Weird news - Trick or treat results in child getting drugged

For parents, the safety of their children is paramount in their thoughts and actions. In parts of the United States where there are problems with increased incidence of drugs, it is even more important to try and ensure that your children do not get into the habit of drugs - many drugs can be highly addictive and also very dangerous, and with the opioid epidemic ever present, there are so many different ways in which people can get ensnared.
However, parents can get very puzzled when they find their children suddenly showing signs of being drugged, especially when the child has gone out for a Halloween trick or treat and is only 5 years old, an age where you would not expect your child to have consumed drugs or come into contact with somebody who could provide drugs (link to article):

This year, rain fell during that two-hour window in the northern Ohio city. Afterward, as Braylen Carwell peeled off his costume and prepared to dive into his haul, he thought his sudden shaking was related to the cold, wet weather. “I was putting my socks on, and then I started to shiver,” the 5-year-old told CBS affiliate WBNS. “And then I couldn’t move my arm or my fingers." The child’s father rushed him to a hospital. By then, “the left side of his face was just droopy, and then he fell and then he couldn’t move his left arm,” his mother, Julia Pence, told WSYX, an ABC affiliate. “And he didn’t know where he was, he didn’t know what he was doing.”