Micro - ch.19 - Epidemiology

what is epidemiology?

study of the distribution, patterns and causes of disease in a population

incidence

the number of new cases of disease that develop in a specific population and defined period of times 

prevalence

proportion of population that has a disease at given time (new and pre-existing)

“50/100 people have asthma now, point prevalence is 5%”

morbidity rate

state of being diseased or unhealthy in a population

mortality rate

number of deaths in a given population durinf specific time period

• per 1000 or 100,000

case fatality rate

percentage of diagnosed cases that result in death over certain period of time

what is the case fatality rate equation?

#of deaths/#of all cases * 100% = CFR

epidemic

sudden increase in case numbers which exceeds normal limit for given population

endemic

constantly present at a steady level within a specific geographic area/population

sporadic

occurs irregularly/infrequently within a population

pandemic

disease outbreak that spreads across countries or continents (global)

reservoirs

natural/living or inanimate “hosts” where a pathogen lives, grows, and multiplies. They serve as a source which other individuals can become infected 

What are some examples of reservoirs?

contact

airborne: particles, droplets

common vehicles: food, water, blood

vectors: bugs 

What are common portals of exit?

ways in which the pathogens leave a host

Examples of portals of exit

respiratory tract - coughing, sneezing, or talking via droplets

GI tract - feces or vomit (cholera, typhoid)

What are some common portals of entry?

respiratory tract

parental route: pathogen enters directly into body tissue (injection, cuts, bites)

Case control study

looking back to compare people with condition (cases) to those without it (controls)

• identify possible exposure/risk factors

• retrospective

Cross section study

snapshot in time, measuring exposure and outcome simultaneously to estimate prevalence and identify associations

Cohort study

prospective or retrospective study which follows a group of people with or without exposure over time to see who develops the outcomes 

predisposing factors

characterized condition that increased likelihood of developing disease and health problems not directly causing it

Examples of predisposing factors

biological (genetics)

behavior (drinking)

environmental ( pollution) 

social (poverty)

prep the soil doesn’t plant the seeds

nosocomial infection

acquired in a hospital/healthcare setting

local

confined to. a small area

“localized”

systemic/generalized

illness that affects the entire body or multiple organ systems

bacteremia

bacteria presence in the bloodstream

• could be harmless (no multiplication)

septicemia

serious blood stream infection where bacteria multiply in blood and release toxins

• leads to sepsis/septic shockWhat is s

what is sepsis?

life threatening condition

What is the CDC stand for?

Center for Disease Control and Prevention

What does the CDC do?

• track disease trends

• collect and analyze health data to guide public

• coordinate with state/local health departments

Notifiable disease

required by law to be reported to public health authorities for monitoring and control

• measles, TB, HIV/AIDS, COVID-19

What does MMWR stand for?

morbidity and mortality weekly report

What is the MMWR?

publication by CDC which reports public trends in the US and informs health professionals and policy makers responds well

Factors that contribute to emerging infectious disease

biological, social/economics, environmental, human behavior

Biological factros

mutation of pathogens

zoonosis (pathogen spillover)

antimicrobial resistence (AMR)

Human behavior/societal factors

unsafe food/water practices

global travel/trade

poor vaccination coverage

Social and economic factors

poverty and healthcare access

environmental factors

habitat changes of wildlife (mosquitos)

deforestation → increase animal and human contact (Ebola) 

toxemia

presence of toxins in the bloodstream

• produced by bacteria and other sources

viremia

presence of viruses in bloodstream