Enterobius vermicularis

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NB. The human helminth, Enterobius vermicularis (EV), is known as 'pinworm' in the US, and 'threadworm' in the UK and Australia, and should not be confused with Strongyloides stercoralis, the roundworm that causes strongyloidiasis and is known as 'pinworm' in the UK and 'threadworm' in the US.

Fossil evidence suggests that the pinworm lineage extends at least as far back as 240 million years, at which point it infected primitive proto-mammals that were the ancestors of modern vertebrates including humans and other primates. [1] Today, EV is distributed worldwide, and is arguably the most successful helminth of the Western world, remaining the most common helminth infection in the US, Western Europe and Oceania.

Disadvantages and potential risks[edit | edit source]

EV will never qualify as a therapeutic helminth because of a number of disadvantages:

its numbers are not controllable
it spreads very easily to other people
it can cause uncomfortable anal itching
it may be a vector for the intestinal protozoan Dientamoeba fragilis [2]
it can cause acute appendicitis [3] and appendiceal colic [4], although this presentation may sometimes only be "pretence". [5]
it can rarely cause colonic obstruction [6]
it can migrate to organs beyond the intestine (e.g., kidney, male urinary tract and female genital tract/uterus [7]
it can cause urinary tract infections and vaginitis [8] and, rarely, pelvic inflammatory disease [9]
it may contribute to a predisposition for dysbiosis or the onset of secondary bacterial infections. [10]
it can, in extremely rare cases, cause Mesenteric Lymphadenopathy [11]
it has even manifested post traumatic stress disorder-like symptoms [12]

The possible therapeutic benefits of hosting E. vermicularis[edit | edit source]

Although the authors of one study, using a population-based analysis, concluded that EV does not reduce the risk for asthma, type 1 diabetes, arthritis or inflammatory bowel disease, [13] there is evidence that this species can in fact provide therapeutic benefits.

One study found that, in atopic children infected with EV, there was not only a lack of any symptoms as a result of the infection, but that, “there seemed to be some indication of immunosuppression in those children with a positive history of allergic disease.” [14]

Therapeutic benefits have also been reported anecdotally by several people who have hosted EV.

I have had em for a few weeks and haven't felt this good in a long time. [15]

I saw my Rhuematologist today and got my latest ANA, sed rate, CRP results. He had to re read them THREE times! Said he just couldn't believe it but seems since my pin worm infection the ANA shows me going into remission and the sed rate has gone from 350 to 40! and my CRP was near normal. [16]

My grandson got pin worms when he started school … the infection was left to run for longer than usual. It was noticeable that his asthma and food allergies got better, and indeed it has never come back as bad as it was. [17]

Prevention and control of E. vermicularis[edit | edit source]

For approaches to prevent and control EV, see the following pages on the CDC website.

About Pinworm Infection.

Preventing pinworm infection

Special care needs to be taken with the handling of bed linen and the clothing of infected individuals because EV eggs attach to dust which can become airborne and, if inhaled, can cause reinfection.

Control of E. vermicularis in those who are hosting therapeutic helminths[edit | edit source]

The use of an anthelmintic drug to eradicate EV would also kill at least some of a colony of therapeutic helminths. So, faced with this dilemma, one self-treater experimented with control options and reported that a low sugar, low refined carbohydrate, high fibre diet significantly reduced EV numbers - judging by the severity of anal itch - and that drinking kefir provided approximately a month's relief.

I drank one glass of kefir and it seemed to eliminate them for about month. I had never tried kefir before. I thought it tasted disgusting but the pinworms went from severe to nothing overnight. [18]

In many parts of the world, garlic has been traditionally considered to be an effective treatment for helminth infections and, although very large amounts would need to be consumed to kill hookworms, (see here) it has been suggested that using a clove of garlic as a suppository might act locally in the rectum to provide effective control of EV. [19]

Hosts of NA who wish to totally eradicate an EV infection could try using an anthelmintic that is known to be more effective against EV but less effective against NA, such as pyrantel pamoate. One self treater who tried using Combantrin (pyrantel pamoate) to terminate his NA colony found that it wasn't very effective against this species, and he was only able to kill all his hookworms by taking albendazole. Another anthelmintic that is recommended for the treatment of EV but which may be less effective against NA is pyrvinium. [20]

Scientific papers[edit | edit source]

Various[edit | edit source]

2026 Jan Immune modulation in pediatric Enterobius vermicularis infection: Investigating IgE and IgA as biomarkers of parasite-driven inflammation
2025 Sep 30 Research on the Influence of Enterobius vermicularis on the Composition and Quality of the Intestinal Microbiota, and the Susceptibility to Co-Infections
2023 Dec 1 Impact of pinworm infection on the development of murine B-cell leukemia/lymphoma in the presence and absence of ETV6::RUNX1 -- Full text | PDF (editorial Worm on stage)
2017 Sep 25 - Impact of Enterobius vermicularis infection and mebendazole treatment on intestinal microbiota and host immune response -- Full text | PDF
2015 May 20 Immune responses in children infected with the pinworm Enterobius vermicularis in central Greece
2012 Jan Helminth infection does not reduce risk for chronic inflammatory disease in a population-based cohort study -- Full text (There are several critical weaknesses in this study, the data from which do not support the authors' broad conclusion that helminthic colonization does not reduce the risk for various immune-mediated diseases. See a rebuttal of this research by the late Joel Weinstock here.)