week 6: epidemiology & infection control -

what does epidemiology track?

• disease occurrence

• when, where, and who’s affected

• what increases and decreases risk

• how to prevent/ctrl disease

what is incidence?

• new cases occurring in a population during a specified period

• nursing use: track new infections & detect outbreaks

what is prevalence?

• existing cases at a point in time or during a specified period

• nursing: describe current disease burden

what is morbidity?

• illness in a population due to disease

• nursing: track nonfatal disease impact

what is mortality?

• deaths in a population due to a disease

• nursing: track fatal outcomes

what is incidence?

new cases occurring over time

what is prevalence?

all cases present, including new and existing cases

what is incidence risk?

the probability of developing a disease during a specified period

what is the formula for incidence risk?

incidence risk = (new cases during the period/population risk at the start) x 100%

what is incidence rate?

the speed at which new cases occur per person-time

what is the formula for incidence rate?

incidence rate = (new cases during the period/person-time at risk)

what is person-time?

the sum of the time each person contributes while at risk

what is the formula for point prevalence?

point prevalence = (existing cases/total population) x 100%

what is a sporadic disease pattern?

occurs occasionally or irregularly

what is a endemic disease pattern?

constantly present at an expected level, an unusual presence in a population

what is a epidemic/outbreak disease pattern?

more cases than expected in a place/time, cluster above baseline

what is a pandemic disease pattern?

epidemic spread across many countries/regions, global spread

what is contact as a mode of transmission?

direct touch or indirect contact with contaminated objects

what is droplet as a mode of transmission?

respiratory particles transmitted mainly at close range

what is airborne as a mode of transmission?

infectious particles that can remain suspended or travel through the air

what is vehicle as a mode of transmission?

transmission through a contaminated nonliving source, like food, water, or blood

what is vector as a mode of transmission?

transmission by an arthropod, such as mosquito or tick

what is a community acquired infection?

infection acquired outside HC setting

what is a healthcare-associated infection (HAI)?

develops during care or afterwards

what is an iatrogenic infection?

from med/surg intervention, may also be a HAI

what can HAIs arise from?

the patients own microbiota or from acquired pathogens

what increases risk for HAIs?

• patient factors

  • very young or old

  • immunosuppression

• pathogen factors

  • antibiotic resistance, spore formation

• healthcare factors

  • lapses in hand hygiene, aseptic technique, or cleaning

what is the standardized infection ration (SIR)?

SIR = observed infections/predicted infections

what does SIR = 1 mean?

observed infection number = predicted infection number

what does SIR > 1 mean?

more infections than predicted

what does SIR < 1 mean?

fewer infections than predicted

what are standard precautions?

• precautions used in all care settings, like:

  • hand hygiene

  • PPE based on anticipated exposure

  • safe sharp practices

  • clean & disinfect surfaces & equipment

what is a fomite?

an inanimate object that can become contaminated and transmit pathogens

what is medical asepsis?

reducing and preventing spread of pathogens

what is surgical asepsis?

exclude all microbes from a sterile field or sterile body site