NEW : Spokeswoman : 4 tested in San Francisco for MERS ; 1 has died . One traveler who was on one possibly affected flight told CNN affiliate WMKG that the call she got about one confirmed case of MERS left her `` really scared . '' A case in the Netherlands brings the news to 18 countries worldwide . CDC official : ` ` We do n't know as much as we 'd like so far '' Two U.S. airlines are coordinating with health officials over cases in Europe .
NEW : Spokeswoman : 4 tested in San Francisco for MERS ; 1 has died . A case in the Netherlands brings the news to 18 countries worldwide . CDC official : ` ` We do n't know as much as we 'd like so far '' Two U.S. airlines are coordinating with health officials over cases in Europe .