Vital Signs: Trypanosomiasis

Mr. Post's escalating fever after a monthlong trip into the bush was not a good sign.

By Claire Panosian DunavanOct 1, 2000 5:00 AM


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Christopher Post was not yet home when he noticed the crimson spot, roughly nickel-sized, on his left biceps. Returning from the trip of a lifetime, a monthlong safari in Africa, he was tired, achy, and hot. Maybe it's eczema, the 50-year-old stockbroker reasoned. He'd be better in a couple of days.

But a few days later, Mr. Post was worse, with a higher fever. The spot on his arm was bigger. His internist was out of town, so he drove to a nearby hospital.

"Did you use malaria pills in Africa?" asked the emergency-room physician.

"Yes, and I also got shots before leaving," Mr. Post said. For the trek to Tanzania and Rwanda, he had prepared by the book: yellow fever and typhoid vaccines, a quinine-type drug to stave off malaria, and a stash of diarrhea pills.

"I'm not sure about that bug bite," the doctor mused, "but your fever is straight from the textbooks. Sounds like malaria to me. We'll start with a blood exam."

An hour later, he returned with microscope slides.

"Mr. Post," he said, looking grave, "your problem is not what I thought. Here are your blood smears. Our hospital is not prepared to take care of you. They're expecting you at the university hospital as soon as you can get there."

Andy Peters was the internal medicine resident on duty at the university hospital ER that day. He liked figuring out infectious diseases— the more exotic, the better. Andy's jaw fell as he scanned through Mr. Post's blood smears. He had expected to see the delicate rings of the malaria parasite within red blood cells. Instead he saw wavy, whip-tailed creatures swimming free like eels. By microscopic standards, they were big eels— twice as long as the patient's blood cells. Andy consulted descriptions of another blood-borne parasite from Africa: Trypanosoma brucei. Bingo. Perfect match.

He headed to the patient's room, introduced himself, and explained his discovery: sleeping sickness.

That's when Christopher Post decided to make out his will.

Swift death is common among victims of East African trypanosomiasis, the variety infecting Mr. Post. In 1906, it killed at least half of Uganda's 6 million inhabitants. West African, or Gambian, trypanosomiasis is the more insidious, classic sleeping sickness, causing creeping inflammation of the brain that over a period from months to years gives rise to seizures, psychosis, stupor, coma, and death.

But whatever its geographic subtype, the insect vector of African trypanosomiasis is always the same: the tsetse fly. Twice as big as a housefly, with predatory mouth parts and scissorlike wings, it breeds in dark, moist niches of sub-Saharan forests and thickets. East African tsetse flies acquire trypanosomes from the blood of infected animals, typically savanna-dwelling bushbucks, or infected humans. West African tsetses tend to acquire the parasite by feeding off infected humans. In both locales, parasites multiply in the fly's stomach, then migrate to salivary glands. At that point, one bite is all it takes to launch a new infection in another animal or human.

Weeks into his illness, Mr. Post recalled brushing off some "really big insects" in Africa. However, at the time, he had no idea they were tsetse flies. Nor in his wildest savanna dreams could he have imagined the battles these parasites would wage in his body.

Trypanosomes have a canny way of dealing with the body's immune defenses. As early as 1910, researchers noticed wave after wave of parasites in the blood of sleeping sickness victims. Today we know that each wave represents a new generation with altered surface proteins. This new coat triggers a fresh volley of host antibodies. The antibodies work at first, but ultimately they fail in the face of yet another battalion of reconfigured parasites.

By the time Mr. Post reached the university hospital, the battle in his bloodstream had been under way for weeks. Not only had the parasites glutted his bloodstream, but he also was taking friendly fire from his own immune system. He had severe anemia, a dangerously low platelet count, malfunctioning kidneys, and a baggy, inflamed heart, all due to his own antibodies attacking his own tissues.

The most dreaded complication of sleeping sickness is brain infection. A test of Mr. Post's spinal fluid would show if the parasites had infiltrated his central nervous system. If we found them there, our only hope for ridding Mr. Post of the infection was melarsoprol, an arsenic-based parasite poison that also kills about six percent of patients.

We have very few treatment options for sleeping sickness, and all of them are toxic. To pick the right drug, we must identify the particular strain of the parasite and its stage of infection. Needless to say, when I got called about Mr. Post, I was concerned. I am the local tropical medicine expert, but I'm not above asking for help.

My first call went to the Centers for Disease Control in Atlanta. They operate a 24-hour hotline for crises involving parasites like Trypanosoma brucei. After hearing that Mr. Post's spinal fluid was clean, the doctor on call recommended suramin, another toxic remedy, used since the 1920s. The only problem was that the CDC has the only supply of suramin in the United States. That meant it could not reach Mr. Post until at least the following day.Could we afford to wait? Over the past 12 hours, his fever had shot even higher, and his follow-up blood smears showed wall-to-wall parasites. In desperation, we gambled on pentamidine, an antiparasitic drug we had in the hospital pharmacy. The following afternoon we started suramin.

The next few days were rocky. Within hours of treatment, the drugs killed the parasites, spilling their remains into the bloodstream. That put the immune system into overdrive. Mr. Post's blood count plummeted, his heart and kidneys worsened, and most telling of all, the bite on his arm grew huge, its borders jagged and magenta. Our dermatologist hadn't seen anything like it. But two weeks later, the victim was the victor. Just about everything we take for granted in modern health care— technology, teamwork, and drugs— contributed to beating the infection.

Today, Mr. Post and I have a special bond. After all, I'm not likely to see another case like his soon. Prior to his arrival at the emergency room, only a handful of red-hot sleeping sickness infections had been seen in the United States in a decade. Mr. Post, in turn, gained a perspective on tropical medicine no textbook could ever teach. Compared with that of fellow sufferers, Mr. Post's care was a high-tech luxury and a miracle beyond imagination.

In the land of the tsetse fly, where even the most fundamental health care is scarce, thousands die from sleeping sickness every year.

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