Etiology and Factors Associated with Pneumonia in Children under 5 Years of Age in Mali: A Prospective Case-Control Study

Background There are very limited data on children with pneumonia in Mali. The objective was to assess the etiology and factors associated with community-acquired pneumonia in hospitalized children <5 years of age in Mali. Methods A prospective hospital-based case-control study was implemented in the Pediatric department of Gabriel Toure University Hospital at Bamako, Mali, between July 2011-December 2012. Cases were children with radiologically-confirmed pneumonia; Controls were hospitalized children without respiratory features, matched for age and period. Respiratory specimens, were collected to identify 19 viruses and 5 bacteria. Whole blood was collected from cases only. Factors associated with pneumonia were assessed by multivariate logistic regression. Results Overall, 118 cases and 98 controls were analyzed; 44.1% were female, median age was 11 months. Among pneumonia cases, 30.5% were hypoxemic at admission, mortality was 4.2%. Pneumonia cases differed from the controls regarding clinical signs and symptoms but not in terms of past medical history. Multivariate analysis of nasal swab findings disclosed that S. pneumoniae (adjusted odds ratio [aOR] = 3.4, 95% confidence interval [95% CI]: 1.6-7.0), human metapneumovirus (aOR = 17.2, 95% CI: 2.0-151.4), respiratory syncytial virus [RSV] (aOR = 7.4, 95% CI: 2.3-23.3), and influenza A virus (aOR = 10.7, 95% CI: 1.0-112.2) were associated with pneumonia, independently of patient age, gender, period, and other pathogens. Distribution of S. pneumoniae and RSV differed by season with higher rates of S. pneumoniae in January-June and of RSV in July-September. Pneumococcal serotypes 1 and 5 were more frequent in pneumonia cases than in the controls (P = 0.009, and P = 0.04, respectively). Conclusions In this non-PCV population from Mali, pneumonia in children was mainly attributed to S. pneumoniae, RSV, human metapneumovirus, and influenza A virus. Increased pneumococcal conjugate vaccine coverage in children could significantly reduce the burden of pneumonia in sub-Saharan African countries.