Ch 17 Infectious Diseases and Vaccines Flashcards
Emerging Disease
something new, not previously observed
example of an emerging disease
- New strains of influenza
- SARS-CoV-2
Re-emerging disease
something old, coming back again
example of a re-emerging disease
measles in the US
What factors can increase the likelihood of emerging diseases?
- increases in international travel
- mass distribution of contaminated food
- improper antibiotic use
- spread of humans into previously uninhabited areas, introducing to novel microbes
What factors can increase the likelihood of re-emerging diseases?
- combinations of diseases (HIV and TB)
- laxity in vaccination program adherence
Example of re-emergence combinations of diseases
HIV and TB
- in the 90s, it was thought that TB would soon disappear as a problem in the US
- the AIDS epidemic resulted in a large increase in immunocompromised individuals, who subsequently became sick with Mycobacterium
- regular treatment of immunocompromised patients with antibiotics resulted in resistant TB strains
Example of re-emergence of disease due to laxity in vaccination program adherence
- diptheria in Soviet Union
- Whooping cough in US
- Measles in US
Passive immunization
delivery of preformed antibody
Protective immunity can be achieved by ___ or ____ immunization.
active;passive
Conditions that warrant passive immunization
- immune deficiency
- toxin or venom exposure with immediate threat to life
- exposure to pathogens that can cause death faster than an effective immune response can develop
Why can passive immunization lead to Type I or III hypersensitivities?
Ab agents are typically made from animals
What is the goal of vaccination?
to provide a primary exposure to a safer form of an antigen, either by exposing to a protein/polysaccharide or by exposure to a weakened (attenuated) form of the pathogen
The goal of vaccination is to provide a ____ ______ to a safer form of an antigen.
primary exposure
Vaccinations provide _____ ______ without the potential negative consequences of a natural infection.
active immunity
Side effects of vaccines, when present, are usually indicators of ____ _____ to a novel pathogen
immune reaction
Herd immunity
resistance to the spread of an infectious disease within a population that is based on pre-existing immunity of a high proportion of individuals as a result of previous infection or vaccination
Basic reproductive number values
the infectibility of a disease
Simplified calculation for finding the percentage of people that need active immunity against an agent to achieve herd immunity is based on the:
basic reproduction number (R0) of the agent
How do you calculate the approximate level of herd immunity required based on the R0 value?
Herd immunity= 1 - 1/R0
Once a vaccine is approved, what other safety measures are in place to ensure that vaccine is still as safe as possible?
after approval by the FDA, every lot of vaccine must be tested before release and manufacturing facilities are checked regularly for compliance of safety and manufacturing procedures
Live attenuated vaccine components
pathogens are weakened by continuous growth in conditions outside of their ‘ideal’
Pros of live attenuated vaccines
- retain their ability to replicate, promoting both humoral and cell-mediated responses
- often do not need boosters
Cons of live attenuated vaccines
- may mutate back (revert) to pathogenic form
- may have more side-effect complications
- may also require a “cold chain” for stability during transport
Inactivated vaccine components
heated or chimically treated to inactivate pathogen
Pros of inactivated vaccines
- no reversion to pathogenic form
- often more stable/easy to store and transport
Cons of inactivated vaccines
- require booster shots
- don’t replicate in host, so often don’t induce cell-mediated immunity well (humoral only)
- possible chemical exposures/adjuvants often required
- potentially dangerous if not all pathogen is killed/inactivated
Subunit vaccine components
- use purified macromolecules derived from pathogen
- inactivated exotoxins/toxoids
- inactivated capsular polysaccharides
- inactivated surface glycoproteins (or recombinant protein Ag_
Pros/cons of subunit vaccines
similar to those of innactivated vaccines
Conjugate/multivalent subunit vaccines
some molecules aren’t strong enough Ags on their won to stimulate a good response
- couple them with something else that is (conjugate)
- deliver them in a mixture of proteins (multivalent)
- have to deliver Ag into cells for presentation in MHC I
