A scourge means something that causes much pain and suffering, like the terrible diseases which Henrietta's unwitting, or unknowing, contribution helped eradicate.
From Red Caps they moved on to Kappas, creepy water-dwellers that looked like scaly monkeys, with webbed hands itching to strangle unwitting waders in their ponds.
The drama began with grainy television footage of Japanese prosecutors boarding the plane that delivered an unwitting Mr Ghosn to his arrest in Tokyo in November 2018.