1. Department of Microbiology, Immunology and Parasitology; Escola Paulista de Medicina; Rua Botucatu, 862, CEP 04023-062 Sao Paulo SP Brazil
2. Foodborne and Diarrheal Diseases Branch, Division of Bacterial and Mycotic Diseases, National Center for Infectious Diseases; Centers for Disease Control and Prevention; Atlanta Georgia 30333 U.S.A.
3. Hospital Infantil Menino Jesus; 01329 Sao Paulo
4. Instituto da Criança; Universidade de São Paulo; CEP, 05403-000 São Paulo SP Brazil