VCDH Microbiology Practice Test

Anaphylaxis is a rapid, systemic allergic reaction caused by widespread release of mediators from mast cells and basophils in response to an allergen. It typically presents with a sudden onset and involves multiple organ systems, most characteristically causing a drop in blood pressure (hypotension), swelling or closure of the airways leading to obstruction, and severe hypoxia. This combination makes it a life-threatening emergency requiring prompt treatment with epinephrine and airway support. This differs from a mild localized allergic reaction, which affects only the skin or a small area and does not cause systemic hypotension or airway compromise. Autoimmune reactions involve damage to the body's own tissues, not a rapid, systemic allergic response. Bacterial infections cause fever and illness from pathogens, not the immediate airway obstruction and shock seen in anaphylaxis.