More than 11,000 people died in the outbreak, which began unnoticed in December 2013 and spread across the region, infecting at least 28,600 people and triggering a global response, including a race to get an effective vaccine tested and into use.
It began unnoticed in the 1950s with two concepts: in biology, with James D. Watson and Francis Crick's description of DNA's double-helix structure, and in computing, with Jack Kilby's and Bob Noyce's independent inventions of the integrated circuit.
In Pennsylvania, the influenza epidemic began almost unnoticed in the middle of September.
The qualifying process for next year's World Cup, which began almost unnoticed more than two years ago with Belize's 5-2 victoverover Montserrat, will conclude over the next week with 22 teams playing 17 matches for the final 11 spots.
The Raoul Moat emergency began almost unnoticed on Thursday 1 July.
For others they begin almost unnoticed and go by for years, virtually undetected until suddenly they are not only part of our lives, but part of our culture.
Where this virus first started - ground zero, can't be pinpointed, but I'll bet it began festering unnoticed in some small-market station before the infection spread via the airwaves from one newsreader to another.
"They began to fall, unnoticed by all but those immediately surrounding them.
He began wandering, largely unnoticed, through the back roads of Iowa and New Hampshire, staying in supporters' homes just as Carter had done.
Many more breaches go completely unnoticed until fraud begins.
Marvel's teaser for "This Is War," a major story line affecting its heroes that begins in October, didn't go unnoticed, either.
