Principles Of Disease And Epidemiology Flashcards
Pathology
the study of disease
Etiology
the study of the cause of a disease
pathogenesis
the development of a disease
infection
colonization of the body by pathogens
disease
an abnormal state in which the body is not functioning normally
transient microbiota
may be present for days, weeks, or months
normal microbiota
permanently colonize the host
symbiosis means
living together. It is the relationship between normal microbiota and the host.
in symbiosis, what is commensalism?
one organism benefits, and the other is unaffected.
mutualism
both organisms benefit
Parasitism
one organism benefits at the expense of the other
Some normal microbiota are
opportunistic pathogens
Microbial antagonism
is a competition between microbes
Normal microbiota protect the host by
Occupying niches that pathogens might occupy
Producing acids
Producing bacteriocins
Probiotics:
live microbes applied to or ingested into the body, intended to exert a beneficial effect
Koch’s postulates (1st step out of 4?)
- The same pathogen must be PRESENT in every case of the disease.
Koch’s postulates (2nd step out of 4?)
- The pathogen must be ISOLATED from the diseased host and grown in pure culture.
Koch’s postulates (3rd step out of 4?)
- The pathogen from the pure culture must cause the disease when it is inoculated into a healthy, susceptible laboratory animal.
Koch’s postulates (4th step out of 4?)
- The pathogen must be isolated from the inoculated animal and must be shown to be the original organism.
Koch’s postulates are used to prove the cause of
An infectious disease
In Koch’s postulates
Some pathogens can cause several disease conditions and can cause disease only in humans
Symptom:
a change in body function that is felt by a patient as a result of disease
Ex: nausea, dizziness, backache
Sign
A change in a body that can be measured or observed as a result of disease
Ex: fever, rash
Syndrome
a specific group of signs and symptoms that accompany a disease
Ex: aids
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
Noncommunicable disease:
a disease that is not transmitted from one host to another
Incidence:
fraction of a population that contracts a disease during a specific time
Prevalence:
fraction of a population having a specific disease at a given time
Sporadic disease
disease that occurs occasionally in a population
Endemic disease
disease constantly present in a population
Epidemic disease
disease acquired by many hosts in a given area in a short time
Pandemic disease
Worldwide epidemic
Acute disease
Symptoms develop rapidly
Chronic disease
disease develops slowly
Subacute disease:
Symptoms between acute and chronic
Latent disease
Disease with a period of no symptoms when the causative agent is inactive
Herd immunity
Immunity in most of a population
Four links in the chain of infection
- Host
- Etiologic agent (microbe causing the disease)
-virulence] = pathogenicity
-location ] = pathogenicity - Reservoir: area of where a pathogen can hang out until it can infect
- Mode of transmission
Local infection:
pathogens are limited to a small area of the body
Systemic infection:
an infection throughout the body
Focal infection:
systemic infection that began as a local infection
Sepsis:
toxic inflammatory condition arising from the spread of microbes, especially bacteria or their toxins, from a focus of infection
Bacteremia:
bacteria in the blood
Septicemia:
growth of bacteria in the blood
Toxemia:
toxins in the blood
Viremia:
viruses in the blood
Primary infection:
(Infection you started with) acute infection that causes the initial illness
Secondary infection:
opportunistic infection after a primary (predisposing) infection
Subclinical disease:
no noticeable signs or symptoms (inapparent infection): a human carrier
Predisposing factors:
Anything that makes patient more susceptible to disease
Predisposing factors make the body more susceptible to
Disease
Ex: Short urethra in females, Inherited traits, such as the sickle cell gene, Climate and weather, Fatigue, Age, Lifestyle, Chemotherapy
Period of convalescence
Immune is trying to recover and build again
Reservoirs of infection (outside the host ex: carriers, humans)
Continual sources of infection
Human: AIDS, gonorrhea
Carriers may have inapparent infections or latent diseases
Animal: rabies, Lyme disease
Some zoonoses may be transmitted to humans
Nonliving: botulism, tetanus
-Soil
Transmission of disease:
Contact
Indirect: spread by fomites (inanimate object that can spread disease (ex: pens and pencils that everyone touches
Droplet: transmission via airborne droplets
Direct: requires close association between an infected and susceptible host
Vehicle transmission
Transmission by an inanimate reservoir (food, water, air)
Vectors:living vehicles
Arthropods, especially fleas, ticks, and mosquitoes
Transmit disease by two general methods:
1. Mechanical transmission: arthropod carries pathogen on feet ex:flies and roaches
2. Biological transmission: pathogen reproduces in vector (take in pathogens through its body and has to transmit it) ex:ticks, mites, mosquitoes
Nosocomial infections (HAI)=hospital acquired infections
Are acquired as a result of a hospital stay
Affect 5–15% of all hospital patients
Emerging infectious diseases
Diseases that are new, increasing in incidence, or showing a potential to increase in the near future.
Contributing factors to emerging infectious diseases:
Antigenic shift
2 or more virus enters host during assembly, they get a mixture of spikes
Epidemiology
The study of where and when diseases occur
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
John snow 1848-1849
Mapped the occurrence of cholera in London
Ignaz Semmelweis 1846-1848
Showed that handwashing decreased the incidence of puerperal fever
Florence nightingale 1858
Showed that improved sanitation decreased the incidence of epidemic typhus (cleaned out wounds/changed bandages)
Case reporting:
health care workers report specified disease to local, state, and national offices
Nationally notifiable diseases:
physicians are required to report occurrence
