I was told years ago by a music teacher that malaria and scarlet fever used to cause insanity and strange mumbling a. People in the mid to late 1800s believed that watermelon was the cause of this insanity and many people wouldn’t touch the fruit. The fact was, the watermelon grew near water and these muddy areas were perfect breeding grounds for mosquitos, which carry malaria.
I have no idea if this is true but that was the impression I have had for 20 years.