Pathogen (noun)

1. A bacterium, virus, or other microorganism that can cause disease.
2. A substance or agent that can cause disease or illness.

Origin:

Late 19th century: from french pathogène, from greek pathos "suffering" + -gène "producing".

Examples:

1. The scientist worked tirelessly to find a cure for the virulent pathogen that was sweeping the country.
2. The pathogen was spread from person to person through contaminated food and water.
3. The new medication was highly effective in treating infections caused by the pathogen.
4. The laboratory was conducting research on the pathogen, trying to understand how it caused such severe illness.
5. The pathogen was a persistent threat to public health, and authorities worked to prevent its spread.