The significance of the sickle-cell trait is that it does not show any symptoms, nor does it cause any major difference in blood cell count. The trait confers about 30% protection against malaria {clarify} and its occurrence appears to have risen tremendously in Africa, India and the Middle East. {over what period of time?} Some findings also show the reduction of the sickle-cell trait in those who retain much more fetal hemoglobin than usual in adulthood. Fetal hemoglobin likely plays a role in the prevention of sickling. Elevated fetal hemoglobin levels have been observed in populations where sickle-cell disease is prevalent.