Gut Parasites - Should I be worried?



Most people think of invasive worms when they think of parasites. In reality, there are many types of common parasites in humans that can cause uncomfortable symptoms like nausea, diarrhea, abdominal pain, and weight loss. While parasites are a serious health concern for some individuals, especially the immunocompromised, many people carry parasites without any symptoms of an infection.

Concern over parasites has increased interest in parasite cleanses and parasite detox products. Unfortunately, there is not much evidence that parasite cleansing is effective, and the impact on gut health hasn’t been studied thoroughly. If you suspect a parasitic infection, you should visit your healthcare provider. A Tiny Health test can also help you learn about your gut microbiome and symptoms that may be clues to your overall gut health.  

Keep reading to learn about common parasites, how to avoid them, symptoms of a parasite infection, and treatment options.

What are intestinal parasites?

First let’s define parasite. Intestinal parasites are organisms that invade the intestinal tract after a person ingests contaminated food or water [1]. They are not bacteria, and they are not viruses. Instead they fall into two main categories: protists and helminths [2], [3].

Let’s break down these two kinds of intestinal parasites some more: 


Protists are eukaryotes (this just means cells with a nucleus) that are not fungi, plants, or animals [3]. They are made up of just one cell, so they aren’t visible to the naked eye.The most common protist parasites in humans are listed below. All of these protist parasites are typically picked up from contaminated food or water.

  • Blastocystis is the most common genus of intestinal parasite in the United States and Canada. It can cause an infection (known as blastocystosis) with abdominal pain and diarrhea [4]. However, people usually carry Blastocystis asymptomatically (meaning without symptoms) without even knowing it [5], [6].
  • Cryptosporidium, which causes cryptosporidiosis.
  • Entamoeba, which causes amebiasis [7].
  • Giardia, which causes giardiasis.
  • Cyclospora cayetanensis, which causes cyclosporiasis.


Helminths are parasitic worms, meaning they are multicellular [2]. They can be large and visible to the human eye, or they can be microscopic. Many helminths that infect humans are soil-transmitted, but they can also be contracted through contaminated food or water [8]. These parasites are much more common than their protist counterparts, and are thought to infect over a billion people worldwide [9]. The most common helminth parasites that affect humans are:

  • Flukes (trematodes) [10], [11]: These are most commonly picked up from eating raw or undercooked foods, often shellfish. 
  • Tapeworms (cestodes) [12]: These are picked up from eating undercooked meats. 
  • Hookworms and roundworms (nematodes) [13]: These are considered to be soil-transmitted helminths, and are most often picked up from contaminated soil or through ingesting helminth eggs directly [14].

Because helminths are multicellular worms, they are not detected by Tiny Health gut tests. Consult your healthcare provider if you believe you’ve been exposed to contaminated food and water and have the symptoms of a helminth infection.

What are the symptoms of a parasite infection?

Both protist and helminth parasites are capable of causing intestinal disease. Parasites are commonly associated with these symptoms: 

  • Diarrhea 
  • Nausea and vomiting 
  • Abdominal pain 
  • Gas or bloating
  • Fatigue
  • Weight loss

However, it is actually very common for parasite colonization to cause no symptoms at all - this is called asymptomatic carriage. We’ll talk more about the rates of asymptomatic parasitical carriage later in this article. 

How do I avoid picking up an intestinal parasite?

Parasites are almost always picked up through a few common avenues:

  • Drinking or swimming in contaminated water 
  • Eating raw or undercooked meat or seafood
  • Eating contaminated, unwashed produce 

The best way to avoid parasites is to practice good hygiene:

  • Wash your hands properly.
  • Wash produce like fruits and veggies before eating.
  • Only drink water from a clean, safe source. This is especially important when traveling abroad where parasites may be endemic.
  • Be sure to always cook meat and seafood to a safe temperature. 
  • The recommended minimum temperatures are [15]:

Parasites can also be picked up during travel to regions where parasites are common. This is especially true in tropical and subtropical regions where a warm climate and biodiversity supports their growth, and access to clean drinking water may be limited [2]. Parasite outbreaks can also affect water sources or fresh produce in places like the United States or Canada. Outbreaks of parasites such as Cyclospora cayetanensis or Cryptosporidium in produce like berries and lettuce do occur in North America, but they are relatively rare [16].

How are intestinal parasites treated?

If you are experiencing symptoms of a parasitic infection, you might find yourself searching for how to treat parasites on your own. It’s recommended that you visit your doctor to test for the presence of a parasite in your stool. From there, your physician can recommend the best strategy for treatment. Let’s dive into common types of treatment for parasites.

Anti-parasite medications

If a parasite is found in your stool, your physician may prescribe anti parasite medication [17]:

  • Blastocystis - Nitazoxanide
  • Entamoeba - Metronidazole 
  • Giardia - Tinidazole or Metronidazole 
  • Cryptosporidium - Nitazoxanide
  • Cyclospora cayetanensis - Trimethoprim-sulfamethoxazole (TMP-SMX)

These medications are only needed in the case of a symptomatic parasite infection. Interestingly, one study reported that population deworming, a public health program that provides parasite treatments to a whole population at once regardless of symptoms, doesn’t improve overall public health outcomes [18].

Since these medications are antibiotics, they may also kill beneficial bacteria in your gut. That’s why it’s best to take them only in case of a symptomatic parasite infection.

Parasite cleanses

Search for parasite treatments online and you’re sure to come across all kinds of claims and social media trends, like Amish parasite cleanses, parasite cleanses for kids, and parasite detox products. Some people opt to take intestinal parasite cleanses even if they are not experiencing symptoms of infection. 

Parasite cleanses come in different forms, from bottled drops and supplements to a regiment of herbs or vegetables you can pick up at the supermarket. Common ingredients in natural parasite cleanses include: 

  • Garlic [19], [20]. 
  • Ginger [20].
  • Black walnut hull
  • Wormwood
  • Clove
  • Papaya seeds [21].
  • Thyme
  • Oregano oil

Here’s the bad news: there is limited or no evidence that these ingredients remove parasites from the intestinal tract. Because parasite cleanse products are not regulated by the Food and Drug Administration (FDA), they aren’t required to back up their claims with clinical studies. There is also limited information about parasite cleanse side effects. 

Altogether, while these ingredients may be safe in general, taking high quantities of them for too long may negatively impact your gut health. Ingredients such as garlic and ginger may even have effects on the community of bacteria in your gut [22], [23]. And further research is needed to understand the effects of other parasite cleanse ingredients on gut health. 

If considering a parasite cleanse, we recommend doing it in consultation with a functional medicine practitioner or your healthcare provider. Maintaining a strong immune system and a healthy gut microbiome is the best thing you can do to avoid a parasitic infection! Keep reading to learn more. 

Should I be worried about intestinal parasites?

Many people worldwide carry intestinal parasites with no symptoms 

Intestinal parasites cause infections when they manage to overpower the immune system. However, it turns out it is relatively common to carry these parasites asymptomatically, or with no symptoms. If you’re not experiencing negative symptoms of a parasitic infection, it may be fine to let your body pass it naturally.

Blastocystis is the most common parasite in North America with prevalence as high as 50% [6]. In other regions of the world prevalence can be as high as 100% [24], [25]. This is of concern for public health, as actual infection with Blastocystis leads to abdominal discomfort and diarrhea. 

However, some research suggests that in otherwise healthy individuals Blastocystis may be more of a commensal, meaning that it relies on a host without causing it harm [26]. In fact, some studies suggest that Blastocystis colonization is more common in a healthy gut [27], [28]. Recent studies associate this presence with a healthy body mass index, low visceral fat, and healthy glucose metabolism [29], [30]. 

In some regions of the world, intestinal parasites are quite common. Countries in Africa and South America see very high rates of asymptomatic carriage. 

Rates of asymptomatic carriage: 

  • Entamoeba - as high as 57% [31], [32], [33].
  • Giardia - as high as 48% [34], [35]. 
  • Cryptosporidium - as high as 9% [35], [32]. 
  • Cyclospora cayetanensis - as high as 17% [34], [32]. 

Parasites are still a global public health problem

While parasites are common and may not cause symptoms, these organisms are still capable of causing major disease. In 2010, the World Health Organization estimated the global loss of life resulting from parasitic infections [36]:

Deaths (in 2010):

  • Cryptosporidium - 27,553
  • Entamoeba - 5,450
  • Ascaris lumbricoides - 2,224

There is mixed evidence on how intestinal parasites affect the  risks of eczema, allergies, and atopic disease

There is concern that carrying parasites in your gut could be associated with an increased risk of asthma, allergies, and other forms of atopic disease. Although there is currently weak evidence for this, an association has been seen between Giardia infection and allergies [37], with people with Giardia being 1.63 times as likely to have allergies. This relationship has also been seen between other protist infections and wheezing [38], with people who have parasites being 3.45 times as likely to have recurrent wheezing. 

Just like protists, helminth infections may affect your likelihood of atopic disease, as they have been shown to alter the immune system and the makeup of the gut microbiome [39]. In one study, helminth infection was associated with an increased likelihood of asthma in young children [40], with people who have parasites being 1.27 times as likely to have asthma. 

However, in another case these associations were not seen [41], and some research even suggests that parasites could be therapeutic for these types of immune disease [42].

How do I know if I’ve got a real problem?

The symptoms of different parasites are all very similar, including diarrhea, nausea and vomiting, abdominal pain, bloating, fatigue, and weight loss. If you are experiencing these symptoms, a visit to your doctor may be in order. 

Here’s the good news: if your immune system is functioning normally, your body should be able to protect you from parasites. Parasites typically only cause infection when they manage to bypass your body’s natural defenses. Within your intestinal tract, your body protects you with:

  • A lining of protective mucus that blocks parasites from reaching your intestinal wall [26].
  • A rich community of immune cells that will release cytokines, chemokines, and other immune molecules to help increase your defenses [26].
  • The beneficial bacteria that live in your gut that will outcompete parasites for nutrients and affect parasite’s ability to colonize and thrive in the intestine [43], [44].

Learn more about your gut microbiome and its strength by taking a Tiny Health test! While our test can’t detect helminthic parasites (worms), it can detect protist parasites (and over 120,000 microbes!) and give you actionable steps to address any gut imbalances to make sure it’s ready to tackle any parasitic infection. If your test detects a parasite but you are not feeling any symptoms, remember that this is totally normal. Always consult your healthcare provider if you have any concerns.


[1] S. Adl and B. Mathison, “Taxonomy and Classification of Human Eukaryotic Parasites,” in Manual of Clinical Microbiology, 12th ed., ASM Press, 2023. [Online]. Available:,%2C%20animals%2C%20and%20fungi).

[2] R. Haque, “Human Intestinal Parasites,” J. Health Popul. Nutr., vol. 25, no. 4, pp. 387–391, Dec. 2007.

[3] “Parasites and Foodborne Illness | Food Safety and Inspection Service.” Accessed: Sep. 12, 2023. [Online]. Available:

[4] K. S. W. Tan, H. Mirza, J. D. W. Teo, B. Wu, and P. A. Macary, “Current Views on the Clinical Relevance of Blastocystis spp,” Curr. Infect. Dis. Rep., vol. 12, no. 1, pp. 28–35, Jan. 2010, doi: 10.1007/s11908-009-0073-8.

[5] S. Popruk, D. E. V. Adao, and W. L. Rivera, “Epidemiology and subtype distribution of Blastocystis in humans: A review,” Infect. Genet. Evol. J. Mol. Epidemiol. Evol. Genet. Infect. Dis., vol. 95, p. 105085, Nov. 2021, doi: 10.1016/j.meegid.2021.105085.

[6] P. D. Scanlan et al., “The microbial eukaryote Blastocystis is a prevalent and diverse member of the healthy human gut microbiota,” FEMS Microbiol. Ecol., vol. 90, no. 1, pp. 326–330, Oct. 2014, doi: 10.1111/1574-6941.12396.

[7] A. Chou and R. L. Austin, “Entamoeba histolytica Infection,” in StatPearls, Treasure Island (FL): StatPearls Publishing, 2023. Accessed: Sep. 12, 2023. [Online]. Available:

[8] “Soil-transmitted helminth infections.” Accessed: Sep. 12, 2023. [Online]. Available:

[9] J. E. Truscott, H. C. Turner, S. H. Farrell, and R. M. Anderson, “Soil-Transmitted Helminths: Mathematical Models of Transmission, the Impact of Mass Drug Administration and Transmission Elimination Criteria,” Adv. Parasitol., vol. 94, pp. 133–198, 2016, doi: 10.1016/bs.apar.2016.08.002.

[10] R. Toledo, M. Álvarez-Izquierdo, J. G. Esteban, and C. Muñoz-Antoli, “Neglected food-borne trematodiases: echinostomiasis and gastrodiscoidiasis,” Parasitology, vol. 149, no. 10, pp. 1319–1326, Sep. 2022, doi: 10.1017/S0031182022000385.

[11] R. Toledo and J. G. Esteban, “An update on human echinostomiasis,” Trans. R. Soc. Trop. Med. Hyg., vol. 110, no. 1, pp. 37–45, Jan. 2016, doi: 10.1093/trstmh/trv099.

[12] D. Heyneman, “Cestodes,” in Medical Microbiology, 4th ed., S. Baron, Ed., Galveston (TX): University of Texas Medical Branch at Galveston, 1996. Accessed: Sep. 12, 2023. [Online]. Available:

[13] J. Bethony et al., “Soil-transmitted helminth infections: ascariasis, trichuriasis, and hookworm,” Lancet Lond. Engl., vol. 367, no. 9521, pp. 1521–1532, May 2006, doi: 10.1016/S0140-6736(06)68653-4.

[14] G. Stepek, D. J. Buttle, I. R. Duce, and J. M. Behnke, “Human gastrointestinal nematode infections: are new control methods required?,” Int. J. Exp. Pathol., vol. 87, no. 5, pp. 325–341, Oct. 2006, doi: 10.1111/j.1365-2613.2006.00495.x.

[15] A. S. for P. Affairs (ASPA), “Cook to a Safe Minimum Internal Temperature,” Accessed: Sep. 12, 2023. [Online]. Available:

[16] S. Almeria, H. N. Cinar, and J. P. Dubey, “Cyclospora cayetanensis and Cyclosporiasis: An Update,” Microorganisms, vol. 7, no. 9, p. 317, Sep. 2019, doi: 10.3390/microorganisms7090317.

[17] S. Kappagoda, U. Singh, and B. G. Blackburn, “Antiparasitic therapy,” Mayo Clin. Proc., vol. 86, no. 6, pp. 561–583, Jun. 2011, doi: 10.4065/mcp.2011.0203.

[18] S. Awasthi et al., “Population deworming every 6 months with albendazole in 1 million pre-school children in North India: DEVTA, a cluster-randomised trial,” Lancet Lond. Engl., vol. 381, no. 9876, pp. 1478–1486, Apr. 2013, doi: 10.1016/S0140-6736(12)62126-6.

[19] M. R. Gaafar, “Efficacy of Allium sativum (garlic) against experimental cryptosporidiosis,” Alex. J. Med., vol. 48, no. 1, pp. 59–66, Mar. 2012, doi: 10.1016/j.ajme.2011.12.003.

[20] E. H. Abdel-Hafeez, A. K. Ahmad, A. M. Kamal, M. Z. M. Abdellatif, and N. H. Abdelgelil, “In vivo antiprotozoan effects of garlic (Allium sativum) and ginger (Zingiber officinale) extracts on experimentally infected mice with Blastocystis spp,” Parasitol. Res., vol. 114, no. 9, pp. 3439–3444, Sep. 2015, doi: 10.1007/s00436-015-4569-x.

[21] J. A. O. Okeniyi, T. A. Ogunlesi, O. A. Oyelami, and L. A. Adeyemi, “Effectiveness of Dried Carica papaya Seeds Against Human Intestinal Parasitosis: A Pilot Study,” J. Med. Food, vol. 10, no. 1, pp. 194–196, Mar. 2007, doi: 10.1089/jmf.2005.065.

[22] K. Chen, Y. Nakasone, K. Xie, K. Sakao, and D.-X. Hou, “Modulation of Allicin-Free Garlic on Gut Microbiome,” Mol. Basel Switz., vol. 25, no. 3, p. 682, Feb. 2020, doi: 10.3390/molecules25030682.

[23] X. Wang et al., “Gut Microbiota Variation With Short-Term Intake of Ginger Juice on Human Health,” Front. Microbiol., vol. 11, p. 576061, 2020, doi: 10.3389/fmicb.2020.576061.

[24] D. El Safadi et al., “Children of Senegal River Basin show the highest prevalence of Blastocystis sp. ever observed worldwide,” BMC Infect. Dis., vol. 14, p. 164, Mar. 2014, doi: 10.1186/1471-2334-14-164.

[25] J. Lukeš, C. R. Stensvold, K. Jirků-Pomajbíková, and L. Wegener Parfrey, “Are Human Intestinal Eukaryotes Beneficial or Commensals?,” PLoS Pathog., vol. 11, no. 8, p. e1005039, Aug. 2015, doi: 10.1371/journal.ppat.1005039.

[26] A. Sardinha-Silva, E. V. C. Alves-Ferreira, and M. E. Grigg, “Intestinal immune responses to commensal and pathogenic protozoa,” Front. Immunol., vol. 13, p. 963723, 2022, doi: 10.3389/fimmu.2022.963723.

[27] C. R. Stensvold and M. van der Giezen, “Associations between Gut Microbiota and Common Luminal Intestinal Parasites,” Trends Parasitol., vol. 34, no. 5, pp. 369–377, May 2018, doi: 10.1016/

[28] C. Audebert et al., “Colonization with the enteric protozoa Blastocystis is associated with increased diversity of human gut bacterial microbiota,” Sci. Rep., vol. 6, p. 25255, May 2016, doi: 10.1038/srep25255.

[29] F. Beghini, E. Pasolli, T. D. Truong, L. Putignani, S. M. Cacciò, and N. Segata, “Large-scale comparative metagenomics of Blastocystis, a common member of the human gut microbiome,” ISME J., vol. 11, no. 12, pp. 2848–2863, Dec. 2017, doi: 10.1038/ismej.2017.139.

[30] F. Asnicar et al., “Microbiome connections with host metabolism and habitual diet from 1,098 deeply phenotyped individuals,” Nat. Med., vol. 27, no. 2, pp. 321–332, Feb. 2021, doi: 10.1038/s41591-020-01183-8.

[31] A. Lokmer et al., “Use of shotgun metagenomics for the identification of protozoa in the gut microbiota of healthy individuals from worldwide populations with various industrialization levels,” PloS One, vol. 14, no. 2, p. e0211139, 2019, doi: 10.1371/journal.pone.0211139.

[32] G. E. Kpene, S. Y. Lokpo, J. G. Deku, E. Agboli, and P. K. Owiafe, “Asymptomatic Intestinal Parasitic Infestations among Children Under Five Years in Selected Communities in the Ho Municipality, Ghana,” Ethiop. J. Health Sci., vol. 30, no. 6, pp. 867–874, Nov. 2020, doi: 10.4314/ejhs.v30i6.3.

[33] G. D. Weedall et al., “Genomic diversity of the human intestinal parasite Entamoeba histolytica,” Genome Biol., vol. 13, no. 5, p. R38, May 2012, doi: 10.1186/gb-2012-13-5-r38.

[34] H. Frickmann, N. G. Schwarz, R. Rakotozandrindrainy, J. May, and R. M. Hagen, “PCR for enteric pathogens in high-prevalence settings. What does a positive signal tell us?,” Infect. Dis. Lond. Engl., vol. 47, no. 7, pp. 491–498, Jul. 2015, doi: 10.3109/23744235.2015.1022212.

[35] A. S. Muadica et al., “Molecular Diversity of Giardia duodenalis, Cryptosporidium spp. and Blastocystis sp. in Asymptomatic School Children in Leganés, Madrid (Spain),” Microorganisms, vol. 8, no. 4, p. 466, Mar. 2020, doi: 10.3390/microorganisms8040466.

[36] P. R. Torgerson et al., “World Health Organization Estimates of the Global and Regional Disease Burden of 11 Foodborne Parasitic Diseases, 2010: A Data Synthesis,” PLoS Med., vol. 12, no. 12, p. e1001920, Dec. 2015, doi: 10.1371/journal.pmed.1001920.

[37] M. C. Di Prisco et al., “Association between giardiasis and allergy,” Ann. Allergy Asthma Immunol. Off. Publ. Am. Coll. Allergy Asthma Immunol., vol. 81, no. 3, pp. 261–265, Sep. 1998, doi: 10.1016/s1081-1206(10)62823-2.

[38] M. M. A. Overeem et al., “Recurrent wheezing is associated with intestinal protozoan infections in Warao Amerindian children in Venezuela: a cross-sectional survey,” BMC Infect. Dis., vol. 14, p. 293, May 2014, doi: 10.1186/1471-2334-14-293.

[39] A. Piazzesi and L. Putignani, “Impact of helminth-microbiome interactions on childhood health and development-A clinical perspective,” Parasite Immunol., vol. 45, no. 4, p. e12949, Apr. 2023, doi: 10.1111/pim.12949.

[40] C. V. Senaratna et al., “Association of helminth infestation with childhood asthma: a nested case-control study,” Int. J. Infect. Dis. IJID Off. Publ. Int. Soc. Infect. Dis., vol. 128, pp. 272–277, Mar. 2023, doi: 10.1016/j.ijid.2023.01.004.

[41] V. M. O. Souza et al., “Giardia lamblia and respiratory allergies: a study of children from an urban area with a high incidence of protozoan infections,” J. Pediatr. (Rio J.), vol. 88, no. 3, pp. 233–238, May 2012, doi: 10.2223/JPED.2184.

[42] Z. Wu, L. Wang, Y. Tang, and X. Sun, “Parasite-Derived Proteins for the Treatment of Allergies and Autoimmune Diseases,” Front. Microbiol., vol. 8, p. 2164, 2017, doi: 10.3389/fmicb.2017.02164.

[43] O. Partida-Rodríguez et al., “Human Intestinal Microbiota: Interaction Between Parasites and the Host Immune Response,” Arch. Med. Res., vol. 48, no. 8, pp. 690–700, Nov. 2017, doi: 10.1016/j.arcmed.2017.11.015.

[44] F. Berrilli, D. Di Cave, S. Cavallero, and S. D’Amelio, “Interactions between parasites and microbial communities in the human gut,” Front. Cell. Infect. Microbiol., vol. 2, p. 141, 2012, doi: 10.3389/fcimb.2012.00141.