You Be the Doctor: What's Making Evan So Sick?

"Mulch exposure can be problematic because it has lots of fungi in it," Akhter said.

When three members of the McClow family got a bad cold, 16-month-old Evan didn't get better.

(ABC News)

"Dr. Akhter never said to me that he was sure it was the mulch pile, the wood chips," Keith said. "But he said it was a good idea to get rid of it."

'What Do We Do Now?'

After being treated with anti-fungals, Evan was sent home after a few days. Keith said his son "looked good" and "was playful," but suddenly his fever returned, and Evan was coughing and couldn't keep food down.

"Of course we immediately hospitalized him," Akhter said.

"I just remember thinking to myself, 'What's the next step? What do we do now?'" Teresa said.

"When I saw the X-ray and the worsening, I knew that we were dealing with some rare and possibly fatal illness and that we had to move to the next [step], which would be an open lung biopsy," Akhter said. "When we saw Evan back again, my anxiety level was much higher. And there was a great sense of urgency that we needed to find out exactly what was wrong with Evan. Otherwise we may lose him."

The Diagnosis

"After we did the biopsy, the results came back the same day," Akhter said. "The pathologists told me two things: One, that Evan had a fungal pneumonia. And two, they also found clusters of what are called granulomas."

Evan had numerous types of fungus in his lungs, as well as the granulomas, which are white blood cells surrounding a foreign invading body.

"Because they can't kill it, they surround it," said Keith.

Evan's white blood cells weren't working. A rare genetic disorder, chronic granulomatous disease of childhood, or CGD, could cause that. But if it was genetic, wouldn't his twin sister have it, too?

As it turns out, not with CGD, which is carried by the mother but only shows up in boys.