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SummaryLittle is known about the epidemiology of respiratory syncytial virus (RSV) infection in tropical and developing countries; the data currently available have been reviewed. In most studies, RSV was found to be the predominant viral cause of acute lower respiratory tract infections (ALRI) in childhood, being responsible for 27-96% of hospitalised cases (mean 65%) in which a virus was found. RSV infection is seasonal in most countries; outbreaks occur most frequently in the cold season in areas with temperate and Mediterranean climates and in the wet season in tropical countries with seasonal rainfall. The situation on islands and in areas of the inner tropics with perennial high rainfall is less clear-cut. The age group mainly affected by RSV in developing countries is children under 6 months of age (mean 39% of hospital patients with RSV). RSV-ALRI is slightly more common in boys than in girls. Very little information is available about the mortality of children infected with RSV, the frequency of bacterial co-infection, or the incidence of further wheezing after RSV. Further studies on RSV should address these questions in more detail. RSV is an important pathogen in young children in tropical and developing countries and a frequent cause of hospital admission. Prevention of RSV infection by vaccination would have a significant impact on the incidence of ALRI in children in developing countries.

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BackgroundThe pneumococcus is a diverse pathogen whose primary niche is the nasopharynx. Over 90 different serotypes exist, and nasopharyngeal carriage of multiple serotypes is common. Understanding pneumococcal carriage is essential for evaluating the impact of pneumococcal vaccines. Traditional serotyping methods are cumbersome and insufficient for detecting multiple serotype carriage, and there are few data comparing the new methods that have been developed over the past decade. We established the PneuCarriage project, a large, international multi-centre study dedicated to the identification of the best pneumococcal serotyping methods for carriage studies.Methods and FindingsReference sample sets were distributed to 15 research groups for blinded testing. Twenty pneumococcal serotyping methods were used to test 81 laboratory-prepared (spiked) samples. The five top-performing methods were used to test 260 nasopharyngeal (field) samples collected from children in six high-burden countries. Sensitivity and positive predictive value (PPV) were determined for the test methods and the reference method (traditional serotyping of >100 colonies from each sample).For the alternate serotyping methods, the overall sensitivity ranged from 1% to 99% (reference method 98%), and PPV from 8% to 100% (reference method 100%), when testing the spiked samples. Fifteen methods had ≥70% sensitivity to detect the dominant (major) serotype, whilst only eight methods had ≥70% sensitivity to detect minor serotypes. For the field samples, the overall sensitivity ranged from 74.2% to 95.8% (reference method 93.8%), and PPV from 82.2% to 96.4% (reference method 99.6%). The microarray had the highest sensitivity (95.8%) and high PPV (93.7%). The major limitation of this study is that not all of the available alternative serotyping methods were included.ConclusionsMost methods were able to detect the dominant serotype in a sample, but many performed poorly in detecting the minor serotype populations. Microarray with a culture amplification step was the top-performing method. Results from this comprehensive evaluation will inform future vaccine evaluation and impact studies, particularly in low-income settings, where pneumococcal disease burden remains high.