Dr. Lee Merritt Claims 'Cancer Is Parasites,' Reviving Debunked Theory

Fact-checkers say there is no evidence parasites cause cancer or MS, and warn against chlorine dioxide 'cleanse'

By [Staff Writer] | September 10, 2026

Orthopedic surgeon Dr. Lee Merritt is again drawing attention for a long-debunked medical claim: that cancer is caused by parasites.

In a recent appearance on The Alix Mayer Show, Merritt promoted the theory that parasites are the true cause of cancer and that modern medicine has concealed the connection. She points to 19th-century pathologist Dr. William Russell's "characteristic organism of cancer," claiming textbooks were altered to remove the parasite explanation.

The claim isn't new for Merritt, who has repeatedly made similar assertions about multiple sclerosis (MS) in recent years.

No Scientific Evidence

Fact-checking organizations, including Health Feedback, have rated the claim as incorrect. As an orthopedic surgeon, Merritt is not qualified as an expert in oncology or neurology, and the scientific consensus does not support the assertion that cancer is caused by parasites.

The exact cause of MS remains unknown. While some evidence suggests certain parasites might reduce the risk of developing the disease, there is no established causal link between parasites and MS.

'Cleanse' Protocol Raises Safety Concerns

Merritt's website sells a "Full Moon Cleanse" recipe that includes garlic juice and supplements. A more recent protocol has been described as combining antiparasitic drugs nitazoxanide and fenbendazole with chlorine dioxide.

Chlorine dioxide—a bleaching agent—can cause serious harm if ingested and is not an established medical treatment. The combination of substances in this protocol has not been proven safe or effective in clinical trials.

Claims Part of Broader Conspiracy Narrative

The parasite theory is part of a broader narrative Merritt promotes, in which medicine is a calculated plan to keep people sick and kill them prematurely. She has also claimed that all major medical publications are controlled by intelligence agencies.

She runs The Medical Rebel website, where she sells supplements, and her book Escaping the Medical Matrix is forthcoming.