Host factor

Host factor (sometimes known as risk factor)^[1] is a medical term referring to the traits of an individual person or animal that affect susceptibility to disease, especially in comparison to other individuals.^[2] The term arose in the context of infectious disease research, in contrast to "organism factors", such as the virulence and infectivity of a microbe. Host factors that may vary in a population and affect disease susceptibility can be innate or acquired.

Some examples: ^[1]

• general health
• psychological characteristics and attitude
• nutritional state
• social ties
• previous exposure to the organism or related antigens
• haplotype or other specific genetic differences of immune function
• substance abuse
• race

The term is now used in oncology and many other medical contexts related to individual differences of disease vulnerability.