New clinical studies prove what the science of health, Natural Hygiene, has always asserted: parasites are not a cause of disease
For decades, the dominant medical model has taught us that parasites are invaders – dangerous intruders that must be eradicated at all costs. Dewormers, anti-parasitic drugs, and routine chemical treatments have become standard, especially in the care of animals. But emerging long-term research now confirms what the science of health, Natural Hygiene or the Terrain Model has always known and taught: parasites are not the cause of disease but a natural consequence of a biological terrain that invites their presence.
The Study That Flipped the Narrative
In 2022, Dr. Martin Nielsen and his team at the University of Kentucky published a groundbreaking study examining a herd of horses that had not been dewormed since 1979, over 40 years without a single chemical intervention. These horses were not suffering. They were thriving.
Despite consistently carrying parasite loads, including Strongylus vulgaris (the bloodworm), the horses remained in good health. The study showed:
- No seasonal rise in egg shedding (debunking previous assumptions)
- Pregnancy, foaling, and lactation had no effect on parasite levels
- Mares transferred antibodies naturally to their foals through colostrum
- The parasites were present year-round, yet disease was virtually absent
“Parasitism is a natural state… worms only extremely rarely cause disease or ill-thrift.”
– Dr. Martin Nielsen
These findings challenge the mainstream belief that the presence of parasites is synonymous with pathology. They also affirm what the terrain model and natural hygiene has taught all along: the health of the host determines the presence, behavior, and impact of microbes, including parasites.
Parasites as Natural Clean-Up Crews
In the terrain model of health, a toxic or compromised internal environment, the “dirty terrain”, is the true foundation of disease. When waste builds up in the body due to improper diet, stress, or poor elimination, nature sends in specialized helpers. Worms and parasites feed on the backlog of decomposing matter and cellular debris.
Just as vultures flock to roadkill, parasites emerge in a sick body, not to cause damage, but to consume what doesn’t belong. They are the clean up crew. Their population expands when there is a bounty of cellular waste for them to feed upon and their population drops when the waste has been cleaned up. But they are always present, waiting for their opportunity to help the body maintain a state of health.
More Evidence from the Field
Another 2022 study in Germany analyzing horses on low-intervention farms found Strongylus vulgaris seropositivity in 21% of horses, without any signs of illness. Even when egg shedding wasn’t detected, antibodies were present, showing that the body had encountered the organism and maintained equilibrium through its internal defense and elimination pathways. This wasn’t a sign of disease, but rather a reflection of a well-functioning internal terrain capable of handling exposures without distress. (Link to full study)
Similarly, a 2016 study in BMC Veterinary Research confirmed that S. vulgaris DNA could be found year-round, even when no active shedding occurred. The key finding? Parasites existed quietly in the background, not causing harm unless other conditions were already at play.
And again, in 2022, long-term monitoring of naturally infected horses (PMC8822790) reaffirmed that parasite burdens alone are not predictors of illness.
The presence of the parasite’s genetic material did not equate to sickness, it simply revealed that these organisms exist in the environment and the body, and are kept in check when the terrain is clean and the lymphatic and circulatory systems are functioning properly.
The Terrain Determines the Outcome
From a terrain model lens, these findings echo a deeper truth: microbes and parasites are not villains, but natural recyclers and responders. They flourish in bodies burdened with waste, just as mold grows on rotting fruit. But if the terrain is clean – supplied with proper nutrition, proper hydration and avoiding drugging or other damaging habits – there’s nothing for them to feed on.
- In healthy animals, parasite presence is mutually harmless
- Disease arises when the body is burdened by inappropriate foods choices or poisoning, not when worms are present
- Attempting to kill parasites without addressing the terrain misses the point. Any substance capable of killing a parasite is also damaging to the animal ingesting that substance. So when we apply dewormers, rather than improving the health of our animals, we are poisoning our animals in order to kill creatures which were put in place intelligently to help the animal clean out the damage from prior exposure to poison. So the animal gets poisoned once, the parasite spring into action increasing their populations to feed upon the cellular waste debris and toxins, and our response is to then poison. The animal, a second time in a vain effort to try to kill the helpers.
This new discovery aligns perfectly with what Natural Hygiene principles have always proven: toxemia, caused by systemic waste buildup, is and has always been the true root of disease. Parasites, bacteria, and viruses are simply symptoms of a toxic terrain. They appear after the body has been injured and are working with the body to clean and repair.
Rethinking Deworming Protocols
Instead of defaulting to pharmaceutical dewormers:
- Clean the terrain: Focus on species-appropriate diets, fasting, and hydration
- Support elimination: Proper bowel function and and a hydrated lymphatic system are essential to maintaining waste levels within the requirements of health.
- Respond to symptoms as warnings and red flags of the mistakes in diet and care that they reflect. Don’t blame parasites or bacteria for a food induced problem. ,
- Honor the Laws of Nature: Nature does not make mistakes; but humans certainly do, especially when profit is a motive, parasites have a role, they are intelligently designed for their role not mistakes. Medicine always bases it’s foundations upon the body being a mechanical robot, poorly built, which requires their various poisons to operate properly. They neglect to remember that they have only been producing their poisons for around 150 years now, but the intelligently designed body has been living in harmony with parasites and bacteria for thousands of years.
As Dr. Nielsen put it, “[This herd] reminds us that parasitism is a natural state.” Indeed, it is the terrain, not the germ, or worm, that matters.
Parasites are not invaders to be feared, but part of the body’s natural cleanup crew. Like bacteria and viruses, they play an essential role in the body’s internal ecology—breaking down waste, aiding in the detox process, and responding to the conditions present. In healthy animals, they exist without causing harm. We do not poison our companions with dewormers—natural or synthetic—because parasites are not the problem. The problem is the terrain. When the body is clean and the diet is aligned with the animal’s biological design, there is no need for chemical interventions. If you’re ready to learn more about how to support your dogs and cats with their species-appropriate diet, start with our Getting Started Guide for Dogs , our Getting Started Guide for Cats, or join our thriving Facebook group for support and community, and explore our videos on the YouTube channel where we teach the truth about pet health and healing through nature’s design.
Published by