(CNN) -- Justine Sacco, a former PR executive who sparked a firestorm of controversy on Twitter, apologized Sunday for her "needless and careless tweet" about AIDS in Africa.
In a written statement. Sacco apologized "for being insensitive to this crisis -- which does not discriminate by race, gender or sexual orientation, but which terrifies us all uniformly -- and to the millions of people living with the virus, I am ashamed."
She added that she is a native of South Africa and was upset that she had hurt so many people there.
"I am very sorry for the pain I caused," she wrote.
Media company IAC "parted ways" Saturday with Sacco after the tweet, which read: "Going to Africa. Hope I don't get AIDS. Just kidding. I'm white!"
"The offensive comment does not reflect the views and values of IAC. We take this issue very seriously, and we have parted ways with the employee in question," an IAC spokesman said in a statement.
"There is no excuse for the hateful statements that have been made and we condemn them unequivocally," he said. "We hope, however, that time and action, and the forgiving human spirit, will not result in the wholesale condemnation of an individual who we have otherwise known to be a decent person at core."
The tweet Sacco sent before she left Friday for Cape Town, South Africa, went viral and created a social media firestorm.
The incident -- Boing Boing called it "the tweet heard round the world" -- was a glaring reminder that every word uttered on the Internet can be heard by seemingly everyone on the Internet, sometimes with serious consequences.
Sacco was the head of corporate communications for IAC, the media company chaired by Barry Diller that operates websites such as The Daily Beast, About.com, CollegeHumor and Match.com. Her whole job revolved around communicating with reporters -- which made her Twitter comment about Africa all the more shocking.
Sacco was in London and about to begin a long vacation in South Africa when she wrote the message. Her Twitter account was relatively obscure when she posted it -- fewer than 500 people were following it. But the message went viral on Friday, unbeknownst to Sacco, who apparently did not have Internet access on her flight.
Websites such as Valleywag and Buzzfeed highlighted Sacco's account, and soon it had thousands of followers -- and thousands of harsh replies directed at it. Some were downright hateful. Others said they felt sorry for Sacco, regardless of how offensive her Twitter message was, because she hadn't had a chance to defend herself during the 12-hour flight.
As Twitter observers parsed through her public posts, many were disturbed by her previous messages. ("I had a sex dream about an autistic kid last night," she once wrote.)
Her account was a laundry list of banal complaints about poor customer service and other apparent indignities.
"It seems she has left a trail of casual racism across social media on her various travels," Chris Taylor, a writer for Mashable, opined.
Still, Taylor wrote, "it was hard to ignore a disturbing feeling in the mob's response" to the Twitter messages "and something creepy in the trial by social media that was going on in her absence."
On Friday afternoon, with hours to go before she landed, another corporate communications representative for IAC issued a statement that tried to address the online controversy.
"This is an outrageous, offensive comment that does not reflect the views and values of IAC," the company said. "Unfortunately, the employee in question is unreachable on an international flight, but this is a very serious matter and we are taking appropriate action."
The statement led many to believe that Sacco would be reprimanded or even terminated when she landed in South Africa.
Parody accounts started to appear on Twitter and Facebook that portrayed Sacco as a mean, bitter person. On Friday evening a Twitter hashtag, #HasJustineLandedYet, became a running commentary about Sacco; some people observed that she'd have to put her crisis communications expertise to the test to save her own career.
Meanwhile, other Twitter users started scoping out Sacco's past messages and flagged other questionable comments she'd made before, like this one: "I can't be fired for things I say while intoxicated right?"
All of those messages disappeared, though, early on Saturday, when someone -- presumably Sacco -- deleted her Twitter account. IAC had no immediate comment about how or why her account was removed.
Some good does seem to have come out of the incident, at least.
Advocates for AIDS relief set up websites to encourage donations; one of the sites read, "The AIDS epidemic is bigger than a tweet from a person in PR. If we want real change, we need to think beyond Justine. Let's turn that anger into something tangible."