The Reference Committee, the Associations of Public Health Laboratories for Microbiological Technology established the Campylobacter Reference Centers of PHIs in Tokyo and six other prefectures, collecting C. jejuni isolates to perform serotyping and drug susceptibility tests. The following is a summary of the Campylobacter enteritis incidence in the whole country during the past 7 years based on the above reports (see IASR 14:143-144, 1993 and 20:107-108, 1999 concerning the incidence before 1998).
The Statistics of Food poisoning: Food poisoning incidents by causative agent show Campylobacter incidents third most prevalent following Salmonella and Vibrio parahaemolyticus incidents until 1997-1999. After 2000, Salmonella and V. parahaemolyticus incidents decreased largely, while Campylobacter incidents showed no decrease (see p. 169 of this issue); until 2003, incidents used to be counted at the level of 400, while increased to 558 in 2004 and to 645 in 2005 (Fig. 1). Campylobacter food poisoning cases used to count at about 1,800 until 1999-2001, but exceeded 2,000 in 2002, and increased to 3,439 in 2005 (Fig. 1), about the same count as salmonellosis after norovirus infection (see p. 169 of this issue). Single-case incidents account for more than 70% of Campylobacter food poisoning incidents (Fig. 1). This was due to the fact that some municipalities started to report single-case food poisoning incidents in 1997.
Isolation reports from PHI/HC: Yearly reports of isolation of Campylobacter during 1999-2005 are shown in Table 1. Food poisoning cases are on the increase as shown above; reports of isolation of the organisms have also been on the increase after 2003, being about 1,200. Most reports of isolation in 1999-2005 completed species identification; C. jejuni accounted for 97% of Campylobacter isolates and C. coli for very low percentage. Imported cases were rare. Such tendency has been unchanged since 1986 (see IASR 20:107-108, 1999). Monthly reports of Campylobacter isolation during 1999-2005 (Fig. 2) show peaks during April-July, as was the case before 1998.
Campylobacter food poisoning outbreaks reported during 1999-2005 by PHI/HC counted at 350, of which C. coli outbreaks were 10 (Table 2). Campylobacter food poisoning is characterized by showing peaks earlier in May-July than Salmonella and V. parahaemolyticus food poisoning, which show peaks in summer and occurs even in winter when Salmonella and V. parahaemolyticus food poisoning occur rarely (Table 2). Outbreaks involving more than 100 cases counted at 5, those involving 50-99 cases 17, those 10-49 cases 165, and those 2-9 cases 146. In 182 of 350 outbreaks, causative food was identified. Meat was most popular. Incriminated meat was mostly chicken and its internal organs. Eating raw internal organs of other animals such as beef lever may sometimes cause food poisoning [Prevention of Campylobacter food poisoning by bovine lever (Q&A). Notice No. 0209001 by the Inspection and Safety Division, the Department of Food Safety, the Ministry of Health, Labour and Welfare, February 9, 2005]. In 1996, the period of saving food samples was extended to 2 weeks (Notification No. 201 by Environmental Health Bureau, Ministry of Health, Labour, and Welfare on July 25, 1996). Campylobacter may not often be isolated from food specimens, because the incubation period of acute gastroenteritis due to this organism is a little longer, 2-7 days, and the organisms are injured by freezing.
In the reports of food surveillance by PHI/HC during 1999-2005 (Table 3), C. jejuni/coli was isolated from chicken meat in 32% and from other meat in 38%, supporting that Campylobacter enteritis is caused by contaminated meat.
The Research Group for Infectious Enteric Diseases, Japan: The age distribution of 397 cases of Campylobacter enteritis admitted to infectious disease hospitals during 2001-2005 (Table 4) shows a similar tendency as in the preceding report that 0-9 years old cases accounting for 28%, 10-19 years 25%, 20-29 years old as high as 29%, and 30 years and older accounted for very low percentage. Of 20-29 year old cases, 28% were acquired infection overseas. There were slightly more male cases than female ones.
Serotypes and drug susceptibilities of the isolates: The Campylobacter Reference Center conducts serotyping of C. jejuni by the Lior system (see p. 173 of this issue). During 1998-2004, 4,596 strains of C. jejuni derived sporadic diarrhea cases were subjected to serotyping. A total of 2,930 strains were typed to a single serotype; LIO4 type was the largest in number, 743 strains, followed by 308 strains of LIO7 type.
Concerning the drug susceptibilities of C. jejuni derived from sporadic cases during 1998-2004, 30-40% were tetracycline-resistant and 30-40% nalidixic acid-resistant and/or fluoroquinolone-resistant. On the other hand, erythromycin-resistant was very rare, 1-3%.
Recently, reports are seen that after Campylobacter enteritis, Guillain-Barré syndrome, a neurological disease, developed in some cases (see IASR 20:111-112, 1999 and p. 175 of this issue).
Campylobacter enteritis is often caused by meat contaminated with this organism. On the other hand, incidents caused by secondary contamination during cooking have also been reported (see p. 171-173 of this issue). For general precaution for prevention of Campylobacter enteritis, eating raw meat should be avoided, cook food sufficiently and avoid secondary contamination to other food (particularly those eaten raw such as raw vegetables) through cutting boards and other cooking utensils and fingers.