Risk factors and patterns of household clusters of respiratory viruses in rural Nepal

Scott, E. M.; Magaret, A.; Kuypers, J.; Tielsch, J. M.; Katz, J.; Khatry, S. K.; Stewart, L.; Shrestha, L.; LeClerq, S. C.; Englund, J. A.; Chu, H. Y.

In over 40% of transmission events of all viruses, preschool children (aged 1-4 years) served as an index case. A higher proportion of initial infection among this group resulted in secondary cases compared to other age groups, including school-age children and mothers, a finding confirmed in our multivariable model of transmission incidence. In RSV transmission, no index cases were older children and 15% of index cases were mothers. In contrast to our findings, a study of RSV transmission in the USA during the 1960s found that older siblings between 2 and 16 years most frequently introduced RSV into a household [11] . Similarly, a Kenyan household study examined sequencingconfirmed RSV transmission in 44 households with infants and identified school-age children as the most common index case resulting in infant infection [6] .