Epidemiology Flashcards
symptoms of cholera
profuse watery diarrhea, vomiting, leg cramps
father of epidemiology
john snow
Developed delivery system for ether; first anesthesiologist in England
john snow
treated queen victoria with chloroform during delivery of 8th child
john snow
epidemiology
the study of the causes, distribution, and transmission of disease
disease
an abnormal state in which the body is not functioning properly
infection
colonization of the body by pathogens
communicable disease
a disease that is spread from one host to another
contagious disease
a disease that is easily spread from one host to another
examples of contagious disease
measles, chicken pox, influenza
noncommunicable disease
a disease that is not transmitted from one host to another
ex of noncommunicable disease
tetanus
etiology
study of the cause of disease
Koch’s postulates
criteria developed by Robert Koch to establish a specific microbial cause for a given disease
2 diseases Koch identified
B. anthracis, M. tuberculosis
1st of Koch’s postulates
- the same pathogen must be present in every case of the disease
2nd of Koch’s postulates
- the pathogen must be isolated from the diseased host and grown in pure culture
3rd of Koch’s postulates
- The pathogen from the pure culture must cause the disease when it is inoculated into a healthy, susceptible laboratory animal
4th of Koch’s postulates
- the pathogen must be isolated from the inoculated animal and must be shown to be the original organism
4 exceptions to Koch’s postulates
- some pathogens cannot be cultured
- some can cause several disease conditions
- some symptoms can be from different pathogens
- some only cause disease in humans
An ex of a pathogen that cannot be cultured
M. leprae (leprosy)
An ex of pathogens that cause several disease conditions
S. pyrogenes
An ex of symptoms from multiple pathogens
pneumonia
2 disease that only cause disease in humans
small pox; HIV/AIDS
3 Modes of Transmission
- Contact (touching/kissing)
- Vehicle (infected water)
- Vector (mosquitoes)
Direct Contact
require close association between infected and susceptible host
Indirect Contact
spread by fomites (ex: tissues, used needles, money)
Droplet contact
transmission via airborne droplets (sneeze)
How many bacteria were found on $1 bills?
Over 3,000; most common one caused acne; also found bacterial species linked to gastric ulcers, pneumonia, food poisoning, staph infections, and diphtheria; Ab resistant strains also found on money
Droplets from a sneeze travel _x to ____x further than previously thought; about - m more.
5x-200x; 4-5m
Vehicle transmission Water
untreated or contaminated water
Vehicle transmission Food
incompletely cook or improperly refrigerated food
Vehicle Transmission Air
airborne droplets, dust particles, spores that can travel by air
mechanical transmission
arthropod carries pathogen on feet (fly -> food)
biological transmission
pathogen reproduces in vector (malaria)
2 Things that dictate how long a pathogen can survive outside of the normal host/growth environment:
- Pathogen (endospores? mycobacteria? enveloped vs nonenveloped virus?)
- Environmental conditions (porous vs nonporous surface; temp; humidity; light (UV); density of pathogen)
How long can most bacteria/viruses live on a surface in general?
24-48 hours
Endospores can survive (8)
dessication, heat, cold, extreme pH, pressure, radiation, chemicals, time
Healthcare Acquired Infections (HAIs)
Infections acquired at a healthcare facility while receiving treatment for other conditions (AKA Nosocomial Infections)
What makes the healthcare such a good place to get an HAI?
microorganisms in hospital environment, compromised host, and chain of transmission
Incidence
fraction of a population that NEWLY CONTRACTS a disease during a specific time
Incident Rate #
new cases per population unit during a specific time
What does incidence rate measure?
risk of getting a disease
Prevalence
fraction of a population that HAS a specific disease at a given time
What does prevalence measure?
the burden of the disease
morbidity
incidence of a specific notifiable disease
mortality
deaths from notifiable diseases
morbidity rate
number of people affected in relation to the total population in a given time period
mortality rate
number of deaths from a disease in relation to the population in a given time
The 2 most common causes of HAIs are:
Methicillin-resistant Staphylococcus aureus (MRSA) and Clostridium difficile (C. diff)
Zoonosis
any disease or infection that is naturally transmissible from vertebrate animals to humans or vice versa
Zoonoses
can be caused by all types of pathogens: bacteria, fungi, parasites, viruses
Food-related diseases affect ________________ of people. It kills _________. It causes more than$__ billion in health care-related costs each year.
tens of millions; thousands; 9
_________, over ____ million people lack access to healthy _____. In the United States, there are ______ of cases of _________ illness each year.
Globally; 900; water; millions; waterborne
Causative agent of cholera:
Vibrio cholerae
What type of bacteria is Vibrio cholerae?
gram negative
How does it work?
produces cholera toxin (AB exotoxin) that causes host cells to secrete electrolytes & water
Reservoir for cholera?
humans
Mode of transmission for cholera?
vehicle: contaminated water
Treatment for cholera?
Rehydration and doxycycline
Prevention of cholera?
clean water
What random item helps filter water in lower-income countries?
Saris
Cholera bacteria form ________ and are associated with ____________.
biofilms; copepods
