Diseases get their names through a surprisingly informal and fragmented process. Unlike living organisms, which follow strict scientific naming rules, diseases have no single universal system for assigning names. Different organizations handle different pieces: the World Health Organization sets best practices for naming new infectious diseases, separate committees name the viruses and bacteria that cause them, and genetic conditions are often named by the doctors who first describe them. The result is a patchwork of old names, new conventions, and ongoing efforts to make disease names clearer and less harmful.
Diseases and Pathogens Get Separate Names
One of the most common sources of confusion is that a disease and the organism causing it are two distinct things, and they’re named by entirely different groups. COVID-19 is the disease; SARS-CoV-2 is the virus. The disease name came from the WHO. The virus name came from the International Committee on Taxonomy of Viruses (ICTV), which classifies and names all viral species worldwide.
This distinction matters more than it might seem. A disease involves not just a pathogen but also how the human body responds to it, how the environment plays a role, and what symptoms appear. Treating the pathogen name and the disease name as interchangeable, as many casual references do, collapses that complexity. Bacteria follow a similar split: the organism gets a formal Latin name governed by the International Code of Nomenclature of Prokaryotes, while the illness it causes gets a separate, less formally regulated name.
How Viruses and Bacteria Are Named
Virus names go through the ICTV, which operates under a few core principles: names should be stable, easy to use, easy to remember, and should not duplicate any existing name. Euphonious names (ones that sound pleasant) are preferred. Before a new virus species can be officially classified, its genome sequence must be deposited in an international database and be complete enough to distinguish it from related viruses. No name is official until the ICTV votes to approve it.
The ICTV also requires that new names avoid national or local sensitivities, and that they not describe the virus so narrowly that the name would seem to exclude undiscovered members of the same group. Practically, this means virus names tend to be technical and abstract rather than descriptive of where the virus was found or what it does.
Bacterial naming follows a different but parallel path. All new bacterial names must be published in a single journal, the International Journal of Systematic and Evolutionary Microbiology (IJSEM), either by being first described there or by appearing on a validation list. This centralized approach means every valid bacterial name can be found in one place, unlike in many other fields where names are scattered across thousands of publications. The guiding principles mirror those for viruses: names should be stable, unambiguous, and backed by a physical type culture stored in a collection so other researchers can verify the classification.
How the WHO Names New Infectious Diseases
In 2015, the WHO published formal best practices for naming new human infectious diseases. These guidelines apply specifically to infections, syndromes, and diseases that have never been recognized before, have potential public health impact, and don’t already have a name in common usage. They’re designed as an interim solution, giving a new disease a usable name before the longer process of formal classification catches up.
The WHO recommends that disease names be built from generic descriptive terms based on symptoms (respiratory disease, neurologic syndrome, watery diarrhea) combined with more specific descriptors when solid information is available, such as severity, who it affects, or seasonality (progressive, juvenile, severe, winter). If the causative pathogen is known, it should be included in the name.
Just as important is what the WHO says to avoid. New disease names should not include:
- Geographic locations (like Middle East Respiratory Syndrome, Spanish Flu, or Rift Valley fever)
- People’s names (like Creutzfeldt-Jakob disease or Chagas disease)
- Animal or food species (like swine flu, bird flu, or monkeypox)
- Cultural, population, industry, or occupational references (like Legionnaires’ disease)
- Terms that incite undue fear (like “unknown,” “fatal,” or “epidemic”)
The motivation behind these restrictions is practical. Disease names that reference places, ethnic groups, or animals have historically triggered backlash against those communities, damaged trade and tourism, and led to unnecessary culling of livestock. The WHO developed these guidelines in collaboration with the World Organisation for Animal Health and the Food and Agriculture Organization of the United Nations specifically to prevent that kind of collateral damage.
How Genetic Conditions Are Named
Genetic diseases follow the least standardized process of all. There is no formal committee that assigns names to genetic conditions. Typically, the doctors who first identify and treat families with a previously unknown disorder propose a name, and it sticks, gets revised, or competes with alternative names over time.
Names for genetic conditions draw from a mix of sources: the underlying biochemical defect (alpha-1 antitrypsin deficiency), the gene where the mutation occurs (TUBB4A-related leukodystrophy), major symptoms (hypermanganesemia with dystonia), the body parts affected (brain-lung-thyroid syndrome), the physician who first described it (Marfan syndrome, after Dr. Antoine Bernard-Jean Marfan), a geographic area (familial Mediterranean fever), or even a well-known patient (amyotrophic lateral sclerosis is often called Lou Gehrig disease).
Genes themselves, by contrast, do have a formal naming authority. The HUGO Gene Nomenclature Committee assigns a unique official name and abbreviation to every known human gene, funded by the U.S. National Human Genome Research Institute and the UK’s Wellcome Trust. This prevents the confusion that arises when multiple research groups studying the same gene each give it a different name. But the diseases linked to those genes remain informally named.
Why Eponyms Are Falling Out of Favor
Many older diseases carry the name of a person, usually the physician credited with first describing them. These eponyms are increasingly seen as problematic for several reasons. Plain-language names that describe symptoms or biological mechanisms are more useful for both patients and medical students. A name like “hereditary hemorrhagic telangiectasia” tells you something about what’s happening in the body. “Osler-Weber-Rendu syndrome” tells you nothing unless you’ve memorized it.
Eponyms also create confusion when the same doctor has multiple diseases named after them, or when different countries use different eponyms for the same condition. Credit is another issue: naming a disease after one person oversimplifies the discovery process when multiple researchers contributed, and disputes over who truly came first are common. The historical record is also uneven. Few disease names recognize the contributions of women or non-European researchers, and some eponyms honor Nazi-era doctors whose “research” involved human experimentation.
Psychiatry moved away from eponyms years ago to create a unified global language. The emerging consensus in other fields is pragmatic: keep established eponyms that don’t have troubling histories, but name all newly discovered conditions based on their biology rather than a person.
How Diseases Get Classified and Coded
Separate from naming, every disease eventually gets a code in the International Classification of Diseases (ICD), maintained by the WHO. The current version, ICD-11, took effect globally on January 1, 2022, and contains codes for tens of thousands of conditions. Its 2024 update alone added over 200 new codes just for allergens.
The ICD isn’t really about naming. It’s a standardized coding system that lets hospitals, insurers, researchers, and governments worldwide record and compare health data using the same framework. When a new disease emerges, as COVID-19 did, the WHO activates emergency codes so the condition can be tracked in health systems even before the full classification process is complete. Countries can adopt ICD-11 at their own pace, and many still use ICD-10, though the WHO encourages prompt transition for consistency.
The relationship between a disease’s common name and its ICD code is worth understanding. The ICD provides a formal, structured place for every condition, but the name a disease carries in everyday use is shaped by a messier combination of medical tradition, WHO guidelines, media coverage, and public habit. Sometimes the formal and informal names align neatly. Sometimes they don’t, and a disease ends up known by a nickname that no governing body chose or endorsed.