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What is Human Intestinal Parasites Infection: Causes, Symptoms, Treatment, Prognosis, Prevention

Intestinal parasites are micro-organisms which live in the small or large intestine of human beings. Infection with such parasites is called as infestation. They survive on the nutrients which they get from the stool or blood of intestinal wall of the host.

There are 100 different types of human intestinal parasites infecting the humans. Due to increased mobility of the people throughout the world, the incidence of these infections has increased. These infections are of great concern since they occur more in small children. These are contagious infections which result in the life threatening conditions.

Human Intestinal Parasites Infection

Human Intestinal Parasites Infection: An Overview

The parasites that infect people include the following:

  • Helminths are multicellular worms which have their own internal organs.
  • Protozoa are the single celled organism (and have no other organs)

Helminths are the intestinal worms which include four species: Ascaris lumbricoides (roundworm), Trichiuris trichiuria (whipworm), Ancylostoma duodenale and Necator americanicus (hookworm).They are few millimeters to few centimeters in length and eat intestinal contents. The adult form of helminths cannot multiply in our body. They reproduce by laying eggs or larvae which develop into adult forms under favorable conditions. The most common protozoa include Giardia intestinalis, Entamoeba histolytica, Cyclospora cayetanenesis and Cryptosporidium spp. These parasites enter human body through mouth and skin, consumption of food and water contaminated with soil and stool samples from infected people.

Both types of human intestinal parasitic infections are observed more in the developing countries of South Asia, Indonesia, Africa, South and Central America where proper sanitation and hygiene precautions are not observed. While in industrialized countries, protozoan infections are observed which are caused due to use of common pools in water parks and handling of pets.

Symptoms of Infections Caused by Human Intestinal Parasites

Parasites cause many ill health conditions. The following symptoms are associated with human intestinal parasite infections:

  • Mild Diarrhea
  • Dysentery (loose motions)
  • Nausea and vomiting
  • Gas and bloating
  • Weight loss due to malabsorption
  • Pale skin (anemia)
  • Tiredness and fatigue
  • Passage of worms and their eggs in the stool
  • Rash or itchy skin
  • Joint pain
  • Restlessness.

These symptoms of human intestinal parasite infections may last for weeks and may return back several times in a year.

Prognosis of Human Intestinal Parasite Infection

Generally, intestinal infections caused by parasites are treatable. After the course of treatment, the doctor calls patient for re-examination to check for the absence (or presence) of infection. If the human intestinal parasite infection is persistent then treatment is continued with some modifications. After successful treatment, the patient should follow precautions so that they should not contract the infection again.

Causes and Risk Factors of Human Intestinal Parasites Infection

  • Poor sanitation and hygiene are the main causes of human intestinal parasitic infections. The food and water contaminated with soil and stool infected with these parasitic organisms.
  • Giardiasis occurs mainly in people with history of hunting, camping or frequent travel.
  • Children and elderly are more likely to be infected with human intestinal parasitic infections.
  • Child and institutional care centers which do not follow strict sanitation precautions are at risk for human intestinal parasitic infections.
  • People who are immuncompromised such suffering from HIV/AIDS are also at high risk for getting human intestinal parasitic infections.
  • Consuming unwashed vegetables and fruits.
  • Consuming undercooked food.
  • Hookworm infections when the larvae burrow through the skin of bare feet.
  • Young children are more susceptible to human intestinal parasite infections.

Complications of Human Intestinal Parasite Infections

  • Once these parasites enter the favorable hosts, they rapidly multiply and cause chronic health problems. They can cause malnutrition or malabsorption which does not allow the food to be properly absorbed. Children with human intestinal parasitic infections have stunted growth and show loss of weight.
  • Hookworm infections cause anemia and intestinal bleeding.
  • Chronic infections lead to mental retardation and slow physical development.
  • Severe human intestinal parasitic infections can cause death.

Diagnosis of Human Intestinal Parasite Infections

The diagnosis of the human intestinal parasitic infections can be confirmed by the following tests:

  • Stool tests for detection of ova/eggs of the parasites
  • Hemoccult to reveal blood in the stool
  • Blood tests to reveal anemia, levels of Vitamin A, C and B12
  • Immunological tests to detect antibodies against these worms especially IgE antibodies. Also Antigen detection tests are being used
  • Molecular based methods such as PCR are used to specifically detect these pathogens
  • Use of Adhesive tape test to collect eggs of worms from the anal region
  • CT scan and biopsy is required to detect cysts in liver, lungs and brain
  • For detection of amoebas, diagnostic tests include stool and serologic assays, biopsy, barium studies, and liver imaging.

Treatment of Human Intestinal Parasite Infections

The treatment for human intestinal parasitic infections often starts with allopathic drugs and then patient is advised to follow home remedies:

  • Anti-parasitic Drugs to Treat Human Intestinal Parasite Infection:
    • Helminth infections are treated with mebendazole.
    • Giardia is treated with metronidazole.
    • Hookworms are treated with albendazole, mebendazole, pyrantel pamoate, iron supplementation and blood transfusion.
    • Treatment for amebiasis include luminal and tissue amebicides to attack both life-cycle stages.
    • Metronidazole, chloroquine, and aspiration are treatments for liver abscess.
    • Cyclospora infections are treated with trimethoprim sulfamethoxazole are used.

Although treated with drugs, the human intestinal parasitic infections may reoccur if the source of infection exists.

  • Home Remedies for Human Intestinal Parasite Infection:
    • One should avoid foods rich in carbohydrates.
    • Eat more of ginger, garlic, green vegetable and salads.
    • Fiber containing foods to be eaten which allows to get of rid of these worms.
    • Consumption of Probiotics (Lactobacillus spp, Saccharomyces spp) to allow retain the normal flora of intestine these help to keep the digestive tract healthy.
    • Zinc containing antibiotics to be taken which support the immune system.
    • Certain ayurvedic medicines which contain herbs help in strengthening the body. Herbs can be taken in form of dried extracts, glycerides and tinctures.

Prevention of Human Intestinal Parasites Infection

One can prevent human intestinal parasitic infections by following certain precautions:

  • Before meals one should wash hands, legs after visiting toilets, touching pets in order to prevent getting human intestinal parasitic infections.
  • One should avoid eating from restaurants which lack hygienic conditions.
  • Meat and fish should be cooked very well.
  • Raw vegetables should be washed and then cooked properly in order to human intestinal parasitic infections.
  • Wearing footwear.
  • Treating sewage and maintaining sanitation.
  • Children should be taught proper hygiene.
  • One should wear gloves while using the cat box and should deworm the pets periodically.


The common human intestinal parasitic infections are caused by helminths and protozoa. The prevalence of human intestinal parasitic infections varies in different countries. The intestinal infections are more commonly observed in developing countries which lack proper sanitation facilities. Although these are treatable, one needs to take care that these infections do not reoccur.


  1. World Health Organization (WHO) – Soil-Transmitted Helminth Infections: https://www.who.int/news-room/fact-sheets/detail/soil-transmitted-helminth-infections

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Team PainAssist
Team PainAssist
Written, Edited or Reviewed By: Team PainAssist, Pain Assist Inc. This article does not provide medical advice. See disclaimer
Last Modified On:August 1, 2023

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