Just 15 years ago, outbreaks of foodborne illness were relatively small and local, often traced to undercooked meat or poultry at a neighborhood restaurant or church supper.  Today, incidents such as last year’s PCA peanut outbreak are regional or national, sickening hundreds of people, and are eventually traced to major food production plants or to distant farms.

That dramatic transition can be attributed in part to changes in the food industry, but it also has to do with profound changes in technology and in the nation’s public health system.  And the crucial reform was the founding in 1995 of PulseNet, the nationwide laboratory system based at the Centers for Disease Control and Prevention in Atlanta.


Dr. Bala Swaminathan, a leading food microbiologist and cofounder of PulseNet, recently stopped at the office of Marler Clark in Seattle to explain how PulseNet came to be and how it works.  Afterwards, he agreed to an interview with Food Safety News.  Here’s an edited version of that discussion.

Q:  How did you find yourself in microbiology?

A:  It took a long time.   At first, I wanted to be an engineer.  Then I went to work as a chemist for Coca Cola in India.  I worked in quality control, helping to open new bottling plants.  And I got very interested in the microbiology of food.  So I got my advanced degrees at the University of  Georgia.

I always had a fascination for detail, and I was interested in disease.  When I was young, I came down with typhoid, which is caused by a type of Salmonella.  I wanted to learn more about the organisms that can kill you.  So I did my PhD work on Salmonella.  Typhoid was a big problem in the US until public health epidemiologists and scientists learned about micro-organisms that are transmitted through contaminated water, and began addressing the problems.  Since then, the incidence of typhoid in this country has gone down significantly.


Q:  How did PulseNet happen?

A.  In 1994, during the Jack in the Box outbreak, it took 39 days to determine that an outbreak was going on.  And it took another six months to identify the subtype.   CDC recognized that it took too long, that too many people were sickened before the outbreak was traced to Jack in the Box.  So, a year after the outbreak had been identified by epidemiologists, CDC  reorganized and created a foodborne illness branch, and I was asked to work on it.  My colleagues were already working on DNA fingerprinting.  We got $150,000 to begin creating a network which would enable us to exchange information more quickly.

PulseNet is a tool for quickly identifying clusters of foodborne disease that could have a common food source by comparing DNA fingerprints of bacteria that cause illnesses.  It helps epidemiologists connect seemingly unrelated cases of foodborne illnesses and recognize foodborne disease outbreaks much faster.  We were up and operating within a year of coming up with the idea.  We started working with a few states, seven or eight labs around the country, and eventually expanded to include all 50 states and Canada.

Q:  So PulseNet has been a tremendous success?


A.    PulseNet is made up of some very dedicated people who have accomplished a great deal in just a few years.  In 1999, we were identified by the Innovations in American Government program, sponsored by the Ford Foundation and administered by Harvard, as one of the 10 most promising programs of the year.  And in 2002, we were named one of the top 10 programs of the previous 10 years.   

Q: How much does it cost taxpayers?

A:  It’s hard to say.  The PulseNet budget is between $5- and $10 million, but there are additional costs in each of the participating states.


Q:  There has been a dramatic transition in foodborne illness from small, localized outbreaks to large, multistate, industrial outbreaks.  Why has that happened?

A: In large measure, it is due to changes in food production and distribution.  In the last decade or two, we’ve seen a remarkable change in the way food is manufactured and distributed, with the resulting concentration of food production in large multinational companies.  Everything is simply bigger.

That can be a good thing or a bad thing.  If a food producer or processor takes the necessary precautions, the large operations can do so with greater efficiency.  But, as we’ve seen with recent outbreaks, when something goes wrong, it goes wrong in a big way.

The other big change, of course, is in technology and PulseNet, which enables us to analyze and track big, multistate outbreaks that would not have been detected 15 or 20 years ago.   So the change has occurred both in the food industry and in our ability to track foodborne illness.

Q:  Are there popular misconceptions about the microbiology of foodborne illness that drive you nuts?

A:  Lately, the media have become more sophisticated in their depiction of foodborne illness.   But reporters still have difficulty understanding what it takes to trace the source of an outbreak.  They think that DNA analysis should be done in a few minutes, like it does on TV shows.  But the reality is that there is still a period of time between when people get sick and CDC identifies an outbreak.  There are so many factors, human variables and analytical variables.  The media doesn’t understand the level of effort required to make this happen.

Photo of Dr. Bala Swaminathan from the Centers for Disease Control and Prevention