Syrup sales flag anthrax outbreak

Over-the-counter cough medicines could give early warning of bioterrorism.

Tracking over-the-counter sales of cough medications for unseasonable surges could be a way of spotting imminent anthrax epidemics, say US researchers¹.

In the wake of the 11 September terrorist attacks in the United States, scientists are working on ways to detect a biological attack quickly and so minimize its effects. Because a sore throat and cough are the first symptoms of anthrax, a large-scale attack could cause a 36% rise in sales of non-prescription cough lozenges and syrups, say Stephen E. Fienberg of Carnegie Mellon University in Pittsburgh, Pennsylvania, and his colleagues. Their prediction model is based on two years’ worth of data from several hundred Pennsylvania stores.

Unfortunately, handfuls of cases, such as the clusters seen in the United States last autumn, would probably have little effect on such sales, Fienberg cautions. “You can’t expect to find a needle in a haystack.” Fienberg’s team draw their conclusions from records of the onset of symptoms in one of the largest anthrax outbreaks ever reported. This accidental release of Bacillus anthracis spores from a military facility in Sverdlovsk, Russia, in 1979 resulted in at least 79 cases of anthrax infection and 68 documented deaths.

There is still a long way to go, however, before scientists will know whether there is in practice any connection between symptoms and sales surges. As Fienberg concedes, “the data are crude and the approach could be refined”. Monitoring medicine purchasing to catch a biological attack in its infancy is nonetheless “a good idea”, says Barbara Rosenberg, chair of the Federation of American Scientists Working Group on Biological Weapons. The figures could be integrated with other types of information, such as reports from hospital emergency rooms and school attendance reports, she says.

One potential hurdle is how scientists might access data from big grocery chains “without compromising the privacy and confidentiality of the individual customers and without exposing the chain to its competitors in some unreasonable form”, warns Rosenberg. But if concerns about privacy can be dealt with, says Fienberg, grocery-store vigilance might allow public-health workers to act quickly enough to prevent an epidemic.

References

1. Goldenberg, A., Shmueli, G. & Caruana, A.R. Early statistical detection of anthrax outbreaks by tracking over-the-counter medication sales. Proceedings of the National Academy of Sciences, 412, 5237 – 5240, (2002).