Chain of Infection, Pertussis, and Principles of Vaccination

Flashcards reviewing key vocabulary terms from the lecture, including the chain of infection for Bordetella pertussis, pathogenesis stages, bacterial toxins, and vaccine principles.

Zoonosis

A disease that is primarily found in animals, derived from the root "zo" meaning animal.

Bordetella pertussis

The gram-negative bacterium that acts as the pathogen responsible for whooping cough.

Filamentous hemagglutinin

A surface protein on the outer part of Bordetella pertussis that acts as the primary virulence factor by adhering directly to host receptors in the throat and trachea.

Catarrhal stage

The initial stage of pertussis lasting days to weeks, during which bacteria slowly multiply and release endotoxins that produce subtle, general symptoms of infection.

Paroxysmal stage

The severe, sudden phase of pertussis characterized by continuous, violent, spasmodic, and uncontrollable coughing fits.

Lipid A

An endotoxin located in the outer cell wall membrane of gram-negative bacteria like Bordetella pertussis, which can trigger an overreactive immune response or shock when released into the blood.

Tracheal cytotoxin

An exotoxin produced by Bordetella pertussis that targets and kills ciliated cells lining the trachea, preventing them from moving mucus.

Pertussis toxin

A bacterial exotoxin that alters normal respiratory secretions, transforming mucus into a thick, ropey substance that cannot be easily moved.

Cilia

Coordinated, finger-like projections on respiratory epithelial cells that beat to sweep mucus upward out of the trachea or downward toward the esophagus.

Antitoxin

A secondary prevention drug treatment that binds and neutralizes circulating exotoxins to halt cell destruction and severe symptom progression.

DTaP

A combination childhood vaccine containing a large pertussis component (indicated by the capital P), routinely scheduled at 2, 4, 6, and 15 months, and at age 5.

Tdap

A booster vaccine formulated with a reduced quantity of pertussis antigens (designated by the lowercase p), given around age 11 or 12, every 10 years thereafter, and during pregnancy.

Active immunity

An adaptive immune defense generated when host exposure to an antigen prompts the formation of specific antibodies and memory cells.

Artificial active immunity

Active protection achieved by introducing non-pathogenic antigen preparations (such as vaccines) to stimulate antibody and memory cell production without an actual infection.

Herd immunity (Community immunity)

The indirect protection of unvaccinated or vulnerable individuals from infection when a sufficient proportion of the population (typically $80\%$ to $95\%$) is immunized.

Attenuated vaccine

A vaccine containing a living but weakened bacterium or virus that replicates inside the host without causing harm, often stimulating long-lasting or lifetime immunity.