Chapter 14

Front 1

Pathogen

Back 1

abiotic or biotic agent that causes disease

Front 2

Pathology

Back 2

The study of disease [‘pathos’ = suffering; ‘logos’ = science]

Front 3

Etiology

Back 3

The study of the cause of a disease

Front 4

Pathogenesis

Back 4

How a pathogen ‘causes the disease

Front 5

Infection

Back 5

Invasion /colonization by pathogens

Front 6

Disease

Back 6

Disruption of the normal physiology

Front 7

Symptom

Back 7

Response or change in function by the host: fever, cough, low energy. Not always apparent to the observer

Front 8

Sign

Back 8

Visual changes produced
in tissues owing to the pathogen
e.g chicken pox lesion, or evidence
the pathogen itself = ringworm

Front 9

Syndrome (Greek = run together)

Back 9

A specific group of signs and symptoms that accompany a disease

Front 10

SARS

Back 10

severe acute respiratory syndrome
Recent example – eventually explained with the identification of the causal coronavirus

Front 11

Microbial antagonism

Back 11

is a competition between microbes.

Front 12

Normal microbiota (not disease causing)

Back 12

protect the host by
-Occupying niches that pathogens might occupy
-Producing acids
-Producing bacteriocins

Front 13

Probiotics

Back 13

Live microbes applied to
or ingested into the body, intended to
exert a beneficial effect

Front 14

Symbiosis

Back 14

relationship between normal micro-biota and the host [biosis = ‘living; sym= together’]

Front 15

Commensalism

Back 15

one of the two benefits (normal bicrobiota and the host)

Front 16

Mutualism

Back 16

both benefit (normal bicrobiota and the host)

Front 17

Association of symbiosis: transient, normal, localized, or systemic

Back 17

Transient – present for days, weeks, or months
Normal - permanently colonize the host
Localized = restricted to one location (organ or tissue)
Systemic = throughout the system

Front 18

Casuality

Back 18

Diseases can be caused by abiotic and biotic factors.
Causality is the relationship between an event (the cause) and a second event (where the second event is a consequence of the first.
Applied to infectious diseases: it is the causal agent

Front 19

Koch's Postulates
‘Germ Theory Isolation’

Back 19

The microorganism must be present in all cases of the disease
The microorganism must be isolated from host and grown in pure culture
When the microorganism from pure culture is inoculated to susceptible host, disease must occur and symptoms must be identical to original
The microorganism must then be re-isolated from the diseased host and grown in culture - and must be the same organism isolated in step one

Front 20

Robert Koch

Back 20

Founder of Bacteriology (animals) (with Louis Pasteur)
Koch’s postulates of germ theory – or ‘proof of causality’
Used this principle first to identify cause of anthrax, cholera, and tuberculosis (Nobel Prize in Medicine 1905)
Most applicable to organisms like bacteria and fungi that can be grown in lab culture; for some viruses-cell culture
-Very difficult for certain kinds of diseases: cancer (unless viral or biotic agent involved).

Front 21

AESCULAÅåPIUS (Asklêpios)… The God of the medical art

Back 21

Son of Apollon and the Trikkaian princess Koronis. His mother died in labor and was laid out on the pyre to be consumed….his father rescued the child, cutting him from her womb = Asklepios "to cut open.”
Raised by the centaur Kheiron who instructed him in the ‘art of medicine’
Asklepios grew so skilled in the craft that he was able to restore the dead to life. However, because this was a crime against the natural order, Zeus destroyed him with a thunderbolt.
After his death Asklepios was placed amongst the stars as the constellation Ophiochus ("the Serpent Holder").

Front 22

Hippocrates

Back 22

Hippocrates categorized illnesses as acute, chronic, endemic and epidemic, and use terms such as, "exacerbation, relapse, resolution, crisis, paroxysm, peak, and convalescence.
Major contributions: descriptions of the symptomatology, physical findings, surgical treatment and prognosis.
Teachings remain relevant to present-day students of pulmonary medicine and chest surgery.
The Hippocratic school of medicine described well the ailments of the human rectum and the treatment thereof, despite the school's poor theory of medicine.

Front 23

Father of Epidemiology

Back 23

The Greek physician Hippocrates is sometimes said to be the father of epidemiology. He is the first person known to have examined the relationships between the occurrence of disease and environmental influences.
He coined the terms endemic (for diseases usually found in some places but not in others) and epidemic (for disease that are seen at some times but not others

Front 24

The Persian physician Avicenna

Back 24

considered a "father of modern medicine," in The Canon of Medicine (1020s), discovered the contagious nature of tuberculosis, and sexually transmitted disease, distribution of diseases through water and soil.
Avicenna stated that bodily secretion is contaminated by foul foreign quarantine as a means of limiting the spread of contagious disease.
He also used the method of risk factor analysis, and proposed the idea of a syndrome in the diagnosis of diseases.

Front 25

an Italian doctor from Verona
Girolamo Fracastoro (mid 16th century)

Back 25

was the first to propose a theory
that these very small particles were alive (germ theory)

Front 26

Epidemiology

Back 26

The study of what is upon the people.

Front 27

Communicable disease

Back 27

A disease that is spread from one host to another

Front 28

Contagious disease

Back 28

A disease that is easily spread from one host to another

Front 29

Sporadic disease

Back 29

Disease that occurs occasionally in a population

Front 30

Non-communicable disease

Back 30

A disease that is not transmitted from one host to another

Front 31

Endemic disease

Back 31

Disease constantly present in a population

Front 32

Epidemic disease

Back 32

Disease acquired by many hosts in a given area in a short time

Front 33

Pandemic disease

Back 33

Worldwide epidemic

Front 34

Herd immunity

Back 34

Immunity in most of a population

Front 35

Acute disease

Back 35

Symptoms develop rapidly

Front 36

Chronic disease

Back 36

Disease develops slowly

Front 37

Subacute disease

Back 37

Symptoms between acute and chronic

Front 38

Latent disease

Back 38

Disease with a period of no symptoms when the causative agent is inactive

Front 39

Local infection

Back 39

Pathogens are limited to a small area of the body

Front 40

Systemic infection

Back 40

An infection throughout the body

Front 41

Focal infection

Back 41

Systemic infection that began as a local infection

Front 42

Epidemiology

Back 42

The study of where and when diseases occur
Centers for Disease Control and Prevention (CDC)
Collects and analyzes epidemiological information in the United States

Front 43

Transmission of Pathogens Direct contact, indirect contact, droplet contact, and vehicular

Back 43

Direct: Requires close association between infected and susceptible host
Indirect: Spread by fomites =an inanimate object (as a dish, toy, book, doorknob, or clothing) that may be contaminated with infectious organisms
Droplet: Transmission by airborne droplets
Vehicular: Food, water, air

Front 44

Arthropod Vectors and their transmission methods: biological and mechanical

Back 44

Arthropods, especially fleas, ticks, and mosquitoes
Mechanical transmission: Arthropod carries pathogen on feet
Biological transmission: Pathogen reproduces in vector

Front 45

Nosocomial Infections

Back 45

Are acquired as a result of a hospital stay
Affect 5–15% of all
hospital patients