The Topic of This Month Vol.20 No.5(No.231)
Campylobacter enteritis, caused by Campylobacter jejuni or C. coli, has drawn special attention, since it has often been implicated in diarrheal diseases in preschool and school children.
The above incidence is compiled independently through each of the following: (1) Notification to the Food Sanitation Division, the Ministry of Health and Welfare complying with the Food Sanitation Law (in the Statistics of Food Poisoning). (2) Reports by prefectural and municipal public health institutes (PHIs) on Campylobacter detection in examination of food poisoning outbreaks performed at PHIs and health centers (in the Infectious Agents Surveillance Report). (3) Individual reports to the Research Group for Infectious Enteric Diseases, Japan of Campylobacter enteritis patients admitted to infectious disease hospitals (IDHs) in Tokyo and designated cities (15 hospitals in 12 cities). The following is a summary of the Campylobacter enteritis incidence in the whole country during the last four years based on the above reports (see IASR, Vol. 14, No. 7 and Vol. 16, No. 7 concerning the incidence before 1994).
The Statistics of Food Poisoning: Campylobacter, designated as a food poisoning agent, is implicated in food poisoning most often after Salmonella, Vibrio parahaemolyticus, and Staphylococcus aureus. Campylobacter food poisoning cases in the whole country suddenly increased to 9,497 in 1985. Thereafter, the number of reports decreased to 948 in 1993. However, it increased once again after 1994 and has remained at between 1,500 and 2,600 to present (Fig. 1). The annual incidents numbered less than 50 before 1995, but increased to 65 in 1996, 257 in 1997 and 553 in 1998. This increase is largely due to the current stream of notifications from some prefectures of bacterial food poisoning episodes implicating no more than a single case.
Isolation reports from PHIs: The reports of Campylobacter isolation in each year between 1983 and 1998 are shown in Table 1. After counting the largest number of cases (2,810) in 1985, the reports show a similar trend of decrease, compared with the Statistics of Food Poisoning, to 599 in 1993. After 1994, however, the number of reports remained stable at about 700-1,300 (less than half of that in 1980s). Among the reports of isolation during 1995 through 1998, 87% mentioned the species differentiated; C. jejuni accounted for 97% and C. coli a very small percent.
Reports of Campylobacter isolation by month during 1995 through 1998 are shown in Fig. 2a. As was the case before 1994, the largest number of reports came out during April through July. This trend is similar to the number of incidents of Campylobacter enteritis in the United Kingdom and the United States (CDSC, CDR, Vol. 8, No. 24, p. 211, 1998). The large peak seen in June 1997 reflects the large-scale outbreak due to school lunch in an elementary school in Nara Prefecture (see IASR, Vol. 18, No. 11).
Outbreaks of Campylobacter food poisoning reported by PHIs during 1993 through 1998 totaled 169 (Table 2; see IASR, Vol. 14, No. 7 concerning the reports before 1992). Twenty outbreaks (12%) involved more than 100 patients, 18 (11%) 50 to 99 patients, 80 (47%) 10 to 49 patients, and 51 (30%) two to nine patients. Five reports coming out after 1996 described incidents caused by C. coli, which had seldom been implicated before. In 49 (29%) of the 169 outbreaks, the source of infection was identified; chicken meat or chicken meat-containing dishes were most often incriminated in 39 outbreaks, drinking water in three, and school lunch in seven. The period required to save specimens of school lunch in case of accident was extended to two weeks in 1996; nevertheless, the rates of identifying causative food in 1997 and 1998 were as low as before. According to the reports of food surveillance done by PHIs (Table 3), C. jejuni/coli has frequently been isolated from chicken meat and surface swabs at poultry slaughterhouses, reflecting that Campylobacter food poisoning is often caused by contaminated chicken meat and through secondary contamination from it (see p. 110 of this issue).
The C. jejuni isolates serotyped by the Campylobacter Reference Centers of PHIs during June 1996 through May 1998 numbered 590 from 51 food poisoning outbreaks and 1,163 from sporadic diarrheal cases. Among the former, 209 isolated from 19 episodes (37%) were type LIO 7, followed by 43 of type LIO 2 from eight episodes (16%). Among the latter, 145 isolates (20%) were type LIO 4, followed by 63 (8.6%) of type LIO 7, 62 (8.5%) of type LIO 1 and 52 (7.1%) of type LIO 2 (see p. 109 of this issue).
Inpatient reports from IDHs: The age distribution of the 214 inpatients diagnosed as Campylobacter enteritis during 1995 through 1998 (Table 4) shows that the age group of 0-9 years accounted for 35%, 20-29 years accounted for 33%, 10-19 years for 17% and over 30 years for a low percent. Of the age group of 20-29 years, 63% of the cases were infected overseas. There were slightly more male cases than female ones. The inpatients were too few to correlate the incidents with the season (Fig. 2b). Inpatients showed such symptoms as watery stool (90%), bloody stool (48%) and mucoid stool (25%). Abdominal pain was noted in 87% and vomiting in 38% of the patients. The maximum body temperature was 38.3C on average.
The drug-sensitivity tests with C. jejuni isolates performed at IDHs detected nalidixic acid (NA)-resistant ones in 5.9% (2/34) of the isolates in 1995, 37% (15/41) in 1996, 33% (11/33) in 1997, and 42% (8/19) in 1998, showing an increasing tendency. The NA-sensitivity used to be an important indicator for identification of C. jejuni and C. coli, but differentiating species of Campylobacter has become difficult because of the increase in NA-resistant organisms. Campylobacter isolates resistant to ofloxasin (OFLX) of the pyridonecarboxylic acid group are also increasing; 31% (5/16) of the isolates proved resistant in 1998. The results obtained by the Campylobacter Reference Centers of PHIs also showed an increase in OFLX-resistant strains (see p. 109 of this issue). On the other hand, erythromycin (EM)-resistant isolates were very few, being 2/159 strains (1.3%).
Recently, cases showing Guillain-Barre syndrome, being a neuropathic disease, or Fisher's syndrome (a subtype of it with extraocular paralysis) developing after C. jejuni enteritis have been reported (see p. 111 of this issue). To date, their relation or their pathogenesis has not fully been understood.
The general precaution to prevent Campylobacter enteritis is thorough heating of chicken meat before consumption. In addition, precaution is necessary to prevent the secondary contamination from raw chicken meat through cookware such as kitchen knives and cutting boards and fingers, all of which can contaminate other food items.