• Pretty Parasites With Dr. Pritt, part 4: Love bugs

Parasites can be pretty: pretty cute, pretty awesome and sometimes pretty creepy. This article is part 4 of a five-part series featuring some of Dr. Bobbi Pritt's "freaky favorites," ranked from 1 (not too scary) to 5 (bad-news bugs).

Freaky factor 4/5: These worms have a cute love story. But they get into the body through the skin (yikes) and their babies are seriously bad news.

This low-power photomicrograph reveals some of the ultrastructural relationship exhibited by coupled male and female, Schistosoma mansoni parasites. Courtesy Centers for Disease Control and Prevention (CDC)/ Dr. D.S. Martin

Schistosoma worms, also called “blood flukes,” are some of the biggest huggers in the parasite world. When a male worm meets a female worm, they mate for life. The larger male worm stores the smaller female in a long groove in his body, and the female leaves only to lay her eggs. So romantic.

Schistosoma haematobium egg. Note its spine at the bottom end of this image, which allows it to be identified in the lab.

The World Health Organization says that about 206.4 million people are at risk of infection. Schistosoma worms are most common in tropical places and are not found in the U.S. The worms get into a person’s body through the skin and make their way to blood vessels in the gut or bladder.

Life cycle of flatworms of the genus, Schistosoma. Courtesy CDC/ Alexander J. da Silva, PhD; Melanie Moser

The worms themselves don’t usually cause any problems. It’s the eggs that can make you sick. There are a lot of them. They can get stuck in the body’s organs and cause irritation and scarring, which can be dangerous.

To find out if a person has a schistosoma infection, a health care provider will look for eggs in urine and stool. An infection can be treated with medicine.

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Bobbi Pritt, M.D., is a pathologist and microbiologist at Mayo Clinic. She loves learning about parasites. You can read her blog, "Creepy Dreadful Wonderful Parasites" and follow @ParasiteGal.Dr. Bobbi Pritt in a lab, looking through a microscope