NEW : Spokeswoman : Two tested in San Antonio for MERS The spread of the potentially fatal Middle East respiratory syndrome has become more serious and urgent , the World Health Organization said Wednesday . ; none has symptoms . A case in the U.S. brings the total to 4 countries affected . CDC official : `` We do n't know as much as we 'd like so far '' 18 San Antonio airlines are coordinating with health officials over cases in U.S .
NEW : Spokeswoman : Two tested in San Antonio for MERS ; none has symptoms . A case in the U.S. brings the total to 4 countries affected . CDC official : `` We do n't know as much as we 'd like so far '' 18 San Antonio airlines are coordinating with health officials over cases in U.S .