Saudi Arabia, which gets millions of visitors each year making their pilgrimage to Mecca, has ordered all young visitors from countries with polio cases to bring proof of vaccination and will vaccinate them again when they arrive, the World Health Organization announced yesterday. In issuing the order, which applies to everyone under age 15 from 19 countries, the kingdom is moving to stem the global spread of the polio virus, which now affects mainly Muslim countries and regions. Although the next pilgrimage, or hajj, will not reach its peak until early January, the order will take effect as soon as...