Meet the Medical Investigator Who Led the Largest Investigation in CDC History

David W. Fraser, a medical epidemiologist, spent decades discovering the root causes of unknown diseases.

David Fraser


Medical investigators are the people charged with uncovering answers about mysterious diseases. Their work enables clinicians to treat patients, and empowers the public with the knowledge needed to better prevent deadly serious illnesses. 

David W. Fraser is a medical epidemiologist, and previously a chief investigator for the Centers for Disease Control and Prevention (CDC). Now retired, Fraser has since turned his attention to fiber arts, weaving colorful geometric sculptures. But in his long and varied career, Fraser is perhaps still best known for leading the largest CDC investigation in history. 

The historic 1976 investigation took place in Philadelphia after more than 200 attendees of a meeting at the American Legion convention fell ill. Within five months, Fraser and his team of investigators were able to find the cause of legionnaires’ disease, so named for the outbreak, which turned out to be a bacteria that had grown in the air conditioning system of the hotel that hosted the convention. And once the cause was identified, a cure could be found.
Fraser sat down with us to talk about how the work of medical investigators provides relief and hope during times of unanswerable questions and widespread fear.

What is the link between your medical investigation experience and the human experience of people suffering from the disease?

With legionnaires’ disease, there was certainly fear because people didn't know what the disease was and why it was happening. And there was some anxiety that something malevolent was happening, some bad actor doing something in 1976 Philadelphia. The difference in that outbreak was that people weren't sick for a long time. It wasn't a chronic disease. People were cured, even though a lot of people died — 29 people died. But unlike AIDS or other mysteries that were chronic diseases, it seems to be a different type, or a different horizon of uncertainty and fear.

There was also the 1972 Lassa fever outbreak in Sierra Leone. It came out of East Africa in 1967-68 — it came out of hospitals and spread from person to person with 50 percent mortality, which is similar to Ebola in that respect — but in 1972 it was occurring in towns, and no one knew the source of the virus or why it was spread in towns or among an open population for the first time. People just knew it was a deadly disease and there was no treatment for it. They didn't know how it was being spread so they didn't know how to protect themselves. That's very similar to the Ebola situation that we have now, except that now we have vaccines. But there again, it wasn't a chronic disease. It wasn't something that people were hearing from their families and friends that, “You're not sick, pull up your socks.” People were bleeding and dying. There was lots of fear.

And then there was the investigation into toxic shock syndrome, which was a life-threatening illness of unknown cause that was attacking healthy women. And there didn't seem to be any reason for these women to be singled out for this devastating disease. I was close enough to that, before the 1980 toxic shock syndrome investigation, when one of my friend's wives was hospitalized back in 1977. She ultimately recovered, but she'd almost died, and I'm certain she had TSS. 

How much contact do medical investigators have with the people who are suffering from the disease they are investigating?

It depends on the outbreak. In Sierra Leon, with Lassa fever, I was sleeping in a wing of the men's ward where people were dying. I was literally in the next room sleeping and listening to them die. That's pretty vivid. But that's unusual. It's certainly what's happening with people doing investigation of Ebola, though, because they are just immersed in this dramatic situation. 

In Philadelphia in 1976, I arranged to have all of the federal field investigators go out and interview and examine every single patient with legionnaires’ disease because we had to understand the disease to come up with a definition of a case. So everybody who was in that investigation laid hands on patients and talked to them, but I didn't spend much time doing that, because that was not my focus since I was leading the team.

With toxic shock, Cathy Sands and I designed an interview of women who'd had toxic shock syndrome and the women they’d identified as their best friends. We interviewed them over the phone and asked them a series of very intimate questions. It was a fascinating, challenging undertaking, but I spoke with probably a fifth of the people we knew about who’d had toxic shock syndrome and their friends. That taught me a lot about the problems they went through, the problems that had precipitated their illness. 

What is the relationship between public health, specifically the work of medical investigators, and the patients they serve?

My job as an epidemiologist is to explain patterns in the disease and to explore questions. It's not the role of the epidemiologist to be personally involved. There is a remove, and to some degree there ought to be, because I have to be systematic and go through the disease in a structural way.

As a public health person, I have sympathy for not just the people who are sick, but the people who might get sick. They're my responsibility also. I want to prevent illness. Now, that's not a situation that clinicians are faced with, but it's very much on the mind of a public health worker and so I'm alert to the fact that people are anxious that they might get sick, and they’re anxious because they don't know how to prevent getting sick. I'm anxious to allay their fears not just by holding their hand, but by solving a problem. I think I'm pretty alert to those emotions, but they aren't what's going to get me to the answer, and what I want to do is get to the answer because that's what they [the public] are looking for.

There have been recent outbreaks of legionnaires’ disease in places like Atlanta and, although it's been decades, legionnaires’ disease is still believed to be under-diagnosed, according to the CDC. What are your thoughts?

There is a lot of diseases out there that we don't know the cause of, but it's one or two cases, so people aren't really concerned about it; it doesn't make the newspaper. But when legionnaires’ breaks out it causes anxiety, and rightly so, because we don't want to have disease spread. It's like car accidents; we pay more attention to plane crashes than car accidents because when they happen they affect a lot more people.

What's the relationship between your past as a medical investigator and your current career as a fiber artist?

I've struggled to figure out the relationship, but in both the art and in epidemic investigation, I'm very interested in understanding the structural systems that lead to certain outcomes. Whether it’s to certain artistic results that I like, or a bad outcome like an epidemic, I want to understand the principles that underlie phenomena that are either the beautiful or the awful.

Lorinda Toledo is a writer and journalist in Los Angeles.