_______________ diseases are caused by pathogens and parasites in human populations.

The term that best describes diseases caused by pathogens and parasites in human populations is infectious diseases. Infectious diseases can be caused by a variety of pathogens, including bacteria, viruses, fungi, and parasites, which can be spread in numerous ways, including direct contact, airborne transmission, and through vectors.

Though vector-borne diseases, which specifically involve transmission through vectors like mosquitoes or ticks, are a subset of infectious diseases, they do not encompass the entire range of diseases caused by various pathogens and parasites. Infectious diseases more broadly include any illness transmitted through these means, regardless of whether a vector is involved.

Contagious diseases are a specific type of infectious disease that can spread through direct contact with an infected individual. Autoimmune diseases, on the other hand, arise from the body's immune system mistakenly attacking its own cells and are not caused by pathogens or parasites. Thus, infectious diseases represent the most comprehensive category encompassing those caused by various pathogens and parasites in human populations.