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Background: Understanding viral etiology and age-specific incidence of acute respiratory infections in infants can help identify risk groups and inform vaccine delivery, but community-based data is lacking from tropical settings., Methods: One thousand four hundred and seventy-eight infants in urban Ho Chi Minh City and 981 infants in a semi-rural district in southern Vietnam were enrolled at birth and followed to 1 year of age. Acute respiratory infection (ARI) episodes were identified through clinic-based illness surveillance, hospital admissions and self-reports. Nasopharyngeal swabs were collected from infants with respiratory symptoms and tested for 14 respiratory pathogens using multiplex reverse transcription-polymerase chain reaction., Results: Estimated incidence of ARI was 542 and 2691 per 1000 infant-years, and hospitalization rates for ARI were 81 and 138 per 1000 infant-years, in urban and semi-rural cohorts, respectively, from clinic- and hospital-based surveillance. However self-reported ARI episodes were just 1.5-fold higher in the semi-rural versus urban cohort, indicating that part of the urban-rural difference was explained by under-ascertainment in the urban cohort. Incidence was higher in infants ≥6 months of age than <6 months, but this was pathogen-specific. One or more viruses were detected in 53% (urban) and 64% (semi-rural) of samples from outpatients with ARI and in 78% and 66% of samples from hospitalized ARI patients, respectively. The most frequently detected viruses were rhinovirus, respiratory syncytial virus, influenza virus A and bocavirus. ARI-associated hospitalizations were associated with longer stays and more frequent ICU admission than other infections., Conclusions: ARI is a significant cause of morbidity in Vietnamese infants and influenza virus A is an under-appreciated cause of vaccine-preventable disease and hospitalizations in this tropical setting. Public health strategies to reduce infant ARI incidence and hospitalization rates are needed.

Background: In Ho Chi Minh City, Vietnam, more than one-third of admissions to the two paediatric hospitals are attributable to four infectious syndromes: dengue, diarrhoeal disease, acute respiratory infection, and hand, foot and mouth disease. We have established a large prospective birth cohort study to investigate individual, environmental, virological, and immunological determinants of infection and disease in infants. Specific research questions are focused on the role of maternal antibody in protection against infection in infancy, and the adaptive immune response to vaccination and natural infection. This paper presents the cohort design, methods, and baseline characteristics of the participants enrolled in the first two years., Methods/design: Women are enrolled prior to delivery at one hospital in each of two catchment areas: an urban district in central HCMC, and a mixed urban/rural district in the Mekong Delta 150 km southwest of HCMC. Infants are enrolled within 3 days of birth, and maternal and cord blood samples are collected. Routine blood samples and data on growth, health status and vaccinations are collected from infants at scheduled visits at 4, 9 and 12 months. Clinical data and specimens are collected from infants presenting at a study clinic, or admitted to hospital, with any of the the four infectious syndromes of interest., Discussion: In four years since since the study began in July 2009, >6400 infants have been enrolled, and enrolment is ongoing. Attrition is low: 84% of participants have completed the full 12-month follow-up period. Baseline characteristics of the first 4300 enrollees are presented here. We have demonstrated the feasibility of establishing a large prospective study of infectious diseases in infancy in a resource-limited setting, with minimal loss to follow-up. Our linked socio-demographic, clinical and laboratory data will help elucidate the viral aetiology and epidemiology of common infectious diseases of infancy, and can inform the implemention of existing and future vaccines. This study furthermore provides a platform to which additional endpoints could be added in the future.

Macrocyclic antibiotics are present in an increasing number of chiral separation applications. In this study, erythromycin and some derivatives, belonging to the group of macrolide antibiotics, were investigated for their potential as chiral selector. Erythromycin A itself and five related substances namely erythromycin A N-oxide, anhydroerythromycin A, anhydroerythromycin A N-oxide, erythralosamine and erythralosamine N-oxide were included. Twenty-one chiral compounds with a wide difference in physico-chemical properties were used to test the chiral activity of the erythromycins. The chiral compounds were analysed using capillary zone electrophoresis with the erythromycins dissolved in the running buffer at different concentrations ranging from 0.1 to 10mM, with three different BGEs: sodium phosphate pHs 3.0 and 7.0 and sodium borate pH 9.2. The erythromycins showed more interactions with the acidic compounds (as observed with leucovorin, dopa, carbidopa, ketoprofen, indoprofen and warfarin) than with the neutral or weakly basic ones, especially in acidic medium. Unfortunately, no chiral separations were obtained for any of the 21 racemic mixtures. The complexation constants were calculated for the compounds showing interaction, based on the variation of electrophoretic mobility of the compounds in the presence of different concentrations of erythromycins. Finally, the size of erythromycin A was calculated using computational modelling. It was shown that the aglycone ring is only half as big as the beta-cyclodextrin cavity, giving a possible explanation for the negative response of erythromycin in this study.