Abstract
297 healthy persons were investigated on a volunteer basis for human brucellosis using S.A.T. 221 of them were in contact with cattle, sheep or goats; and 14.9 per cent of such people were found reactors. Those who were not in contact with animals (76 persons) gave 14.5 per cent rate of reactivity. To interpretate the S.A.T. for diagnosis of human brucellosis in the Sudan, the significant titre needs to be 160 I.U./ml or over (for persons not in contact with animals), and 320 I.U./ml or over for persons in contact with animals.