(CNN) -- Katy Berteau, the fiancée of ESPN reporter Edward Aschoff, thanked people for their support and further explained how he died on his 34th birthday.
"The outpouring of love, admiration, and gratitude for his life have been so incredible, and have helped me through these last few days," she wrote in a series of 12 tweets posted to his Twitter account. "It has brought me brief moments of joy in this darkness to see all the pictures, videos, and memories of all the lives he touched."
Aschoff died Tuesday and ESPN said he had passed after a brief illness. Aschoff had tweeted about having pneumonia.
Berteau explained he was admitted to a hospital a week after they first went to the emergency room. He was diagnosed with pneumonia in several parts of his lungs.
Antibiotics didn't work and his symptoms got worse, she wrote.
He had many tests, including ones that looked at his bone marrow and biopsies of his lungs. Doctors began to treat him for a presumed diagnosis of HLH (hemophagocytic lymphohistiocytosis).
"If you have HLH, your body's defense system, called your immune system, does not work normally," the website of Johns Hopkins says. "Certain white blood cells — histiocytes and lymphocytes — attack your other blood cells.
He died three days after being moved to intensive care.
"I want to share the brightness that he showed, even up until the last day he was awake," she wrote. "He kept the doctors and nurses constantly laughing, and always made a point to thank them and tell them what a great job they were doing.
"He also loved Christmas so much that, even from the ICU, he was coordinating with my friend about wrapping my presents so I could be surprised."
Aschoff and Berteau were to be married in New Orleans in April, ESPN said.
On December 4 he had posted on Instagram, thanking Berteau for helping him during an illness.
"Having pneumonia is pretty terrible. Like the absolute worst. But it helps having this sweet angel taking care of you even when she's risking getting this soul-crushing illness herself. All the soup, tea and delicious meals have kept me from crawling into a corner and crying the days away. Love you, babe. Thanks for putting up with my 5 am coughing fits."
According to ESPN, Aschoff started working for ESPN.com as a reporter based in Atlanta. He moved to Los Angeles in 2017 to begin a more expanded national role that included television coverage.
Over the past three seasons, Aschoff reported from campuses across the country for ESPN.com, SportsCenter, SEC Network and ESPN Radio, and worked as a television and radio sideline reporter during college football games, a release from ESPN said.
His final assignment was at the Ohio State-Michigan football game in Ann Arbor, Michigan, on November 30.
Berteau said there will be a small memorial service in Oxford, Mississippi, where he grew up, and a main service in Atlanta. Details are still being finalized, she said.