[1] Ctr Dis Control & Prevent, Meningitis & Special Pathogens Branch, Div Bacterial & Mycot Dis, Natl Ctr Infect Dis,CDC, Atlanta, GA 30333 USA
[2] Univ Texas, SW Med Ctr, Dallas, TX 75230 USA
[3] St Marys Hosp, Imperial Coll London, Fac Med, Dept Infect Dis Epidemiol, London, England