No, it's not true.
There isn't an Ebola outbreak in Atlanta.
But if you were following the Twitter account of Yahoo News at 4:41 pm EST on Sunday, you might have thought it was true - for a while at least.
Here is the tweet that appeared (and has since been deleted):
BREAKING EBOLA OUTBREAK IN ATLANTA! Estimated 145 people infected so far since Doctors carrying the disease were flown in from Africa.
A few minutes later, everyone's less favourite search engine tweeted a retraction:
Earlier, an unauthorized tweet with misinformation on Ebola was sent from this account; please disregard that tweet.
— Yahoo News (@YahooNews) August 10, 2014
Although many media reports have said that Yahoo News's Twitter account was "hacked", I personally think that's unlikely.
Wouldn't a genuine hacker have had more fun that simply posting one message? It wouldn't be unusual for instance for a hacker of a Twitter account to post links to spam websites, or try to encourage followers to visit a phishing site, or post mischievous messages designed to damage the brand of the organisation that has had its social media account hacked.
And also, take a look at Yahoo's wording. They say it was an "unauthorised tweet", not a hack.
It sounds more to me like someone didn't go through the proper approval process when posting that tweet (and maybe hadn't checked their sources), or was posting a test message not realising that it would go public.
It just doesn't smell like a hacker to me. My suspicion is that it's someone internal to Yahoo instead.
And, if I'm right about that, Yahoo is in good company. A couple of months ago, the BBC News app found itself making the news after one of its staff didn't realise a test message would be seen by the outside world.