Fatores de risco e proteção à infecção respiratória aguda em lactentes

Abstract

OBJECTIVE:To analyze the effectiveness of maternal pneumococcal polysaccharide vaccine and the risk and protective factors for acute respiratory infections in infants. METHODS:Nested cross-sectional study of a clinical trial evaluating children of 139 women selected in a public prenatal care unit in the municipality of São Paulo, Southeastern Brazil, from 2005 to 2006. Subjects were randomly assigned to three groups: non-immunized (n=46); immunized with pneumococcal polysaccharide vaccine in the last trimester of pregnancy (n=42); and immunized with the vaccine immediately after childbirth (n=45). Infants were followed up for infections presumably caused by pneumococcus at the age of three and six months and nasopharyngeal samples were collected. Risk factors such as smokers living in the same household, siblings and exclusive maternal breastfeeding were investigated. RESULTS:The pneumococcal polysaccharide vaccine did not provide protection against pneumococcus infections. However, exclusive maternal breastfeeding until the age of six months protected infants against respiratory infections (OR= 7.331). Pneumococcal nasopharyngeal colonization at the age of three or six months increased the likelihood of occurrence of respiratory infections (OR= 2.792). CONCLUSIONS:Exclusive breastfeeding for six months protects infants against presumably pneumococcal infections regardless of pneumococcal vaccination. DESCRIpTORS Acute respiratory infections in infants Lopes CRC & Berezin ENAcute respiratory infections are a major cause of morbidity in children especially in infants younger than six months. Nasopharyngeal colonization with Streptococcus pneumoniae can lead to invasive respiratory infections. 4 The main pathogenic bacteria of acute respiratory infections is pneumococcus.In developing countries it is estimated that pneumococcus causes more than 1 million death a year in children under five, mostly due to pneumonia, 11,15,16,22 at a rate of two children dying per hour in Latin America. In 2007, pneumococcal disease killed 8,000 children in Brazil. aThe main predisposing factors for respiratory infections are: attendance of child day care centers, passive smoking, children of mothers with low schooling, overcrowding, and early termination of breastfeeding. Infants with these factors are more likely to develop respiratory infections, particularly S. pneumoniae infections. 4 In Brazil, 30% of children under two are colonized with S. pneumoniae. 1,4,10,21 The rate of pneumococcal nasopharyngeal colonization (PNC) in infants attending child day care centers is about 60%. 17 A recent study showed that children exposed to smoking were more likely to have their nasopharynx colonized with acute middle ear infection pathogens (Moraxella catarrhalis, Haemophilus influenzae, and pneumococcus). 20

Incidence of community-acquired infections of lower airways among infants

“… 3 Previous studies have listed the risk factors for acquiring respiratory infections, among which are socioeconomic factors (low household income, poor parental education, and high number of persons per household), early cessation of breastfeeding, low birth weight, malnutrition, passive smoking, and daycare attendance. 5 , 6 …”

Perfil de internações hospitalares por doenças respiratórias em crianças e adolescentes da cidade de São Paulo, 2000-2004

“…This increased oxygen demand means that larger quantities of air are inhaled and, as a result, exposure to the pollutants in tropospheric air is also greater (23,24) . Furthermore, living conditions, nutrition and access to health services can impact on onset and severity of acute infections of the respiratory tract (17,18) . The principal causes of hospital admission of 14-to-19-year-olds were the interstitial (J80-J84) and suppurative (J85-J86) diseases, which are apparently more serious -serious enough to take adolescents to hospital and for them to be admitted.…”

“…While the metropolitan area of Greater São Paulo, which has approximately 19 million inhabitants, does not undergo the large magnitude temperature variations seen in temperate countries, it does have distinct seasonality which means that respiratory diseases are the most common conditions seen in children and adolescents during the coldest months of the year, irrespective of effect indicator analyzed (4,8,15,16) . Additionally, the importance of smoking as a risk factor for childhood respiratory diseases cannot be ignored and passive smoking of at least 10 cigarettes per day is a risk factor both for disease incidence and disease exacerbation (8,17,18) . It is against this background that the present study was conducted with the objective of describing the principal characteristics of the temporal, age group and specific cause distribution of hospital morbidity due to respiratory diseases in childhood and adolescence in the city of São Paulo, Brazil, using admission records from Brazilian National Health Service (SUS -Sistema Único de Saúde) hospitals from 2000 to 2004.…”