It is estimated that about 300 million cases of scabies occur annually worldwide, and has been reported for over 2,500 years.
Those are the basics. But let’s take a microscopic look at this condition. I must warn you, though. The details are rather creepy for those who have a natural aversion to bugs.
How does Scabies Start and How do you Get it?
As mentioned, scabies is caused by the human itch mite. A mite is a tiny eight-legged parasite measuring only 1/3 of a millimeter long. It is the female mites that do the infesting. The mite is unable to fly or jump, but it does crawl. And, even though they are immobile at temperatures below 20 degrees C (68 F), they can survive for long periods of time at these temperatures.
https://www.empowher.com/scabies/content/scabies-facts-symptoms-and-treatments