Chapter 14 - Principles of Disease and Epidemiology Flashcards
1
Q
Pathology
A
-the scientific study of disease
2
Q
Etiology
A
-the cause of the disease
3
Q
Infection
A
-the invasion or colonization of the body by microorganisms
3
Q
Pathogenesis
A
-the manner in which the disease develops
3
Q
Disease
A
-occurs when an infection results in any change from a state of health
-abnormal state where normal functions don’t perform
4
Q
In Utero
A
before birth
5
Q
Absence of Symptoms
A
-infections can occur in the absence of symptoms
6
Q
Microbiomes
A
-microbial communities
-live in and on the human body
6
Q
Normal Microbiota
A
-colonize but don’t produce disease under normal conditions
7
Q
Transient Microbiota
A
-present for several days, weeks, or months then disappear
8
Q
Factors that Affect Normal Microbiota
A
-age
-nutrition
-diet
-health status
-disability
-hospitalization
-stress
-climate
-geography
-living conditions
-occupation
-lifestyles
9
Q
Normal Microbiota: SKIN
A
-propionibacterium
-staphylococcus
-corynebacterium
-micrococcus
-acinetobacter
-fungi
10
Q
Skin
A
-secretions in sweat and oil glands have antimicrobial properties
-keratin resistant barrier
-low pH
-low moisture content
11
Q
Eye
A
-same microbiota found on skin
-tears and blinking eliminate/inhibit microbes
12
Q
Nose and Throat (URS)
A
-microbial antagonism
-nasal secretions and mucus remove microbes
13
Q
Mouth
A
-moisture, warmth, food support large populations
-saliva has antimicrobial substances
14
Q
Large Intestine
A
-largest numbers of resident microbiota
-mucous has antimicrobial agents
15
Q
Urinary & Reproductive
A
-vagina: acid tolerant population
-pH and urine flow remove microorganisms
16
Q
Microbial Antagonism/Competitive Exclusion
A
-normal microbiota benefit host by preventing overgrowth of harmful microorganisms
-nutrients, conditions, invasion
17
Q
Candida albicans
A
-grow in vagina
-a yeast
-flourish in neutral pH
18
Q
Symbiosis
A
-one organism is dependent on the other
-ie. normal microbiota and host
19
Q
Bacteriocins
A
-produced in large intestine by E. coli cells
-proteins that inhibit the growth of closely related bacteria
20
Q
Commensalism
A
-one organism benefits and the other is unaffected
-ie. S. epidermidis
21
Q
Mutualism
A
-both organisms benefit
-ie. E. coli
22
Parasitism
-one organism benefits at the expense of the other
-ie. Influenza
23
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Opportunistic Pathogens
-when a mutual organism can become harmful
-don't cause disease in normal habitat but may in a different environment
-ie. E. coli
26
Koch's Postulates
-showed how a specific infectious disease (anthrax) is caused by a specific microorganism (B. anthracis)
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Koch's Postulates
1. same pathogen must be present in every case
2. pathogen must be isolated from host and grown in pure culture
3. pathogen must cause disease in a healthy animal
4. pathogen must be isolated and shown as the original organism
29
Exceptions to Koch's Postulates
-some pathogens can't be grown on artificial media
-some pathogens cause several disease conditions
-some diseases cause different/similar signs and symptoms
30
Symptoms
-changes in body function
-evidence of an altered state
-subjective
-ie. pain
31
Signs
-objective changes
-observable and measurable
-ie. fever
32
Syndrome
-specific group of signs/symptoms that always accompany a particular disease
33
Communicable Disease
-a disease where an infectious person transmits an infectious agent
-directly or indirectly
-the other person becomes infected
-ie. chicken pox, herpes
33
Contagious Diseases
-capable of spreading easily and rapidly
-very communicable
-ie. measles and chicken pox
33
Noncommunicable Disease
-not spread from one host to another
-caused by microorganisms that normally inhabit the body
-occasionally produce disease
-ie. C. tetani
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Incidence
-the number of people in a population who develop a disease during a particular time period
-an indicator of spread
35
Prevalence
-number of people in a population who develop a disease at a specific time
-accounts for old and new cases
36
Epidemic Disease
-many people in a given area acquire a disease in a short period
-ie. influenza, AIDS
36
Endemic Disease
-a disease constantly present in a population
-ie. common cold
37
Pandemic Disease
-an epidemic that occurs worldwide
-ie. AIDS, Covid-19
38
Acute Disease
-develops rapidly but lasts only a short time
-ie. influenza
39
Chronic Disease
-develops more slowly
-occurs for a long period of time
-ie. TB, Hep B
40
Subacute Disease
-between acute and chronic
-ie. Subacute sclerosing panencephalitis
41
Latent Disease
-causative agent remains inactive for a certain time then becomes active to produce symptoms
-ie. Shingles
42
Herd Immunity
-an advantage of vaccination
-if most people in a population are immune
-outbreaks are limited, still susceptible people
43
Local Infection
-invading microorganisms are limited to a smaller region of the body
-ie. abscesses
44
Systemic (Generalized) Infection
-microorganisms are spread throughout the body by blood or lymph
-ie. measles
45
Focal Infection
-when a local infection enters a vessel and spreads to specific areas of the body
46
Sepsis
-toxic inflammatory condition
-arises from microbial spread via bacteria or toxins
46
Septicemia
-aka blood poisoning
-systemic infection arising from pathogen multiplication in the blood
46
Bacteremia
-the presence of bacteria in the blood
47
Toxemia
-presence of toxins in the blood
48
Viremia
-presence of viruses in the blood
49
Primary Infection
-an acute infection that causes the initial illness
50
Secondary Infection
-caused by an opportunistic pathogen after the primary infection has weakened the body's defences
51
Subclinical Infection
-doesn't cause any noticeable illness
-ie. Polio and Hep A (in some cases)
52
Predisposing Factor
-makes the body more susceptible to a disease
-alter the course and occurrence of the disease
53
Incubation Period
-between initial infection and first appearance of signs and symptoms
-may be variable
-some diseases can be spread during this phase
54
Prodromal Period
-relatively short
-follows period of incubation
-early, mild symptoms
-ie. aches
55
Period of Illness
-disease is most severe
-overt signs and symptoms
-WBC count may change
-if disease not treated, patient dies in this phase
56
Period of Decline
-signs and symptoms subside
-patient is vulnerable to secondary infection
57
Period of Convalescence
-person regains strength
-recovery has occurred
58
Reservoir of Infection
-a source of infection, where the organism survives till it finds a new host
59
Human Reservoirs
-principal living reservoir
-may have signs and symptoms or not
60
Carriers
-asymptomatic disease carriers
61
Zoonoses
-diseases that occur in animals that can be transmitted to humans
-ie. rabies, lyme disease
62
Nonliving Reservoirs
-ie. soil and water and food
-can carry Clostridium, Cholera, Salmonella
63
Contact Transmission
-spread of a disease agent by direct contact, indirect contact, or droplets
64
Direct Contact Transmission
-physical contact between source and host
-no intermediate object involved
-ie. kissing, touch, sex
65
Congenital Transmission
-transmission of disease from mother to fetus at birth
-via placenta or contact with blood
66
Indirect Contact Transmission
-agent is spread from reservoir to host via nonliving object
-ie. stethoscope
67
Fomite
nonliving object involved in the spread of an infection
68
Droplet Transmission
-microbes spread in droplet nuclei
-discharged by coughing, sneezing, laughing, talking
-travel less than 1m to host
69
Vehicle Transmission
-transmission of disease via a medium
-air, water, food, blood, body fluids
-ie. Salmonella
70
Airborne Transmission
-spread of agents in droplet nuclei in dust
-travel more than 1m
-ie. measles, TB
71
Waterborne Transmission
-contaminated or untreated sewage
-ie. cholera, shigellosis
72
Foodborne Transmission
-transmitted in foods that aren't cooked, poorly refrigerated, prepared in unsanitary conditions
73
Vectors
animals that carry pathogens from one host to another
74
Mechanical Transmission
-the passive transport of the pathogen on the insects feet or other body parts
-commonly spread to food and then ingested
75
Biological Transmission
-active process
-bite, infected blood, pathogens reproduce in the vector
-or via feces or saliva
-ie. Zika virus, Malaria
76
Healthcare-associated Infections/Nosocomial Infections
-patients acquire while receiving treatment for other conditions
-8th leading cause of death in the US
77
Factors Contributing to HAIs
1. many organisms in hospital
2. weakened status of the host
3. chain of transmission in hospitals
78
Compromised Host
-resistance to infection is impaired by disease
-broken skin or suppressed immune system
79
HAIs
-catheters
-surgical site infections
-UTIs
-ventilators
-C. diff
-bloodstream
-ventilation/water system
-via staff
-food
80
Universal Precaution
-designed to protect staff and patients
-standard and transmission-based precautions
81
Standard Precautions
-basic, minimum practices
-all levels of care
-gloves, masks, gowns, disinfection
82
Transmission Based Precautions
-used with individuals with known or suspected transmissible infections
83
Contact Precautions
-feces, urine, body fluids
-ie. Salmonella, C. diff
84
Droplet Precautions
-droplets spread short distanced
-ie. influenza, meningitis
85
Airborne Precautions
-long distance droplet nuclei
-ie. chicken pox, measles, TB
86
Emerging Infectious Diseases (EIDs)
-diseases that are new or changing
-many are zoonotic
87
Genetic Recombination
-new strains of E. coli and avian influenza (H5N1)
88
Evolution of Existing Microorganisms
-ie. a new serovar like V. cholerae O139
89
Unwarranted Use of Antibiotics and Pesticides
-growth of more resistant microbes and vectors that carry them
90
Global Warming
-increase survival and distribution of reservoirs and vectors
-ie. malaria
91
Modern Transportation
-known diseases spread to new places
-ie. Zika virus, West Nile
92
Human Travellers
-brought by insect vectors on travellers
-ie. Yellow fever
93
Animal Control
-increase in Lyme disease due to rising deer populations
94
Bioterrorism
-act of violence to produce death and disease
-ie. Anthrax
