Invertebrate organisms that live on or in another organism (the host), and benefit at the expense of the other. Traditionally excluded from definition of parasites are pathogenic BACTERIA; FUNGI; VIRUSES; and PLANTS; though they may live parasitically.
Parasite
D010272
Parasitic Diseases
Infections or infestations with PARASITES. They are often contracted through contact with an intermediate vector, but may occur as the result of direct exposure.