On Thursday, pilgrims will make the short trip to Mina, about 5 kilometers (3 miles) from Mecca, where they will spend the night praying. Thursday's journey marks the official start of the hajj, begun annually on the eighth day of the Muslim calendar month of Dhul Hijja.

All Muslims who are physically and financially able to must observe the 1,400-year-old rite at least once in their lifetimes. The hajj lasts about five days and in its present form was established by the Muhammad - Islam's founder and central figure, who, in the year 630, gave his final sermon on Mount Arafat, where the pilgrimage officially ends. Hajjis will spend Friday night sleeping under the stars in Muzdalifah before returning to Mina Saturday for three more days of rituals.

Men wear a seamless two-piece white garment, meant to symbolize a state of purity and emphasize their unity regardless of social status or nationality. Women also generally wear white, exposing only their faces and hands.

This year, Saudi Arabia banned pilgrims from Sierra Leone, Liberia and Guinea, the countries hardest-hit by the current Ebola outbreak. The MERS coronavirus, which has hit Saudi Arabia especially hard, has also weighed heavily on officials' minds.

mkg/kms (AFP, AP)