Original ResearchReassuringly low carriage of enteropathogens among healthy Swedish children in day care centres
Introduction
Preschools and child day care centres (DCCs) represent a high-risk environment for infections. The facilities are often crowded, full of young individuals with an immature immune system, a high degree of physical interaction and a limited awareness of hygiene and infectious control. Studies from Denmark have demonstrated an increased risk up to 7-fold for infectious diseases among young children in DCCs1 compared to children who are cared for in their homes. The incidence of gastroenteritis in children at DCCs might be two or three times higher2, 3 than estimations for the same age group in the paediatric population not attending DCCs.
Still, colonization of microbes among toddlers is not necessarily synonymous with symptomatic infection. Young children are more prone to asymptomatic carriage of potential pathogens, as compared to adults, and may thus act as a reservoir for spread of disease to other children and to the community in general.1 This is of particular interest in environments such as DCCs where many children congregate.4, 5, 6 The asymptomatic carriage of group A Streptococcus, a common cause of pharyngitis, has been demonstrated to be 12% among children at large,7 and among healthy preschool children in Belgium as many as 69% carry Streptococcus pneumoniae, 67% Moraxella catarrhalis and 83% Haemophilus influenzae in the nasopharynx.8 We may hypothesize that a corresponding carriage may also be the case for pathogens in the gastrointestinal tract, but this is not yet known.
Infectious gastroenteritis is one of the most common diseases among children worldwide and has a considerable global impact on community health and socio-economy. The disease burden of gastroenteritis among children younger than 5 years of age is significantly higher than in the rest of the population.9 Even though the mortality of gastroenteritis is low in industrialized countries such as Sweden, the morbidity remains high. The incidence of episodes of infectious gastroenteritis in Swedish children up to 5 years old requiring hospital care is estimated at 770/100,000 individuals per year.10 In the low-income countries, bacterial and parasitic causes of gastroenteritis have decreased in frequency during recent decades as a result of improvements in sanitation and public health, while the impact of viral infections remains high.
Studies on asymptomatic carriage using modern, sensitive molecular methods are scarce but sorely needed if we are to understand the spread of disease in the community. Most previous studies have focussed on causes of gastroenteritis among symptomatic children admitted to healthcare providers and some have investigated the occurrence of enteropathogens in the community, often with older methods and divergent results but nevertheless indicating a high prevalence of single-pathogen colonization in asymptomatic children.11, 12, 13 Studies on asymptomatic carriage using sensitive molecular methods are scarce but sorely needed if we are to understand the spread of disease in the community.
The objectives of this study were to use molecular techniques to estimate the prevalence of asymptomatic carriage of multiple enteropathogens during late spring and autumn among healthy children in a high-risk environment and investigate to what extent this population constitutes a reservoir for gastrointestinal disease.
Section snippets
Study setting and coverage
In 2010, when this study was conducted, 86% of Swedish children between 1 and 5 years old were attending DCCs, according to data from the Swedish National Agency for Education. The corresponding figure for Uppsala was 83%. The average size of the preschool group in DCCs was 17 children nationwide and 17.7 children per group in Uppsala.14
Study design
Faecal samples from individual diapers were collected in June (n = 125) and from September to October 2010 (n = 313). The children participating in the study
Results
Altogether 125 spring and 313 autumn samples were analysed with the xTAG® GPP. A total of 16 of the 438 samples were positive for enteropathogens, while using confirmatory PCR assays. Three out of 3 samples were found to be positive for Campylobacter spp. (MFI 538, 897, and 1211, respectively), 3 out of 14 samples were found to be positive for norovirus GI/GII (1 GI with MFI 986 and 2 GII with MFI 528 and 402, respectively), and 7 out of 8 samples were found to be positive for enteric
Discussion
Studies using newer molecular methods targeting the whole spectrum of microbes that may cause gastroenteritis among healthy children are still lacking. Data on carriage of enteropathogens among healthy children in DCCs or preschools, where children congregate and might hence spread pathogens, are scarse and very few studies have been published.18, 19, 20, 21 To the best of our knowledge, no study has previously been performed in Sweden. Since molecular methods have a higher sensitivity than
Acknowledgements
We thank the staff at the participating preschools for collecting the diapers. Without their help, this study would not have been possible. Further, we would like to thank Luminex Corporation (Toronto, Canada) for providing us with early versions of the xTAG® GPP kits. We also thank Professor Björn Olsen, whose never-failing ability to see possibilities in research where obstacles emerge, has been of great help. Further, we thank Anna Nilsson and Patrik Boman for their contributions with
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