My 18 month old Bengal cat, Jessie, became lethargic, and I took her to my vet. She said Jessie had a virus, and gave her a shot that she said would “bring her around”. Four days later she wasn’t any better, and suddenly took a turn for the worse at about midnight. She died at 5 am.
I did not make the connection to the flea drops until months later, when I read an article in the local newspaper.