I just saw this tweet (which I archived, just in case) from parody account CatheeMcKennnna

She's responding to a Tweet from the  genuine Catherine McKenna, Canada's Minister of Environment & Climate Change

Her point is that people have forgotten, in their sympathy for the Famine Irish, how bad it was for the receiving countries. It was a lot like the Camp of The Saints, and the cholera from the fever ships killed not only the emigrants, but a lot of both Canadiansd and Americans.

I made this point in 2001 in an article headed The Camp Of St. Patrick, and again on St. Patrick's Day, 2017:

One of the earliest things I wrote for the site was a piece called The Camp Of St. Patrick, [March 17, 2001] pointing out how much like the  "Camp Of The Saints" the Famine Irish exodus was for the receiving countries in North America.

There are memorials in various places (like Grosse Île, Quebec) to the dead, who didn't die of famine, but of cholera, which they brought with them. Wikipedia's article on cholera outbreaks and pandemics says

Cholera hit Ireland in 1849 and killed many of the Irish Famine survivors, already weakened by starvation and fever.^[12] In 1849, cholera claimed 5,308 lives in the major port city of Liverpool, England, an embarkation point for immigrants to North America, and 1,834 in Hull, England.^[6] An outbreak in North America took the life of former U.S. President James K. Polk. Cholera, believed spread from Irish immigrant ship(s) from England, spread throughout the Mississippi river system, killing over 4,500 in St. Louis^[6] and over 3,000 in New Orleans.^[6] Thousands died in New York, a major destination for Irish immigrants.^[6]

However, the survivors became part of America's white majority. In Alien Nation, VDARE.com Editor Peter Brimelow mentioned 19th century anti-cheap labor activist Denis Kearney (right) who fought Chinese immigration.

Brimelow wrote “[A]n Irish immigrant, Dennis Kearney, was a leader of the agitation that halted Chinese immigration into California. (His—probably mythical—slogan: 'Americay for Americans, Begorrah!')”

Modern-day immigrants from places with Ebola or whatever are unlikely, if they (a) don't kill us all, and (b) survive themselves, to assimilate to the American nation the way the Irish did.