Pediatric Pulmonology 35:184–191 (2003) Viral Respiratory Infections in Young Children Attending Day Care in Urban Northeast Brazil Leda Solano de Freitas Souza, MD, PhD, 1 * Eduardo Anto ˆ nio Gonc ¸ alves Ramos, MD, PhD, 2 Fernando Martins Carvalho, MD, PhD, 1 Virgı ´nia Maria Castro Ribeiro Guedes, MD, 1 Lı ´dia Silva Souza, MD, 1 Cristiane Machado Rocha, MD, 1 Andre ´ a Barreto Soares, MD, 1 Luciana de Freitas Velloso, MD, 1 Izolete Santos Macedo, MSc, 3 Fernanda Edna Araujo Moura, MD, 2 Marilda Siqueira, PhD, 4 Silvana Fortes, 4 Cibele Cruz de Jesus, 2 Christiane Maria Gaspar Santiago, 2 Ana Maria da Silva Carvalho, 2 and Eurico Arruda, MD, PhD 3 Summary. A cohort of children attending a day care center in Salvador (Bahia, Brazil) was studied prospectively to determine the incidence of viral respiratory infectious episodes and to identify the viruses associated with them. Two hundred seventy-one nasopharyngeal samples were collected over a 1-year period for examination, using indirect immunofluorescence with monoclonal anti- bodies against adenovirus, influenza A and B, parainfluenzae 1–3, and respiratory syncytial virus, and reverse transcriptase-polymerase chain reaction for picornavirus. Examination yielded positive results in 116 samples (42.8%). Rhinovirus was identified alone in 56 samples (48.3%) and was observed along with other viruses in 11 additional samples. Incidence density of viral respiratory infectious episodes was 7.66 episodes/1,000 child-days. Pediatr Pulmonol. 2003; 35:184–191. ß 2003 Wiley-Liss, Inc. Key words: acute respiratory infections; viral respiratory infections; rhinovirus; day care center; infants; epidemiology; wheezing. INTRODUCTION Acute respiratory infections (ARI) are prevalent world- wide, and rival diarrhea as the leading cause of death in children less than 1 year old in developing countries. 1,2 Several community-based studies have established the importance of common viral ARI in tropical countries. 3 Providing suitable day care for young children has become an important economic issue, especially in de- veloping nations, where mothers from underprivileged classes join the work force to contribute to the family income. Some studies have shown that attending day care can be a risk factor for respiratory diseases in young children. 4–8 Therefore, it is relevant to carry out studies on the etiology of ARI in day care facilities which constitute probably the most favorable environment for the transmis- sion of common respiratory viruses among assembled sus- ceptible hosts. Surprisingly, studies on the viral etiologies of ARI in children attending day care are relatively few in the indexed literature. 9–11 The institution of possible inter- ventions for the prevention of ARI in day care children in tropical areas will depend on assessing the frequency, etiologies, and seasonality of these infections. We shall report results of a day care-based ARI study, carried out over a 12-month period to determine the frequency, seasonality, and certain clinical features of common viral ARI in children younger than 2 years old in Salvador, Bahia, Northeast Brazil. 1 Department of Pediatrics and Department of Preventive Medicine, Faculty of Medicine Federal University of Bahia, Salvador, Bahia, Brazil. 2 Gonc ¸alo Moniz Research Center, Oswaldo Cruz Foundation, Salvador, Bahia, Brazil. 3 Virology Laboratory, Department of Cell and Molecular Biology, University of Sa ˜o Paulo School of Medicine, Ribeira ˜o Preto, Sa ˜o Paulo, Brazil. 4 Oswaldo Cruz Foundation, Rio de Janeiro, Brazil. Grant sponsor: FAPESP; Grant sponsor: FIOCRUZ and PAPES Program and CPGM; Grant sponsor: CNPq. *Correspondence to: Leda Solano de Freitas Souza, M.D., Ph.D., Rua Ernesto de Melo Jr 79, Pituba 41820-060, Salvador, Bahia, Brazil. E-mail: ledasolano@bol.com.br Received 19 February 2001; Accepted 12 April 2002. DOI 10.1002/ppul.10194 Published online in Wiley InterScience (www.interscience.wiley.com). ß 2003 Wiley-Liss, Inc.