Viruses do not exist
A claim revived from 19th-century 'terrain theory' holds that viruses have never been isolated and do not cause disease. Viruses have been photographed with electron microscopes since the 1930s, grown in cell culture and sequenced millions of times, and the German court case often cited as proof did not rule that the measles virus does not exist.
What we know
The claim that viruses do not exist is a modern version of 'terrain theory', an idea associated with the 19th-century French chemist Antoine Béchamp, a rival of Louis Pasteur. In this view illness arises only from the internal condition of the body, shaped by diet and lifestyle, so there is nothing to catch. Present-day versions add that no virus has ever been 'isolated' and that images and genome sequences are artifacts.
Viruses can be seen. They are too small for ordinary light microscopes, but electron microscopes have been used to image virus particles since the 1930s, and the technique has contributed to the discovery of many viruses and to the diagnosis of infections. Their structures are described in standard medical textbooks: particles with a protein shell, sometimes a lipid envelope, and a genome made of DNA or RNA.
Viruses are also isolated and read. When a new pneumonia appeared in Wuhan, researchers reported in the New England Journal of Medicine in early 2020 that they had grown a previously unknown coronavirus from patients' airway samples in human cells, photographed the particles by electron microscopy and sequenced the complete genome. CDC scientists independently isolated the same virus from the first US patient and made the isolate available to other laboratories. Since then the virus has been sampled and sequenced millions of times by laboratories around the world, and the sequences are stored in public databases where they can be compared. The same holds for influenza, RSV and many other viruses.
The complaint that a virus has 'never been isolated' usually rests on a private definition of the word. Viruses can only reproduce inside living cells, so virologists isolate them by growing them from a patient sample in cell culture and then identifying them by imaging, genetic sequencing and their effects on cells. Demanding a virus obtained without any host cells asks for something that the biology rules out.
A German court case is often presented as legal proof. In 2011 the biologist Stefan Lanka offered 100,000 euros to anyone who could prove that the measles virus exists. A doctor submitted six scientific papers and a regional court ordered Lanka to pay. A higher court overturned that ruling in 2016, but only because Lanka's offer had required the proof to appear in a single publication, which six papers together did not satisfy. The court itself described the existence of the measles virus as 'the unanimous opinion in science', and Germany's Federal Court of Justice later declined to hear a further appeal. No court ruled that the virus does not exist.
Terrain theory contains one fair point: a person's general health affects how severely an infection hits them. That does not make the infection imaginary. The spread of measles through unvaccinated groups, or of influenza through a household, follows contact with an infected person, which is what germ theory predicts and terrain theory cannot explain.
Common claims
- No virus has ever been isolated.False. Viruses are routinely isolated from patients in cell culture, imaged and sequenced.
- Electron microscope images show cell debris, not viruses.Not supported. Virus particles have consistent, well described structures that match their genomes.
- A German court ruled that the measles virus does not exist.False. The appeal turned on the wording of a prize offer; the court called the virus's existence the unanimous opinion in science.
- Illness comes only from the body's internal 'terrain', not from germs.False. General health affects severity, but infections spread from person to person.
- Viral genome sequences are computer fabrications.Not supported. Independent laboratories worldwide obtain matching sequences from patient samples.
Evidence hierarchy
All sources
- A Novel Coronavirus from Patients with Pneumonia in China, 2019Zhu et al., New England Journal of Medicine · 2020
- Severe Acute Respiratory Syndrome Coronavirus 2 from Patient with Coronavirus Disease, United StatesHarcourt et al., Emerging Infectious Diseases · 2020
- Viral detection by electron microscopy: past, present and futureRoingeard, Biology of the Cell · 2008
- Structure and Classification of VirusesMedical Microbiology, 4th edition, NCBI Bookshelf · 1996
- A German court did not rule that the measles virus doesn't existFull Fact · 2024
- Viruses are real and you can 'catch' themFull Fact · 2024