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There is a possibility that you have been infected with an intestinal parasite.

Read this page to learn what intestinal parasitosis is, how it is diagnosed, and what can be done to eradicate it.

What is an intestinal parasitic infestation?

In medical circles, an 'intestinal parasite' (or 'intestinal worm') is defined as a multicellular organism that needs to nest in the intestine of the host in order to carry out its life cycle.

Virtually every mammal is liable to intestinal parasitosis, including humans, and the worms responsible for them are called helminths (hence the term helminthiasis to refer to their infestation).

These worms prefer to nest and grow in the human gastrointestinal tract, but in situations of need they can invade other organs as well, such as the liver.

How many types of intestinal worms can infect our intestines?

Three main types of helminths are known so far: nematodes, cestodes and trematodes.

Some types, such as filariasis belonging to nematodes, can indiscriminately infect both humans and animals, giving rise to filariasis.

All types of intestinal parasites however, regardless of their classification, have certain common characteristics, such as:

• The nutrient taken away from the host, particularly in the form of sugars;
  
• The obligatory nature of the parasitic mechanism to reproduce and complete the life cycle;
  
• The immune response they stimulate in the host, which gives rise to an inflammatory reaction known as parasitosis

It is worth remembering that intestinal parasites, together with protozoa and ectoparasites (the fleas, lice, ticks, mites, etc.) form the three major etiological classes that give rise to parasitoses in humans and, in general, in mammals.

What do intestinal worms look like?

The shape (morphology), size and proper characteristics of intestinal worms vary greatly according to their type and family, as well as their life and development status.

Morphologically, a first subdivision can be made according to the shape of their bodies: cylindrical in the case of nematodes, flat in the case of cestodes and trematodes (which, for this reason, are called flatworms).

For example, the tapeworm is a flatworm.

The evolutionary rate of helminths is one of the most prolific among multicellular organisms: thousands of species exist and are recognized, with a varied and articulated taxonomy that is difficult to list specifically.

How much do worms multiply in the human intestine?

A lot: in their natural host environment, intestinal worms, if not extirpated by appropriate medical therapy, can generate more than 100,000 eggs per worm, reaching in some cases of tapeworms, as much as 20 meters in length as a single parasite.

This immediately makes it clear that intestinal worm parasitosis is no joke, and that in many countries of the world, complicit in poor hygienic conditions, it is a real scourge, difficult to eradicate.

How does intestinal parasite infection occur?

Helminth parasitosis, in humans, occurs mainly by ingestion of contaminated food.

Such food may be pork or beef, raw or undercooked meat contaminated with parasite larvae.

This danger increases if the meat consumed comes from countries where slaughter rules are deficient or nonexistent.

In the European Union and United States, the rules for slaughtering cattle and pigs are strict, and the quality standards of meat is very high, so the greatest danger, speaking of parasite infection, comes mainly with the consumption of meat imported or consumed in other countries outside the Western bloc.

Intestinal worm infection is a cycle, which cows and pigs perpetuate without their knowledge, by ingesting worm eggs directly from the environment (infected food or contaminated vegetables).

When the animal ingests the parasites' eggs, the onychospheres nest in their muscle fibers, maturing into a semi-larval form (cysticercus) that, when eaten by humans, infects them.

In humans, cysticercus will finish their life cycle by nesting in the intestines and maturing, reproducing with many new eggs that, released from the feces, will be released into the environment, thus completing the infectious cycle.

Cysticercus are thermolabile, so they die if they are cooked at the right temperature.

That is why infection, in humans, is possible only with the consumption of meat that is not well cooked, or completely raw.

Infected meat is not the only gateway for parasite eggs, however.

Infection is also possible by drinking contaminated water, and this danger increases as the hygienic-hydric conditions of the country where one resides decrease.

Again, to kill the worm onychospheres permanently, simply boil the water before consumption.

Of course, direct contact with infected material (e.g., manure used as fertilizer) can also be a source of entry for the parasite, as eggs may remain on hands that are not well washed or protected, which can trigger infection upon contact with the mouth.

Some types of intestinal worms, such as Ancylostoma, Necator americanus, and Strongyloides stercoralis, do not need ingestion to infest the human intestine, but can penetrate directly by piercing the epidermis, and thus one can become infected even by simple direct contact with contaminated objects or soil.

Direct infestation by human fecal contact, i.e., contaminated human feces, is possible but is unlikely, at least in industrialized countries.

This is because contaminated human feces become infectious about 2-3 weeks after evacuation.

This time, in countries with sewer pipes and separation of clear and dark water, is sufficient to prevent the spread of infection, but it can be a problem in backward countries (such as South Korea) where human feces are used to fertilize soil.

What is the cycle of worm infestation in humans?

The cycle of the larvae, once it enters the human being (by contamination of meat or water, or even by direct lip contact), is precise and follows an equally precise pattern.

Ingestion brings the eggs into the stomach where, resisting the action of gastric juices, they penetrate the duodenal valve and end up of the duodenum, that is, the first part of the small intestine.

There the eggs absorb directly from the chyme (the bolus that comes from the stomach, i.e., food that has already been chopped up) the nutrients they need to mature, becoming true larvae.

The larvae then burrow through the intestinal wall and enter the bloodstream, where they are transported by the effluent blood to the lungs, their intermediate target.

In the lungs, or rather in the pulmonary capillaries, the larvae nest and complete their growth cycle, then ascend up the trachea.

Some of the larvae that attempt to relax the trachea are eliminated by mucus and phlegm, but some survive, and are ingested again by the host (without realizing it), thus returning to the stomach.

From the stomach the larvae, now much larger and having become almost adult, again pass through the duodenal valve and again infest the intestines, feeding even more and becoming true adult worms.

Once adults, the worms will pass the iliac valve and nest permanently in the colon, where they can travel as far as the anus, depositing their eggs that will infect human feces.

Once the infected feces is expelled, the cycle of the parasite will be over and therefore ready to start again.

What are the major dangers of intestinal worm infection?

Once the life cycle of intestinal worms is known, it is immediate to assume that the major risk factors for infection is given by all those deficient sanitary conditions, where there is a danger of contact between organic waste and food (or food animals).

In European Union and the West in general, standard acts of animal husbandry and agriculture have all but eliminated this risk, which nevertheless remains in developing countries, or those too poor to have efficient hygiene protocols in place.

Not coincidentally, intestinal parasite infection is considered endemic in many countries that do not yet have effective cordons sanitaire, and cattle and pig farms are in direct contact with sewage and wastewater.

In general, there is always a risk of intestinal parasite infestation in countries where:

• There is poor sanitation and poor control over meat slaughtering;
  
• There is no efficient sewage system or no sewage system at all;
  
• The water and aqueduct system is not regularly controlled, and clear water comes into contact with sewage;
  
• Wastewater is used for crop irrigation;
  
• Human feces or feces of infected animals are used for fertilizing crops;
  
• There is a situation of extreme poverty and overcrowding in urban centers;
  
• The social habits of the population are hygiene-deficient

All these conditions facilitate the spread of intestinal parasitosis, often to levels that are considered endemic.

In Western World, these risks are practically absent: western countries have strict controls of livestock farms and slaughterhouses, irrigation with wastewater is prohibited, and aqueducts are periodically maintained and controlled, and there is no mixing of the sewage system and the drinking system.

This makes the risks of intestinal parasitosis very low, and the cases recorded each year are mostly from travelers or people who have consumed imported meat from abroad that has not been checked.

What are the symptoms of intestinal parasitosis?

There are many symptoms that can be caused by intestinal parasitosis, and among them:

• Chronic diarrhea;
  
• Meteorism, cramping, and abdominal pain;
  
• Nausea, vomiting, and lack of appetite;
  
• Pronounced and rapid weight loss;
  
• Lassitude, weakness and apathy;
  
• Anal itching, peri-anal dermatitis, and excessive mucus production;
  
• Presence of whitish, stringy fragments in stool

It should be noted that these symptoms may also be common to other diseases (not necessarily benign), and therefore the patient experiencing them should only seek the advice of a Physician for the possible diagnosis of intestinal parasitosis.

How is the diagnosis of intestinal parasitosis made?

The diagnosis of parasitosis is made by both an objective examination and a stool culture test.

During the medical history, the Physician should carefully inquire about the patient's behavioral and dietary habits, and retrieve any diagnostic elements that may be helpful in directing the diagnosis of parasitosis, or refuting it.

Confirmation of the diagnosis is diagnostic, however, and is done by stool examination (macro and microscopic).

The test is performed on two or more fecal samples collected within a short distance of each other, and aims to search for the presence of parasitic eggs or, in many cases, even whole parts of the worm.

Alternatively, it is also possible to perform the tape test, in which a small piece of tape is briefly placed on the anus and then sent to the laboratory for possible confirmation of the presence of parasite eggs.

Electronic Endoscopic Videoproscopy can also be helpful in directing the right diagnosis: with the video camera, the doctor can look for traces of eggs or worm fragments in the rectum.

What is the therapy for intestinal parasitic infestations?

Therapy for the eradication of intestinal worms is now almost exclusively pharmacological: in fact, effective drugs are available that can eradicate almost all types of parasites in a few days, provided, logically, that the exact type has first been ascertained by stool examination.

Albedanzol, mebendazole, niclosamide, pyrantel pamoate, praziquantel drugs may be used, depending on the specific type of pest.

However, almost all of these drugs have the same mechanism of action, which is to inhibit the worm from assimilating glucose.

With no more energy from sugar, the parasite dies within a few days and is then excreted with feces.

Sometimes laxatives are also combined with the antiparasitic drugs, only for a short time, to facilitate the expulsion of the now-dead worm carcasses.

Surgical access with mechanical worm removal is practically no longer performed, and is used quite exceptionally when (rarely) drug therapy is ineffective.

Is there a prophylaxis to follow to avoid getting intestinal parasitosis?

Yes, prophylaxis of intestinal parasitosis is easy and does not require much effort, and is (as is always the case with any disease) far preferable to drug treatment.

With the understanding that the greatest risks of contracting intestinal worms are outside the US or European Union (and the West in general), it is always good to keep in mind that:

• Meat, of any kind, should always be eaten well cooked;
  
• When traveling to countries of questionable hygiene, it is always imperative to consume water that is bottled and sealed, or previously cooked (beware of ice in drinks!);
  
• Before any meal or mouth contact, hands should always be well washed, especially under the nails;
  
• Raw foods of dubious origin, or drinks with ice, unsealed and not previously boiled should not be consumed

Which Physician can diagnose and treat intestinal parasitosis?

Any physician, even a general practitioner, should be able to diagnose and pharmacologically treat intestinal parasitosis.

However, even considering the hyper-specialization of current Medicine, the professionals indicated to best treat the possible parasitosis are the Proctology Physician and the Gastroenterology Physician.