Ascariasis: History & Prevalence

History

People who live in developing countries around the world today know of some parasitic worms, especially large ones like Ascaris lumbricoides. Sure, they might not know the scientific name, but they are aware of them. So, it's equally likely our very earliest ancestors were very much aware of them as well. Why? Well, it's because this worm can grow up to 35 cm in length! You can't miss that as it emerges from your hind end on its own or as it leaves your bowel when you defecate.

There is also some evidence for the basic awareness of worms like Ascaris lumbricoides found in the Bible, ancient Chinese works, ancient Egyptian medical texts, and ancient Greek texts as well. The ancient Roman physician Galen appears to have described Ascaris lumbricoides itself.

Ascaris lumbricoides

We know for a fact that ancient peoples were infected by this worm because evidence of Ascaris lumbricoides has been found in an ancient Egyptian mummy that dates from around 1938 BCE. Its eggs have also been found in fossilized feces from Peru, dated to 2277 BCE.

Swedish naturalist Carl Linnaeus described and named Ascaris lumbricoides in the 1700s, just as the study of parasitic worms was really beginning to take shape. It wasn't until the 1800s that the mode of transmission of this worm was elucidated as scientists, such as Giovanni Battista Grassi, infected themselves with this worm's eggs in order to figure this out! And, in 1922, Japanese physician Shimesu Koino infected himself and a volunteer to figure out the life cycle of this worm as well.

Prevalence

Ascariasis has a worldwide prevalence of roughly 25%. This means that over 1.5 billion people are affected right now! It's especially prevalent in warm and wet regions. This means tropical and subtropical places around the world. This is especially true if the region is known for inadequate sanitation and hygienic practices. Most of the people with ascariasis, 73%, are found in Asia; with 12% in Africa, and 8% in South America.