A concise history of helminthic therapy
The gradual loss of intestinal worms in industrialised societies that began in the mid-19th century, leading to their virtual eradication during the 20th century, has undoubtedly relieved these populations of the health issues associated with pathogenic helminths, but it has also led to inflammation-associated deficiencies in immune function that have contributed to widespread epidemics of allergy and autoimmune disease, as well as metabolic and neuropsychiatric disorders. [1] [2] However, this wasn’t recognised as a potential problem until the mid-to-late 20th century. [3] [4]
The first evidence that reintroducing helminths might prove beneficial was reported in 1948 after 25 patients had been relieved of their polycythemia as a result of being experimentally colonised by hookworms. [5] In 1976, a parasitologist writing in the Lancet described how the hay-fever from which he had suffered for 25 years had been completely relieved after he had colonised his small intestine with hookworms. See: IgE, parasites, and allergy. (PDF)
While editing journal articles on parasites of the liver and intestine, the late Joel Weinstock from Iowa University began to consider the possibility that the reintroduction of helminths might help his IBD patients. [6] (Internet Archive copy) This eventually led Weinstock to carry out ground-breaking studies in which IBD patients were given TSO, the ova of the pig whipworm, Trichuris suis, which were revealed to be safe and shown to reduce disease activity. [7]
The product used in the Iowa trials, which had been granted regulatory approval by the Thai FDA, became the first "therapeutic" helminth to be made available to the public when it was introduced for sale in 2003. The human hookworm, Necator americanus, also became available for purchase in 2007, followed by the human whipworm, Trichuris trichiura, in 2009. The fourth organism to be domesticated for use in helminthic therapy was the rat tapeworm, Hymenolepis diminuta, which was first offered to the public in 2013, in the larval (cysticerci) form that was referred to as HDC.
Research had suggested that the use of these helminth species to reconstitute the human biome may be the best solution to the biome depletion caused by industrialisation. [8] (PDF) However the majority of clinical trials conducted during the first two decades of the 21st century produced lacklustre results due to flawed trial design and a failure to accommodate the nuances of therapy using living worms. In particular, there was a failure to address the effect of product formulation on the efficacy of helminths, and to accommodate the very large range of helminth doses typically needed within any cohort of individuals. [9]
The poor results from these clinical trials were at odds with other strands of evidence that include numerous positive results in animal models, the positive results reported for individuals self-treating with helminths [10] (PDF) [11] and the positive reports from clinical examination following accidental exposure to helminths. [12] [13] [14]
As a result of the disappointing clinical trial results published in the second decade of the 21st century, medical researchers had, by the start of the 2020s, largely switched from using living worms to working towards "helminth-derived product therapy" (HDPT) by seeking to create helminth-inspired pharmaceuticals using synthetic versions of the molecules excreted/secreted by helminths. [15] [16] [17] Some researchers also began investigating the use of living helminths that have been custom engineered to perform specific roles, such as seeking out and destroying cancer cells, [18] or protecting soldiers from chemical and biological weapons. [19]
In the absence of the availability from mainstream medicine of helminthic therapy using living worms, a global, online community comprising many thousands of helminth self-treaters took over the development of the therapeutic use of living helminths, [20] to the extent that this community has, according to at least one group of scientists, become the primary "laboratory” for helminthic therapy. These scientists have further suggested that, with the impetus no longer being provided by medical researchers, the self-treatment community’s “biohacking” endeavours may yet prove to be critical for public health by addressing the helminth deficiency that is a fundamental cause of disease in Western society. [21]
Scientists from a range of disciplines have expressed support for therapy using living worms, [22] [23] [24] with some of them arguing that biome reconstitution will always be preferable to the use of synthesised pharmaceutical products. [25] [26] [27] Living helminths offer patients a convenient self-administered, "probiotic" treatment that is very safe, [28] remarkably effective, [29] (PDF) and available for immediate use from a range of vetted suppliers. [30]
For a much more detailed account of the development of helmithic therapy, see The history of helminthic therapy.