Assessing the use of minimally invasive self-sampling at home for long-term monitoring of the microbiota within UK families.

Monitoring the presence of commensal and pathogenic respiratory microorganisms is of critical global importance. However, community-based surveillance is difficult because nasopharyngeal swabs are uncomfortable and painful for a wide age range of participants. We designed a methodology for minimally invasive self-sampling at home and assessed its use for longitudinal monitoring of the oral, nasal and hand microbiota of adults and children within families. Healthy families with two adults and up to three children, living in and near Liverpool, United Kingdom, self-collected saliva, nasal lining fluid using synthetic absorptive matrices and hand swabs at home every two weeks for six months. Questionnaires were used to collect demographic and epidemiological data and assess feasibility and acceptability. Participants were invited to take part in an exit interview. Thirty-three families completed the study. Sampling using our approach was acceptable to 25/33 (76%) families, as sampling was fast (76%), easy (76%) and painless (60%). Saliva and hand sampling was acceptable to all participants of any age, whereas nasal sampling was accepted mostly by adults and children older than 5 years. Multi-niche self-sampling at home can be used by adults and children for longitudinal surveillance of respiratory microorganisms, providing key data for design of future studies.

Prevalence of Helicobacter pylori infection in Kenyan schoolchildren aged 3-15 years and risk factors for infection.

OBJECTIVES: To determine the prevalence of Helicobacter pylori (Hp) infection in Kenyan schoolchildren aged 3-15 years and the risk factors for infection. DESIGN: A cross-sectional survey and study of risk factors. SUBJECTS: Primary-school children in Trans Nzoia district, Kenya. METHODS: Hp status was determined using the 13C-urea breath test. Risk factors were assessed using a structured interview schedule. RESULTS: Of 205 children interviewed, valid breath test results were obtained for 192 (93.7%), of whom 155 (80.7% (95% CI 75.2-86.3)) were infected. Univariate analysis showed weak associations between Hp infection and rural areas (location of home, Relative Risk (RR)= 1.2 (1.0-1.4); location of school, RR = 1.2 (1.0-1.3)) and lower socio-economic status (RR = 1.2 (1.0-1.4)). Access to only a pit-latrine in the home (RR = 1.2 (1.0-1.4)) and plate-sharing with other family members in the home also increased the likelihood of Hp infection (RR = 1.3 (1.1 -1.6)). However, after logistic regression modelling only plate-sharing in the home remained as an independent risk factor (odds ratio (OR) = 2.8 (1.3-6.3)). CONCLUSIONS: The prevalence of Hp infection in Kenyan schoolchildren aged 3-15 years is already high, suggesting that most acquisition occurs before age 3 years. Children who normally shared a plate with other family members during meals in the home had a higher prevalence of infection, suggesting that oro-oral transmission may be important in this population. Future studies in developing countries should focus on younger children (before age 3 years), and consider the possibility of adult-child, oro-oral transmission in order to establish likely modes of transmission.

Epidemiology of Helicobacter pylori: transmission, translocation and extragastric reservoirs.

Although H. pylori infection is endemic and despite more than 10 years of research, the mode and route of transmission remain elusive. This may, in part, be due to the inherent problems of detecting H. pylori noninvasively. The prevalence of infection varies between countries and is closely related to Growth Domestic Product. An age-cohort effect and data from longitudinal studies suggest that the incidence of infection is much higher in children than adults. In developing countries the prevalence of infection is often more than 80% in young adults, in contrast to less than 10% for similar age groups in developed countries. The observations of mosaicism (in the VacA gene) and a panmycytic population structure imply exchange of genetic material either in or outside of the host, which is supported by the increasing recognition of polyclonal infection and suggests that secondary infection occurs after primary acquisition. In addition, in children persistent primary infection may sometimes occur only after previous (repeated) exposure and/or transient colonisation of the gastric mucosa. H. pylori and other gastric Helicobacter spp are always noninvasive, but other human nongastric Helicobacter spp have sometimes been isolated from the systemic circulation in immunocompromised patients. For nonhuman hosts, intestinal Helicobacter spp are thought to translocate more frequently from the colon to the liver. Within the human host, the oral cavity is the principal extragastric reservoir, although case reports suggest that H. pylori may sometimes be found beyond the 2nd part of the duodenum. The hypothesis that H. pylori is a zoonosis or transmitted as coccoid forms by a vector (pets, houseflies) is not supported by recent research showing that H. pylori is entirely unable to support an aerobic or anaerobic metabolism and that coccoid forms are non-viable. H. pylori is primarily acquired in infancy, most probably via the oroorogastric route, from other family members or close contacts encountered after weaning or socialisation. Further studies to support or refute this hypothesis are required.