Hundreds of thousands of muslims are gathering in Mecca for the start of this year’s hajj pilgrimage.The occasion has been marred in the past by political protests, stampedes and even deaths. But this year there’s a new worry: swine flu. The concentration of so many people provides an ideal breeding ground for the virus. It’s feared sick people will return home and spark a virulent new epidemic. Saudi authorities are taking no risks. “I’m very confident,” said Health Minister Dr Abdullah al-Rabeeah. “Confident, first of all, in the preparations. Confident in the team of the Ministry of Health, confident in our supplies, and confident in the facilities that are enough if needed.” Saudi Arabia has urged young and elderly pilgrims and those already ill to stay away, and has installed detection devices at ports and airports to screen arrivals. Tunisia has gone further, banning its citizens from making the hajj this year. Masks are available on the streets of Mecca, but there is a serious religious problem. Staunch pilgrims are not allowed to wear anything knitted or made of gauze, as masks are, so the careful precautions may prove useless.