part of has part material entity infection Lindsay Cowell A part of an extended organism that itself has as part a population of one or more infectious agents and that (1) exists as a result of processes initiated by members of the infectious agent population and is (2) clinically abnormal in virtue of the presence of this infectious agent population, or (3) has a disposition to bring clinical abnormality to immunocompetent organisms of the same Species as the host (the organism corresponding to the extended organism) through transmission of a member or offspring of a member of the infectious agent population. Albert Goldfain Alexander Diehl The organism corresponding to the extended organism is host to the infectious agents. By this definition, parts of the host can be considered part of the infection. infectious agent immunodeficiency extended organism