What does pathogen mean?
A pathogen is an organism or agent capable of causing disease, with the word most often referring to microorganisms such as viruses, bacteria, fungi, and parasites. Its role is usually identified as the cause of an infection or other illness, as in a public-health report discussing the pathogen behind an outbreak. The term is especially common in medicine, microbiology, epidemiology, and public-health communication, where identifying a pathogen is important for diagnosis, treatment, prevention, and control. Although “pathogen” can broadly mean any agent that produces disease, its everyday use usually emphasizes a potentially harmful biological source. The word can carry serious connotations because pathogens are associated with infection, illness, and outbreaks, although many are not inherently dangerous. Related terms such as “pathogenic” and “pathology” are sometimes confused with it, but they describe, respectively, the quality of causing disease and the study or processes of disease.
An organism, especially a microorganism, capable of causing disease.
"The pathogen was transmitted through contaminated water."
The word is most often used in medical, scientific, and public-health contexts.
An agent or factor that causes or contributes to disease.
"Researchers examined whether the chemical could act as a pathogen in the workplace."
This broader sense is less common than the standard reference to a disease-causing microorganism.
The plural is formed by adding -s.
"New pathogens can emerge when a virus crosses from an animal population into humans."
A pathogen can be microscopic, yet its effects may range from a mild infection to a global pandemic.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Where does pathogen come from?
The word was formed in scientific usage from Greek pathos, meaning “suffering” or “disease,” and the element -gen, meaning “producing” or “born of.” Its development followed Greek and Latin medical terminology, with related English words including “pathology,” “pathogenic,” and “pathogenesis.”
Related word forms
How pathogen is actually used
In modern medical and scientific usage, “pathogen” most often refers to a disease-causing microorganism. The broader sense, including nonbiological agents, is less common. “Germ” is more informal and is not always used for every type of pathogen.
Easily confused with pathogen
A pathogen is a thing that can cause disease, while pathogenic is an adjective describing something capable of causing disease.
A pathogen is a disease-causing agent, while pathology is the study of diseases or the processes and conditions associated with disease.