Johnson noted that it is possible that Kemna's immune system may not have been functioning properly despite his being an apparently healthy man. But Glatt said that even this alone would not have predisposed Kemna to the problems he experienced.
"Even the vast majority of immunocompromised people would not have this happen to them," Glatt said.
Kemna admits to feeling frustrated that he cannot get around as quickly as he would like to. He still does not own a van large enough to fit his wheelchair. But he said he doesn't have time to be down, as he is staying busy with his children. And there are changes ahead.
"I know I will walk again," said Kemna, having recently been fitted for prosthetic legs. "I'm happy to be alive."
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Dan Childs contributed to this report.