Strong Pulse

By Wendy Wolfson  |  Posted 09-01-2004

Foodborne diseases kill more and more people every year, yet they do not get the attention or funding showered on more exotic contagious diseases such as smallpox and anthrax, which strike only a few people per year, but do have the potential to be used as bioterror agents. In 1997, a year the Centers for Disease Control and Prevention uses as an indicator, an estimated 76 million Americans contracted a foodborne infection. One in four got sick enough to miss work; 325,000 were hospitalized; 5,000 died.

Food poisoning is like a stealthy serial killer. An outbreak that lasts over several months and across different states can be very difficult to detect. But if epidemiologists and public health labs could use computers to identify, compare and track bacterial strains back to their source quickly, the chances of bringing effective remediation efforts to bear on the outbreak would be much improved.

So in 1996, a group of entrepreneurial CDC public health doctors began an effort called PulseNet, on a shoestring, $150,000 budget. PulseNet is now the CDC's primary surveillance system for foodborne disease. Each main foodborne pathogen—such things as salmonella, shigella, E. coli , listeria and campylobacter—has thousands of variants. The probability that two people will get sick from the same bug but contract it from different sources is very low. In forensic terms, it is like two bullets with the exact same markings coming out of two different gun barrels.

PulseNet "fingerprints" bacterial DNA, comparing it with other samples collected in its central database. If a match is found, the information is shared over a client-server network linked to state and local public health departments across the country, as well as the U.S. Department of Agriculture and the Food and Drug Administration. Outbreak information is also posted to a WebBoard where there is constant dialogue.

Thanks to PulseNet, improved detection has been linked to lowered rates of most of the main foodborne diseases in the U.S., Now, PulseNet is being replicated in other countries around the world including Canada, Europe, South America and Asia—at their request. Yet PulseNet's current operating budget is estimated at under $15 million a year—and that covers all 50 participating state and local labs, the FDA and USDA, as well as the CDC. Not a bad return on investment.