Epidemiology Flashcards
Epidemiology
Science that evaluates occurrence, determinants, distribution, and control of health and disease in a human population. John Snow was the first epidemiologist.
CDC
Develops and applies disease prevention and controls. Also focuses on environmental health and health education. WHO is world counterpart.
Goals of Epidemiology
Determine: causative agent, reservoir of disease agent, mechanism of transmission, host/environmental factors that facilitate disease development, and the best control measures.
Sporadic Disease
Occurs occasionally and at sporadic intervals.
Endemic Disease
Steady low-level frequency at regular interval.
Hyperendemic
Gradually increases frequency above endemic level.
Outbreak
Sudden, unexpected occurrence of disease, usually in a limited segment of population.
Epidemic
Sudden increase in frequency of disease above expected level. Index case = first case.
Pandemic
Increase in disease occurrence within a large population, over wide region (worldwide).
Epidemiological Methods
Public health surveillance: protect population, improve public health, apply methodological approach to identify potential problems (review death certificates, field investigation, actual investigation).
Morbidity Rate
Incidence rate; # of new cases in given time / # individuals in population
Prevalence Rate
Total number of individuals infected at a given time.
Mortality Rate
deaths due to given disease / # individuals with disease
Types of Epidemics
Common Source: single, common, contaminated source (food)
Propagated: one individual with infection spreads it to a susceptible group
Herd Immunity
If greater than 70% of a population is immune to a specific disease, the susceptible individuals will be well protected against it.
Emerging Infections in US
Emerging disease mortality in US has increased since 1982. Due to population growth, increased travel, habitat disruption, microbial evolution and resistance development, inadequate public infrastructure, climate change, social unrest, food processing, technology, immunosuppression.
Nonsocomial Infections
Hospital-acquired; affect 10% of all hospital patients; commonly caused by normal microbiota; UTI, pneumonia, surgical site infection, blood infections.
Epidemic Control Measures
Reduce or eliminate reservoir of infection; break connection between reservoir and host; reduce number of susceptible hosts (vaccinate)
Vaccines
May consist of killed, living, attenuated, or inactivated bacterial toxins, cell material, recombinant vectors, or DNA. Induce antibodies and activated T cells to protect against future infection.
Whole Cell Vacines
Usually either killed or attenuated; may not work on occasion and attenuated versions may affect immunosuppressed individuals
Acellular Vaccines
Use of subunits of microbes to vaccinate. i.e. capsular polysaccharides, recombinant surface antigens, and inactivated exotoxins.
