1976 I think .... Also Ebola's Zoophilic cousin, Raphson already visited USA once.
The whole issue of these types of viruses started in the 1960s in Marburg, Germany and Belgrade, Yugoslavia(Serbia) when Marburg was first encountered:
You must be registered for see links
Apparently, Uganda is currently experiencing an outbreak of it, as well:
You must be registered for see links
The symptoms are very similar to Ebola as is the theoretical method of transmission. Specific epidemiology, reservoirs, etc is still largely theoretical.
Ebola was first encountered in Zaire (Democratic Republic of The Congo) in 1976.
There was an outbreak of Ebola-Reston in Reston, Virginia in 1989 among a bunch of crab-eating Macaques from the Philippines. No one knows how the virus got into the primates, or where it is located within the ecology of the Philippines.
You must be registered for see links
Honestly, deliberate reston-virus infection into humans might be an expedient "crack-vaccine" against Zaire (which is what is running amok, currently).
Ebola isn't 'natural' to humans. Wherever it survives (and no one knows for sure), it has found an animal(s) to infect routinely without causing the kind of organ-melting death that it can cause in most primates.
So, while it has 'been around' for a while - that isn't to say that it has been infecting humans all of that time. There have been flare-ups out outbreaks over the years where a few people will get the virus - but, until now, the outbreak has rarely ever swelled beyond a hundred people or so in small villages and towns.
The virus simply failed to live within humans because it killed too quickly with relatively little opportunity to spread (or, in one case, because many of the people were receiving injections from syringes that were simply rinsed out between patients - so a whole town was pretty much isnta-gibbed by the virus).
That has changed. The latest outbreak was into a larger, more mobile population. Burial practices certainly didn't help, though it has spread sufficiently so that ceasing the burial customs has still failed to curb the spread of the virus.
Ebola is still too hot to survive in humans, naturally.
It will eventually burn itself out, no matter how many people it infects and no matter how many continents it chews through. Worst case scenario, the world population goes from about 7 billion people to about 2 billion people after 30% survive, and those survivors are literally in a post-apocalyptic environment where they may only be able to preserve a fraction of the technologies and capabilities we enjoy, today.
Of course - the problem also becomes where else in the world it could find animal reservoirs. Since these strains of Ebola are unknown outside of the ancient rainforests of Africa - allowing them to spread into South America, Asia, North America, Europe, etc could find them infecting a wide range of other animals that could serve to make it a lasting threat to humanity - with the occasional outbreak that occurs in the Congo being mirrored the world over.
Like I said - it will eventually burn itself out. What we need to worry about is limiting how many people it has the opportunity to burn through and how many regions that have never known it remain untouched by it (to prevent it from finding reservoirs).