Chapter 15: epidemiology and nosocomial infections Flashcards
Epidemiology
Study of frequency and spread of disease
Etiology
Study of the cause of disease
Incidence
Number of new cases in a population in a time period
Prevalence
Total number of cases (old and new) in the population in a time period
- provides info about severity of outbreak
Endemic
Disease is present at low level all the time with no public health threat
- ex: chicken pox in US
Epidemic
Sudden higher than normal incidence of a specific disease
Pandemic
Worldwide epidemic, random, unpredictable disease pattern
Reservoirs of infection
Site where pathogen can persist and maintain ability to infect
Human carrier
Sick person who has recovered from a disease but still harbors the gene
- ex: Typhoid Mary
Zoonoses
Animals that can carry disease (Arthropoda, vertebrates)
- ex: rabies from a dog
Non-living disease carriers
Water, soil
Portals of entry
Pathogen must get from reservoir to person through portal of entry
- skin: broken skin, follicles
- mucus membrane: urinary tract, anus, eyes, ears, nose, placenta
- parenteral sites (injured tissue)
Portals of exit
- feces
- body fluids
- skin flakes
Challenges in controlling transmission
Carrier status
STDs
Zoonoses
Disease cycles
Modes of transmission
- contact: direct body, indirect with fomite. Ex: cough, sneeze, talking
- vehicles: nonliving carrier of pathogen. Ex: air, food
- vectors: living carrier of pathogen (mechanical or biological)
Herd immunity
Enough of a population are vaccinated prevent the few that aren’t from becoming sick
Controlling acquired disease transmission
Isolation Quarantine Immunization Vector control Sanitization and hygiene
Public health organizations
CDC: us government. In charge of vaccination schedules, best practices
WHO: worldwide. Deal with epidemics and provide healthcare and education to 100 of the poorest countries
Notifiable diseases
Nosocomial infections
Infections acquired while in a medical facility
Exogenous
Source outside of you
- patient/ doctor
Endogenous
Source from inside your own body
- c. Diff may be in microflora, but antibiotics allow it to grow faster
Contributing factors to infection
Patient susceptibility
Microbial virulence
Disruption of microflora
Controlling transmission
Universal precautions: gloves, face masks
Minimizing invasive procedures
Surveillance: monitoring for pathogens
Antibiotic use: don’t over prescribe
Common source outbreak
Due to all coming in contact with a contaminated source
Propagated epidemic
Passed from person to person (colds)
