BACKGROUND The emergence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variants has become a major concern contributing to increased morbidity and mortality worldwide. OBJECTIVES Here we describe the replacement of the Gamma variant of concern (VOC) with Delta in the western Brazilian Amazon. METHODS In this study, we analysed 540 SARS-CoV-2 positive samples determined by qualitative real-time RT-PCR selected in the state of Rondônia between June and December 2021. The positive cohort was sequenced through next-generation sequencing (NGS) and each sample was quantified using real-time RT-qPCR, the whole genome sequence was obtained, SARS-CoV-2 lineages were classified using the system Pango and the maximum likelihood (ML) method was used to conduct phylogenetic analyses. FINDINGS A total of 540 high-quality genomes were obtained, where the Delta VOC showed the highest prevalence making up 72%, with strain AY.43 being the most abundant, while the Gamma VOC was present in 28%, where the P.1 strain was the most frequent. In this study population, only 32.96% (178/540) had completed the vaccination schedule. MAIN CONCLUSIONS This study highlighted the presence of Gamma and Delta variants of SARS-CoV-2 in RO. Furthermore, we observed the replacement of the Gamma VOC with the Delta VOC and its lineages.

BACKGROUND The coronaviruses (CoVs) called the attention of the world for causing outbreaks of severe acute respiratory syndrome (SARS-CoV), in Asia in 2002-03, and respiratory disease in the Middle East (MERS-CoV), in 2012. In December 2019, yet again a new coronavirus (SARS-CoV-2) first identified in Wuhan, China, was associated with a severe respiratory infection, known today as COVID-19. This new virus quickly spread throughout China and 30 additional countries. As result, the World Health Organization (WHO) elevated the status of the COVID-19 outbreak from emergency of international concern to pandemic on March 11, 2020. The impact of COVID-19 on public health and economy fueled a worldwide race to approve therapeutic and prophylactic agents, but so far, there are no specific antiviral drugs or vaccines available. In current scenario, the development of in vitro systems for viral mass production and for testing antiviral and vaccine candidates proves to be an urgent matter. OBJECTIVE The objective of this paper is study the biology of SARS-CoV-2 in Vero-E6 cells at the ultrastructural level. METHODS In this study, we documented, by transmission electron microscopy and real-time reverse transcription polymerase chain reaction (RT-PCR), the infection of Vero-E6 cells with SARS-CoV-2 samples isolated from Brazilian patients. FINDINGS The infected cells presented cytopathic effects and SARS-CoV-2 particles were observed attached to the cell surface and inside cytoplasmic vesicles. The entry of the virus into cells occurred through the endocytic pathway or by fusion of the viral envelope with the cell membrane. Assembled nucleocapsids were verified inside rough endoplasmic reticulum cisterns (RER). Viral maturation seemed to occur by budding of viral particles from the RER into smooth membrane vesicles. MAIN CONCLUSIONS Therefore, the susceptibility of Vero-E6 cells to SARS-CoV-2 infection and the viral pathway inside the cells were demonstrated by ultrastructural analysis.

Coronavirus disease 2019 (COVID-19) surveillance, in Brazil, initiated shortly after its description, in China. Our aim was to detect severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and additional pathogens in samples from the initial phase of the outbreak in Brazil, from late February to late March. From 707 samples analysed, 29 (4.1%) were SARS-CoV-2 positive. Fever and cough were their most prevalent symptoms. Co-detection of rhinovirus was observed in 2 (6.9%) cases. Additional pathogens were identified in 66.1% of the SARS-CoV-2 negative cases, mainly rhinovirus and influenza A(H1N1)pdm09. Thus, we emphasise the importance of differential diagnosis in COVID-19 suspected cases.

This study presents preliminary results from a sewage-based surveillance to monitor the spread of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in the municipality of Niterói, State of Rio de Janeiro, Brazil. By using ultracentrifugation method associated to quantitative reverse transcription polymerase chain reaction (RT-qPCR) we detected SARS-CoV-2 in 41.6% (5/12) of raw sewage samples obtained from sewage treatment plants and sewers network in the city. This pioneer study carried out in Brazil aims to subsidise information for health surveillance concerning the viral circulation in different areas of the city and, revealed the insertion and importance of environmental virology in health public policies.

BACKGROUND Field testing required to license the combined measles, mumps, and rubella (MMR) vaccine must take into account the current recommendation of the vaccine in Brazil: first dose at 12 months and second dose at 15 months of age in combination with a varicella vaccine. OBJECTIVES This study aimed to evaluate the clinical consistency, immunogenicity, and reactogenicity of three batches of MMR vaccine prepared with active pharmaceutical ingredients (API) from Bio-Manguinhos, Fiocruz (MMR-Bio), and compare it to a vaccine (MMR produced by GlaxoSmithKline) with different API. METHODS This was a phase III, randomised, double-blind, non-inferiority study of the MMR-Bio administered in infants immunised at health care units in Pará, Brazil, from February 2015 to January 2016. Antibody levels were titrated by immunoenzymatic assays. Adverse events were recorded in diaries. FINDINGS Seropositivity levels after MMR-Bio were 97.6% for measles, 84.7% for mumps, and 98.0% for rubella. After the MMRV vaccine, seroconversion rates and GMT increased substantially for mumps. In contrast, approximately 35% of the children had no detectable antibodies to varicella. Systemic adverse events were more frequent than local events. CONCLUSION The demonstration of batch consistency and non-inferiority of the Bio-MMR vaccine completed the technology transfer. This is a significant technological achievement with implications for immunisation programs.

A non-controlled longitudinal study was conducted to evaluate the combined vaccine against measles, mumps and rubella (MMR) immunogenicity in 150 children vaccinated in the routine of three health units in the city of Rio de Janeiro, Brazil, 2008-2009, without other vaccines administered during the period from 30 days before to 30 days after vaccination. A previous study conducted in Brazil in 2007, in 1,769 children ranging from 12-15 months of age vaccinated against yellow fever and MMR simultaneously or at intervals of 30 days or more between doses, had shown low seroconversion for mumps regardless of the interval between administration of the two vaccines. The current study showed 89.5% (95% confidence interval: 83.3; 94.0) seroconversion rate for mumps. All children seroconverted for measles and rubella. After revaccination, high antibody titres and seroconversion rates were achieved against mumps. The results of this study and others suggest that two MMR doses confer optimal immunoresponses for all three antigens and the possible need for additional doses should be studied taking into account not only serological, but also epidemiological data, as there is no serological correlate of protection for mumps.

Erythrovirus B19 (B19V) infection may cause red cell aplasia in patients infected with human immunodeficiency virus (HIV). The introduction of highly active antiretroviral therapy (HAART) has improved the immune function of these patients by modifying the course of B19V infection. The purpose of this study was to estimate the frequency of B19 seroconversion in a cohort of HIV-infected patients and evaluate the occurrence of B19V-related anaemia during the seroconversion period. Adult HIV-infected patients were studied at a public hospital in Niterói, state of Rio de Janeiro, Brazil. IgG and IgM antibodies against B19V were detected by an enzyme-linked immunosorbent assay and B19 viraemia was assayed by polymerase chain reaction. Medical records were reviewed for any clinical evaluation of anaemia. Seroconversion was detected in 31.8% of the 88 individuals who began the study as anti-B19V IgG-negative. No clinical manifestations of B19V infection were detected during the period of seroconversion. Patients who seroconverted were 5.40 times more likely to have anaemia than those who did not [odds ratio 5.40 (95% confidence interval: 1.33-22.93)]. Anaemia was detected in eight patients. All patients recovered from anaemia by either beginning or continuing HAART, without requiring blood transfusions. In the HAART era, B19V infection may only be associated with a course of disease characterised by less severe chronic anaemia. This milder course of B19V-associated disease is likely due to the increased immune function of HAART-treated patients.

Dengue virus (DENV) and parvovirus B19 (B19V) infections are acute exanthematic febrile illnesses that are not easily differentiated on clinical grounds and affect the paediatric population. Patients with these acute exanthematic diseases were studied. Fever was more frequent in DENV than in B19V-infected patients. Arthritis/arthralgias with DENV infection were shown to be significantly more frequent in adults than in children. The circulating levels of interleukin (IL)-1 receptor antagonist (Ra), CXCL10/inducible protein-10 (IP-10), CCL4/macrophage inflammatory protein-1 beta and CCL2/monocyte chemotactic protein-1 (MCP-1) were determined by multiplex immunoassay in serum samples obtained from B19V (37) and DENV-infected (36) patients and from healthy individuals (7). Forward stepwise logistic regression analysis revealed that circulating CXCL10/IP-10 tends to be associated with DENV infection and that IL-1Ra was significantly associated with DENV infection. Similar analysis showed that circulating CCL2/MCP-1 tends to be associated with B19V infection. In dengue fever, increased circulating IL-1Ra may exert antipyretic actions in an effort to counteract the already increased concentrations of IL-1β, while CXCL10/IP-10 was confirmed as a strong pro-inflammatory marker. Recruitment of monocytes/macrophages and upregulation of the humoral immune response by CCL2/MCP-1 by B19V may be involved in the persistence of the infection. Children with B19V or DENV infections had levels of these cytokines similar to those of adult patients.

Heteroduplex mobility assay, single-stranded conformation polymorphism and nucleotide sequencing were utilised to genotype human parvovirus B19 samples from Brazil and Paraguay. Ninety-seven serum samples were collected from individuals presenting with abortion or erythema infectiosum, arthropathies, severe anaemia and transient aplastic crisis; two additional skin samples were collected by biopsy. After the procedure, all clinical samples were classified as genotype 1.

OBJECTIVE: To describe rubella outbreaks and control strategies in the Brazilian state of Rio Grande do Sul before rubella elimination. METHODS: We analyzed rubella and congenital rubella syndrome surveillance data for the state of Rio Grande do Sul and calculated age- and gender-specific incidence of confirmed rubella cases in 2007. We obtained data on measles-rubella doses administered during the outbreak from the state immunization program and reviewed the timing of suspect case notification and implementation of control measures. RESULTS: Of 2 842 confirmed rubella cases reported to the state health department in 2007, 2 145 (75.5%) were in males (39.5 cases per 100 000 population) and 697 (24.5%) were in females (12.3 per 100 000 population). Incidence among 15- to 39-year-olds was 1.8 to 5.5 times higher in males than in females. Rubella genotype 2B was detected in nasopharyngeal specimens from 13 patients from multiple chains of transmission. Eight children were born with congenital rubella syndrome (5.9 cases per 100 000 births in 2008). Delayed notification of initial cases hampered early control efforts, resulting in outbreak spread throughout the state. Rubella transmission was interrupted after mass vaccination of adult men and women as part of a national vaccination campaign. CONCLUSIONS: Routine vaccination strategies and mass vaccination of adolescents and adults for accelerated rubella control and elimination should target men and women.

OBJETIVO: Describir los brotes de rubéola y las estrategias para el control de la enfermedad anteriores a la eliminación de la rubéola en el estado brasileño de Rio Grande do Sul. MÉTODOS: Se analizaron los datos de vigilancia epidemiológica sobre la rubéola y el síndrome de rubéola congénita del estado de Rio Grande do Sul y se calculó la incidencia específica por edad y sexo de los casos confirmados de rubéola en el 2007. A partir del programa de vacunación estatal se obtuvieron datos sobre las dosis de vacunación antisarampionosa y antirrubeólica administradas durante el brote y se analizaron el momento de notificación de los casos sospechosos y la puesta en práctica de medidas de control. RESULTADOS: De los 2842 casos confirmados de rubéola notificados al departamento de salud estatal en el 2007, 2 145 (75,5%) correspondieron a hombres (39,5 casos por 100000 habitantes) y 697 (24,5%) a mujeres (12,3 por 100000 habitantes). La incidencia en las personas de 15 a 39 años de edad fue de 1,8 a 5,5 veces mayor en los varones que en las mujeres. En 13 pacientes provenientes de distintas cadenas de transmisión se detectó el genotipo 2B del virus de la rubéola en muestras obtenidas de la nasofaringe. Nacieron 8 niños con síndrome de rubéola congénita (5,9 casos por 100000 nacimientos en el 2008). La demora en la notificación de los casos iniciales obstaculizó la adopción temprana de medidas de control, lo que hizo que el brote se propagara a todo el estado. La transmisión de la rubéola se interrumpió después de la vacunación masiva de varones y mujeres adultos como parte de una campaña nacional de vacunación. CONCLUSIONES: Las estrategias de vacunación sistemática y la vacunación masiva de adolescentes y adultos tendientes a acelerar el control y la eliminación de la rubéola deben dirigirse tanto a varones como a mujeres.

OBJETIVO: Avaliar a acurácia da definição de caso suspeito de rubéola entre pacientes com doenças exantemáticas atendidos em unidades de saúde pública. MÉTODOS: A população de estudo foi constituída de pacientes com doença exantemática, com ou sem febre, atendidos em serviços de saúde pública, de janeiro de 1994 a dezembro de 2002 no município de Niterói, RJ. Dados clínicos e sorológicos foram utilizados para estimar os valores preditivos positivos da definição de caso suspeito de rubéola do Ministério da Saúde do Brasil e outras combinações de sinais e sintomas, considerando o resultado da sorologia como referência. A detecção de IgM específica para rubéola em amostras sangüíneas foi realizada por ensaio imunoenzimático. Foram calculados os valores preditivos positivos e respectivos intervalos de confiança de 95%. RESULTADOS: Foram estudados 1.186 pacientes com uma doença caracterizada por uma variada combinação de rash com ou sem febre, artropatia e linfoadenopatia. Pacientes com exantema, independentemente da presença de outros sinais e sintomas, apresentaram uma probabilidade de 8,8% de serem IgM positivos para rubéola. A definição de caso suspeito de rubéola utilizada no Brasil apresentou baixo valor preditivo positivo (13,5%). Esta definição de caso identificou corretamente 42,3% dos casos IgM positivos, e classificou de forma incorreta 26,1% dos IgM negativos. CONCLUSÕES: Os resultados indicam que as doenças exantemáticas devem ser investigadas em conjunto para fins de vigilância epidemiológica e coleta de espécimens clínicos para o diagnóstico laboratorial. Esta estratégia aumenta os custos, mas gera benefícios na interrupção da circulação do vírus e na prevenção da síndrome da rubéola congênita.

OBJECTIVE: To assess the performance of the rubella suspect case definition among patients with rash diseases seen at primary care units. METHODS: From January 1994 to December 2002, patients with acute rash, with or without fever, were seen at two large primary health care units and at a public general hospital in the municipality of Niterói, metropolitan area of Rio de Janeiro, Brazil. Data from clinical and serologic assessment were used to estimate the positive predictive values of the definition of rubella suspect case from the Brazilian Ministry of Health and other combination of signs/symptoms taking serologic status as the reference. Serum samples were tested for anti-rubella virus IgM using commercially available enzyme immunoassays. Positive predictive values and respective 95% confidence intervals were calculated. RESULTS: A total of 1,186 patients with an illness characterized by variable combinations of rash with fever, arthropathy and lymphadenopathy were studied. Patients with rash, regardless of other signs and symptoms, had 8.8% likelihood of being IgM-positive for rubella. The Brazilian suspect case definition (fever and lymphadenopathy in addition to rash) had low predictive value (13.5%). This case definition would correctly identify 42.3% of the IgM-positive cases, and misclassify 26.1% of the IgM-negative cases. CONCLUSIONS: These results support the recommendation to investigate and collect clinical specimens for laboratory diagnosis of all cases of rash, for surveillance purposes. Although this strategy may increase costs, the benefits of interrupting the circulation of rubella virus and preventing the occurrence of congenital rubella syndrome should pay off.

OBJETIVO: Avaliar a acurácia da definição de caso suspeito de rubéola entre pacientes com doenças exantemáticas atendidos em unidades de saúde pública. MÉTODOS: A população de estudo foi constituída de pacientes com doença exantemática, com ou sem febre, atendidos em serviços de saúde pública, de janeiro de 1994 a dezembro de 2002 no município de Niterói, RJ. Dados clínicos e sorológicos foram utilizados para estimar os valores preditivos positivos da definição de caso suspeito de rubéola do Ministério da Saúde do Brasil e outras combinações de sinais e sintomas, considerando o resultado da sorologia como referência. A detecção de IgM específica para rubéola em amostras sangüíneas foi realizada por ensaio imunoenzimático. Foram calculados os valores preditivos positivos e respectivos intervalos de confiança de 95%. RESULTADOS: Foram estudados 1.186 pacientes com uma doença caracterizada por uma variada combinação de rash com ou sem febre, artropatia e linfoadenopatia. Pacientes com exantema, independentemente da presença de outros sinais e sintomas, apresentaram uma probabilidade de 8,8% de serem IgM positivos para rubéola. A definição de caso suspeito de rubéola utilizada no Brasil apresentou baixo valor preditivo positivo (13,5%). Esta definição de caso identificou corretamente 42,3% dos casos IgM positivos, e classificou de forma incorreta 26,1% dos IgM negativos. CONCLUSÕES: Os resultados indicam que as doenças exantemáticas devem ser investigadas em conjunto para fins de vigilância epidemiológica e coleta de espécimens clínicos para o diagnóstico laboratorial. Esta estratégia aumenta os custos, mas gera benefícios na interrupção da circulação do vírus e na prevenção da síndrome da rubéola congênita.

OBJECTIVE: To assess the performance of the rubella suspect case definition among patients with rash diseases seen at primary care units. METHODS: From January 1994 to December 2002, patients with acute rash, with or without fever, were seen at two large primary health care units and at a public general hospital in the municipality of Niterói, metropolitan area of Rio de Janeiro, Brazil. Data from clinical and serologic assessment were used to estimate the positive predictive values of the definition of rubella suspect case from the Brazilian Ministry of Health and other combination of signs/symptoms taking serologic status as the reference. Serum samples were tested for anti-rubella virus IgM using commercially available enzyme immunoassays. Positive predictive values and respective 95% confidence intervals were calculated. RESULTS: A total of 1,186 patients with an illness characterized by variable combinations of rash with fever, arthropathy and lymphadenopathy were studied. Patients with rash, regardless of other signs and symptoms, had 8.8% likelihood of being IgM-positive for rubella. The Brazilian suspect case definition (fever and lymphadenopathy in addition to rash) had low predictive value (13.5%). This case definition would correctly identify 42.3% of the IgM-positive cases, and misclassify 26.1% of the IgM-negative cases. CONCLUSIONS: These results support the recommendation to investigate and collect clinical specimens for laboratory diagnosis of all cases of rash, for surveillance purposes. Although this strategy may increase costs, the benefits of interrupting the circulation of rubella virus and preventing the occurrence of congenital rubella syndrome should pay off.

OBJECTIVE: To assess the performance, in Brazil, of the definition of a suspected measles case among patients with rash diseases that has been adopted in Brazil and many other countries. METHODS: From January 1994 to December 2003, patients with acute rash were seen at two large primary health care units and a public general hospital in Niterói, a city in the metropolitan area of the city of Rio de Janeiro, Brazil. Data from clinical and serologic assessment were used to estimate sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of the definition of a suspected measles case that has been adopted in Brazil, as well as other combinations of signs and symptoms; serologic status was taken as the reference. Using enzyme immunoassay, serum samples were tested for immunoglobulin M (IgM) antibodies against measles virus. RESULTS: A total of 1 221 patients with an illness characterized by different combinations of rash with other signs and symptoms were studied. The suspected case definition that has been adopted in Brazil (rash, fever, and at least one of the following: cough, coryza, or conjunctivitis) had an overall sensitivity of 100%, and a specificity of 58.7%. Confirmed measles cases were 2.4 times as likely as were other rash diseases to have that combination of signs/symptoms. The suspected case definition adopted in Brazil had a 6% PPV and 100% NPV. The combination of all five signs and symptoms had the highest specificity, PPV, and likelihood ratio, for both children (< 15 years old) and adults (> 15 years). That was achieved at the expense of sensitivity, which dropped to 89%, but the NPV was still very high. CONCLUSIONS: Our results show that the suspected measles case definition adopted in Brazil is extremely sensitive for measles surveillance among patients with rash diseases. However, the high false-positive rates that were found may result in a substantial number of other rash diseases being misclassified as measles, leading to the misdirection of control measures and increases in their cost.

OBJETIVO: Evaluar la utilidad, en el Brasil, de la definición de "caso sospechado de sarampión", aplicada en pacientes con enfermedades exantemáticas, que se ha adoptado en el Brasil y en muchos otros países. MÉTODOS: De enero de 1994 a diciembre de 2003, se examinó a pacientes con erupción cutánea aguda en dos grandes unidades de atención primaria y en un hospital general estatal en Niterói, en la zona metropolitana de la ciudad de Río de Janeiro, Brasil. Se usaron datos de la evaluación clínica y serológica para estimar la sensibilidad, especificidad, valor pronóstico de un resultado positivo (VPRP), y valor pronóstico de un resultado negativo (VPRN) aplicables a la definición de "caso sospechado de sarampión" adoptada en el Brasil, así como otras combinaciones de signos y síntomas; el resultado de pruebas serológicas se usó como parámetro de referencia. Usando la técnica de inmunoensayo enzimático, las muestras de suero se examinaron para detectar la presencia de anticuerpos de immunoglobulina M (IgM) contra el virus del sarampión. RESULTADOS: Se estudió a un total de 1 221 pacientes con una enfermedad caracterizada por exantema cutáneo más otros signos y síntomas en diversas combinaciones. La definición de "caso sospechado" adoptada en el Brasil (erupción, fiebre y por lo menos un síntoma más, que puede ser tos, congestión nasal o conjuntivitis), tuvo una sensibilidad general de 100% y una especificidad de 58.7%. La probabilidad de encontrar esa combinación de síntomas o signos fue 2,4 mayor entre los casos confirmados de sarampión que entre los casos de otras enfermedades exantemáticas. La definición de "caso sospechado" que se ha adoptado en el Brasil tuvo un VPRP de 6% y un VPRN de 100%. La presencia combinada de todos los cinco signos y síntomas tuvo la mayor especificidad, el mayor VPRP y la mayor razón de verosimilitud, tanto en niños (< 15 años de edad) como en adultos (> 15 años). Eso se logró a expensas de la sensibilidad, que se redujo a 89%, pero el VPRN siguió siendo muy alto. CONCLUSIONES: Nuestros resultados demuestran que la definición de "caso sospechado de sarampión" adoptada en el Brasil posee gran sensibilidad para la vigilancia de la enfermedad entre pacientes con enfermedades exantemáticas. No obstante, los elevados porcentajes de resultados positivos falsos que se detectaron podrían llevar a que se clasifiquen como sarampión, por error, muchas enfermedades exantemáticas de otra índole, lo que a su vez daría por resultado una mala orientación de las medidas de control y un aumento de su carestía.

Analisou-se características clínicas e evolutivas em crianças menores de um ano internadas com infecção do trato respiratório inferior por vírus sincicial respiratório (VSR). Feito estudo transversal com 89 lactentes hospitalizados durante as épocas de maior incidência do VSR, em 1997 e 1998, na cidade do Rio de Janeiro. Foram pesquisados antígenos virais, nas secreções de nasofaringe, com anticorpos monoclonais anti-VSR, antiinfluenza A e B e antiparainfluenza tipo 3, por ensaio de imunofluorescência indireta. Formaram-se três grupos: bronquiolite ou bronquite sibilante (n=44), pneumonia (n=26) e bronquiolite e pneumonia (n=19). Houve positividade para o VSR em 42 (47,1%) pacientes. Em 1997 a média de dias de oxigenoterapia foi de 5,2 e em 1998, de 2,5 dias (p> 0,05). Não houve diferença de apresentação clínica entre os lactentes que apresentaram positividade para o VSR e aqueles cujo resultado foi negativo. A sensibilidade e especificidade da sibilância em relação ao isolamento de VSR foram 85% e 65%, respectivamente. O VSR foi o principal causador de infeções do trato respiratório inferior em lactentes que necessitaram de hospitalização.

For analysis of clinical features and outcome of hospitalized infants with respiratory syncytial virus lower respiratory tract infection, was carried out. Cross-sectional study with 89 infants, hospitalized in two public hospitals during the 1997 and 1998 RSV seasons, in Rio de Janeiro city. Nasopharyngeal secretions were obtained and specimens processed for viral antigens detection by indirect immunofluorescence assay with the use of anti RSV, antiinfluenza A and B and anti parainfluenza type 3 monoclonal antibodies. Patients were allocated into three diagnostic groups: bronchiolitis or wheeze bronchitis (n = 44); Pneumonia (n = 26) and bronchiolitis or wheeze bronchitis and pneumonia (n = 19). Positivity for RSV was found in 42 (47.1%) patients. More days of hospitalization were seen in 1997 in comparison with the follow year (p >0.05). No clinical differences were found between RSV positive and negative children. The sensitivity and specificity for wheezing concerning the isolation of RSV were, respectively, 85% and 65%. RSV was the major cause of LRTI in hospitalized infants.

Acute respiratory infections (ARI) caused by respiratory syncytial virus (RSV) were studied in 482 children from Salvador, BA, Brazil, over a period of 12 months. The epidemic period of RSV infections in Salvador occurred from February (summer) to August (winter), with peaks in May, June, and July. The grouping characteristics of 84 RSV present in nasopharyngeal secretions of children seen at a reference university hospital were analyzed. RSV represented 17.4% of all cases and 54.5% of the positive samples. Sixty-four RSV strains were assigned to group A and 14 to group B. Both groups circulated in the five months of the epidemic period studied. Infections by both groups of RSV were more frequent in children up to one year of age. The incidence of RSV ARI was slightly more frequent in males, although group B had more infected females.