Intestinal parasites are a diverse group of microorganisms that include single-celled protozoans and multi-cellular intestinal worms, called helminthes, that affect the gastro-intestinal tract of humans and other animals. When these intestinal parasites are ingested, they move freely inside the body. Both types of parasites can live in the large intestine or small intestine where they lay eggs and grow. They feed on blood or stool that arrives to the intestine. For this reason, the intestinal parasites can disrupt the absorption of nutrients. There are some parasites that reside in the intestine and some will move to other organs of the body. They are usually acquired in contaminated food and water or through hands, nonsexual intimate contact (such as changing diapers), sexual contact (oral and anal), skin absorption or accidental contact with infected feces or infected soil. Intestinal parasites are more common in places that have poor sanitation and in developing countries of the tropics. They can be more aggressive to children and elderly than to middle-aged people.
Common protozoans include: cryptosporidium, giardia lamblia, cyclospora, entamoeba hystolytica. Cryptosporidium is not communicable when in contact with another individual, rather it is acquired through ingestion of contaminated soil or water. Giardia lamblia is the most widespread intestinal parasite in the United States and it can live in humans as well as in animals. It can be acquired through ingestion of contaminated water or food. On the other hand, cyclospora is the most widespread diarrhea-causing protozoa in the planet and it can be acquired by drinking contaminated water, or through direct contact with another person or animal. Entamoeba hystolytica is commonly found in people who traveled to developing countries and may cause amebiasis.
Common helminthes include: roundworms or ascariasis, tapeworms, pinworms, hookworms and strongyloidiasis. Roundworms or ascariasis are the most common type of intestinal parasite in the world. This worm not only affects humans, but it can also affect animals like pigs. It is not communicable; it can only be acquired through eating of the worm's eggs (present in infected foods). Tapeworms can be found in animals that roam in the open where they are exposed to contaminated water or soil. Humans can be infected after ingesting contaminated meat or fish. There are three types of tapeworms: fish tapeworm or diphyllobothrium latum, pork tapeworm or taenia solium and beef tapeworm or taenia saginata. Pinworms are also called seatworm or threadworm and live in the rectum. People can be infected after direct oral contact with a contaminated object. This worm only comes out at night in order to lay eggs in the perineum, contaminating objects like bed sheets. Hookworms live in wet or damp ground and can penetrate the skin after a person comes in contact with the contaminated land (for example: after walking with bare feet on infected earth). Strongyloidiasis may affect immunocompromised patients after contact with a contaminated soil. This parasite has a unique life cycle and it can penetrate the skin and attack the lungs, intestine and other organs.
The following conditions or situations are associated with higher exposure and likelihood of infection by an intestinal parasite:
- Immunocompromising diseases – e.g. HIV and AIDS
- Traveling to a parasite prone country
- Poor self-hygiene
- Uncooked meat and fishes
- Contaminated water
- Walking barefoot
- Dirty environment and objects
- Exposed stool
Some people experience no symptoms when an intestinal parasite infects them, and it can stay in the body for several years. Here are some symptoms of intestinal parasites that may serve as indicators of an infection:
- Weight loss
- Presence of worm in the stool
- Certain area of the body is itchy and rashes are present – area where the parasite entered or laid eggs (perineum, rectum or vulva)
- Stomach pain
- Pale skin
- Abdominal cramps
- Blood in the stool with or without pus (dysentery)
- Skin ulcers
- Rectal prolapse
- Mental problems
- Lung congestion
- Memory loss
- Night sweats
- Muscle spasms
Intestinal parasites can be detected through microscopic analysis of fecal material after the collection of stool samples. Some parasites (strongyloidiasis or entamoeba hystolytica) are detected through blood tests which will identify an elevation of the red blood cells, Immunoglobulin E (IgE) antibodies and a decrease in ferritin level if an infection is present. A scotch tape test or cellophane tape test is used to detect presence of pinworms. This procedure is done by placing the tape on the anus repeatedly followed by a microscopic examination of the tape. An abdominal x-ray or protoscopy (the doctor inserts a thin tube that has a light into the rectum) may be performed to diagnose the presence of intestinal worms.
The most effective treatments for intestinal parasites involves administration of anti-parasitic drugs such as furazolidone, quinacrine, trimethoprim-sulfametoxazol (can be used for cyclospora), tinidazole, metronidazole, paramomycin (can be used in pregnant women), praziquantel (for tapeworms). Iron supplements are given to mange anemia, which is a common complication from intestinal parasite infections.
Daily consumption of probiotics can help recover and prevent invasion of intestinal parasites. Most of these parasites are opportunistic, and you are less likely to be affected by them if you maintain your immunity by taking vitamin and mineral supplements.
The prognosis of intestinal parasites is normally very good since there are effective medications to eradicate the presence of common parasites in the body. Few parasitic infections are not treatable but proper clinical management cal help recover from then. In contrast with treatable cases, recovery time may be long in uncommon and severe parasitic infections.
Proper hygiene is critical to prevention of intestinal parasites. Implement good hygiene habits in your daily routine, which may include: hand-wash before meals; avoid walking barefoot; cooking meat and fish well; ensuring drinking water is clean; using condom during sexual intercourse; washing fruits and vegetables thoroughly; and wash clothes or sheets frequently. Take caution in public places and, particularly, in public swimming pools or water parks.
Having an intestinal parasite in the stomach is shocking, embarrassing and at the same time depressing, but you shouldn't be too depressed about it. There are treatments that can easily eliminate the invading organisms. Always follow the recommended lifestyle changes and take the medications as instructed. Avoid eating raw or uncooked meat and follow good-hygiene practices.
The increased risk of HIV/AIDS patients to intestinal parasites is an area of current research focus. Epidemiologic studies are also geared towards understanding the factors leading to frequent intestinal parasite cases in underdeveloped regions. Since travelers pose additional risk of spreading these parasites to all areas in the globe (including areas where some parasites are practically absent), researchers are developing effective and practical methods for traveler screening.