Let us venture for a moment into a topic that can cause mild discomfort from the very reading of it. Parasites. And no, this is not about the acquaintance who always "forgets" to return borrowed money or eats your snacks from the fridge. We are talking about far less welcome tenants.

These clever microscopic "freeloaders" often feel remarkably comfortable inside us. The problem is that when they settle in as though they were at home, it is our health and wellbeing that suffers.

Parasites have accompanied humans for thousands of years. Although many people associate them exclusively with exotic countries or extreme neglect of hygiene, parasitic infections in reality also occur in developed countries and affect both children and adults. [1,2]

They do not always produce violent symptoms. Sometimes for a long period the body sends only subtle signals: chronic fatigue, digestive problems, lowered immunity, recurring allergies or difficulty concentrating. Parasites can function in the body for years, affecting the immune system, inflammatory processes and the absorption of nutrients. [1,2]

At this point there is well-documented research showing that some parasites can lead to serious health consequences, including organ damage, anaemia, neurological disorders and even an increased risk of cancer. [3,6,7,8,14,15]

How does a parasitic infection occur?

Most often infection occurs via the oral route or through contact with a contaminated environment. Typical sources include:

  • unwashed fruit and vegetables,
  • raw or undercooked meat,
  • contaminated water,
  • contact with soil or sand,
  • inadequate hand hygiene,
  • contact with animals and their faeces,
  • travel to countries with low sanitation standards. [1,11,12,13]

Children are particularly at risk — due to frequent contact with peers, playing in sandpits and the natural habit of putting their hands in their mouths.

Symptoms of parasites — when the body is trying to say something is wrong?

Parasites can affect virtually the entire body. Symptoms depend on the type of parasite, where it resides and the condition of the host's immune system. [1,2]

Among the most commonly described symptoms are:

Most commonly described symptoms

Digestive symptoms: [1,11,12,13]

abdominal pain, bloating, diarrhoea or constipation, nausea, loss of appetite, digestive disturbances.

General systemic symptoms: [2,11]

chronic fatigue, weakness, vitamin and mineral deficiencies, weight loss, anaemia, lowered immunity.

Neurological and psychological symptoms: [9,10]

difficulty concentrating, sleep disturbances, irritability, mood swings, headaches.

Skin and allergic symptoms: [1,2]

skin itching, rashes, allergic reactions, dark circles under the eyes.

Many of these symptoms can also occur in other conditions, which is why the basis should always be sound diagnosis and consultation with a specialist.

The impact of parasites on health — what does science say?

Modern medicine has no doubt that some parasites can cause very serious diseases. The mechanisms of their action are complex and include, among others:

  • chronic inflammation,
  • tissue damage,
  • oxidative stress,
  • impairment of immune system function,
  • effects on the intestinal microbiome,
  • secretion of biologically active substances. [2,14]

Parasites and cancer

The International Agency for Research on Cancer (IARC, WHO) has officially recognised several parasites as human carcinogens. This applies to, among others:

—Schistosoma haematobium — increasing the risk of bladder cancer,

—Opisthorchis viverrini and Clonorchis sinensis — associated with bile duct cancers. [14,15]

Research shows that parasites can secrete proteins that stimulate host cell proliferation and intensify inflammatory processes and DNA damage. The protein Ov-GRN-1, secreted by Opisthorchis viverrini, which may stimulate proliferation of bile duct cells, has been described. [3,4,5]

This is an important point: science confirms the link between certain parasites and specific cancers, but this does not mean that "most cancers are caused by parasites". Such claims are inconsistent with current medical knowledge.

Parasites and the nervous system

Some parasites can affect the brain and nervous system. An example is Toxoplasma gondii, which can form cysts in nervous tissue and cause:

  • encephalitis,
  • seizures,
  • neurological disorders,
  • foetal damage during pregnancy. [9]

Experimental studies in mice have even demonstrated behavioural changes in infected animals. [10]

Parasites and deficiencies and anaemia

Intestinal parasites can impair the absorption of nutrients or lead to chronic blood loss. This particularly applies to hookworms, which feed on the host's blood and can lead to anaemia and chronic weakness. In children they can cause stunted growth. [2,11]

WHO considers hookworm infection one of the main causes of parasitic anaemia worldwide. [11]

Parasites and liver and intestinal diseases

Entamoeba histolytica, i.e. the dysentery amoeba, can cause:

  • bloody diarrhoea,
  • severe intestinal inflammation,
  • liver abscesses,
  • intestinal perforation. [12]

Giardia lamblia in turn causes:

  • chronic diarrhoea,
  • malabsorption,
  • vitamin deficiencies,
  • weight loss. [13]

The most common parasites in humans

Pinworms

Most common in children. They primarily cause itching around the anus, sleep problems and irritability.

Giardia (Giardia lamblia)

A microscopic protozoan causing chronic intestinal problems, bloating and malabsorption. [13]

Tapeworms

Can live in the body for many years and lead to nutritional deficiencies, abdominal pain and weight loss. [1]

Hookworms

Parasites of the small intestine causing chronic blood loss and anaemia. [11]

Trichinella spiralis

Infection usually occurs through the consumption of undercooked meat. The parasite can damage muscles and cause high fever, muscle pain and swelling.

Human flukes

Human flukes (e.g. liver fluke, intestinal fluke, blood fluke) live in the human body in the liver, bile ducts, intestines and even in the blood vessels. [3,6,7,8]

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Prevention — how to reduce the risk of infection?

The most important elements of prevention are:

  • thorough washing of hands, fruit and vegetables,
  • avoiding raw meat and unsafe water,
  • regular deworming of pets,
  • maintaining a healthy intestinal microbiome,
  • supporting immunity through an appropriate diet and sleep,
  • exercising caution when travelling,
  • avoiding bathing in contaminated bodies of water,
  • strengthening the body through adequate intake of vitamins and minerals. [1,2]

Summary

Parasites are a real health problem that is not worth ignoring. Modern science confirms that some parasitic infections can lead to serious health consequences, especially if they remain undetected for a long time. [1,2,14]

The best approach remains a combination of sound diagnosis, prevention, supporting immunity and individually tailored therapy. The body possesses enormous regenerative capacity — especially when we create the conditions for it to regain balance. [2]

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FAQ

Frequently asked questions

Yes — some parasites spread very easily between members of the same household. A shared bathroom, towels, bedding or contact with surfaces on which parasite eggs are present is enough. That is why the holistic approach looks not only at one individual, but at the entire "ecosystem" of the home — hygiene, the immunity of household members, gut health and everyday habits.

Unfortunately yes. Parasites can act very discreetly and for a long time give no clear symptoms. The body may gradually lose energy, absorb nutrients less well and function in a state of chronic burden. In the holistic approach it is often said that parasites "steal" not only nutrients, but also the vital forces of the body.

The body possesses enormous regenerative and defensive capacity — especially when we support immunity, the intestinal microbiome and the body's natural cleansing processes. An appropriate diet, hygiene, healthy intestines, sleep and stress reduction create an environment in which parasites find it harder to settle. Many people also support the body with herbs and natural anti-parasitic preparations.

Children explore the world with all their senses — they touch the ground, put their hands in their mouths, play close together and do not always remember hygiene. In addition, their immune systems are still developing. That is why in the natural approach great emphasis is placed on building intestinal immunity, an appropriate diet and daily hygiene rituals without creating excessive sterility.

Yes — and this happens more often than many people suspect. Some parasites do not produce acute symptoms for a long time. Instead the body may send more subtle signals, such as chronic fatigue, skin problems, bloating, brain fog, sleep problems or a low mood.

Animals can be a source of certain parasites, but this does not mean one needs to be afraid of them. The holistic approach assumes rather conscious prevention: taking care of the pet's hygiene, regular cleansing, a healthy diet for the animal and maintaining good immunity in all household members.

A growing body of research shows that gut health is closely linked to the nervous system and our wellbeing. Chronic parasitic burden can be associated with irritability, sleep problems, difficulty concentrating or a feeling of constant fatigue. In the holistic view, body and mind are inseparably connected.

This depends on the species. Some parasites function in the body for only a few weeks, while others can reside for years if conditions are favourable. That is why it is so important not only to "cleanse", but also to change the body's internal environment — so that parasites do not want to return.

Yes, especially travel to places with a hot climate and lower sanitation standards. It is worth paying attention to the quality of water, thorough washing of produce and avoiding raw meat and seafood. A well-nourished and strong body generally copes better during travel too.

Important: This article is for educational purposes only.

Scientific sources

  • 1. Hechenbleikner EM, McQuade JA. Parasitic colitis. Clin Colon Rectal Surg. 2015;28(2):79-86. doi:10.1055/s-0035-1547335. thieme-connect.de
  • 2. Shea-Donohue T, Qin B, Smith A. Parasites, nutrition, immune responses and biology of metabolic tissues. Parasite Immunol. 2017;39(5):e12422. doi:10.1111/pim.12422. onlinelibrary.wiley.com
  • 3. Smout MJ, Laha T, Mulvenna J, et al. A Granulin-Like Growth Factor Secreted by the Carcinogenic Liver Fluke Opisthorchis viverrini Promotes Proliferation of Host Cells. PLoS Pathog. 2009;5(10):e1000611. journals.plos.org
  • 4. Arunsan P, Smout MJ, Cochran CJ, et al. Suppression of Ov-grn-1 encoding granulin of Opisthorchis viverrini inhibits proliferation of biliary epithelial cells. Exp Parasitol. 2015;148:17-23. pmc.ncbi.nlm.nih.gov
  • 5. Chaiyadet S, Krueajampa W, Hipkaeo W, et al. Suppression of mRNAs encoding granulin of Opisthorchis viverrini inhibits proliferation of biliary epithelial cells. Exp Parasitol. 2015;148:17-23. sciencedirect.com
  • 6. Hsieh MH, Bility MT, Luyima E, et al. IPSE, an abundant egg-secreted protein of Schistosoma haematobium, promotes proliferation of bladder cancer cells and angiogenesis. Infect Agents Cancer. 2020;15:79. link.springer.com
  • 7. Botelho MC, Machado JC, da Costa JM. Schistosoma haematobium and bladder cancer: what lies beneath? Virulence. 2010;1(2):84-87. tandfonline.com
  • 8. Mostafa MH, Sheweita SA, O'Connor PJ. Relationship between schistosomiasis and bladder cancer. Clin Microbiol Rev. 1999;12(1):97-111. journals.asm.org
  • 9. Machicado JD, Marcos LA. Toxoplasmosis: epidemiology, diagnosis and treatment. Rev Gastroenterol Peru. 2016;36(2):151-158. scielo.org.pe
  • 10. House PK, Vyas A, Sapolsky R. Mice Infected with Low-Virulence Strains of Toxoplasma gondii Lose Their Innate Aversion to Cat Urine. PLoS One. 2011;6(9):e25795. journals.plos.org
  • 11. Hotez PJ, Brooker S, Bethony JM, et al. Hookworm infection. N Engl J Med. 2004;351:799-807. nejm.org
  • 12. Stanley SL Jr. Amoebiasis. Lancet. 2003;361(9362):1025-1034. sciencedirect.com
  • 13. Adam RD. Biology of Giardia lamblia. Clin Microbiol Rev. 2001;14(3):447-475. journals.asm.org
  • 14. Tanowitz HB, Weiss LM, Wittner M. Parasites and human cancer. Parasitol Today. 1993;9(11):437-442. sciencedirect.com
  • 15. Bouvard V, Baan R, Straif K, et al. A review of human carcinogens — Part B: biological agents. Lancet Oncol. 2009;10(4):321-322. sciencedirect.com