Pathogen

A pathogen is a microorganism or a virus that causes disease in humans and animals. Pathogens cause a wide range of diseases, from common illnesses such as the flu and the common cold to more serious conditions like HIV and cancer. Pathogens are an important factor in public health because they can be spread from person to person, through food, water and air, or through contact with animals. Pathogens can also be spread through contact with contaminated surfaces or objects. An understanding of pathogens is essential for preventing and controlling the spread of infectious diseases, and for maintaining a healthy environment.