Viral pneumonia is an important cause of death and morbidity among infants worldwide. Transmission of non-influenza respiratory viruses in households can inform preventative interventions and has not been well-characterised in South Asia. From April 2011 to April 2012, household members of pregnant women enrolled in a randomised trial of influenza vaccine in rural Nepal were surveyed weekly for respiratory illness until 180 days after birth. Nasal swabs were tested by polymerase chain reaction for respiratory viruses in symptomatic individuals. A transmission event was defined as a secondary case of the same virus within 14 days of initial infection within a household. From 555 households, 825 initial viral illness episodes occurred, resulting in 79 transmission events. The overall incidence of transmission was 1.14 events per 100 person-weeks. Risk of transmission incidence was associated with an index case age 1–4 years (incidence rate ratio (IRR) 2.35; 95% confidence interval (CI) 1.40–3.96), coinfection as initial infection (IRR 1.94; 95% CI 1.05–3.61) and no electricity in household (IRR 2.70; 95% CI 1.41–5.00). Preventive interventions targeting preschool-age children in households in resource-limited settings may decrease the risk of transmission to vulnerable household members, such as young infants.

A Spanish household was identified through a Public Health follow up on a Shiga toxin-producing Escherichia coli (STEC)-positive 14-month-old girl reporting bloody diarrhoea, with the four household members experiencing either symptomatic or asymptomatic STEC and/or atypical enteropathogenic E. coli (aEPEC) shedding. In total, two different O76:H19 STEC strains and six aEPEC strains belonging to multiple serotypes were isolated and characterized in the household during a 5-month period. Prolonged asymptomatic shedding of O76:H19 STEC and O51:H49 aEPEC was detected in two family members. Although there was no conclusive evidence, consumption of vegetables fertilized with sheep manure was the suspected source of infection. This study highlights the risk of cross-infections posed by prolonged asymptomatic carriage and close household contact between family members, and illustrates the importance of molecular epidemiology in understanding disease clusters.