Worms and Intestinal Parasites: Causes, Symptoms and Treatment

Worms and Intestinal Parasites: Causes, Symptoms and Treatment. Intestinal parasites, commonly called intestinal worms or parasitic worms, are unicellular or multicellular organisms that infect the gastro-intestinal tract of both humans and other animals and live off their host. Infection with parasitic worms occurs much more frequently than one might believe. While children are often more likely to get parasitic worms, adults that do not keep a rigorous hygiene can also be at risk. If left untreated, intestinal parasites infections can prove life-threatening.

Consuming infected food or water, coming into contact with fecal matter and ingesting it as a result of poor hygiene can get one infected with a variety of parasitic worms, ranging from ascaris, giardia, the trichina worm to tapeworms, the hookworm and so on. While an intestinal parasite infection presents symptoms and can be diagnosed through simple tests, many people who are infected are often oblivious to the infection and let it go undiagnosed until the parasite starts causing more serious health problems.

Intestinal worms

The key to understanding parasitic infections of the gastro-intestinal tract and the reason why they have such a harmful impact on one’s health lies in understanding what intestinal parasites are and what is their mechanism of infection. A parasite is an organism that lives in and feeds off another organism. Intestinal parasites, often referred to as intestinal worms or parasitic worms, are single-cell or multi-cell organisms that can potentially infect humans. They may be as little as a few millimiters or as big as a few meters, depending on their type. Intestinal parasites go through three main phases of evolution: egg, larvae and adult. Again, depending on their type, they may reside in various animals (fish, rats, pigs, cows, humans, birds) and various parts of the body (intestines, lungs, liver, brain, eyes or lymphatic system).

Where can they be found? Intestinal parasites can live on fruits and vegetables, especially on crops fertilized naturally, with animal manure coming from cows, pigs, sheep and so on. They can be found in the soil, almost everywhere, usually in the first 15 cm from the ground. They can be found in rivers, lakes and puddles. And because they can infect almost every living organism from mosquitoes, ants, wasps, fish, birds, pigs, cows, dogs, cats to humans, intestinal parasites are abundant in the fecal matter of all infected hosts and transmitted further from there.

While there are intestinal parasites that prefer certain hosts, most can thrive off any living organism. Here are the most common 5 types of intestinal parasites that can infect humans:

1) Roundworms, half of which are parasitic. The most common type of roundworm infection is attributed to Ascaris lumbricoides, an intestinal parasite that causes ascariasis. This type of roundworm infects over 20% of the world’s population and cases occur just as frequently in developed countries with proper sanitation as they occur in developing ones. Children are a high risk category for Ascaris infection because they are more likely to play with pets or stray animals that haven’t been dewormed and thus may come into contact with parasite eggs from their bowel movements.

Ascaris eggs can remain dormant for years and become ‘active’ following ingestion. Ascaris parasites are highly dangerous because once the ingested eggs hatch, the larvae migrate from the intestines to the heart, lungs, liver and even eyes (or get lost in other organs) to then return to the intestines as adults ready to reproduce. If left untreated, ascariasis can lead to death (it is estimated that about 20,000 children die annually as a result of  severe Ascaris infection).

Signs and symptoms of an infection often include eliminating worms or eggs through stools, but more severe cases may include shortness of breath, nausea, diarrhea, bloody stools, fatigue, abdominal pain, vomiting worms. Fortunately, the infection can be detected easily through stool examination and treated successfully with mebendazole, taken orally.

2) Pinworms. The pinworm, also called threadworm or seatworm is another common intestinal parasite and a type of roundworm. Out of three major pinworm species, Enterobius vermicularis is the only one to potentially infect humans and cause what is known as enterobiasis. This type of pinworm completes its life cycle in 8-13 weeks and colonizes the gastro-intestinal tract. A telling sign of pinworm infestation is itching in the perineal area.

If the area is scratched, the eggs of this parasite get attached to fingernails, hands, underwear or bed linen, from where they can easily be transferred to the mouth and ingested. Pinworm infections have extremely high rates of (re)infection, which makes it common for most household member to become carriers of the parasite at one point. Following treatment, strict personal hygiene and household hygiene are imperative.

3) Flatworms. The most problematic types of flatworms for humans (and livestock) are tapeworms and flukes. Tapeworms are the ones that reach monstruous lengths of almost 17 meters. Usually, people become infected with tapeworm larvae after consuming poorly cooked food. The larvea thrives within the intestines by anchoring itself to intestinal walls with hooks and some specimens may live up to 20 years.

A mature female tapeworm can lay millions of eggs every day which are then excreted, increasing reinfestation risks. Infestation is dangerous because tapeworm larvae may migrate to the lungs or liver where they form cysts. Pork, beef, fish, dog and sheep tapeworms are the most common potential causes of tapeworm infestation.

While tapeworm infections may be asymptomatic, sometimes, the following signs and symptoms may appear: continuous hunger, weakness, tiredness due to nutrient deficiencies caused by the parasite feeding off its host, nausea, headaches, diarrhea, indigestion, even weight loss or failure to gain weight despite eating well. Taenia solium (the pork tapeworm), Taenia saginata (the beef tapeworm) and Taenis asiatica (the Asian tapeworm) are known to cause the disease known as taeniasis. In the final stages of taeniasis, the parasites reach the brain and may cause severe neurological problems.

4) Whipworms. Trichuris trichiura is a 30-50 millimeter roundworm known as the whipworm. It causes the disease known as trichuriasis, also called whipworm infection. The name of the parasite has to do with its appearance, reminiscent of a whip. Whipworm infection is estimated to affect about 10% of the world’s population annually as a result of oral contact with soil contaminated with whipworm eggs. While the infection may not show symptoms at all in many individuals, when the worm population in the intestines begins to rise, fatigue, abdominal pain and bloody diarrhea may appear.

Trichuriasis is more likely to occur in tropical and subtropical areas of developing countries, where sanitation is practically inexistent. The infection occurs when people do not wash their fruits and vegetables properly, do not cook their food well or forget to wash their hands, especially after having contact with infected soil, animal or human bowel movements, both of which are often used as fertilizer.

5) HookwormsAncylostoma duodenale and Necator americanus are the main parasites causing hookworm infestation, known either as ancylostomiasis, or as necatoriasis. Hookworm infection occurs as a result of poor hygiene and infection rates are visibly higher in rural areas, tropical and subtropical regions, children, adults working in unsanitary conditions and so on. This type of parasite has a lifespan of around 5 years and inhabits the small intestine from where it feeds off blood. As a result, the most telling sign of infestation is anemia, closely followed by iron deficiency.

Unlike other intestinal parasites, hookworms usually infect people by penetrating their skin. For example, if you walk barefoot or handle infected soil, the larvae (and only them) transfer themselves to your skin, penetrate it to reach your circulatory system and then lungs. Their aim is to get to the trachea from where they are swallowed and end up in the intestines where they mature. A single female can lay up to 30,000 eggs in a day and larvae may remain dormant in tissues and become activated when other adult worms die.

Intestinal parasites

Some of these parasites fall into the category of protozoa (single-cell organisms), while the others into the category of helminths (multicellular organisms). An infection with the parasites known as helminths is called helminthiasis. It is estimated there are about 1 million species of parasites that may infect humans, as well as other animals. Most of them are thin, either round or flat and have a whitish-yellowish, sometimes transparent color.

While some feed off the nutrients we take from the food we eat, causing visible weight loss and growing hunger, others prefer blood, triggering anemia and iron deficiencies. When parasites grow in numbers, they become less discrete and telling symptoms such as rashes, itching in the groin area or eliminating live worms in stools may appear.

Depending on the type of parasite inhabiting one’s intestines, the degree of infection and the incubation period, intestinal parasite infestations may be more or less hard to detect. Usually, a doctor will examine one or more stool samples under the microscope to identify the parasites. It is also common for a doctor to place some duct tape around the anal region, then remove it to check it under the microscope for eggs. Ultrasounds are rarely used, but aim to locate parasites in the lymphatic system, while colonoscopies are only performed when your doctor suspects you have an intestinal parasite, but cannot find proof in stools (often because you may have only a few adults causing your health problems).

How to tell if you have intestinal parasites? Here are the most telling 8 signs and symptoms you have an intestinal parasite:

1) Abdominal pain or tenderness.
2) Itching and rashes in the groin area.
3) Passing worms in stools.
4) Tiredness, fatigue.
5) Visible weight loss.
6) Increased appetite.
7) Gas, bloating, nausea and vomiting.
8) Diarrhea, often with blood.

Less common signs and symptoms associated with a severe intestinal parasite infestation include:

1) Irritable bowel syndrome symptoms.
2) Difficulty falling asleep.
3) Screeching teeth during sleep.
4) Unexplained skin rashes, hives, rosacea or eczema.
5) Muscle or joint pain.
6) Frequent feelings of apathy, depression, chronic fatigue, anxiety.
7) Constant feeling of hunger.
8) Hypoglycemia.
9) B vitamins deficiency.
10) Excessive mucus in stools, often accompanied by visible (or invisible) traces of blood.
11) Cough.
12) Jaundice.
13) Night sweats or chills.
14) Colitis.




Some of these symptoms are caused by parasites releasing toxins or fecal matters into the host’s bloodstream and are the result of a severe infestation. For this reason, they rarely occur in individuals in developed countries, but are more common in poor, developing countries lacking sanitation and good hygiene education.

What causes an intestinal parasite infection?

1) Contaminated water.
2) Contaminated and unwashed fruits and vegetables.
3) Raw or uncooked contaminated meat.
4) Walking barefoot or handling contaminated soil.
5) Working with natural fertilizers such as human and animal manure.
6) Lack of good personal hygiene (hand washing) and sanitation (lack of toilets).

Once a person acquires an intestinal parasite and remains untreated, it is only a matter of time until he or she infects other members of the household, coworkers and so on. Seeing that transmission can occur fairly easily, prevention remains crucial in reducing both infection and reinfection rates. Here is how to prevent intestinal parasites:

1) Practice good hygiene. The most important thing you can do to prevent a great number of diseases, including intestinal parasites infections is to wash your hands thoroughly before you eat as well as before and after you use the toilet. Changing your bed linen and underwear regurlarly and washing them at high temperatures can help destroy excreted eggs and prevent infection of other people as well as reinfestation.

2) Drink clean water. Whether you have a certified clean water source, drink bottled water (which is best), filter or even boil and cool you drinking water, it is important to keep to your practice to avoid consuming contaminated water.

3) Wash your food and cook it well. Wash fruits and vegetables well before eating them and avoid consuming undercooked meat such as pork, beef or fish. Also, you may want to avoid foods fertilized with untreated human and animal manure.

4) Disinfect your shoes and house regularly. If you went for a walk in the park, leave your shoes at the door and change into a clean pair you use only inside the house. Disinfect your outsoles with diluted chlorine and do the same with the floors once in a while.

5) Avoid playing with unwormed animals. Stray cats and dogs and even household pets that have not been dewormed are very likely to carry one or more intestinal parasites that can infect humans. Being an adult, you will most likely wash your hands well after petting an unwormed animal, but children might put their hands into their mouth soon after touching the fur or tail of a stray animal, which might lead to the transmission of a potentially dangerous parasite.

How to treat intestinal parasites?

1) Medication used to treat intestinal parasites is called antihelmintic medication. It includes Benzimidazoles (mebendazole, albendazole, fenbendazole), Ivermectin, Praziquantel and so on. The most effective is mebendazole therapy, often prescribed in one dose or smaller doses taken over a period of three days, twice a day, with a last dose recommended 10-14 days after the completion of the first treatment (to kill remaining eggs).

What is interesting is that mebendazole has shown promising results in cancer treatment as well, with testimonies showing that it can induce partial and total remission in terminal cancer patients. It was shown to help reduce tumor size and prevent further cancer spread.

2) Surgery. This is a last resort and is recommended only in cases of extremely severe intestinal parasites infestation, when worms clump together in the abdomen, for example, expanding it visibly and putting great strain on the host’s body. Such cases are only seen in individuals living in extreme poverty, lacking hygiene possibilities. If the condition is left untreated and ends up in worms clumping together in various parts of the body (intestines, lymphatic system), medication is no longer effective and surgery becomes imperative.

Food for thought. While it may not seem as much of an issue, remember that intestinal parasites are extremely dangerous and can lead to long-term health problems. For example, Toxocara canis, an ascarid found in unwormed pet dogs, which can infect humans as well, can damage the heart muscle, the liver, the retina, cause seizures and coma. Another parasite appears to increase bladder cancer risks in adults, while many cause retarded physical and cognitive development in children. Basic hygiene rules and prevention can mean the world.




17 Replies to “Worms and Intestinal Parasites: Causes, Symptoms and Treatment”

  1. This article is informative to me as I suspect I have one of these parasites. I want to known which foods especially vegetables destroy these parasites in the body.

    • Hello, Sandile. My honest opinion is that if you suspect you have an intestinal parasite, you should go see a doctor and get a prescription for antiparasitic medication. Antiparasitics are by far the most efficient for dealing with worms and intestinal parasites. While certain foods such as ginger, garlic, onions, oregano, cardamom, cloves, black walnuts may have a protective action, their effect is very likely not strong enough to cure an existing parasite infection. At most, they have a mild protective action and may be consumed to prevent a potential infestation. But, honestly, it really depends on the type of parasite, the source of the infection, the magnitude of the infection, your tolerance of these foods (many foods for intestinal parasites such as ginger may upset hemorrhoids, garlic and onions may worsen acid reflux, gastritis and so on). In any case, the surest way to get rid of parasites is with a prescription from you doctor. Wishing you lots of health.

  2. Been dealing with pinworms and have taken mebendazole as directed, almost 3 months, haven’t come back. There are several cases at elementary school. Using food grade diatomaceous earth to prevent intestinal parasites, also probiotics, coconut oil and eating garlic. Due to pricing in US, could not afford enverm for my husband and myself, only my child. Found mebendazole at the market in Spain for mom and dad. Counting on the DE to keep them away. Saw 1 worm on child January 10, none since.

    • Hello, Lee. If you are taking the medication prescribed to you (mebendazole), then you should get rid of intestinal parasites for good. But you do have to prevent reinfestation. If there are still children with intestinal parasites at your child’s school, then you and your family have to keep to strict hygiene rules to prevent getting the worms again. For example, it is extremely important to wash your hands throughout the day, before eating especially, avoid touching your mouth if you haven’t washed you hands first, keep nails short (intestinal parasites eggs can get under the nails and from there we may end up ingesting them) and wash undergarments and towels at 90 degrees Celsius if possible (in case there are eggs on them). If you suspect a reinfestation, go to the doctor. Wishing you lots of health.

  3. My 8 yr old daughter has been vomiting spasmodically (strangely weekends only, and usually 4 or 5 am) for over 6 months. Some months it’s every weekend, others sometimes can be weeks without vomiting. She has recently had a stool test, blood tests, allergy tests, ultrasounds completed with the only answer being she had cryptosporidium. Could it be that this parasite has infected her gut so badly that it remains there? She’s vomited again today and has been in pain for 24 hrs. We are under the care of a pediatric gastroenterologist who is suggesting we wait for second stool test results and if she still has cryptosporidium an important conversation must be had. What could this important conversation be?

    • Hi, Rochelle. I can only assume that the doctor is concerned with making your daughter healthy again and is making serious efforts to find the right treatment for her. From my experience and knowledge, worms and intestinal parasites in general can be very difficult to get rid of, especially in children who often overlook the importance of strict hygiene and generally have more opportunities to be exposed to intestinal parasites. Cryptosporidium is one of those parasites that are extremely difficult to treat, but incredibly easy to get. They can infect drinking water, untreated sources of water (wells, lakes), swimming pools (chlorine is not always efficient against them) etc. and are prevalent among children and people with a compromised or weakened immune system. What’s worse is that the parasitic infection can return if the parasite is still present around us.

      Managing and treating cryptosporidium infestations and all intestinal parasites infections focuses on taking the right antiparasitic medication and preventing a recurrence of the parasite. The medication will be recommended by your doctor and needs to be taken accordingly. As for strict hygiene, it is recommended to:
      1) Wash hands throroughly multiple times a day, especially before eating and after going to the toilet.
      2) Use a liquid soap (it’s more hygienic).
      3) Boil drinking water is you suspect water sources are contaminated.
      4) Wash fruits and vegetables you may eat raw with clean, uncontaminated water.
      5) Take profilactic treatment. If a member of the family has an intestinal worm, everyone can get it too.
      In the case of small children, day cares and other similar venues can be a source of recurrent infection.
      6) Avoid swimming pools until the infection is cleared (we can transmit the parasite to others too for several weeks after getting rid of it, through the eggs we continue to eliminate).
      7) Pets can, in some cases, transmit a form of this parasite too, so take your cat or dog to the vet for tests.
      8) Wash undergarments, towels and changing pads at 90 degrees Celsius to eliminate potential parasites and their eggs.
      9) Keep nails short.
      10) Avoid touching your mouth or face with your hand.
      11) Disinfect floors, table and other surfaces.

      Experts also recommend to manage the symptoms: diarrhea and vomiting causing dehydration. Whether you are and adult or a child, dehydration can be dangerous. It is recommended to stay hydrated by drinking water, herbal teas or, even better, electrolyte solutions or sports drinks with electrolytes etc. It is important to also eat well and take multivitamins to keep the body strong to fight infection. Zinc, vitamin C for the immune system, B vitamins for energy and appetite and so on. When I had nausea and would feel like vomiting if I ate, I would make myself a bowl of plain, boiled white rice and maybe grated a fresh apple on top. That was the only thing I could eat without vomiting. Wishing you lots of health and hope to hear good news.

  4. Hey, what might be the causes of the absence of fish parasites on the skin, intestines and gills of the fish? Thank you.

  5. Suffering from shortness of breath, saliva from mouth on bed which is unusual for me and itching in the sensitive area, extreme fatigue. Please help me identify type of parasite. I bought benzimidazole and was told to take 200mg pills a day for 3 days and another after 14 days.

    • Hi, Bob. If you haven’t yet, see a doctor. And take the medication you have been prescribed as recommended. The first cycle is to eliminate mature intestinal worms or parasites and, after 14 days, their eggs. So follow your health care provider’s recommendations. Also, it is important to maintain a strict hygiene by washing hands before and after eating, keeping nails short and clean, washing underclothes with hot water (90 degrees Celsius), washing fruits and vegetables well, cooking meat thoroughly etc. If symptoms persists after completing the treatment, have some tests to see if you still have intestinal parasites or if you are sufferring from another condition altogether. Wishing you lots of health.

    • Yes, it is possible. But an intestinal worms infestation doesn’t show symptoms right away. At this point it can be intestinal worms, something you ate that didn’t agree with you, stress or several other possible causes. If the symptoms persist, make sure you make an appointment with your doctor. Hope this helps.

  6. I’m making an appt tomorrow, but I’ve been having very short breath and sometimes the feeling of a lot of caffeine but I don’t consume caffeine since I’m very sensitive to it. Also my stomach has been hurting and I get really hungry but once I start to eat, I lose appetite and feel nausea. I guess I just want to know if worms could be the cause and what the severe symptoms are. Given I take care of myself very well and am always on edge about what I consume, I wouldn’t think anything could have caused them. But I am worried.

    • Hello, Ameila. Intestinal worms can give some very strange symptoms, for example, you are always hungry and eat a lot, but lose weight or feel low on energy. Truthfully, you never know if you have intestinal parasites because they are so easy to get even with great hygiene. So see a doctor and have a test called a coproculture which can tell you if you have intestinal worms or not. Even if you do, it’s easy to get rid of them with medication. But considering the symptoms you describe, your problem might very well be stomach-related. Gastritis can make you really hungry or make your stomach hurt. Hunger is also an ulcer symptom, along with pain (the ulcer hunger pangs). Peptic ulcers can cause one to lose appetite and feel nauseous as well as throw up. And the feeling you get, the shortness of breath and the caffeine-like rush you experience can be caused by the stomach juices going up into the esophagus (acid reflux). I’ve experienced the same two symptoms when I had gastritis. So you could also tell your doctor about these symptoms, describe your diet and lifestyle and ask to know if you might have gastritis or a stomach ulcer. These are usually diagnosed via ultrasound (or ecography), an endoscopy (or gastroscopy) or other tests and exams. Hope this helps.

  7. I always have this indigestion. Any time I eat food it will not go down because I will be feeling it around my neck. What could cause that pls?

    • Hello, Emmanuel. It is possible that what you are experiencing is a globus sensation (when you feel like you have a lump in the throat). This can be a result of stress, anxiety, acid reflux disease, eating foods that are too dry or hard, taking large bites of food, maybe an injury from food. In any case, you should see a doctor. Tell the doctor if you experience other symptoms like pain or if the food actually gets stuck and when this sensation started. This is important information that will help with the diagnosis. Wishing you lots of health.

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