The prevalence of Crohn ' s disease in the Israeli Kibbutz population

An epidemiological study of Crohn’s disease was performed in 279 Israeli Kibbutzim (rural communities) (population 121,403). The prevalence on December 31, 1987 was 25.53 per 100,000 population. When the data were stratified according to ethnic group, the highest point prevalence was found in Asian/African-born Jews (41.76 per 100,000 population), greater than in Israeli-born, or European/American-born Kibbutz members (38.92 and 17.35 cases per 100,000 population, respectively). There were 15 women and 16 men (female to male ratio 0.94). The average age of patients was 45 years in the survey year, and 35 years at diagnosis. Terminal ileitis was found in 69%, ileocolitis in 19%, and colitis in 12%. Probable complications of Crohn’s disease were observed in 10 cases (32%). Anemia was demonstrated in two cases (6%). The high rate of Crohn’s disease prevalence among Israeli-born versus European/American-born Kibbutz members may point to a role for environmental factors in the etiology of the disease.

T l IE PREVALl:.NCE OF CRO! IN'S DIS- ease varies in <lifferent area5 of the world, and is repone<l to be high among peoples of Europea n origin.The high anc.lvariable inci<lence and prevalence of Crohn's dbease in Jews can possibly be explained by an interaction of ge netic and environmental factors.In all countries surveyed the prevalence is 10 to 70 cases per 100,000 populat ion, three to eight t imes more common among Jews compare<l to non-Jews (1-12).An overall increase in inci<lcnce an<l prevalence in many recent studies was shown for Crohn's J iscase (13,15).In Israel.Crohn's d isease is fou r times more prevalent among Ashkenazi Jews than among non-Ashkenazim, with a greatly increased frequency among Israeli Jews born in Europe or the U n ited Scates.Nevertheless, the prevalence in t he latter group is three to 10 times lo wer than among Jews living outside Israel (16)(17)(18)(19)(20) .
A s a high incidence and prevalence of ulce rative colitis was found in members of a Kibbutz (an Israeli rural community) (2 l ), a survey of a ll of the Kibbutzim in Israel was performed to detennine the Crohn's disease point prevalence in this particular population.

PATIENTS AND METHODS
A community-based survey was con-ducte<l.T he ILJcal ph ysician of every Kibbutz was a<ldressed by mail and telephone and his o r her agreement to participate in this survey was obtained.A questionnaire concerning Crohn's  The data were studie<l carefully to ensu re that no patient with Crohn's disease represented a duplicate case.

General demograph ic d ata:
The total populau on of 279 Kibbutz im on the prevalence Jay was 121,403 Jew ish residents.St ratification by place of birth was Europe/America 62%, Israel 25%, and Asia/Africa 6% (Table l ).
P revalence: Thin y-s1x Crohn 's diseasl.' panenrs were residents of t he Kibbutzim on the pre\'alence day.Patients whod1J not fulfil I res1Je1ll y criteria ( three rem porary residents) and those whose d1ag noses we re not conf I rmcd in ,1 gastroenternlogy cl inic (two cases) were excluded.
Thus, 31 cases were 111cluded in thl.' sruJy (Tahlc l ).There were 15 wnn1l'n and 16 men (femn le to male rat1n 0.94 ).The prevalence was 2 5. 5 3 per l 00,000 populauon.The pre\'aleille m men wa, slightly higher than that in women.A breakdown of prevalenle races by eth nic group is given in Tahlc I. Thi Thu~. the increase of Crohn's Ji ea~e prevalence m A~ian/Afncan-hom II-raeli Jews was almost four times that in European/American-born Israe li Jews.Asian/American-bo rn Kibbutz members had a higher point prevalence of Crohn's disease than the others, and the prevalence ra te in Israeli-born members exceedeJ that in Europea n/ American-born memhers.However, most of the Jsrae li-bom Kibbutz me mhers were of European/Ame rican origin, either first or second ge neration in Israel.Thus, it is no t clear whethe r environmental fac tors play a more important role than genet ic facto rs.S ince the peak incidence of C ro hn's disease occurs in the second and third decades of life, and European/Ame rican-and Asian/African-horn groups may be older than Israeli-born patients, these results become even more significant. The

TABLE 1
Point prevalence of Crohn's disease in the Kibbutz population of Israel(1987) (23 )e level of medical care in the Kibbu tz is somewhat above average Israeli fa mily medicine, and as every Kibbutz has its own clinic, the author be lieves tha t almost e ve ry C rohn's disease case could be t raced.People with known Crohn's disease canno t become me mbers of a Kibbutz, since the criteria fo r accepting new me mbers are ve ry strict, a nd inc lude 'perfect health'.The high pre valence n oted in this study may relate also to the very steady Kibbutz population allowing inclusion of some cases with delayed diagnoses.Some cases may possibly have been added in a colorecral screening program of fecal nccult blood testing, as secondary prevention of cancer is very popular in the Kibbutzim.Mayberry et al(23 )fo und two cases of Crohn's disease out o f 481 patients screened via feca l occult blood test.