He donned his white coat and hurried down the hall, toward the cries for help.

Mandera was one of Kenya’s poorest counties. Per capita income was 267 US dollars—less than 75 cents per day. The dusty, dirt road town lay at the crossroads of three nations: Kenya, Somalia, and Ethiopia. People in Mandera lived off the land, often barely scraping by, and found joy where they could. It was a place of breathtaking beauty and unspeakable brutality.

The world’s deadliest diseases were endemic to the region, but they were far from the most dangerous elements in the area. Al-Shabaab, an Islamic terror group and affiliate of al-Qaeda, attacked the villages and government facilities frequently. Their ruthlessness was staggering. Less than a year ago, al-Shabaab militants stopped a bus outside Mandera and ordered all the Muslim passengers to get off. They refused and instead crowded around the Christian passengers. Al-Shabaab dragged everyone from the bus—both Muslim and Christian—lined them up, and shot them. Thirty-seven people died that day.

As Elim raced down the dingy hall, that was his first thought—another al-Shabaab attack.

To his surprise, he found two young white men in the exam room, their dark brown hair long and shaggy, their thick beards dripping with sweat. One man stood by the door, holding a video camera. The other lay on the exam table, rolling side to side, his eyes closed. The stench of diarrhea and vomit was overwhelming.

Two nurses were leaning over the man, performing an intake exam. One drew a thermometer from the man’s mouth and turned to Elim. “A hundred and four, Doctor.”

The young man with the video camera let it fall to the side and caught Elim by the upper arm.

“You’ve gotta help him!”

Elim pulled free and extended his arm to push the man into the corner, away from the exam table.

“I will. Back away, please.”

Elim’s initial diagnosis was malaria. The disease was rampant in tropical and subtropical regions, especially impoverished areas like Mandera, which was only about two hundred and fifty miles from the equator. Worldwide, over two hundred million people were infected with malaria each year, and nearly half a million died from the disease. Ninety percent of those deaths took place in Africa, where a child died of malaria every minute. Westerners visiting Kenya frequently came down with malaria as well. It was treatable, and that gave Elim some hope as he snapped on a pair of blue gloves and began his exam.

The patient was barely conscious. His head tossed from side to side as he mumbled. When Elim pulled the man’s shirt up, his diagnosis changed immediately. A rash ran from his abdomen to his chest.

Typhoid fit these symptoms better. It was also endemic to the region, and was caused by bacteria—Salmonella typhi—that bred in open pools of water. Typhoid was manageable. Curable. Fluoroquinolones—one of the few antibiotics they had on hand—would treat it.

Elim’s hope vanished when the man’s eyelids parted. Yellow, jaundiced eyes stared up at him. Blood pooled at the corner of his left eye, then trickled down the man’s face.