analysis of isolates･ Bacteria were placed in wells onthe in Thailand, Indonesia, and other Southeast Asian countries top of Incert Agarose Gel, lysed with lysozymeand treated with (2). It is quite possible that theぶ. Paratyphi, which caused proteinase K for proteolysIS andthen with BlnI restriction enzyme the present outbreak, was not resident in thisarea but probably for DNA digestion･ The gel electrophoresis was performed with BioRad CHEF-DRII under the followlng COnditions: voltage, 6 V/ a strain imported from these other countries. It should tnt noted cm; pulsetime, 5-50 see; temperature, 17.C; duration, 23 h. Lane I: that the affected area is a famous tourist resort in Japan. In isolate fromanunderwater mud sample fromthe harbor. bnes 219: addition, many people from the SoutheastAsia come to work isolates from patients. L: ladder marker. in this area. REFERENCES had dia汀hea at the time of investigation･ Stool specimens were collected from 344 persons. Samples from one person 1. Tenover, F. C., Arbeit, R. D., Goenng, R. V., Mickelsen, (patient #13) were fd血nd to be positive for S. Paratyphi A; P. A., Murray, B. E., Persing, D. H.and Swaminathan, that patient was, however, asymptomatic. Stool specimens B. (1995): Interpreting chromosomal DNA restriction 254 Jpn. J. Infect. Dis., 52, 1999 pattems produced by pulsed-field gel electrophoresis: Control Division, Ministry of Healthand Welfare ( I 996): Criteria for bacterialstrain typing. J. Clin. Microbio1., 33, Typhloid fever and paratyphoid fever, Japan, January 2233-2239. I 994-September I 996. Infect. Agents Surveillance Rep･ , 2. National Institute of HeaIthand Infectious Diseases 17, 296'-297'. 255.