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The Most Common Worms in Humans

Gable Rhoads has an AD in radiography. She is passionate about her family, animals, gardening, and the odd and unusual.

Elephantiasis patient. Name A. C., age 19. Her lower extremities were enlarged from childhood after "post-scarlatinal edema".

Elephantiasis patient. Name A. C., age 19. Her lower extremities were enlarged from childhood after "post-scarlatinal edema".

Worms in Humans

Worms in humans have been a cause of misery for millennia. These parasites contribute to disease, disability, disfigurement and death in many of the world's population.

We'll look at the most common worms in humans as well as some less common parasites.

Lymphatic Filariodidea, Phylum Roundworm

Wuchereria bancrofti, Brugia malayi, and Brugia timori: These filarial worms cause the disease lymphatic filariasis, commonly known as elephantiasis. The worms are indigenous to the tropical areas of Asia, Africa, and Central and South America.

According to the World Health Organization, over 120 million people worldwide are currently infected with filarial worms. Most people infected have mild infestations and exhibit no symptoms, although 40 million of those infected are badly disabled and disfigured.

These worms are spread from human to human by mosquitoes. While feeding on a human's blood, the mosquito will transmit the worm larvae into the skin. The larvae then reside and reproduce in the human circulatory and lymph system.

The larvae mature in the lymph nodes, and severe infestations block the lymph ducts. This causes extreme lymphedema of the extremities and genitals. The worms can live in the human body for seven years,

Infection usually occurs in childhood, with severe disfiguration occurring later in life.


  1. Inflammation of skin and lymph nodes
  2. Tissue swelling
  3. Tissue thickening - elephantiasis
  4. Fluid accumulation in groin, breasts, or extremities.
  5. Kidney damage
  6. Lymphatic system damage


The disease can be detected by microscopic examination of the patient's blood.


Diethylcarbamazine (DEC) is the most prescribed treatment for filarial worms. A combination of albendazole and ivermectin is also used.




Pinworms, also known as threadworms, are the most common parasitic worm infection in the United States. They affect everybody equally without regard to race, gender, or economics status.

Pinworms do not affect dogs or cats, but different types of pinworms do infect horses and rabbits.

Pinworm eggs are easily spread by physical contact with an infected person, bedding, a pet's fur, and even through dust in the air. The eggs may be inhaled, or ingested orally by thumbsucking or nail biting. Eggs around the anus of an infected person may hatch, and the larvae can reenter the body through the rectum, repeating the cycle of infection.

Once inside the body, the eggs hatch in the duodenum, the first part of the small intestine. The worms then travel into the large intestine where the males and females copulate. The males die and are expelled along with the feces. The female worm attaches herself to the mucousa of the large intestine and ileum, where she feeds as her eggs mature.

After 5 weeks, the female exits the body through the rectum and lays her eggs around the anus. The eggs are then ready to be spread and to begin the cycle again. The adult pinworm is about the length of a staple.


  1. Most infected people do not exhibit symptoms
  2. Itchy skin eruptions
  3. Loss of appetite
  4. Diarrhea
  5. Abdominal pain
  6. Difficulty breathing
  7. Cough


A stool sample is generally not an effective means of detecting pinworms. The best method to detect the worms is to apply tape to a person's perianal region after they have been asleep for a few hours. The worms will be most active at this time. The tape will then be removed and looked at under a microscope. Scrapings can also be taken from under a person's fingernails.


Mebendazole, pyrantel pamoate, and albendazole are all used to treat pinworms. A single dose will be given, followed by a single second dose two weeks later. All people living in the same household should be treated.

Heavy attack of larva migrans cutanea, hookworms under the skin.

Heavy attack of larva migrans cutanea, hookworms under the skin.


Hookworms are also a common parasitic infection in humans. Cats and dogs also can carry hookworms, but only one species of canine hookworms has infected humans. This was an isolated incident that happened to 150 people in Australia.

Hookworms are spread through contact with infected feces. A person may ingest the larvae orally or, more commonly, become infected by walking barefoot through feces-contaminated dirt. Once the worms have penetrated the skin, they enter the bloodstream. Most worms travel to the lungs, then the trachea, where they are swallowed. The hookworm then migrates to the intestines, where it reproduces and lays eggs.

The eggs are expelled in the feces, then hatch, and the lifecycle is repeated. Some hookworms become dormant in muscle fibers, and later become active during a woman's pregnancy. The larvae will pass into the mother's milk, subsequently infecting her newborn with worms.

Hookworms in the Skin: cutaneous larva migrans

In the Americas, subcutaneous larva migrans, also known as creeping eruptions, are caused by the animal hookworm larvae of the species Ancylostoma braziliense. It is also known as sandworms in some areas of the southern United States.

People will become infected with hookworms by coming into direct contact with contaminated feces deposited in the soil or sand. The larvae of these hookworms will burrow under the skin and will cause intense itching, skin rashes, and visible raised tracks on the skin.

Cutaneous larva migrans are the most common skin disease occurring in people who have traveled to tropical or subtropical regions of the world. Complications like skin infections and allergic reactions, together with the extreme itchy rashes and the detrimental, long-lasting effects of the disease, make treatment a must.


  1. Light infestations will usually be asymptomatic
  2. Vitamin A deficiency
  3. Rectal prolapse
  4. Anemia
  5. Bloody diarrhea


Hookworms will be diagnosed by analyzing a stool sample. In the case of creeping eruptions, skin analysis and tissue biopsies are used to diagnose the condition.


Both intestinal and cutaneous infections will be treated with albendazole and mebendazole. The medication will be taken for up to three days and has few side effects.



Whipworms: Trichuris Trichiura

Named for their resemblance to a whip, whipworms are an intestinal parasite. They are found in warmer climates in countries around the globe.

An estimated 2 million people in the southeastern states of the US are believed to be infected by whipworms, with many of the sufferers showing no symptoms. An estimated 795 million people are infected with whipworms worldwide.

Whipworms enter the human body by ingesting unwashed fruits, vegetables, or dry goods or by hand-to-mouth contact.

Whipworms reproduce in the small intestine, with the resulting larvae hatching and maturing in the cecum. Some eggs are expelled through the feces, and the whipworm eggs contaminate anything the feces touches.


  • Nausea
  • Vitamin and mineral deficiencies
  • Weight loss
  • Fatigue
  • Loss of appetite
  • Abdominal pain
  • Diarrhea
  • Hunger
  • Segments of worm in stool
  • Blindness
  • Epileptic seizures


Whipworm infections are diagnosed by examining a stool sample using a microscope.


Albendazole and mebendazole pills are given for three consecutive days to kill the whipworms.

Taenia saginata tapeworm.

Taenia saginata tapeworm.


Tapeworms are a type of flatworm that live in the intestines of animals. All vertebrates have at least one type of flatworm that can infect it.

There are more than 1,000 different varieties of flatworms recognized by scientists, but only six species are known to live in humans.

Tapeworms can be transmitted to humans by eating undercooked beef, pork, or fish which are infected with the tapeworm larvae. People can also be infected by being bitten by insects and by coming into contact with fecal matter contaminated with tapeworm eggs.

Some species of tapeworm can grow over 100 feet in length, although the tapeworms that infect humans will typically be less than 30 feet long.

Tapeworms can live for up to 30 years in the digestive tract. The adult worms have "hooks" in their mouths which they use to attach themselves to the abdominal wall.

Tapeworms can invade other tissues in the body also. When the worms find their way into the brain, it will cause a disease known as neurocysticercosis.


  1. Weight loss.
  2. Eggs, larvae, or segments from the tapeworm in stools.
  3. Abdominal pain.
  4. Vomiting.
  5. Nausea.
  6. Weakness
  7. Diarrhea


Tapeworms can be diagnosed by examining a stool sample or checking the blood for an antibody produced by a tapeworm infection.


The most commonly used medicines used to kill tapeworms are bactericide oral and albendazole. The medication will kill the tapeworms, which will then dissolve and pass out with feces. The medications are 95% effective.

Loa loa

Loa loa is a filiarial worm found in areas of West Africa, and the worm can actually live inside a human's eye! Loa loa is spread by the bite of flies; the fly transmits the loa loa larvae into the person's skin while the fly is feeding. The larvae then burrow down into the subcutaneous tissue. The loa loa lives inside the host, travelling throughout the person's body.

The disease caused by the worm is known as "African eye worm, Loaiasis, Loa loa filariasis, Filaria lacrimalis, Filaria subconjunctivalis, and Fugitive swellings", among others.

The disease causes a rash and eye problems in the infected person. It can cause eye pain or vision changes when the worm moves across a person's eye.


  1. Eye pain
  2. Watery, itchy eyes
  3. Lymphedema


The loa loa worm can be detected by seeing the worm in the eye, or upon removal of the worm from the skin. The worm can also be detected by examining blood from an infected person. A blood test can also be used to detect antibodies, but this may give a false positive if the person has had a past infection.


According to the CDC there are two medications used to treat the loa loa infection: "Diethylcarbamazine (DEC), which kills both the larvae and the adult worms and is the treatment of choice, and albendazole, which is thought to kill the adult worms. There is a risk of fatal brain inflammation from treatment with DEC."

Loa loa worm in an eyeball.

Loa loa worm in an eyeball.

The life cycle of ascariasis worm.

The life cycle of ascariasis worm.

Ascariasis, Phylum Roundworm

According to the CDC, ascariasis is present in almost 45% of the world's population, accounting for much of the world's diseases. Ascariasis is uncommon in the United States.

Ascariasis is spread through ingesting the ascariasis eggs, usually by eating contaminated food or by hand-to-mouth contact.

After the ascariasis eggs are ingested, they travel to the intestines, where they hatch. The larvae then burrow through the intestinal wall and travel into the lungs, where they burrow into the alveoli.

The ascariasis larvae then travel up the trachea to the esophagus, where they are swallowed by their host. The larvae mature in the intestines, lay more eggs, and the cycle begins anew. Eggs from the mature worms are expelled through the feces of an infected person.


  1. Cough
  2. Fatigue
  3. Shortness of breath
  4. Presence of worms in vomit or stool
  5. Blood in the stool


Ascariasis can be detected by looking at a stool sample with a microscope.


Albendazole and mebendazole are used to treat Ascaris infections. the patient is generally treated for 1-3 days.

Guinea Worms: Dracunculus medinensis

The almost total worldwide eradication of the Guinea worm is near. In the 1980s, there were tens of millions of people infected, but in 2019, only 49 cases were reported in 4 African countries. If this parasitic disease is eradicated, it would be the first one removed in humans.

The Guinea worm is transmitted by drinking water containing water fleas infected by the Guinea worm nematode. The flea is dissolved in the stomach, but the nematode survives, eventually drilling out of the intestines and migrating into muscle and connective tissue by way of the blood vessels. The female worm, sometimes reaching 1 meter in length, eventually burrows to the skin's surface. Every time the host contacts water, the female expels eggs, contaminating the water supply and continuing the cycle. The female is removed by slowly pulling it from the skin over the course of weeks or months.


  1. Typically the first symptom is a searing pain in an extremity, usually the leg, as the worm moves through tissue. Fever, nausea, and vomiting may also be present.
  2. Female worms cause allergic reactions as they move up towards the skin. Swelling, diarrhea, rashes, and dizziness are common side effects of the reaction.
  3. The first sign of an emerging Guinea worm is a blister that may feel as though it is on fire. Once the head of the worm emerges, the wound may become red and inflamed due to a secondary infection.
Guinea worm  removal.

Guinea worm removal.

Botfly Larvae

Technically fly larvae, the human botfly, Dermatobia hominis, is a member of the Oestridae family. It is the only botfly known to inhabit humans flesh.

Mosquitoes, muscoid flies, and ticks are the vectors of the botflies eggs. The female fly attaches her eggs to the host, and as the host feeds it releases the botfly eggs. The eggs enter the skin where they incubate for 8 weeks and hatch. After this time the botfly larvae crawl out of the skin, drop to the ground, and metamorphosize into new botflies to begin a new cycle.

Petroleum jelly is sometimes used to smother the larva under the skin. The larva can then be safely removed with a pair of sterilized tweezers.


Ringworm is NOT a worm. It is a fungus. It is spread through contact with contaminated animals or surfaces. Ringworm can be treated with a topical antifungicide.

Can Pets Transmit Worms to People?

Yes, many worms can be transmitted from pets to people. For more information, read Pet to People Worms.


Lymphatic filariasis. (2018, May 11). Retrieved from

This content is accurate and true to the best of the author’s knowledge and does not substitute for diagnosis, prognosis, treatment, prescription, and/or dietary advice from a licensed health professional. Drugs, supplements, and natural remedies may have dangerous side effects. If pregnant or nursing, consult with a qualified provider on an individual basis. Seek immediate help if you are experiencing a medical emergency.

© 2013 Gable Rhoads


Gable Rhoads (author) from North Dakota on November 15, 2016:

Thank you for your kind words Credence2. I do have some medical training, but I must confess most of my knowledge comes from having a fascination with strange things.

While people worry about terrorist attacks, it is the lowly mosquito which kills so many of us.

Credence2 on November 07, 2016:

I wanted to get better acquainted with the work of those whom I follow. This article about parasitic worms opened my eyes in addition to giving me 'chicken skin'. That, hopefully, not the result of worms. It disturbs me that the source of infection can be found in the ubiquitous. ever present mosquito and fly.

This is a scholarly written article, and it appears that you either have or have acquired more than a laymen's knowledge of the topic at hand. The pictures of the infestation victims were quite graphic. Living in the Southeastern US where infection from these various parasites could easily effect me through what would be considered an innocent routine during the day is reason for pause.

Thanks for sharing, I need to keep an eye over my environment just that more carefully.

Gable Rhoads (author) from North Dakota on March 05, 2016:

Thank you RJ. You've made my day!

Ralph Schwartz from Idaho Falls, Idaho on March 04, 2016:

This was the grossest but also most interesting thing I've read in a while. Highly educational.

Gable Rhoads (author) from North Dakota on January 26, 2016:

Thank you for the kind words, fpherj. I find the oddest things fascinating and love to read about them.

Suzie from Carson City on January 26, 2016:

This article is invaluable. Thank you for such in depth, clear and complete information of this vital topic. You have presented a superb education and one I feel will be "new" facts the vast majority did not know. I certainly knew very little and am most impressed.

I see several of your works I am eager to read. Excellent job!...Peace, Paula

Gable Rhoads (author) from North Dakota on April 24, 2014:

Thank you for reading, Sheila.

sheila Holcomb on April 23, 2014:

Most interesting, thank you for the information,

Gail Louise Stevenson from Mason City on July 06, 2013:

Very interesting hub about worms and very informative. Worms sure are gross. I voted up, and very educational.

Gable Rhoads (author) from North Dakota on March 18, 2013:

Thank you, LongTimeMother. :)

LongTimeMother from Australia on March 18, 2013:

Hi Gcrhoads64. Peru is now officially off my bucket list. lol.

Voted up.

Gable Rhoads (author) from North Dakota on March 16, 2013:

It seems it would be - yuck! I will check it out, just let me know when it is published.

Alex Munkachy from Honolulu, Hawaii on March 16, 2013:

Wonderfully gross. I'm working on an article for involving parasites that infiltrate the private parts. I did some extensive research about the candiru fish the other day... disgusting! :)

Gable Rhoads (author) from North Dakota on March 13, 2013:

Thank you peachpurple. :)

peachy from Home Sweet Home on March 12, 2013:

thanks for the information on worms. Luckily we don't see such cases in Malaysia. Thank GOD! Voted useful