During the recent E. coli spinach contamination outbreak, officials at the Wisconsin state public health lab posted E. coli patterns on a PulseNet list serve that helps track this pathogen. Not long after, health department analysts in Oregon were alerted to this information, and linked an E. coli case in their state to a possible bag of spinach. 

This is a concrete example of how the online public health network – PulseNet -- is helping officials track disease outbreaks. PulseNet is a national network of public health and food regulatory agency laboratories coordinated by the Centers for Disease Control and Prevention (CDC). The network consists of: state health departments, local health departments, and federal agencies (CDC, USDA/FSIS, FDA).

PulseNet participants perform standardized molecular subtyping (or "fingerprinting") of foodborne disease-causing bacteria by pulsed-field gel electrophoresis (PFGE). PFGE can be used to distinguish strains of organisms such asEscherichia coli O157:H7, Salmonella, Shigella, Listeria, or Campylobacter at the DNA level. DNA "fingerprints," or patterns, are submitted electronically to a dynamic database at the CDC. These databases are available on-demand to participants—this allows for rapid comparison of the patterns.

In recent years, advanced software permits CDC and other officials to identify individual strains of bacteria much more quickly. The PulseNet system uses BioNumerics software designed by AppliedMaths, a company based in Belgium that has a North American office in Austin, Tex.

"[PulseNet] has improved tracking greatly," says Dave Boxford, a bacteriology lab specialist at the Minnesota Dept. of Public Health in St. Paul. "The changes that have occurred in the past 10 years are really astounding," he adds. 

The software allows local health departments to input information about a particular strain of a bacteria or other pathogen -- based on its specific DNA fingerprinting -- into the system. "We detect clusters of patterns that are indistinguishable; the epidemiologists decide if it's an outbreak," says Kelly Hise, PulseNet database team leader at the CDC, in Atlanta.

Every state health department in the U.S., the FDA, and the U. S. Dept. of Agriculture uses PulseNet. It also has a global reach, with officials in Canada, Europe, and the Asia-Pacific regions relying on this system to track disease outbreaks. Boxford says the software is particularly helpful in sharing information among all the different state labs, particularly when an outbreak involves many parts of the country but only a few cases occur in each state.

The BioNumerics software can evaluate the way DNA bands in the PulseNet system are marked, and it can determine relationships among the more than 10,000 DNA patterns very quickly.  Becoming aware of outbreaks as quickly as possible plays a very important role in protecting the public from infectious disease. "If you had to do this by hand, it would take weeks," says Hise.

PulseNet provides several types of information concurrently.  In addition to analyzing DNA patterns of pathogens, it can also analyze appropriate antibiotic strains that can be used in treatment.  "There is no other program that allows you to analyze multiple techniques [at the same time]," says Kyle Kingsley, technical support person at Applied-Maths. "It gives you a better picture."

Read the entire Oct. 11 issue of Digital HealthCare & Productivity.