NEW : Twenty - two cases of swine flu confirmed by health officials worldwide . U.S. urges travelers to avoid nonessential travel to Mexico . Mexican health official : The median age of all the U.S. cases is 16 years , Besser said . As many as 149 deaths may be from swine flu . Mexico closes all schools until at least May 6 .
NEW : Twenty - two cases of swine flu confirmed by health officials worldwide . U.S. urges travelers to avoid nonessential travel to Mexico . Mexican health official : As many as 149 deaths may be from swine flu . Mexico closes all schools until at least May 6 .