What type of pathogen can cause diseases such as the flu or common cold?

Viruses are responsible for causing diseases such as the flu and the common cold. Unlike bacteria, which are single-celled organisms that can reproduce on their own, viruses require a host cell to replicate and thrive. They invade a host's cells and hijack the cellular machinery to make copies of themselves, ultimately leading to illness.

Flu viruses and the viruses responsible for the common cold specifically target the respiratory system and can spread through respiratory droplets when an infected person coughs or sneezes, or through contact with contaminated surfaces. Understanding the role of viruses in these common illnesses is crucial for recognizing their symptoms and knowing the importance of prevention methods, such as vaccinations and good hygiene practices.