Betsy Arakawa Hackman died of the Sin Nombre variant of the virus, which is the one in the US Southwest. Her home was free of mice but outbuildings such as several storage sheds and the garage had evidence of mice. There is a lengthy gestation period but once flu symptoms appear, you have only a very short time to get treatment before it develops into a life-threatening illness.
One more point, I was exposed last year and hospitalized for a short period of time. Testing determined I had prior antibodies but it did not develop beyond light flu symptoms. Whether an earlier exposure (years of hiking, backpacking and outdoor ground camping, garage cleaning, etc.) caused antibodies, I do not know but blood testing from the NM hospital was repeated in the Texas hospital with the same results - tier one results had antibodies, tier two results (additional chemical signs indicating a developing HPS condition) were negative.
I will also say that when I first went to the ER with flu symptoms and described recent possible exposure, they did not hesitate. They isolated me, then transported me to a major Texas hospital in Lubbock. My stay there was brief, as their chief virologist examined me and said I wasn’t developing HPS. Testing, which took two weeks for results, verified his diagnosis.
Poor lady. She took good care of Gene until she couldn’t.