Meet the Scientists
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Ali S. Khan

Disease Detective

Ali S. KhanAli S. Khan, M.D., is a field epidemiologist, or disease detective. He travels to remote places all over the world where mysterious outbreaks of disease are occurring. His job is to try to figure out what bad microbe is causing the disease and to help people figure out how to avoid and treat these infections. He’s grappled with some of the scariest, deadliest viruses in the world including Ebola and Hantavirus. He has worked in war zones, jungles and deserts. He loves his job.

You work with the Centers for Disease Control and Prevention, or CDC, which is America’s national public health agency.

I work with the Viral Special Pathogens Branch at CDC. This is the branch that deals with all those scary diseases you may have heard about like Ebola hemorrhagic fever, Congo-Crimea hemorrhagic fever, and a bunch of other severe diseases.

What exactly does a field epidemiologist do?

My job is probably no different from any other detective in the world, except I try to figure out how people in a community are getting sick.

What we do is we’ve got to find all the clues first. Then we’ve got to put all those little clues together like a puzzle to try to figure out what’s going on in the community—who was the first person sick, who was the second, who was the third, what were their associations, what were the things that they did that got them infected. And the nice thing about what we do as disease detectives is that we don’t just solve a mystery. Once we solve it, that tells us how we can actually make a difference—how we can make this disease go away.

I travel a lot as part of my job. However, I don’t do what people would usually consider "fun" travel. I don’t go to big cities all over the world. I go to teeny tiny villages out in the middle of Central Africa or the middle of the Amazon or the Patagonia Mountains in Chile. I go to very remote places because all these diseases tend to be associated with animals—usually mice, sometimes bats, sometimes mosquitos—and these host animals that pass the disease to people don’t tend to occur in cities like Paris.

The places we go, it’s camping to the extreme. There is no electricity, there is no phone, there is no running water. A bath is a luxury you wait for when you get back to the main city sometimes weeks later.

How long are you typically out in the field?

You spend weeks or months in an area, depending on the outbreak.

What are some of the disease outbreaks you’ve worked on?

In 1993, at the end of my first two years with CDC, there was an outbreak in the southwest United States where New Mexico and Colorado and Utah come together. There were all these Native Americans who got sick, all these young, healthy people who all of a sudden had difficulty breathing. And many of them died—about half to three-quarters of them died. No one knew what was going on. CDC was asked to come investigate this outbreak.

It turned out to be a brand new disease in the United States called Hantavirus pulmonary syndrome. It’s caused by a virus carried by mice. There were these weather conditions that occurred that caused the mice to increase—there were a lot more mice. The virus carried by the mice infected people and people started getting sick. Once we figured out it was the mice, we could tell people, this is how you protect yourself. You fix your houses to keep the mice from getting into the houses.

  Khan bleeding monkey in Philippines
Khan (right) taking blood sample from monkey

I did an outbreak of Ebola virus in the Philippines. I had to learn how to bleed cynomolgus monkeys. These monkeys have these teeth, these FANGS on them. The handler would be holding the monkey from behind with its tail, and you’d be there literally inches away from this mad monkey’s mouth. And I’m thinking, ‘Ok, if this guy lets go of this monkey, a) I’m going to lose my hand and b) I’m likely to get rabies or herpes B virus, both of which could kill me!’

Isn’t it scary to work around people and animals that have these really nasty viruses that could be fatal?

Sometimes my job, I must admit, can be very scary. Many of the diseases we’re dealing with tend to kill you if you get infected and there’s no treatment for them and there’s usually no vaccine.

I was very scared when I was in Kikwit, Zaire, investigating an outbreak of Ebola. All these people were dying from this fever and they were bleeding from their noses and vomiting up blood and having bloody diarrhea. This disease can go from person to person. We showed up at Kikwit to the main hospital, which was essentially deserted except for a a guy who had a broken hip who couldn’t move, so he couldn’t flee. There were these two wards. Both were full of patients with Ebola, one with health care workers—doctors and nurses—who’d gotten sick. There were bodies that had not been removed. I had to take care of some of these patients and draw blood from them and I had to be very careful. I wore gloves and a gown and mask so I didn’t get infected myself.

But as epidemiologists we know how to protect ourselves when we do this and the information we get helps us keep other people from becoming sick. We hope we’ve taken the appropriate precautions, not just for our sake, but for the sake of the people we’re trying to help.

How do you protect yourselves when you’re working on outbreaks?

Biosafety lab in the field  
Scientists wearing protective gear outside a makeshift biosafety lab in the field

We wear latex gloves and plastic gowns and masks. Sometimes we put up what we call our portable biosafety level 4 lab in the field. That usually means taking over the room of a hospital or a shack or hut away from as many people as possible and sealing all the windows and doors.

We go in wearing almost scuba-like outfits with gowns, gloves and a plastic hood that goes over your head with a respirator device that sucks air in, filters it and blows it over your face. We work on samples from the field to process them or maybe make a quick diagnosis.

  Protective gear
Protective clothing, including respirator

Sometimes the place itself can be scary. I’ve been in war zones. The time I was most in physical jeopardy was when I was in Zaire (now called the the Democratic Republic of the Congo) investigating monkey pox, a virus that infects squirrels and people catch the squirrels to eat them and get infected with the virus. This was when Kabila’s forces were advancing on the capital Kinshasa held by Mobutu’s forces. We were smack in the middle of the war zone. We’d keep track every day of the advancing front of Kabila’s forces. In the end, we found out that the forces had moved faster than we thought and were actually only half a day from us. So in the middle of the day we just stopped everything, shut down, got in our cars and ran away to a nearby town where we radioed for a plane. There were actually gunshots fired when we were getting on the plane.

What are some of the neat or fun things about your job?

We get to meet some very interesting people and learn about cultures that most people never so much as hear about or ever get an opportunity to see.

For example, I got to meet the Masai who are these very handsome, tall, black people of Tanzania and Kenya. We worked with them when they had an outbreak of Rift Valley fever, a disease that kills livestock—their cows and goats and sheep. This is a big deal if you’re a Masai because they don’t have bank accounts. Their animals are their money. So we explained to them how they could protect their animals and how to protect themselves, because this is a mosquito-borne disease that also infects people.

When I was in Tanzania and Kenya we used to drive to these small villages to do our studies. We’d be trying to get where we needed to go and all of a sudden we had to stop because the giraffe were crossing the road.

  Taking blood samples in Oman
Khan taking blood samples from villagers in Oman

You also establish very intense relationships with the other members of the team you’re working with. You’re all very goal-oriented and you’re all together for a specific purpose. You develop really good friendships during those periods. One person I’ve worked with a lot is Dr. Joel Williams, a veterinarian. One time, we were doing an investigation of Congo-Crimea hemorrhagic fever in Oman, which is on the Arabian peninsula near Saudi Arabia and Kuwait. We’d go from place to place and Joel would bleed goats, checking for virus. One day one of the goats went behind Joel and started eating up all his papers on which he was recording all his data. I’ve never seen Joel so mad. I was pretty sure he was going to try to get the papers out of the goat’s stomach. Fortunately, he’d been recording all his data into his computer each night.

Did you think this is what you’d be doing one day when you grew up?

No, I always thought that I would be a doctor in a hospital seeing patients and making sure they got the right treatment. That’s what I thought I would do when I grew up.

How did you become a virus hunter?

I went to medical school and I did a four-year residency—that’s where you spend some time getting practical experience dealing with patients. I was planning at that point to go on and do what’s called a fellowship in infectious diseases. But I had a great mentor who had gone to CDC. He said, ‘Why don’t you spend two years at CDC? They have this really nice program called EIS—Epidemic Intelligence Service. This is a program to teach physicians and other public health people how to be disease detectives. When you’re done you can go back and become an infectious disease doctor working in a hospital.’ So I came to CDC to learn how to be a disease detective. And those were probably the two best years of my life. I got the opportunity to go all the way to Russia to do a study in kids looking at a new vaccine for influenza that you spray up the nose. I did an interesting disease in Wyoming, an outbreak of vertigo. There were all these dizzy people showing up in the emergency rooms in Demopolis, Wyoming.

Do you have to be a doctor to become a field epidemiologist?

Lots of people do this type of work. You don’t have to be a doctor. You could be a veterinarian. You could be an entomologist (a scientist who studies insects). You could be an epidemiologist, you could be a microbiologist—there’s lots of different ways to be a disease detective. The skills of many different people are needed.

This is pretty intense work. Do you ever think about doing something else?

I absolutely enjoy what I do. Sometimes I think it would be nice to have a more leisurely life. But I help people. I really help people everyday with my job. And I solve puzzles. Intellectually my job is very challenging. My brain works every day. I don’t think I could find that intellectual challenge anywhere else.