Epidemiology and clinical presentation of respiratory syncytial virus infections in Fortaleza city, Northeast Brazil

O vÃrus sincicial respiratÃrio (VSR) destaca-se como patÃgeno importante de infecÃÃes das vias aÃreas inferiores (IVAI) infantis, principalmente no primeiro ano de vida. Este estudo teve como objetivos: determinar a prevalÃncia do VSR em casos de infecÃÃes respiratÃrias agudas (IRAs) em crianÃas atendidas no Hospital Infantil Albert Sabin, em Fortaleza - CE, entre janeiro de 2001 e julho de 2004; descrever o padrÃo de sazonalidade de circulaÃÃo do VSR ao longo do perÃodo de estudo; observar caracterÃsticas clÃnico-epidemiolÃgicas dessas infecÃÃes; caracterizar antigenicamente os VSR circulantes nos perÃodos epidÃmicos de 2003 e 2004 e determinar a taxa de isolamento do VSR em cultura de cÃlulas HEp-2 a partir de amostras coletadas em 2002, 2003 e 2004 e estocadas a â20ÂC. Aspirados de nasofaringe foram coletados de crianÃas com atà sete dias de inÃcio dos sintomas de IRA e submetidos à reaÃÃo de imunofluorescÃncia indireta (IFI). Amostras coletadas em 2002, 2003 e 2004, armazenadas a â20ÂC, foram inoculadas em monocamadas de cÃlulas HEp-2. Nos 43 meses de estudo, o VSR foi identificado em 21,0% (409/1950) dos espÃcimes clÃnicos coletados. A circulaÃÃo do vÃrus foi inicialmente observada nos meses de janeiro ou fevereiro e os Ãltimos casos foram registrados em julho ou agosto de cada ano de estudo. O pico dessas infecÃÃes foi observado nos meses de marÃo a julho, sendo associado à estaÃÃo chuvosa da cidade. As infecÃÃes causadas pelo VSR foram mais freqÃentes em crianÃas de sexo masculino e naquelas com atà dois anos de idade. Bronquiolite e pneumonia foram as sÃndromes clÃnicas mais associadas ao vÃrus. DispnÃia, dor de garganta, coriza, espirros e cianose foram os sinais e sintomas clÃnicos associados significativamente nas IRAs causadas pelo VSR. Cerca de 9,5% (39/409) das crianÃas infectadas apresentaram problemas associados, como prematuridade, cardiopatia e doenÃas pulmonares congÃnitas. Entre os fatores de risco associados a essas infecÃÃes, destacou-se a exposiÃÃo à IRA no domicÃlio. Cepas de VSR A e B co-circularam nos perÃodos epidÃmicos analisados, sem uma predominÃncia significativa de qualquer grupo antigÃnico. Cerca de 29,8% (122/409) das amostras positivas para VSR, estocadas a â20ÂC, foram inoculadas em monocamadas de cÃlulas HEp-2. O percentual de isolamento variou de 0,0%, em amostras coletadas em 2002, a 36,8%, em 2004. Nossos resultados confirmam a importÃncia do VSR como agente etiolÃgico de IRAs, especialmente IVAI, em crianÃas jovens. A ocorrÃncia do VSR na cidade de Fortaleza mostrou um padrÃo sazonal regular associado Ãs chuvas. A conservaÃÃo de amostras a â20ÂC nÃo impossibilitou o isolamento em cultura de cÃlulas atà um ano apÃs seu congelamento.Respiratory syncytial virus (RSV) is detached as an important pathogen of lower respiratory tract infections (LRTI) in children, mainly in the first year of life. This study had as purposes: to determine the prevalence of RSV in cases of acute respiratory infections (ARIs) in children served in Albert Sabin Children Hospital, in Fortaleza â CE, over the period of January 2001 to July 2004; describe the seasonality pattern of RSV circulation along the study period; observe characteristics clinical-epidemiological of these infections; characterize antigenically the circulating RSV in the epidemic period from 2003 to 2004 and determine the isolation rate of RSV in HEp-2 cells culture from samples collected in 2002, 2003, and 2004 and stored at â20ÂC. Aspirated from nasopharynx were collected from children with up to seven days from the beginning of ARIs symptoms and submitted to the reaction of indirect immunofluorescence (IIF). Samples collected in 2002, 2003, and 2004, and stored at â20ÂC, were inoculated in monolayers of HEp-2 cells. During the 43 months of study, RSV was identified in 21.0% (409/1950) of the clinical specimens collected. Virus circulation was initially observed during the months of January or February and the last cases were recorded in July or August of each year of study. The peak of these infections was observed from March to July, associated with the rainy season of the city. The infections caused by RSV were more frequent in male children and those with up to two years of age. Bronchiolitis and pneumonia were the clinical syndromes more associated with the virus. Dyspnea, throat pain, coryza, sneezes and cyanosis were the significant clinical signs and symptoms in ARIs caused by RSV. About 9.5 % (39/409) of the infected children presented problems associated, such as prematurity, heart diseases and congenital pulmonary diseases. Among the risk factors associated with these infections, was pointed out the exposure to ARIs in the domicile. Strains of RSV A and B co-circulated during the epidemical periods analyzed, without a significant predominance of any antigenical group. About 29.8 % (122/409) of the positive samples for RSV, stored at â20ÂC, were inoculated in monolayers of HEp-2 cells. The isolation percentage varied from 0.0 %, in samples collected in 2002, to 36.8 %, in 2004. Our results confirm the importance of the RSV as etiological agent of ARIs, especially LRTI, in young children. The occurrence of RSV in the city of Fortaleza showed a regular seasonal pattern associated with the rains. The conservation of samples at â20ÂC did not make impossible the isolation in cells culture up to one year after freezing