Jimmy Schenk has acute lymphocytic leukemia, which occurs when cancerous white cells reproduce at an abnormal rate, eventually invading and expelling other useful blood cells from the bone marrow.
Despite weekly routines of painful chemotherapy and its hazardous side effects, Jimmy nevertheless refuses to let his illness interfere with his passion for playing baseball.
"It's my favorite sport," he whispers bashfully, explaining why he pursues the pastime throughout his treatment.
"He needs to have something to do that's normal," said LouJean, of Funkstown, pointing out that his weekly schedules consist of blood counts and chemotherapy injections at Johns Hopkins Hospital in Baltimore. "This is a kid who lives, eats and breathes baseball."
Jimmy Schenk was first diagnosed with leukemia Feb. 11 after his parents discovered severe swellings on his body and heard his complaints of overtiredness.
When his pediatrician suggested they visit doctors at Johns Hopkins Hospital, LouJean said she "was pretty sure that something was going on."
"It only took them an hour to decide it was leukemia," she said.
Jimmy had an unusually high white blood count, swollen lymph nodes throughout his body and an abnormally large spleen - clear indications of leukemia, said Dr. Elizabeth Lowe, a fellow in pediatric oncology at Johns Hopkins Hospital and Jimmy's doctor.
"Jimmy's chemotherapy has been more intensive than that of most other children, so he's had a lot of side effects," Lowe said. "But he's a fighter. He's definitely bounced back every time."
When he does bounce back, Jimmy makes a point to attend every Hartle's game, playing in the outfield when his blood count is high, filling in as base coach when it's moderate and just watching when it's low.
"It was amazing when he always used to show up in the beginning, because he had just gotten out of the hospital the day before," said Chris Luipersbeck, of Hagerstown, the "team mother" whose 12-year-old son Danny also plays with Jimmy. "Even when he doesn't play, he still shows up in his uniform. One day right when he got home from the clinic, he came and watched a game."
He used to be catcher, his favorite position on the field, until his parents worried that a ball flying toward his face or chest might harm him. Then again, Jimmy used to be many things before his disease.
"He was like the second fastest kid on the team," said his father, Michael.
"It's hard for him out there. He gets kind of embarrassed because he doesn't have the strength to do the kinds of things he used to do," LouJean said.
But he gets a lot of support from the crowd at baseball games, his parents said.
"He knows when he's out there that everyone is looking at him," said Luipersbeck, whose husband Patrick also has been diagnosed with a different type of leukemia. "He's really brave. I have to give him a lot of credit."
His teammate, Danny, described Jimmy as determined, a ballplayer whose illness does not stop him from swinging at a decent pitch and racing to first base as fast as he can.
"After all that he's gone through, I don't think I'd have the energy to do that," Danny said.
Jimmy's parents said dealing with the trauma and treatment, which will last for at least another two and a half years, was most difficult during the beginning stages.
"You just ask yourself, `What did I do wrong? What could I have done different to stop this?'" Michael said. "It's hard to believe it started in February and it's been this long."
But doctors predict a bright future for Jimmy since his form of leukemia, one in about 10 different types and the one most prevalent in infected children, has at least a 74 percent cure rate, according to Marsha Fonte, office manager of the Maryland chapter of the Leukemia Society of America.
Patients are considered "cured" if their blood cells continue in remission with no signs of cancer for five years, Fonte said. But she added that those diagnosed with leukemia could suffer a relapse later in life, when one remaining cancerous cell, hidden from treatment, begins multiplying again.
What's frustrating to the Schenks is that doctors "still haven't even discovered a cause for this thing," LouJean said.
"Yet," piped up Jimmy.
"Yet," confirmed LouJean.
And when they do, they'll be able to find Jimmy on the ballfield.