Worms in the Human Body

"…are you saying that God created this worm that can live in no other way than in an innocent child’s eyeball?" — David Attenborough, as quoted by Warren Shipton, 2019¹

Summary

Degeneration can plausibly explain some of the worms that live in people, but not all of them.  The worms it explains least are among the most harmful.  The young-earth literature itself proposes a test:  a harmful worm that descends from a harmless one should have harmless relatives.  Applied to six worms, that test sorts them into three groups.

• A harmless relative is close. Hookworms share a suborder with many nematodes that ride on insects rather than feed on them, and a hookworm spends its early life free in the soil. The large roundworm, Ascaris, sits inside a group of millipede gut worms that "might even be classed as commensals," meaning they live off the host's gut contents without damaging it.²²³
• A proposal exists, but the evidence runs against it. Warren Shipton proposed in 2019 that the river-blindness worm arose from mermithids, nematodes that parasitise black flies. Mermithids and filarial worms sit in different subclasses of the nematode tree.²¹
• No close harmless relative is known. The filarial worms (river blindness and the African eye worm) and the Guinea worm belong to the suborder Spirurina, and "all of its members are obligate animal parasites." Whipworm's nearest named relatives are parasites too.²³

The burden is large.  About 1.5 billion people carry intestinal worms, river blindness had cost 1.15 million people their sight by a 2017 estimate, and Guinea worm fell from about 3.5 million cases in the mid-1980s to 10 in 2025.⁴⁵⁶⁷

The case that worms help people is weaker than its first reports.  Joel Weinstock's group reported in 2005 that pig-whipworm eggs helped patients with bowel disease, but the two large Crohn's trials that followed found no benefit over placebo.  The only controlled hookworm trial in multiple sclerosis missed its main goal.  Hookworm is linked with less asthma, but no worm therapy has yet worked in a large trial.^89101112

Verdict.  For hookworm and Ascaris, the young-earth claim that a harmless ancestor became harmful fits the known relatives, though it does not explain the equipment the worms use to feed on a host.  For whipworm the fit is weak.  For river blindness, the African eye worm and the Guinea worm, the claim is currently a hope without evidence.

Part 1: What the worms cost

Guinea worm

A person catches Guinea worm, Dracunculus medinensis, by drinking water that holds tiny crustaceans called copepods, or water fleas, carrying the larvae.  The larvae leave the gut and travel through the body until "a fertilized female, measuring 60–100 cm, settles beneath the skin."  Ten to fourteen months later she breaks out, usually through the leg.  The burning pain drives the patient into water, where the worm releases thousands of new larvae.⁶

In the mid-1980s there were about 3.5 million cases a year in 20 countries.  In 2025 the Carter Center counted 10 human cases:  four in Chad, four in Ethiopia and two in South Sudan.  The last obstacle is animals.  Dogs and other animals carry the same species, and the Carter Center's country figures for 2025 add up to 683 animal infections.⁶⁷⁷

Hookworm, the large roundworm and whipworm

The World Health Organization counts about 1.5 billion people, 24% of the world, infected with soil-transmitted worms.  The main species are the large roundworm Ascaris lumbricoides, the whipworm Trichuris trichiura, and two hookworms, Necator americanus and Ancylostoma duodenale.  Eggs leave in faeces and need about three weeks in soil to become infective.  Ascaris and whipworm eggs are swallowed.  Hookworm eggs hatch in the soil, and the larvae burrow in through bare skin.  Hookworms feed on blood and cause "chronic intestinal blood loss that can result in anaemia."⁴⁴⁴

Harm depends on the number of worms:  "People with infections of light intensity (few worms) usually do not suffer from the infection."  Heavier infections cause diarrhoea, malnutrition and impaired growth.⁴

River blindness

Onchocerca volvulus is carried by black flies that breed in fast rivers.  A biting fly takes up the worm's microscopic young, called microfilariae, which develop inside it and pass to the next person it bites.  Adults live in nodules under the skin for 10 to 15 years.  The symptoms come from the microfilariae, which "induce intense inflammatory responses when they die":  severe itching, skin disease and blindness.  In 2024, 252.3 million people needed preventive treatment.  The Global Burden of Disease study estimated for 2017 that 14.6 million infected people had skin disease and 1.15 million had vision loss.⁵⁵

The African eye worm

Loa loa, a filarial worm carried by deer flies, is known for crawling across the eye, and "loiasis is still considered a benign condition."  In 2017 Cédric Chesnais and colleagues tested that in Cameroonian villages first surveyed in 2001.  Adults over 25 with more than 30,000 microfilariae per millilitre of blood died significantly sooner than uninfected neighbours.  The team attributed 14.5% of deaths in the population to the infection.  A second cohort in the Republic of Congo, published in 2023, found a median survival of 39.2 years for infected people against 58.5 years for uninfected.  Both studies are observational, so they show an association, not a proven cause.¹³¹⁴

Part 2: Where the worms sit in the nematode tree

Why the relatives matter

A living harmless relative is the best evidence that a worm's ancestor could have been harmless.  It does not show when the change happened, and it does not explain new equipment for invading a host.  As the parent article puts it, dependence on a host is different from invasion of one.

Mark Blaxter and Georgios Koutsovoulos reviewed the molecular tree of nematodes in 2015.  They found that "parasitism of plants and animals has arisen at least 15 times independently," five times in parasites of vertebrates.  The six worms here come from three of those five.  The phylum has three subclasses:  "Nematoda comprises the subclasses Enoplia, Dorylaimia and Chromadoria."²²²

Hookworm

"The Strongylomorpha (in Rhabditina), a major group of gut and airway parasites of vertebrates, are sisters to the Heterorhabditidae," which are worms that invade insect larvae and release bacteria that kill them.  One model proposes that an insect-parasitic ancestor captured a vertebrate host.  Rhabditina also contains groups "where many species are phoretic or necromenic associates of arthropods but very few parasites have been found."  These worms ride on insects without feeding on them while they live.²²

So a hookworm has close relatives that live harmlessly, and its own larvae live free in the soil.  But Blaxter and Koutsovoulos note that parasites gain as well as lose:  "Morphological novelties are common in parasitic nematodes: buccal teeth in hookworms."  Loss explains why a worm needs a host.  It does not explain the teeth it uses to cut into the gut wall.²

The large roundworm

In 2026 S. Nagae and K. Hasegawa built a molecular tree of Spirurina.  Ascaris was "placed within Rhigonematomorpha (Rhigonematoidea and Ransomnematoidea), a group that primarily parasitizes millipedes."  Blaxter and Koutsovoulos had described those millipede worms as ones that "feed on gut contents or other nematode parasites rather than on host tissue, and might even be classed as commensals."  If Nagae and Hasegawa are right, the large roundworm's closest relatives live in a gut without eating their host, close to the harmless partner a young-earth model needs.²³

Two cautions apply.  This is one recent study.  And a commensal gut worm is still a gut worm, not a free-living one.  The roundworm's larvae also make a costly trip through the blood and lungs before settling in the gut.  Blaxter and Koutsovoulos report that this "migration is an adaptive trait maintained by selection" because it lets the worm grow larger and lay more eggs.²

Whipworm

Whipworm sits in another subclass, Dorylaimia, in a group Blaxter and Koutsovoulos list as a separate origin of vertebrate parasitism, "Trichinellida plus Dioctophymatida."  Its closest named relatives, such as Trichinella, are parasites too.  Whipworm is mild in light infections, and its pig cousin is used as therapy, but that is harmlessness at low dose or in the wrong host, not a harmless relative.²

Filarial worms and Guinea worm

"The Spirurina (Chromadoria; Rhabditida) are all parasites, mostly in vertebrates."  Nagae and Hasegawa infer that the group's ancestor lived free, and that "A major transition from free‐living to parasitic lifestyles occurred at the base of the large clade" that holds Ascaris, the pinworms, the filarial worms and Guinea worm's group.  The filarial worms use insect carriers.  Guinea worm's group, Camallanomorpha, uses copepods as intermediate hosts:  "The superfamily Camallanoidea and the family Philometridae use fish as definitive hosts, whereas the family Dracunculidae parasitizes mammals and reptiles."  No free-living or commensal member of either branch is known.²³³³

A degeneration account would therefore start at the base of that branch.  No creationist has yet said whether it is one created kind or several.

Part 3: River blindness and its bacterium

The river-blindness worm carries bacteria called Wolbachia inside its cells, and cannot do without them.  In filarial worms, "killing of the Wolbachia with antibiotics such as tetracyclines also affects the viability of the nematode host, with loss of fecundity and nematode death."²

In a placebo-controlled trial in Ghana, Achim Hoerauf and colleagues gave 67 patients 200 mg of doxycycline a day for four or six weeks.  "The 6-week treatment was macrofilaricidal":  more than 60% of the adult female worms were found dead.  An antibiotic aimed at the bacteria killed the worm.¹⁵

The bacteria also drive much of the damage.  In 2002 Amy Saint André and colleagues injected worm extracts into mouse corneas and found that "the predominant inflammatory response in the cornea was due to species of endosymbiotic Wolbachia bacteria."  This was a mouse model, not a study of human eyes.¹⁶

So the river-blindness worm is a working partnership of worm and bacterium, and nothing about it looks broken.  The eye worm shows the reverse case.  Loa loa and some others "have lost the infection and are now Wolbachia-free," and the loss did not make the eye worm harmless.²

Part 4: Worms as medicine

The first reports

Crohn's disease is common where worms are rare and rare where most people carry them.  In 2005 Robert Summers, Joel Weinstock and colleagues at the University of Iowa gave 29 Crohn's patients 2,500 live eggs of the pig whipworm, Trichuris suis, every three weeks.  At 24 weeks, 21 of the 29 were in remission.  There was no placebo group.⁸

A placebo-controlled trial by the same group in 54 ulcerative colitis patients found improvement in 13 of 30 on eggs against 4 of 24 on placebo (P = .04), but no significant difference in near-complete remission.¹⁷

The larger trials

Two large, blinded Crohn's trials followed.  TRUST-I, run in the United States by Coronado Biosciences, gave 7,500 eggs or placebo to 250 patients every two weeks for 12 weeks.  The company reported in October 2013:  "In the overall patient population, response rate of patients on TSO did not separate from that of placebo."  No full peer-reviewed report of TRUST-I was found.¹⁰

TRUST-2, in Europe, randomised 252 patients to three doses or placebo.  Remission at 12 weeks was 38.5%, 35.2% and 47.2% on the three doses and 42.9% on placebo.  The authors concluded that "no TSO dose showed a clinically relevant effect over placebo for induction of clinical remission or response."  The eggs were safe and raised an immune response.  The 42.9% placebo rate shows why an uncontrolled 72% remission rate in 2005 could not settle the question.¹¹

Multiple sclerosis

The multiple-sclerosis work began with an observation.  In 2007 Jorge Correale and Mauricio Farez in Argentina followed 12 patients who had picked up intestinal parasites and compared them with uninfected patients.  Over 4.6 years the infected patients had fewer relapses and fewer new brain lesions.  No worms were given to anyone.¹⁸

In 2011 John Fleming's team gave pig-whipworm eggs to five patients.  New brain lesions fell from an average of 6.6 to 2.0 during treatment and rose to 5.8 two months after it stopped.  There was no control group.¹⁹

The first controlled trial came in 2020.  Radu Tanasescu and colleagues in Nottingham gave 71 patients either 25 hookworm larvae through the skin or a placebo.  "The primary outcome did not reach significance, likely because of a low level of disease activity."  Relapses were 14.3% on hookworm against 30.6% on placebo, a secondary result the trial was not designed to test.¹²

The "old friends" idea and its evidence

The theory behind this is the hygiene, or "old friends," hypothesis.  Graham Rook stated it in 2010:  inflammatory diseases have risen partly because people have lost contact with organisms that "have evolved an essential role in the establishment of the immune system."  He called this "an example of ‘evolved dependence’."²⁰

The evidence is species by species.  A 2006 meta-analysis of 33 studies by Jo Leonardi-Bee, David Pritchard and John Britton found that any parasite infection was linked with slightly more asthma, not less.  Ascaris was linked with significantly higher odds of asthma (odds ratio 1.34), and hookworm with significantly lower odds (0.50).  Their conclusion:  "Parasite infections do not in general protect against asthma, but infection with hookworm may reduce the risk of this disease."⁹

What the clinicians said

A 2015 newspaper story is the source of the claim that some worms do no harm.  Neilanjan Nandi, a gastroenterologist at Drexel University, said that certain helminth species "don't have any deleterious effect on the host. They may have benefit, but they don't have harm."  The same story says Nandi does not recommend them to his own patients.  The pediatrician who called helminths "much safer than any medication" uses a rat tapeworm, not a roundworm.  The story also dates the Argentine multiple-sclerosis study to 2008, when it appeared in February 2007.¹⁸²¹²¹

The record as it stands:  therapy worms are safe in small doses, hookworm may lower asthma risk, and no worm therapy has worked in a large controlled trial.  The main therapy worm, the pig whipworm, is a parasite of pigs, which John Fleming's team called "the non-pathogenic helminth."  Its mildness in people reflects a mismatch of host, not an originally harmless human worm.¹⁹

Part 5: What the young-earth models say

The general proposals

Robert Gurney, writing for Creation Ministries International in 2009, offered three routes.  Some parasites may have been "independent and free-living" at first, and "They degenerated, lost their ability to live independently or symbiotically, and became harmfully dependent on their hosts."  Where a life cycle is too complex for loss to explain, "the information may have been there from the beginning," in a "‘switched off’ mode before the Fall."  He also allowed that God may have made them harmful "miraculously."²²

David Boyd wrote for Answers in Genesis in 2017:  "The simple answer is that God created nematodes during creation week as a normal, beneficial part of the environment."  "Only after the fall did some roundworms take on a parasitic role, as part of the curse on creation."  His example is the threadworm Strongyloides stercoralis, which can live in soil and switch to a parasitic generation.²³

Frank Sherwin of the Institute for Creation Research wrote in 2020:  "Before the Fall, parasites were not yet parasites. Rather, they were most likely free-living creatures independent from Adam, Eve, and the animals."  Matthew Ingle, in the Answers Research Journal in 2015, took a different line:  "symbiotic animals that now live as parasites may have been created to provide some selective pressure on hosts."²⁴²⁵

David Coppedge argued from worm therapy in 2015 that helminth therapy "has proven effective for severe food allergies and inflammatory bowel disease."  TRUST-I had contradicted that for Crohn's disease two years earlier.  His closing rule is the right one:  "Each case needs its own evidence."¹⁰²⁶

None of these names a free-living ancestor for any of the six worms in this article.  Boyd's threadworm is the right kind of evidence, but it belongs to a third origin of vertebrate parasitism, not to the hookworms or to Spirurina.

Shipton's proposal for river blindness

Warren Shipton's 2019 paper in the Journal of Creation is the only young-earth proposal found for a specific human worm.  He suggests that "some nematodes were designed to regulate insect populations," and asks:  "Could it have been possible that the filarial parasites arose from the Merminthid nematode parasites of black flies with the aid of bacterial symbionts?"  He is candid about the gaps and calls the whole account insufficiently known "to make any conclusive remarks."¹¹

The idea has a real strength.  Mermithids are genuine insect parasites with free-living adults, so an insect-regulating role before the Fall is a coherent design proposal.²  Shipton is also right that Wolbachia "performs a vital function in the nematode's lifestyle."¹

But the tree does not support the proposed ancestor.  Mermithids belong to Dorylaimia, and filarial worms to Chromadoria, two of the phylum's three subclasses.  If mermithids are close to any human worm, it is the whipworm, which shares their subclass.  The filarial worms' close relatives also use many carriers:  "the Onchocercinae, parasitizing rodents, ungulates and primates, utilize mosquitoes, tabanid flies, black flies and mites as vectors."  The lineage is not tied to black flies.²²

For the African eye worm, Shipton suggests that remnants of Wolbachia genes in its genome may be "potentially responsible for the pathogenic abilities now shown by the eye worm parasite."  That is a hypothesis, and no test of it was found.¹

Objections and responses

"The tree assumes common descent, so a creationist need not accept it."  A degeneration account is itself a claim of descent:  a harmful worm descended from a harmless one.  Shipton's own proposal is a descent claim, and he cites a nematode phylogeny for it.  The tree is the relevant test.¹

"A missing harmless relative may simply be undiscovered or extinct."  That is possible.  But the argument then rests on evidence no one has, which is the definition of a proposal without evidence.

"The worms that heal show that worms were designed to be good."  The trials do not show that yet, and Ascaris is linked with more asthma, not less.  Even a working therapy would show a use, not an original purpose, as the parent article argues for malaria proteins used against cancer.

"Light infections cause no symptoms, so these worms are nearly harmless."  Heavy ones cause anaemia, stunting, blindness and early death.  A worm that cripples in large numbers is still a harm to explain.

"The models also allow switched-on, front-loaded information, not just degeneration."  Gurney and Shipton both allow it.  But a pre-loaded program for harming a host raises a sharper design question than a breakdown does, as the parent article notes, and no one has identified such dormant information in these worms.

Issues and unanswered questions

• The tree is still moving. The Ascaris result rests on one 2026 study. Blaxter and Koutsovoulos read the millipede worms as descended from vertebrate parasites, while Nagae and Hasegawa make millipedes the ancestral hosts. On the older view, Ascaris's commensal-like relatives are not models of its ancestor.²
• No creationist study of nematode kinds exists. Without one, it is unclear whether a degeneration account for Spirurina needs one ancestor or several. Either way the diversification into ascarids, pinworms, filarial worms and Guinea worms would have to fit in a few thousand years. No model has attempted this.
• Two gaps in this article's own checking. Only two phylogeny sources were read, so whipworm may have a harmless relative not covered here. Shipton's references for the eye worm's gene remnants were not read.
• Guinea worm has no young-earth answer at all. It is the plainest case in this article: a worm with no harmless relative, a life cycle that needs two hosts, and no published creationist proposal.
• The therapy record is not closed. Trials after 2020 were not surveyed here.

Verdict

The young-earth claim that parasitic worms descend from harmless ones is testable, and the result is split.  Hookworm and the large roundworm pass:  their close relatives include harmless insect riders and possible gut commensals.  Even for them, loss explains only dependence, not the hookworm's teeth or the roundworm's lung migration.

Whipworm fits weakly.  River blindness has one proposal, and the nematode tree puts its proposed ancestor in the wrong subclass.  The African eye worm and the Guinea worm have no harmless relative and no tested proposal.  These worms blind, cripple and shorten lives, and for them the young-earth account currently has no evidence to offer.  Worm therapy does not change this:  it has not worked in a large trial, and a use would not show an original purpose.

Sources