Globetrotting Pathogens

In a world where diseases hop borders as easily as people do, vigilance and skepticism are required in equal doses, as Dallas? Dr. Assefa Tulu well knows.


On a Saturday afternoon last November, Dr. Assefa Tulu was at home reading when his Motorola Airtouch pager started trilling insistently. It was his answering service. When he called back, Dr. Tulu, the communicable disease expert at the Dallas County Health Department, received the most alarming message of his career: A doctor in a Dallas emergency room had just admitted a young woman who had all the symptoms of Ebola, one of the deadliest viral hemorrhagic fevers in the world.

A 31-year-old African woman living in Dallas had been brought to the emergency room of Medical City Hospital by her brother, who had dropped her off and then left. The woman had complained that she was bleeding internally. E.R. nurses initially suspected a gynecological problem, but when a physician’s assistant began to examine her, the woman started vomiting blood. She also had blood in her rectum and blood oozing from her gums; when the P.A. stuck her with a needle, she wouldn’t stop bleeding. Her blood pressure was extraordinarily low, and her heart rate unusually high. The woman was so groggy that it was hard to extract much information. She did divulge that within the last 72 hours she had returned from a month-long trip to Zimbabwe–though she couldn’t remember where else she had traveled while in Africa.

Just then, health officials in Uganda were mounting an all-out campaign to stifle the most severe outbreak of Ebola ever seen. But the admitting physician, Dr. Kerry Johnson, didn’t want to jump to a far-fetched conclusion. Perhaps she had malaria or HIV, or was having an adverse reaction to a drug. The woman maintained that she couldn’t have HIV, however, and she denied taking any medication other than Mylanta. A blood sample tested negative for malaria parasites.

Whatever she had, it looked serious. The woman’s blood platelet count had been measured at 10,000 per microliter, though normal platelet counts run from 150,000 to 450,000 per microliter of blood. To minimize the risk of contagion, Johnson ordered that the patient wear a mask, that a minimal number of staff be allowed into her room, and that they wear protective garb while there. Meanwhile, he kept trying to decipher the cause of the woman’s rapid deterioration.

In the back of his mind, Johnson knew that if the woman had Ebola, or any similar disease, then several staff members, including himself, had already been exposed. According to Arleen Furey, the E.R. supervisor on duty that night, some of the E.R. staff pooh-poohed the notion that Ebola could turn up in Dallas. It seemed too outlandish, the idea of such an alien disease making its way into the Medical City E.R. Furey told them to wake up; the world had changed around them, and there was no telling what might come through the doors. “There are no borders anymore,” she told her staff. “Just keep wearing your masks and gloves.”

Though Johnson decided that she belonged in the hospital’s Intensive Care Unit, the I.C.U. staff felt that their primary mission was to keep germs out of the area, and they approached this task with the zeal of Cold War hard-liners battling communism. They didn’t want an Ebola patient. A doctor in the I.C.U. told Dr. Johnson that he thought there might be a countywide plan to send patients with things like viral hemorrhagic fever over to Parkland Hospital, or to some other facility.

Uncertain how to proceed, Dr. Johnson contacted Linda Miller, one of the nurses on Medical City’s infectious disease control team, and she called Dr. Tulu. Tulu explained to Miller that there was no plan to divert Ebola patients to Parkland–such an idea had been discussed, but it was decided that moving highly contagious patients around Dallas would only increase the risk of sowing infection around the city. Medical City should keep the patient, Dr. Tulu instructed. The hospital staff should keep her movements to an absolute minimum. If she needed an X-ray, they should bring the machine to her, instead of the other way around. Finally, Dr. Tulu arranged to consult with the doctors working on the case, as he wanted to make sure that they had a sound basis for their suspicions before he alerted the Centers for Disease Control and Prevention (CDC) to the chance of an Ebola outbreak in Dallas.

If the woman did have Ebola, it would be the first full-blown case anywhere in the United States–and a national emergency, as the disease, which is highly contagious, has no known cure. Dr. Tulu had to figure out whether this was an epidemiological crisis or a false alarm.

People who spend their entire lives in the United States generally enjoy a sense of immunity from exotic scourges. But globalization has made the world a smaller place in all kinds of ways. In this era of mass immigration and cheap airplane tickets, diseases move from country to country more rapidly than ever before. Today, local health officials such as Dr. Tulu are on the front lines of a war to keep foreign pathogens out of this country.

The Dallas County Health Department operates out of a nondescript concrete building alongside of a freeway. Dr. Tulu’s office is on the fifth floor, one wall of which is dominated by a huge laminated map of the city. When I visited, I found Dr. Tulu so soft-spoken that I kept having to lean forward to catch what he said. He is a tall, thin man with exquisite manners and a mournful air.

Dr. Tulu is originally from Ethiopia. He got his M.D. in that country, subsequently obtained a Ph.D. in public health in London, and then trained at the CDC in Atlanta, where he participated in the prestigious internship program known as the epidemiological intelligence service. Now he is on call 24 hours a day, seven days a week. “In this job, you really don’t have any time of your own,” he said. “But my life has always been like this.” His wife and three sons have grown accustomed to the way that Dr. Tulu appears and disappears at all hours.

Over the past two decades, thanks to its international airport, Dallas has become a common point of entry for immigrants from around the world. The neighborhoods depicted on Dr. Tulu’s map are home to Albanians, Kurds, Hmong, Indians, Pakistanis, Serbs, Sierra Leonians, Somalis, Sudanese, Thai and Vietnamese, among other nationalities. Last year, thirty million people boarded airplanes taking off from the Dallas-Fort Worth International Airport, and thirty million people got off planes that landed there. All this coming and going constantly ferries exotic viruses and bacteria and parasites into the area, too. “We have an increasingly larger and larger population in the whole world, as well as a greater volume of international travel,” observed Dr. Tulu. “It really is a condition for the greater transmission of any infectious disease. Any pathogen–it could be a parasite, it could be a bacteria, it could be a virus–you really stand a greater chance of acquiring it here, just because of the sheer number of people that you have in the world today.”

Dr. Tulu’s years of experience in rural Africa often come in handy in Dallas. The city has lots of hepatitis-B, because that disease is endemic in children from Southeast Asia. Tuberculosis, which is endemic in Africa and Eastern Europe, has been on the rise. So far this year, Dr. Tulu has gotten reports of four cases of malaria (the subject of his dissertation), which is rampant in the developing world. And Dr. Tulu knows that once the summer holidays end, he will hear reports of hepatitis-A among schoolchildren who have spent the summer visiting their extended families in Mexico. “When they come back, typically you have a big wave,” said Dr. Tulu. “Hepatitis-A is much more endemic in Mexico than it is here.”

It’s not just poor immigrants who bring diseases into this country with them. Part of Dr. Tulu’s work involves warning Dallas residents about health hazards they may encounter if they travel in the developing world. Wealthy individuals who like to frequent resorts in exotic locations and workers who labor on development projects in remote sites are particularly at risk. Dr. Tulu advises such travelers against swimming in freshwater lakes in Africa, for example. “They might think they are okay, but there are parasites there which carry diseases like schistosomiasis,” he said. Symptoms of that disease, caused by tiny worms, include diarrhea and anemia; in rare instances, if the worms burrow into the brain or the spinal cord, victims can also suffer seizures or paralysis. It’s fairly common among refugees who have settled in Dallas.

To Dr. Tulu’s mind, the greatest imaginable public health disaster would be one in which some strange communicable disease infiltrated Dallas, and then went unnoticed for a considerable length of time. “The worst-case scenario is, you have a certain disease that isn’t recognized early on,” said Dr. Tulu, “and it has spread very much by the time it is discovered, so that it is too late to control it.” Of course if the illness happened to be highly contagious, things could spiral out of control very quickly. For a few days last fall, Dr. Tulu actually feared that might have happened.

On the night the woman with Ebola symptoms was admitted to the Medical City E.R., Dr. Johnson summoned three of the hospital’s physicians to consult with him–specialists in internal medicine, hematology, and infectious disease. They discussed the possibility that the woman had AIDS. Dr. Steven Seidenfeld, the hospital’s infectious disease specialist, knew that HIV infection rates in parts of Africa were more than 30 percent. But this didn’t look like any AIDS case that the doctors had ever seen. Even if the woman was HIV-positive, they figured she must have an acute infection on top of that, given her raging fever and all the bleeding.

Word of “the Ebola lady” spread through the ranks of the Medical City staff faster than any virus ever could. The supervisor of the orderlies called Miller, the infectious disease control nurse, at 6:15 on Sunday morning: Was it safe to clean the room the Ebola patient had been in down in the E.R.? Miller assured the supervisor that regular medical disinfectants would kill even Ebola. Meanwhile, similar fears were compromising the work of the hospital’s laboratory. Technicians there decided not to continue examining specimens from the woman, because they feared that the Ebola virus might permanently contaminate their equipment. Hospital staffers were failing to perform their jobs according to regulations, due to the irrational fears now blooming in their minds.

Later that day, Seidenfeld was able to elicit a far more complete history. The woman said that she had never traveled to Uganda. In fact, during the month that she spent in Africa, she never left Zimbabwe’s capitol city of Harare at all. She had, however, taken a rather meandering journey home. Dr. Seidenfeld listened with dawning horror as the woman related that from Harare, she had flown to Cairo, Egypt, where she had waited for 16 hours, then caught a plane to Newark, New Jersey. From there, the woman had taken a Greyhound bus to Dallas. She had started to feel sick on the flight to Newark, and had vomited in the plane’s bathroom. Her condition had worsened on the trip to Dallas; she had vomited repeatedly in the bus’s bathroom, and for the first time had noticed blood in her vomit and urine.

A stunned Dr. Seidenfeld had visions of countless people getting on and off the Greyhound bus at every stop along its route from Newark to Dallas. He couldn’t even begin to calculate how many individuals the woman might have infected herself, let alone how many other people those individuals might have gone on to infect across the eastern and central parts of the United States. If this woman had Ebola, then it sounded as though she had probably spewn the virus over scores of people in a dozen different states. He might have an exploding public health catastrophe on his hands. Dr. Seidenfeld broke the news about the bus trip to Dr. Tulu in one of their frequent phone conversations. “Both of us, we were really terrified,” said Dr. Tulu. “You can imagine all the exposures that we had with her.”

While it was Dr. Seidenfeld’s job to worry about the havoc that the woman could wreak upon Medical City, Dr. Tulu had the luxury of being more skeptical. Being from Africa originally, he also had a keen sense of just how rare it is for anybody to come down with Ebola at all–particularly in a large city. “Most of the viral hemorrhagic fevers are usually confined to rural areas,” he observed. And to the best of his knowledge, there had been no reports of Ebola in Harare or Cairo. That weekend, Tulu spoke with Stuart Nichol, of the CDC’s special pathogens branch. “There is really not much in the history that would lead me to believe that this person could be suffering from any of the viral hemorrhagic fevers,” Dr. Tulu told Dr. Nichol during one of their talks. Nichol agreed that the woman probably had an unusual presentation of a common illness, quoting a saying popular among epidemiologists: “When you hear hoofbeats, you should be thinking horses, not zebras.”

Still, the two epidemiologists wanted to rule out all of the viral hemorrhagic fevers, because the woman had just been to Africa, and her symptoms were so like those of Ebola. Since there was no facility in Texas where he could test for those diseases, Dr. Tulu agreed to have the Medical City staff send blood samples to the CDC as soon as possible.

Over the weekend, the Medical City staff had located the woman’s brother and her boyfriend, and had put the two men in isolation as well. On Monday, the woman’s brother told doctors that his sister had been to the funeral of a small child while in Africa. Neither the patient nor her brother could say what the child had died of. Suddenly the prospect of some fatal contagion seemed more real. At about that time, the I.C.U. staff learned that the hospital’s lab had not sent any blood samples to the CDC, as ordered. The day before, the hospital’s infectious disease control team had assured the lab staff that Ebola would not permanently contaminate their equipment. After that, the lab technicians had proceeded with the rest of their experiments, but then they had mutinied again: Lab staffers were supposed to have taken blood samples to the airport, where they were going to be sent to Atlanta via FedEx, but nobody would agree to carry the blood there. After Dr. Seidenfeld knocked some heads around, the blood was finally sent off.

Late Monday evening, the hospital lab informed Dr. Seidenfeld that the African woman’s immune system was severely compromised. She had HIV after all–though that didn’t mean that she did not have Ebola. On Tuesday, however, Stuart Nichol called from Atlanta to say that the woman had tested negative for Ebola. She had tested negative for Marburg disease and Crimean Congo fever as well. She didn’t have yellow fever, or dengue fever. What exactly she did have, other than AIDS, the doctors at Medical City never discovered. HIV has long baffled the medical community due to the bewildering variety of guises that it can assume, and the clinical literature does record a few cases where HIV alone has brought on Ebola-like symptoms. Today Dr. Tulu believes that the woman simply had a bizarre case of HIV.

Still, for the staff at Medical City, the brief transit of the bleeding African woman through their institution was a jolting wake-up call. Despite the resolution of her case to the contrary, it told them that in today’s world, Ebola can arrive in Dallas. “It will happen,” said the E.R.’s Dr. Johnson. “It’s not a matter of if, it’s a matter of when. That was the take-home message for me–you have to keep your guard up. The world’s just getting so small.”

From the vantage point of his fifth-floor office, where Dr. Tulu keeps meticulous records of all that Dallas does and does not contend with, the case held a dif
erent significance. To Dr. Tulu’s min
, the case proved that undue alarm over rare illnesses may be the one thing that is even more contagious than the worst of Africa’s fevers. “The thing that probably prompted the suspicion of Ebola was, first, the travel history, and second, the coincidence of the Ebola outbreak in Uganda,” said Dr. Tulu. “It was all in the medical media as well as the mainstream media. That may have affected the perception with regards to her.”

Dr. Tulu believes that the staff at Medical City should be commended for their actions; he thinks the hospital did everything right. But he views the story of the African woman as a morality tale with paradoxical instructions. “There are two lessons,” he said. “One is that you may have to think of the common thing first, before you think of the rare things. The second lesson is that we need to be prepared, even for such a rare occurrence.” For Dr. Tulu, the case defines the permeable era in which we live, where both germs and information travel faster than they ever have before. He has to be equally ready to believe, and to doubt, in anything.

Skepticism was, in this instance, a particular virtue, because it encouraged the medical experts involved to keep their suspicions quiet. Had the hospital staff broadcast their fears, they would have almost certainly caused a needless uproar–as indeed a hospital in Canada did this past February, when faced with the identical circumstances. “We decided to make nothing public until we ruled out all the common things, because there was no good cause for alarm,” Dr. Tulu said. “If we had made our fears public, it would have diverted resources away from our main focus, which was investigating this case, because we would have spent all of our time answering media calls. And if the word had gotten out, it would have created unwarranted hysteria. Probably everybody would have avoided that hospital, and maybe even Dallas, to a certain extent.”

To an epidemiologist with a less steady temperament, the very notoriety attached to Ebola–which has been the subject of a best-selling book and two Hollywood movies–could itself become a dangerous distraction. Dr. Tulu feels fairly certain that, should the health of the residents of Dallas ever be seriously compromised, Ebola will not be the cause. What Dr. Tulu fears most are not “hot” viruses that get everybody’s attention and persuade entire institutions to operate at peak performance, but seemingly mundane pathogens that evoke no such zealous response. The health issues that creep up on a city slowly are the ones that keep him up at night.

Tuberculosis is a disease that nobody in Hollywood considers making a film about. “It doesn’t present as readily as the scary diseases,” said Dr. Tulu. “But it’s highly prevalent in developing countries, and many people don’t complete treatment there, which creates a high incidence of drug-resistant tuberculosis. That is going to be imported here through people who emigrate to work. And because it really takes some time for symptoms to manifest themselves, that leaves a lot of time for other people to be infected.”

Lack of affordable health insurance and massive numbers of new immigrants have combined to create conditions ripe for a steep rise in TB cases. Periodically, nurses from the Dallas County Health Department fan out across the city to administer TB tests, but who knows how many cases they miss, as the testing is voluntary. Some monster bug might take this city by storm, but it’s far more likely, Dr. Tulu believes, that Dallas will slowly surrender to a less dire threat. He just sent off to the CDC the list of the “reportable diseases” that he had compiled for February. There were 26 new cases of TB, 2 percent more than the same month last year. Every month, Dr. Tulu watches as the number of TB cases ticks upwards slightly; he wonders whether, one day, in the not-too-distant future, Dallas residents may wake up and find that their TB rates have approached those of a Third World country. Not even his recent brush with Ebola has dissuaded him from thinking that this is the real danger facing his adopted hometown.

Helen Thorpe has written for The New York Times Magazine, Texas Monthly, Slate and other publications.