(Cam Cottrill for The Washington Post)

Why is he so tired, Jackie Mann wondered, not for the first time, as Evan, the middle of her three children, wandered off to his bedroom to take an after-school nap.

Small for his age, the 12-year-old seemed to fall asleep easily and anywhere: in the car on the way to soccer or gymnastics, on the afternoons he came straight home from school, while doing his homework and, once, while waiting to see the pediatrician.

But his parents noticed that Evan seemed decidedly more energetic on the weekends in the semirural community outside Oakland, Calif., where the family lives. Then he went fishing, hunting and hiking with little difficulty.

“We just kind of thought he was faking it,” said Mann, recalling the discussions she and her husband, an orthopedic surgeon, had about Evan beginning in 2010. “He would step it up with his friends.”

Evan Mann has grown considerably since he had surgery in 2014 and began receiving regular infusions of drugs. Now 17 years old, he stands 5-foot-6 and weighs 122 pounds. (Courtesy of Jackie Mann)

But Mann’s concerns intensified after a trip to Lake Tahoe, where the family rents a cabin. Evan, an avid skier, would complete a run or two, complain that he was tired and go back to the cabin to sleep for several hours.

For 18 months, as Evan’s fatigue worsened, his growth stalled and he wrestled with unexplained low-grade fevers and joint pain, a series of doctors sought to figure out what was making him sick.

The answer, when it came in January 2012, was a surprise. While his mother said that in retrospect there were abundant clues, there were also red herrings that misled doctors, including those in Evan’s family.

“Evan did not have the typical symptoms,” his mother said. “Sometimes the pieces don’t fall into place until things get really bad.”

Genetics, or something else?

Mann’s initial concern was not her son’s fatigue.

When Evan was in fifth grade, she began asking the pediatrician about his unusually small size. But the doctor, who told Mann that he didn’t believe in growth charts, a cornerstone of pediatric practice, was reassuring. All of her children were small, he pointed out, a reflection of genetics. Their father, a long-distance runner and former college gymnast, is 5-foot-6 and Mann is 5-3.

Despite the pediatrician’s reassurance, Mann felt uneasy. And she was baffled by Evan’s fatigue, which continued even after he dropped several after-school activities. In the spring of 2011, Evan, during a long wait to see the pediatrician, fell asleep on the exam room table.

That was when Mann decided to switch doctors, fearing that her concerns weren’t being taken seriously. At the time Evan weighed 63 pounds and was 4-4, seven inches shorter and 25 pounds lighter than average for a boy his age.

“This just didn’t feel right,” she recalled. She also found an allergist to determine whether Evan’s frequent sinus infections were the result of allergies that might be impeding his growth and causing his fatigue. As a child, he had taken antibiotics frequently for ear infections, and he was often prescribed the drugs for sinusitis as he got older.

But the work-up found no allergies.

A few months later, Evan visited his new pediatrician. Mann noted that her son showed no signs of starting puberty and looked more like the twin of his sister Eliana, who was two years younger. The doctor was concerned, particularly after he plotted a growth chart, which showed that Evan hadn’t grown in at least two years.

Shortly after that visit, Evan developed a bad case of hives and was prescribed several weeks of prednisone, a corticosteroid used to suppress inflammation. The change was dramatic: His energy level and appetite ticked up. The boy who could only eat half a grilled cheese at a sitting was downing two sandwiches. “It was the healthiest he’d been” in years, Mann recalled.

But when school started and Evan stopped taking steroids, the fatigue returned.

Some days, he seemed fine. But on other days, Evan would come home from school, take a long nap, eat dinner and then go back to bed and sleep through the night.

During a hike with relatives, one of whom is an internist, Mann confided her fear that Evan had recurring fevers or Lyme disease. The relative was skeptical. “I’m looking at your son charging up a hill. He looks pretty good to me,” she remembers him saying. “What’s his temperature?”

Mann said she didn’t use a thermometer, but she thought Evan felt hot.

“Oh, you’re using the ‘mom-o-meter,’ ” the internist quipped. He advised her to keep a record of Evan’s temperature, along with a symptom diary.

Mann did, and noticed a pattern. Evan’s fatigue seemed to descend every third day or so. On those afternoons, he had a fever of about 101 degrees and often complained of a headache and achy joints. Some days he also had mild diarrhea.

“Saying there was a measurable fever got everyone’s attention,” Mann recalled. When she showed the temperature and symptom chart to the new pediatrician, he immediately referred Evan to a specialist in pediatric infectious diseases.

Absolute certainty

Evan’s hives, fevers and fatigue seemed to suggest an environmental cause. The family lives on a 40-acre ranch containing horses, chickens and other animals. The Manns frequently hike in national parks, including Yosemite, which was the epicenter of a 2012 outbreak of hantavirus infection, a mouse-borne illness that killed three people. Evan liked to shoot and skin squirrels. And he had been bitten by ticks repeatedly.

But extensive testing ruled out many zoonotic exposures (diseases that can be transmitted from animals to people) including Lyme and hantavirus, as well as other infections.

The infectious-disease specialist referred Evan to a pediatric gastroenterologist.

During the initial appointment on Jan. 10, 2012, the GI specialist looked at Evan’s fingers and at the cold sores that seemed ­ever-present on the corners of his mouth, and he felt the boy’s abdomen. Within 10 minutes, he turned to Evan’s parents.

“Your son has Crohn’s disease,” Mann remembers him announcing. “I’m sure of it.”

Mann and her husband were shocked — and skeptical. Crohn’s, a serious, chronic and incurable autoimmune disorder characterized by severe abdominal cramps and diarrhea, seemed unlikely to them. Evan had only occasional, mild diarrhea.

“How can you be so sure?” Mann remembers asking. The doctor ticked off the telltale signs: Evan’s growth was stunted. He had chronic cold cores on the corners of his mouth, a common Crohn’s symptom. The ends of his fingers were clubbed. When he pressed on Evan’s lower right abdomen, the boy felt pain. Several tests had indicated unusually high levels of inflammation. Evan had greatly improved while taking steroids, a mainstay treatment for Crohn’s.

There was a family history: Evan’s great-grandmother and another relative had been diagnosed with Crohn’s, and another close relative had a similar disorder, ulcerative colitis. Evan also had taken a lot of antibiotics at a young age, which can raise the risk of Crohn’s. And finally, the Manns are Ashkenazi Jews, whose descendants came from Central and Eastern Europe; Crohn’s is more common among Ashkenazi Jews than in the general population. Scientists have recently discovered several genetic mutations among Ashkenazi Jews that raise the risk of Crohn’s.

The disease, which is believed to result from an interplay between genetics and the environment, can look different in children and adolescents, said Sabina Ali, a pediatric gastroenterologist who has treated Evan since 2013. Pediatric patients sometimes don’t have the classic symptoms seen in adults with Crohn’s — chiefly, severe cramps and frequent diarrhea — which can mislead doctors.

“Evan had extra-intestinal symptoms,” Ali noted, adding that extreme fatigue is not common and may point to a second, as yet unidentified problem. “These kids can get sidetracked into other specialties because no one realizes they have a GI problem.” In addition “some of these kids may get frequent illnesses or fevers,” the latter of which are regarded as signs of infection but actually are signals of inflammation.

An endoscopy and a colonoscopy confirmed the diagnosis. Because of the severity of Evan’s disease, doctors recommended surgery to remove sections of his inflamed intestines.

Since his 2014 surgery, Evan has received regular infusions of Remicade, a drug commonly used to manage Crohn’s. He takes vitamins to counteract nutritional deficiencies.

Now 17, he has grown significantly and is, his mother says, “the healthiest he has been in years.” At 5-6, one inch shorter than his older brother, he weighs 122 pounds. He is in his senior year of high school and hopes to attend a California university to study watershed management.

After Evan was diagnosed with Crohn’s, his sister was evaluated for the disease. Although healthy, her parents were concerned that her small size might reflect an underlying digestive problem.

“She doesn’t have the disease at this time,” Mann said of her daughter, who is now 15. “At 4-9, she’s just plain short.”

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