Lecture 13: Epidemiology and Vaccines Flashcards
What are the two types of natural acquired immunity?
Active and Passive
Active immunity is obtained from infection, while passive immunity is acquired from the mother through the placenta or milk.
How long does passive immunity last?
Weeks to months
Passive immunity can be transferred from mother to infant.
What is the best method to diagnose HIV in infants?
PCR HIV test
This test looks for viral DNA in cells, unlike ELISA which detects antibodies.
What are the two types of artificial acquired immunity?
Active and Passive
immunity comes from vaccines, while passive immunity comes from gamma-globulin shots or antiserum.
How long can immunity from vaccines last?
Lifetime or few years
Immunity duration depends on the vaccine and the immune response it induces.
What type of vaccines are killed organisms?
Killed with heat or chemicals
These still elicit a primary immune response.
Give an example of an attenuated vaccine.
BCG, Measles, Yellow fever
Attenuated vaccines are live vaccines that have been passaged in culture.
What is epidemiology?
Study of the distribution and determinants of disease frequency in human populations
It involves understanding how diseases spread and their impact on populations.
Define an outbreak.
Sudden occurrence higher than expected in a small group
Example: Legionnaire’s Disease.
What is an endemic disease?
Steady frequency in population
Often at low levels, such as herpes viruses.
What distinguishes a pandemic from an epidemic?
Occurrence higher than expected worldwide
Examples include Influenza and HIV.
What is a nosocomial infection?
Illnesses associated with hospitalization
Approximately 10% of hospital patients develop such infections.
Name a zoonosis.
Giardia, Hanta virus, Plague, Rabies
These are animal diseases transmitted to humans.
What does morbidity rate refer to?
% individuals in population that become ill
It measures the prevalence of illness in a specific population.
What is the mortality rate?
% of individuals in population who die
This statistic indicates the death rate within a specific population.
List some factors affecting epidemics.
- Source of infection
- Route of pathogen transmission
- Susceptibility of population
- Microbe’s ability to change its antigens
- Size and mobility of population
- Virulence and pathogenicity of the microbe
What is a reservoir in the context of infection?
Natural environment of pathogen from which infection occurs
Reservoirs can be animate (living) or inanimate (non-living).
What are vectors in epidemiology?
Organisms that spread disease from one host to another
Examples include insects and animals.
What is herd immunity?
Resistance of a population to infection due to immunity
This can be achieved through natural infection or vaccination.
What is antigenic drift?
Small changes in antigens (mutations)
This can decrease herd immunity, as seen in influenza.
What is antigenic shift?
Large changes in antigens
This also decreases herd immunity and can occur with influenza through genome segment exchange.
Description of Attenuated (Live) Vaccines
Description: Contain live, weakened pathogens that have been passaged in culture until they are no longer pathogenic.
Examples: TB (BCG), Measles, Yellow fever, Sabin polio, Smallpox.
Advantages: Provide long-lasting immunity as they closely mimic a natural infection.
Disadvantages: Small risk of causing disease, especially in immunocompromised individuals.
Description of Killed (Inactivated) Vaccines
Description: Contain pathogens that have been killed with heat or chemicals.
Examples: Whole organism vaccines like pertussis, Salk polio.
Advantages: Safe as they cannot cause disease.
Disadvantages: May require booster shots to maintain immunity.
Description of Subunit Vaccines
Description: Contain purified components of a killed microbe, such as proteins or polysaccharides.
Examples: Streptococcus pneumoniae (capsule).
Advantages: Lower risk of side effects as they contain only essential antigens.
Disadvantages: May require adjuvants to enhance immune response.
Description of Recombinant Protein Vaccines
Description: Genetically engineered proteins that elicit an immune response.
Examples: Hepatitis B vaccine.
Advantages: Highly specific and safe.
Disadvantages: May require multiple doses.
Description of Recombinant DNA Vaccines
Description: Involve injecting plasmids that express antigens in host tissues.
Examples: Experimental vaccines for various diseases.
Advantages: Can induce both humoral and cellular immunity.
Disadvantages: Still under research and development.
