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Researchers report on their study of households with an influenza-infected child to measure the prevalence of influenza contamination, the effect of handwashing, and associations with humidity and temperature; their research appearsÂ in the latest issue of Clinical Infectious Diseases.
Simmerman, et al. (2010) identified children with influenza and randomly assigned their households to handwashing and control arms. Six common household surfaces and the fingertips of the index patient and symptomatic family members were swabbed. Specimens were tested by real-time reverse-transcription polymerase chain reaction (rRT-PCR), and specimens with positive results were placed on cell culture. A handheld psychrometer measured meteorological data.
The researchers report that 16 of 90 households (17.8 percent) had influenza A-positive surfaces by rRT-PCR, but no viruses could be cultured. The fingertips of 15 (16.6 percent) of the index patients had results positive for influenza A, and one virus was cultured. Index patients with seasonal influenza infections shed more virus than did patients with pandemic influenza infection. Control households had a higher prevalence of surface contamination (11 of 45) than did handwashing households (5 of 45). Households in which the age of the index patient was 8 years had a significantly higher prevalence of contamination.
Simmerman, et al. (2010) conclude that homes with younger children were more likely than homes of older children to have contaminated surfaces, and that lower absolute humidity favors surface contamination in households with multiple infections. They add that increased handwashing can reduce influenza contamination in the home.
Reference: Simmerman JM, Suntarattiwong P, Levy J, Gibbons RV, Cruz C, Shaman J, Jarman RG and Chotpitayasunondh T. Influenza Virus Contamination of Common Household Surfaces during the 2009 Influenza A (H1N1) Pandemic in Bangkok, Thailand: Implications for Contact Transmission. Clinical Infectious Diseases 2010;51:10531061.