Karni A, Kahana E, Zilber N, Abramsky O, Alter M, Karussis D.
Department of Neurology, Barzilai Medical Center, Ashkelon, Israel.
A comparison of the incidence rate (IR) and the prevalence rate (PR) of multiple sclerosis (MS) in subgroups of the same ethnic origin, but born and living in different geographical areas, may delineate the relationship between environmental and genetic risk factors for MS.
Previous epidemiological studies of MS in Israel did not include the Arab population and used diagnostic criteria that did not include MRI findings.
Therefore, we studied the age-adjusted IR and PR of MS in a more recent sample in different population groups, including Arabs, of Greater Jerusalem.
We found that the PR of MS in Israeli Jews is higher than previously described.
Furthermore, the PR was significantly lower among immigrant Jews from Asia/Africa (A/A) than among native-born Jews of Asian/African origin (I-A/A).
Since these groups have similar genetic susceptibilities to MS, the higher PR in the latter is probably due to environmental factors.
Our study does not support the effect of latitude on the risk of developing MS since no difference in the PR was found between immigrant Jews from Europe/America (E/A) and native-born Jews of European/American origin (I-E/A).
Among Arabs, the PR was similar to that among A/A.
Therefore, we hypothesized similarity in environmental etiologic factors for MS between the countries of origin of A/A immigrants and of Arabs communities in Greater Jerusalem.
The IR of I-E/A was higher than that of I-A/A and Arabs, although this difference did not reach statistical significance.