The Challenge: A 50-year-old woman feels tired and feverish after a trip to her home in Kenya. Can you figure out why?

Every month, the Diagnosis column of The New York Times Magazine asks Well readers to sift through a difficult real-life medical case and solve a diagnostic riddle. In this case, a middle-aged woman living in Chicago visits her family in Kenya, her first trip back in over a decade. When she gets home she starts feeling sick — tired, hot, sweaty and nauseated. She wonders: Could this be malaria? It takes almost two months for her doctors to answer that question.

I will provide you with much of the information available to the doctors involved in the case. It is up to you to use this information to make the correct diagnosis.

As usual, the first person to crack the case gets a copy of my book, “Every Patient Tells a Story,” and, of course, that fabulous feeling you get when you figure out a tough problem.

Sick and Tired

“You really need to call your doctor,” her friend said. She was shocked by the changes she saw in the 50-year-old woman who had come to the door. “Gosh, you look awful.”

The woman had just been discharged from the hospital, but she didn’t look or feel any better than when she had gone in the week before. Indeed, she hadn’t felt well since she’d returned to Chicago from a visit to her home in Kenya three months earlier.

To the visitor, the woman seemed a ghost of her former self. She had lost nearly 20 pounds — from a frame that was small to begin with. Her eyes and cheekbones found a new prominence in this thinner face. Her skin looked gray behind the usual deep brown color, and her lips were pallid.

She knew her friend hadn’t been well, but she had assumed she would get better once she was under the care of doctors. And yet she looked sicker now than she ever had.

The Patient’s Story

The woman considered herself pretty healthy. She had a doctor she saw every year or so just for a checkup but really had no medical problems and took no medications. She grew up in Kenya and had a couple of bouts of malaria as a child.

She had moved to the United States in her late teens and traveled back to Kenya every few years to see her family. A busy job and growing family here had made trips home a little less frequent, but she’d decided that it was time for her and her two children to make the long journey.

Before going she had gotten the whole family vaccinated against hepatitis A, typhoid and yellow fever and made sure they all took the medicines to prevent malaria, starting two weeks before their trip and continuing until they’d been back in Illinois for two weeks. They’d traveled all over the country, visiting relatives and seeing the sights. It had been a wonderful trip.

A Rough Homecoming

Coming back had been brutal. The jet lag was so much worse than she remembered. Everyone else seemed to get back into the groove right away. But somehow she couldn’t.

Initially she felt exhausted. She figured it was just jet lag. But the fatigue didn’t ease. And her stomach had turned sour. She constantly felt like she was going to throw up, though she didn’t — at least not at first.

After about a week of feeling lousy she went to one of those doc-in-a-box clinics at her local Walgreens. The young doctor there asked about travel and she mentioned her trip to Kenya. It felt a little like her old bouts of malaria, she told the doctor. I don’t treat malaria, you really need to see your regular doctor for that, he told her.

She had tried to see her regular doctor, but when she called she was told that her doctor was out of the office. That’s why she’d gone to the drugstore. But if he couldn’t help her, she’d need to find another doctor. She called her local hospital and they gave her the name of one of the doctors accepting new patients..

Malaria?

The doctor she ended up seeing agreed that malaria was possible. Although she and her family had taken the medication to prevent the infection, there were forms of malaria that were resistant to these drugs. If she’d been exposed to that infection, she could still have malaria.

He started her on a three-day course of an antimalarial drug. It didn’t help.

Over the next week, even as she took the medication, she began to feel worse. She felt so weak and sick she could hardly move. She was hot and sweaty. Her heart was pounding furiously. And she was vomiting nonstop. She wasn’t able to eat for four days and wasn’t able to even get out of bed for two.

She called the doctor again, and he promptly sent her to the emergency room.

A Treatment Worse Than the Disease?

In the E.R., her heart was racing and her blood pressure was high. Her white blood cell count was dangerously low, and her liver showed some evidence of injury. It wasn’t clear what was wrong, and she was admitted to the hospital.

The E.R. and admission notes from that hospitalization can be seen here.

At the hospital, the doctors gave her medicine to stop the vomiting, which helped. But after several days it still wasn’t clear what had made her so sick.

It probably wasn’t malaria. She’d had three blood smears examined in the lab, and although she wasn’t having a fever when the blood was drawn — that’s when the test for malaria is most sensitive — none showed any sign of the parasite that causes this febrile illness.

When she was able to keep food down she was sent home. The tests that had been done, looking for infections in her blood, urine and liver, had all been unrevealing. It was an unsatisfying resolution, but the thinking among the doctors was that she had an adverse reaction to the medication she’d been given to treat the presumed malaria.

Wasting Away

Once the patient got home, though, she started throwing up again. She toughed it out for just over a week but finally dragged herself back to the same community hospital where she’d been seen before.

The doctors there were worried enough about her to transfer her to the larger academic hospital where many of them had gotten their training. They’d be able to figure it out.

But they weren’t. The patient spent a week getting IV fluids, a variety of antibiotics and test after test. You can see the emergency department notes and the admission notes from that hospitalization here.

The infectious disease doctor at the hospital looked for other parasites, viruses and mosquito-borne infections endemic to the areas in Africa she’d visited. Nothing.

A liver biopsy showed injury but no sign of what might have caused it. A work-up for autoimmune diseases led nowhere. Cancer was looked for but not found.

Medications relieved her vomiting, and she was sent home to follow up with the infectious disease specialist the following week. You can read the discharge summary, with results from all the testing she had, here.

Her Regular Doctor

When the patient returned home she called her friend. Could she come and help out with the family, since she was still too sick to manage her home and kids? Of course, her friend agreed.

And that was when she saw how very sick her friend had been. She had to see her regular doctor, her friend urged. She needed to call the doctor who had known her and cared for her for nearly 20 years.

The friend picked up the phone and made an appointment for the next day. Your doctor will know what to do, she assured her friend.

Solving the Mystery

And indeed, her old doctor did figure out what to do. With less data than you have at your disposal, this doctor was able to come up with a diagnosis.

So what did this patient have?

Post your thoughts in the comments section. The first person to offer the correct diagnosis will get a copy of my book and that wonderful sense of satisfaction that comes from figuring out a tough diagnosis when the patient really needs it.

Rules and Regulations: The winner will be contacted. Reader comments may also appear in a coming issue of The New York Times Magazine.