Catch the bus and catch a cold

U. NOTTINGHAM (UK) — Ride a bus or tram and you’re six times more likely to end up at the doctor’s office with cold symptoms. Daily riders, however, may be somewhat protected.

The case-control study by researchers at the University of Nottingham medical was carried out during the 2008/2009 influenza season. The study ran during a local flu outbreak between December 2, 2008 (week 49) and January 15, 2009 (week two) which peaked in week 51.

One hundred and thirty eight patients—72 cases of acute respiratory infection (ARI) and 66 control patients—from a Nottingham GP practice were asked to fill in a questionnaire on bus or tram usages in the five days preceding the onset of their illness or the five days before consultation.

“We found a statistically significant association between ARI and bus or tram use in the five days before symptom onset. The risk appeared greatest among occasional bus or tram users,” says Jonathan Van Tam, a professor of health protection.

“These data are very plausible when we think about the greater likelihood of developing protective antibodies to common respiratory viruses if repeatedly exposed. The findings have differing implications for the control of seasonal acute respiratory infections and for pandemic influenza. In the latter case we don’t have an opportunity to build up any immunity beforehand because it’s, by definition, a new virus.”

The team’s findings are reported in the online journal BMC Infectious Diseases.

“This is a small exploratory study whose findings require confirmation by a larger study,” adds Tam. “However, the findings justify the need to practice good respiratory and hand hygiene when using public transport during periods when winter viruses are circulating and where possible to avoid situations where you might spread your germs to others when you have a respiratory illness.”

The relationship between public transport use and acquisition of ARI is not well understood but potentially important during epidemics and pandemics.

The research was funded by the Health Protection Agency.

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