Disease

Definition

An abnormal condition that disrupts the normal structure or function of an organism, arising from pathogenic infection, physiological dysfunction, genetic defect, or environmental stress. In arthropods, diseases may be caused by bacterial, viral, fungal, or protozoan pathogens; may manifest as behavioral, developmental, or mortality syndromes; and are studied in contexts ranging from honey bee colony collapse to biological control of insect pests via entomopathogens.

Etymology

Middle English disese, from Old French desaise, from des- 'without, away' + aise 'ease'

Example

American foulbrood is a fatal bacterial disease of honey bee larvae caused by Paenibacillus larvae, characterized by darkened, sunken brood cells and a distinctive glue-like consistency of dead larvae.

Synonyms

• pathological condition
• morbidity
• illness

Related Terms

• Pathogen
• Vector
• Epidemiology
• Parasite
• Immunity
• entomopathogen
• Host
• Reservoir
• Virulence
• Zoonosis

Usage Notes

In entomology, 'disease' typically implies an infectious or parasitic etiology rather than physical injury. The term is often qualified by pathogen type (bacterial disease, viral disease) or host (honey bee disease, mosquito-borne disease). Contrast with 'disorder' (often genetic or developmental) and 'syndrome' (a recognizable pattern of signs without confirmed etiology). 'Disease' in medical entomology frequently refers to the condition in the vertebrate host (e.g., Lyme disease) rather than in the arthropod vector, which may be merely infected or merely a carrier.