My lazy ass neighbour cuts their grass maybe 2-3 times a year. They still haven't cut it yet.Right now it's about 8-9" high. I have no doubt it's full of ticks.
You must not have read it very well because it was almost the exact same strain of swine flu that spread a few years ago. Thankfully medicine and vaccines kept the death toll under the 50-100 million mark.
Rather non-scientific view. Virus mutate and our close contact with animals (swine in 1918) allowed the swine virus to swap some DNA with a Human base flu allowing the virus to jump species. The spread can be traced to WWI. Whether the first outbreak was in a military hospital in France or Stateside army camps, the deployment and the demilitarization meant millions of people travelled from the area of infection.
Thankfully basic hygiene and medicine have improved since then so the spread can more easily be controlled.
p.s. viruses jumping species is also how many Europeans gained immunity to smallpox.
