What is the primary cause of the common cold and flu?

The primary cause of the common cold and flu is a virus. Viruses are microscopic infectious agents that replicate only inside the living cells of an organism. In the case of the common cold, various strains of rhinoviruses are typically responsible, while influenza, the flu, is primarily caused by the influenza virus.

The viral nature of these illnesses means that they can spread easily from person to person, especially in crowded spaces. When an infected person coughs, sneezes, or talks, droplets containing the virus can be transmitted to others. Furthermore, viruses can also survive on surfaces for a limited time, leading to indirect transmission if a person touches a contaminated surface and then their face.

Understanding that the common cold and flu are caused by viruses highlights the significance of preventive measures such as vaccinations for the flu and personal hygiene practices like handwashing to reduce the likelihood of infection. In contrast, fungi, bacteria, and parasites cause different types of diseases and require different treatment approaches, thus reinforcing the unique nature of viral infections like the cold and flu.