Clinical patterns and seasonal trends in respiratory syncytial virus hospitalizations in São Paulo, Brazil

Abstract

The respiratory viruses are recognized as the most frequent lower respiratory tract pathogens for infants and young children in developed countries but less is known for developing populations. The authors conducted a prospective study to evaluate the occurrence, clinical patterns, and seasonal trends of viral infections among hospitalized children with lower respiratory tract disease (Group A). The presence of respiratory viruses in children's nasopharyngeal was assessed at admission in a pediatric ward. Cell cultures and immunofluorescence assays were used for viral identification. Complementary tests included blood and pleural cultures conducted for bacterial investigation. Clinical data and radiological exams were recorded at admission and throughout the hospitalization period. To better evaluate the results, a non- respiratory group of patients (Group B) was also constituted for comparison. Starting in February 1995, during a period of 18 months, 414 children were included- 239 in Group A and 175 in Group B. In Group A, 111 children (46.4%) had 114 viruses detected while only 5 children (2.9%) presented viruses in Group B. Respiratory Syncytial Virus was detected in 100 children from Group A (41.8%), Adenovirus in 11 (4.6%), Influenza A virus in 2 (0.8%), and Parainfluenza virus in one child (0.4%). In Group A, aerobic bacteria were found in 14 cases (5.8%). Respiratory Syncytial Virus was associated to other viruses and/or bacteria in six cases. There were two seasonal trends for Respiratory Syncytial Virus cases, which peaked in May and June. All children affected by the virus were younger than 3 years of age, mostly less than one year old. Episodic diffuse bronchial commitment and/or focal alveolar condensation were the clinical patterns more often associated to Respiratory Syncytial Virus cases. All children from Group A survived. In conclusion, it was observed that Respiratory Syncytial Virus was the most frequent pathogen found in hospitalized children admitted for severe respiratory diseases. Affected children were predominantly infants and boys presenting bronchiolitis and focal pneumonias. Similarly to what occurs in other subtropical regions, the virus outbreaks peak in the fall and their occurrence extends to the winter, which parallels an increase in hospital admissions due to respiratory diseases.

Molecular characterization of adenoviruses from children presenting with acute respiratory disease in Uberlândia, Minas Gerais, Brazil, and detection of an isolate genetically related to feline adenovirus

“…This rate (7.1%) is similar to the rate (6%) in Southern Brazil described by Straliotto et al (2002). However, other studies carried out in Brazil reported prevalence rates that varied from a slightly higher rate (9.9%) for cases in the Northeast (de Arruda et al 1991), to a slightly lower rate (4.6%) in the Southeast (Vieira et al 2001) and a much lower rate (0.8%) in the South (Tsuchiya et al 2005).…”

Human respiratory syncytial virus detection in children admitted at a community hospital in Botucatu, SP, Brazil

“…In conclusion, our results show that in Botucatu city, representing a large area of São Paulo state inlands, HRSV occurrence has a similar pattern of that observed in other cities of Brazil's southeast (4,27).…”

“…While in the north rainfall is the main climatic determinat, temperature variations play a more significant role in the south and southeast. Climate diversity can also be noted among different areas of the southeast region of Brazil, such as more defined cold seasons in the higher lands than in coastal areas of São Paulo and Rio de Janeiro states (4,27). There is a corresponding seasonality of respiratory illnesses that may vary among different regions of the country, and even among geographically different areas within the same region.…”

Respiratory syncytial virus infections during an epidemic period in Salvador, Brazil: viral antigenic group analysis and description of clinical and epidemiological aspects

“…This correlation was also reported in a study from Belém, a Northern Brazilian city with equatorial climate (Mello & Silva 1992). In studies from the cities of Rio de Janeiro and São Paulo, both located in Southeast Brazil, with a subtropical climate, the RSV outbreaks began in late March or early April, peaking in May and lasting five months , Vieira et al 2001. The peak of RSV infections in these cities cannot be associated with the rainy seasons, which lasts from January through March and from September through November, nor with the coldest months (June, July, August).…”

“…Brazilian data about the pattern of RSV infection and circulation of the RSV groups have been obtained mostly from cities in the Southeastern, Southern and Northern regions , Mello & Silva 1992, Sutmoller et al 1995, Cintra et al 2001, Vieira et al 2001, Straliotto et al 2001, Checon et al 2002.…”