If you trace back the spread of Lyme disease in time, you get two points. One in Connecticut, and one on Long Island, where workers got on the boats to Plum Island.
The lab was studying diseases similar to Lyme disease at the time.
All those are facts.
The conspiracy theory is that Lyme disease was accidentally released by that lab.
https://en.wikipedia.org/wiki/Building_257#Discredited_consp...
> Additionally, Lyme disease was never a topic of research at Plum Island, according to the US Department of Homeland Security and Department of Agriculture.
These are facts, too, in your link. ¯\_(ツ)_/¯