5 Parasites That Breed On and In Your Skin

By: Jonathan Strickland  | 

lice
Lice are gross and common among school-aged children because they spread so easily. SciePro/Shutterstock

Out of the three main classes of parasites that can cause disease in humans — protozoa, helminths and ectoparasites — it's the ectoparasites that are the worst vectors of disease, according to the U.S. Centers of Disease Control and Prevention (CDC). That's because these include the creepy crawlies that latch onto — or burrow into — our skin. Unlike protozoa and helminths, which live in gastrointestinal tracts, ectoparasites depend on our blood for survival. These include everything from ticks and fleas to lice and mite.

But how many of those go on to actually breed on or in our skin?

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5: Lice

Lice are a real pest. If you're a parent of a school-aged child, you probably already know that.

There are three broad categories of lice that plague humans — head, body and pubic lice. Lice feed by biting and drinking the blood of their hosts. Body lice don't live on the skin itself — they inhabit clothing and only move to the skin to feed. But head and pubic lice live directly on the skin.

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The louse can't fly or jump — it can only crawl. When a female louse lays eggs, it does so at the base of a shaft of hair. The eggs — or nits — are oval and usually white, yellow or a color similar to that of the hair to which they're attached. Larvae hatch from the eggs after a few days. A little more than a week later, the larvae have matured into adults capable of reproducing.

There are several treatments for lice. Most of these treatments are in the form of medicated shampoos. Human lice are transferred by close contact with infected humans — in other words, you won't catch lice from animals.

4: The Chigoe Flea

chigoe flea
The chigoe flea is a parasite that latches onto its host's skin to feed — typically the toes, sole and heel of the foot. World Health Organization

The chigoe flea (Tunga penetrans) is known by many names, including the jigger flea and the sand flea. Regardless of what you call it, the parasite latches onto its host's skin to feed — typically the toes, sole and heel of the foot. Then the flea breathes, defecates and lays eggs through its hind legs — the only part of the flea that remains exposed to air once it latches on.

Female jigger fleas penetrate into the skin of the host and lay hundreds of eggs. This egg-laying period can last up to three weeks. Then, the female dies and eventually falls off the host. Once her eggs hatch, the fleas bite their host and the cycle continues. As these new fleas develop, area around them swells and becomes painful and itchy. The infection is called tungiasis.

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The chigoe flea is found mainly in South American and African regions. It normally attacks between the toes of hosts but can latch onto other parts of the body as well. The fleas can also cause necrosis — tissue death — that often must be removed with surgical tools.

3: Scabies

scabies
Scabies are tiny mites that breed under the skin and cause an incredibly itchy rash. Artemida-psy/Shutterstock

Another microscopic parasite that breeds under our skin is the scabies (Sarcoptes scabiei). These tiny mites transfer from person to person through skin contact and cause an intensely itchy skin rash where the scabies burrow. Scabies are especially troublesome within a household or any community with a dense population. Prisons, nursing homes and childcare facilities can be vulnerable to outbreaks. What's worse, the first time someone is infected, they may have no symptoms for up to two months, but will still be contagious during that time.

The scabies mite burrows into the skin and lives out its life cycle there, including laying eggs. One variety called Norwegian, or crusted, scabies is particularly severe. It is characterized by thick crusts of skin with large numbers of scabies mites and eggs. It mostly occurs in people who are immunocompromised and the elderly. Crusted scabies is very contagious and can spread by direct contact and through contaminated clothes, bedding and furniture.

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Scabies is relatively easy to treat with scabicidesprescriptions that kill the mites and eggs. The most common versions come in the form of a lotion or cream.

2: Loa Loa Worm

Loa loa worm
This example from La Paz Hospital in Madrid, Spain, is from an 18-year-old woman who complained of a foreign body in her eye. Doctors found a dead 1.8 inch (4.7 centimeter) Loa loa worm, which they surgically removed. The American Journal of Tropical Medicine and Hygiene

File this one under "I hope this never happens to me." The Loa loa worm is a several-centimeter-long nematode that infects millions in Western and Central Africa via deerfly (Chrysops) bites. It can stay in a host human's body undetected for years. Some people may have itchy swelling that comes and goes on the body, most commonly near the joints. Less common symptoms include itching all over the body, muscle pain, joint pain and fatigue.

But one day the infected person may feel something strange in their eye and look in the mirror only to see — gasp — a tiny worm on their eyeball. That's how the Loa loa worm got its nickname, "African eye worm." It's endemic to countries like Cameroon and Sudan.

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Once it's been detected, the infection (loiasis) can be treated with the drug diethylcarbamazine. That will kill early stages of the parasite in the bloodstream. But adult worms in the eye requires surgical removal.

1: Human Botfly

Human botfly
Human botfly larvae is being treated with petroleum jelly to force the larvae out of the skin. Journal of Emergency Medicine

The human botfly (Dermatobia hominis) is found in tropical areas of Central and South America and the Caribbean. It's one of several flies that can cause tissue infection by a fly larvae (maggots). The fly itself doesn't harbor any diseases, but the larvae infest the skin of mammals — preferably humans — and lives out the larval stage in the subcutaneous layer. It wreaks havoc there creating painful pustules. This type of infestation is called myiasis.

Botflies depend other feeding insects to get their work done. They capture other bloodsuckers and deposit their mature eggs on them — usually mosquitoes or ticks. When these guys go in for blood, the eggs react and hatch. The larvae then enter the skin where they can stay for up to 10 weeks, breathing through an airhole.

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Human botfly larvae can cause a raised lesion in the skin that becomes hard and painful. Sometimes people infected can even feel the larvae moving. That's why treatment often includes using petroleum jelly to block the airhole, which causes the maggot to pop out, though other times it must be surgically removed.

Originally Published: Jun 8, 2010

Skin Parasites FAQ

What are the symptoms of having a parasite?
Different signs and symptoms may arise depending on what parasite a person has, but some of the most common are ongoing gut issues without an obvious reason, mood wings, drastic energy and weight changes, skin issues outside a person's norm, and autoimmune issues.
What kind of parasites burrow into human skin?
Some common types include the chigoe flea, bot fly, scabies mite, screwworm, and cercariae. Many of these creatures mate, burrow under the skin, and lay their eggs, which eventually emerge through a person's skin.
Can internal parasites cause itching?
Though it won't happen in all cases, intestinal worms can cause a rash and itching around the rectum or vulva.
What is the most common parasitic disease in the U.S.?
Parasites aren't very common in the United States anymore — most Americans get them when traveling in other countries — but that doesn't mean they're completely eradicated. These parasitic infections are a concern for the CDC: chagas disease, cyclosporiasis, cysticercosis, toxocariasis, toxoplasmosis, and trichomoniasis.
What parasites cause itchy skin?
The most common parasites that cause itching skin are scabies, crab lice, and bedbugs.
What parasites can live in human hair?
Skin mites (scabies), hair or head lice, and body lice (crab lice), demodex (hair follicle mites), and ticks can all live and hide in human hair.

Lots More Information

Related Articles

  • Centers for Disease Control and Prevention. "About Parasites." March 21, 2022. (Aug. 4, 2022) https://www.cdc.gov/parasites/about.html
  • Centers for Disease Control and Prevention. "Lice." May 16, 2008. (May 27, 2010) https://www.cdc.gov/parasites/lice/
  • Centers for Disease Control and Prevention. "Parasites – Myiasis." Sept. 23, 2020. (Aug. 4, 2022) https://www.cdc.gov/parasites/myiasis/index.html
  • Centers for Disease Control and Prevention. "Scabies." Nov. 10, 2008. (May 27, 2010) https://www.cdc.gov/parasites/scabies/
  • Eisenstadt, Leah. "Creature Feature: African eye worm (Loa loa)." The Broad Institute. April 25, 2013. (Aug. 4, 2022) https://www.broadinstitute.org/blog/creature-feature-african-eye-worm-loa-loa
  • Feldmeier, Hermann, et al. "Severe Tungiasis in Underprivileged Communities: Case Series from Brazil."
  • Hill, Stephanie K. and Connelly, C. Roxanne. "Featured Creatures Human Bot Fly." University of Florida Entomology and Nematology. April 2018. (Aug. 4, 2022) https://entnemdept.ufl.edu/creatures/misc/flies/human_bot_fly.htm
  • Genetic and Rare Diseases Information Center. "Crusted Scabies." Nov. 8, 2021. (Aug. 4, 2022) https://rarediseases.info.nih.gov/diseases/12151/crusted-scabies
  • Mayo Clinic. "Lice." Feb. 18, 2010. (May 27, 2010) https://www.mayoclinic.org/diseases-conditions/lice/symptoms-causes/syc-20374399
  • Mayo Clinic. "Scabies." July 28, 2022. (Aug. 4, 2022) https://www.mayoclinic.org/diseases-conditions/scabies/symptoms-causes/syc-20377378
  • Stewart, J.W. "Common Insect & Mite Pests On Humans." Texas Agricultural Extension Service, Texas
  • World Health Organization. "Filariasis." Nov. 5, 2020. (Aug. 4, 2022) https://www.who.int/news-room/fact-sheets/detail/tungiasis

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