Chapter 1 Flashcards
(111 cards)
1
Q
Define agent
A
A biological, physical, or chemical entity capable of causing disease
2
Q
Define anamnestic response
A
The accelerated rise in Ab titre in an individual which had previously developed a primary immune response to the particular Ag
3
Q
Define antibiogram
A
A list of antibiotics that a particular microorganism is sensitive or resistant to
4
Q
Define antibiotic sensitivity
A
The identification of the testing concentration of various antibiotics to which a microorganism is sensitive to
5
Q
Define antigenic character
A
The chemical arrangement of the antigenic components of an agent, which arrangement and components are unique to each species or strain of agents, and which are responsible for the specificity of immunity resulting from infection with that agent
6
Q
Define antigenicity
A
The ability of an agent or its products to stimulate the formation of antibodies
7
Q
Define antisepsis
A
The prevention of sepsis by inhibition or destruction of the causative organism
8
Q
Define antitoxin
A
Antibody to the toxin of a microorganism that combines with a specific toxin to neutralise toxicity
9
Q
Define arboviruses
A
Viruses that are transmitted from one host to another by one or more kinds of arthropods
10
Q
Define asepsis
A
The absence of infectious microorganisms
11
Q
Define aseptic technique
A
Procedures designed to exclude infectious agents
12
Q
Define bacteriophage
A
A virus that lyses bacteria
13
Q
Define carrier
A
A person or animal that harbours a specific infectious agent (but manifests no discernible clinical disease) and is a potential source of infection for another individual
14
Q
Define case
A
An infected or diseased individual that has specific clinical, laboratory and epidemiologic characteristics
15
Q
Define confirmed case
A
An individual from whom a disease-producing agent has been isolated and identified or from whom has been obtained laboratory evidence of the presence of an etiologic agent
16
Q
Define presumptive case
A
An individual with a clinical syndrome compatible with a disease, but without laboratory confirmation of the etiological agent
17
Q
Define chemoprophylaxis
A
The administration of chemical, including antibiotics, to prevent the development of an infection or progression of infection to clinical disease
18
Q
Define colonization
A
The propagation of a microorganism on or within a host without causing cellular injury. A colonized host can serve as a source of infection
19
Q
Define the period of communicability
A
The interval during which a person or animal that has an infectious disease is a potential source of infection
20
Q
Define communicable disease
A
An illness which is caused by a specific infectious agent or its toxic products, and which arises through transmission of that agent or its products from a reservoir to a susceptible host
21
Q
Define discriminatory power
A
The ability of a test to generate distinct and discrete units of information from different isolates, usually at a subspecies level
22
Q
Define endemic
A
The constant presence or usual prevalence of a disease or infectious agent in populations within a geographic area
23
Q
Define enzootic
A
The constant presence or usual prevalence of a disease or infectious agent in human and animal populations within a given geographic area
24
Q
Define epidemic
A
The occurrence of cases of similar nature in populations in a particular geographic area, clearly in excess of the usual incidence
25
Define common-source epidemic
An epidemic in which one individual or a specific vehicle has been the main means of transmitting the agent to cases identified
26
Define propagating epidemic
An epidemic in which infections are transmitted from person-to-person or animal-to-animal in a fashion that cases cannot be attributed to agents transmitted from a single source
27
Define epidemiology
The study of the distribution and determinants of disease in populations
28
Define epizootic
The occurrence of cases of similar nature in animal populations in particular geographic areas clearly in excess of normal incidence - may result from common or propagated sources of infection
29
Define etiology
The study of the causation of disease; the sum of knowledge regarding causes
30
Define fomites
A subclass of vehicles, including inanimate objects, such as clothing, that can become contaminated and transmit agents
31
Define primary (definitive) host
Hosts in which the parasite attains maturity or passes through its sexual stage
32
Define secondary (intermediate) host
Hosts in which the parasite exists in the larval stage or other asexual stages
33
Define accidental (dead-end) host
A host that has no role in the propagation or transmission of a particular infectious agent
34
Define immune serum globulin
A sterile solution of globulins which contain those Ab normally present in adult human blood
35
Define immunodeficient
Lacking in the ability to produce Ab in response to Ag
36
Define incidence
Number of new cases of a disease occurring within a particular population during a specified period of time
37
Define incubation period
The interval between effective exposure of a susceptible host to an agent (infection) and onset of clinical signs/symptoms of disease in that host
38
Define index case
The first case among a number of similar cases which are epidemiologically related - often identified as a source of contamination or infection
39
Define inapparent infection
An infection resulting in no perceptible clinical signs and symptoms
40
Define apparent infection
An infection resulting in clinical signs and symptoms (disease)
41
Define inflammation
Normal tissue response to cellular injury or foreign material, characterised by dilation of small blood vessels (capillaries) and mobilisation of defence cells (blood and tissue leukocytes and phagocytes)
42
Define interference phenomenon
State of temporary resistance to infections by viruses, induced by existing virus infection
43
Define interferon
Low molecular-weight protein produced by cells infected with viruses, can block viral infection of healthy cells and suppress viral multiplication in cells already infected
44
Define invasiveness
The ability of a microorganism to enter the body and to spread throughout the tissues
45
Define latent period
The time interval between exposure to toxic chemical agents and the onset of signs and symptoms of illness
46
Define nosocomial infection
An infection resulting from exposure to a source within a health-care facility - infections among inpatients, visitors and hospital personnel
47
Define pandemic
An epidemic disease affecting people in several countries or continents
48
Define pathogenicity
The capacity of an agent to cause disease in a susceptible host
49
Define phage typing
The characterisation of a bacterium by the infection of those bacteriophages to which the bacterium is susceptible
50
Define phylogeny
The study of lines of descent or evolutionary development of an organism
51
Define prodromal period
The lapse of time between the first symptom of disease and the first sign/symptom upon which a diagnosis can be based
52
Define prodrome
A symptom indicating the onset of disease
53
Define morbidity rate
A measure of the frequency of illness/disease in a population
54
Define incidence rate
A type of morbidity rate which is a measure of the frequency of cases of disease in a particular population, the times of onset which occurred during a specified period of time
55
Define prevalence rate
A type of morbidity rate which is a measure of all current cases of a disease within a particular population, either at a specified time or period
56
Define passive immunity
Immunity that is acquired either naturally (maternal transfer) or artificially (inoculation of Ab, convalescent/immune serum or immune serum globulin) and only last days or months
57
Define active immunity
Immunity that lasts for months to years and is acquired either naturally (infection, with or without clinical signs), or artificially (by inoculation of fractions of the infectious agent, in killed, modified, or variant form)
58
Define inherent resistence
An ability to resist disease without the action of Ab or of specifically developed tissue response
59
Define rickettsia
A class of microbial agents resembling small bacteria and multiplying by simple fission, but only within a living cell
60
Define sepsis
The presence of pathogenic microorganisms or their toxins in the blood or other tissue
61
Define serotyping
The characterisation of a microorganism by the identification of the Ag possessed by that organism
62
Define sporadic case
A case that has no epidemiologic relationship to any other cases
63
Define sterilisation
The complete destruction of microorganisms on or in an object usually by means of heat/chemicals
64
Define strain
An isolate or group of isolates exhibiting phenotypic and/or genotypic traits belonging to the same lineage, distinct from those of other isolates of the same species
65
Define surveillance of disease
The continuing scrutiny of all those aspects of other occurrence and spread of a disease that are pertient to effective control
66
Define susceptible
An individual lacking sufficient resistance to a particular pathogenic agent to prevent disease if or when exposed
67
Define endotoxin
A toxin found within bacterial cells but not in cell-free filtrates of intact bacteria - released from a bacterium when its cell wall is ruptured
68
Define exotoxin
A toxin produced by a bacteria that is released by the bacterial cell into the culture medium and hence found in cell-free filtrates and cultures of intact bacteria
69
Define vector
An arthropod which transfers an infectious agent from a source of infection to a susceptible host
70
Define vehicle
An object or substance that is a source of infection or intoxication
71
Define virulence
The degree of pathogenicity of an infectious agent
72
Which of the following statements best fit the definition of epidemiology, as used in your notes?
a) The science dealing with aetiology, distribution, and treatment of communicable and non-communicable diseases in a population
b) The study of the distribution and determinants of disease in populations
c) The study of the cause , effect, and prevention of communicable and non-communicable diseases in a population
d) The study of measures to prevent or control epidemics
b) The study of the distribution and determinants of disease in populations
73
If a disease simultaneously affects animals of several countries, or of more than one continent, and affects them in numbers clearly in excess of normal expectancy, the disease is said to be:
a) Endemic
b) Epidemic
c) Pandemic
c) Pandemic
74
Endemic means that a disease is:
a) Occurring clearly in excess of normal expectancy
b) Constantly present
c) Affecting a large number of countries simultaneously
b) Constantly present
75
Before Pasteur and Koch announced certain of their discoveries, no one was able to adequately describe the chain of infection in certain epidemic diseases because there was no objective evidence for:
a) Host susceptibility
b) Reservoirs
c) Microbiologic agents
d) Modes of transmission
e) Portals of exit and portals of entry
c) Microbiologic agents
76
Which one of the following does not belong in any of the basic classes of agents discussed in the test that cause disease?
a) Bacteria and virus
b) Pesticides and other chemicals
c) Vibration and temperatures
d) Fungi
e) Psychological factors
e) Psychological factors
77
Host factors are important since they affect which of the following?
a) Resistance or susceptibility to disease
b) The antigenic character of the agent
c) The risk of exposure
d) A and C
e) All of the above
d) A and C
78
In the case of a particular infectious disease, which of the following cannot be specified with certainty unless the "chain of infection" is known?
a) Risk of exposure
b) Appropriate control measures
c) Pathogenicity of the agent
d) Host resistance
e) Host susceptibility
b) Appropriate control measures
79
Which of the following statements contradicts the text?
a) Rickettsia have some characteristics like those of bacteria; they also have some like those of viruses
b) Bacteria in the environment usually grow and multiply
c) Fungi usually have an environmental reservoir and are transmitted indirectly
d) Viruses are usually transmitted indirectly
e) Some metazoa have extra-host developmental states
d) Viruses are usually transmitted indirectly
80
Which of the following contributes to a biological agent's ability to cause disease?
a) Host specificity
b) Ability to survive and remain infectious outside the host
c) Ability to multiply outside the host
d) Virulence
e) All of the above
e) All of the above
81
The capacity of an infectious agent to cause disease in a susceptible host is termed:
a) Pathogenicity
b) Invasiveness
c) Infectivity
d) Virulence
e) Incidence
a) Pathogenicity
82
Which of the following determines whether an infection is apparent or inapparent?
a) A rise or fall in antibody titres
b) Degree of infectivity of the host
c) Presence of absence of clinical signs and symptoms
d) Mild or severe clinical signs and symptoms
e) Isolation and identification of an infectious agent
c) Presence of absence of clinical signs and symptoms
83
Which of the following statements concerning infectious diseases is NOT correct?
a) Wide variety of biological agents can produce similar clinical syndromes
b) Many biological agents cause illness in only a fraction of animals who become infected
c) The laboratory is exceedingly important in establishing the aetiology of an infection
d) Case fatality rates are a means of comparing the risk of death associated with infectious diseases
e) All individuals exposed to an infectious agent in the same way will become infected
e) All individuals exposed to an infectious agent in the same way will become infected
84
The natural habitat in which an infectious agent lives, grows, and multiplies, is called a:
a) Vehicle
b) Reservoir
c) Clinical case
d) Source of infection
e) Fomite
b) Reservoir
85
Which one of the following do you conclude is never a reservoir for infectious agents?
a) Humans
b) Animals
c) Soil
d) Air
e) Water
d) Air
86
Carriers are defined in the test are those animals which:
a) Have passive immunity due to natural or artificial mechanisms
b) Are immune to disease because of a previously acquired infection
c) Harbour specific infectious agents in the absence of discernible clinical disease and serve as potential sources of infection
d) Transmit relatively little infection to humans
e) Are acutely ill and serve as potential sources of infection for susceptible animals
c) Harbour specific infectious agents in the absence of discernible clinical disease and serve as potential sources of infection
87
Which of the following is NOT characteristics of carriers?
a) They shed infectious agents even before signs/symptoms of illness appear
b) They are infected, and though they manifest no signs/symptoms, they are capable of being sources of infection
c) They are infected and manifest mild clinical signs/symptoms
d) They continue to be infectious during convalescence from illness and after recovery
e) They harbour infectious agents for a year or more and are capable of being sources of infection
c) They are infected and manifest mild clinical signs/symptoms
88
Which of the following is NOT considered a portal of exit for infectious agents?
a) Alimentary tract
b) Cardiovascular system
c) Skin
d) Respiratory tract
e) Genitourinary tract
b) Cardiovascular system
89
Which of the following about portals of exit is NOT correct?
a) Portals of exit are applicable in the cases of human and animal reservoirs but not environment
b) The path by which an infectious agent leaves it host is commonly referred to as the portal of exit
c) Infections transmitted by means of saliva represent exit by the alimentary portal
d) The transplacental portal of exit is quite important in that the placenta is generally ineffective in protecting the foetus against maternal infections
e) The percutaneous mechanism of exit by the way of skin includes bites of arthropods and penetrating objects such as needles
d) The transplacental portal of exit is quite important in that the placenta is generally ineffective in protecting the foetus against maternal infections
90
Which of the following portals of exit is generally the most important as well as the most difficult to control?
a) Respiratory tract
b) Alimentary tract
c) Genitourinary tract
d) Skin
e) Placenta
a) Respiratory tract
91
The direct mode of transmission is characterised by:
a) A particular portal of exit from the reservoir
b) The severity of the disease
c) The presence of a vehicle or vector
d) An immediate transmission between portals of exit and entry
e) The infectious agent's portal of entry into the host
d) An immediate transmission between portals of exit and entry
92
Which comment(s) about the transmission of tuberculosis is in accord with the text?
a) The agent is transmitted directly by droplet spread
b) The agent is mechanically transmitted by vectors
c) The agent is transmitted directly by inanimate means
d) The agent is transmitted by a vehicle
e) Both "A" and "C" are correct
e) Both "A" and "C" are correct
93
Which of the following modes of transmission is "direct"?
a) Vectorborne
b) Vehicleborne
c) Droplet spread
d) Fomites
e) Droplet nuclei
c) Droplet spread
94
Which one of the following is NOT a general factor of resistance to infection?
a) The gastric acid
b) The cilia in RT
c) The cough reflex
d) The antitoxins
e) The mucous membranes
d) The antitoxins
95
Susceptibility to infection is increased by which of the following conditions?
a) Malnutrition
b) Pre-existing ill health
c) Artificially depressed immunologic response mechanisms
d) None of these
e) A, B and C
e) A, B and C
96
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Host resistance to disease is influenced to the greatest extent by specific acquired immunity which may be obtained naturally or artificially. Questions 25-31 are based on situations leading to acquired immunity:
Toxoid confers which kind of immunity?
a) Natural active
b) Artificial active
c) Natural passive
d) Artificial passive
e) General resistance
```
b) Artificial active
97
Host resistance to disease is influenced to the greatest extent by specific acquired immunity which may be obtained naturally or artificially. Questions 25-31 are based on situations leading to acquired immunity:
Passage of maternal antibodies to the foetus confers which kind of immunity?
a) Natural active
b) Artificial active
c) Natural passive
d) Artificial passive
e) General resistance
c) Natural passive
98
Host resistance to disease is influenced to the greatest extent by specific acquired immunity which may be obtained naturally or artificially. Questions 25-31 are based on situations leading to acquired immunity:
Immune serum globulin (ISG) confers which type of immunity?
a) Natural active
b) Artificial active
c) Natural passive
d) Artificial passive
e) General resistance
d) Artificial passive
99
Host resistance to disease is influenced to the greatest extent by specific acquired immunity which may be obtained naturally or artificially. Questions 25-31 are based on situations leading to acquired immunity:
A vaccine confers which type of immunity?
a) Natural active
b) Artificial active
c) Natural passive
d) Artificial passive
e) General resistance
b) Artificial passive
100
Host resistance to disease is influenced to the greatest extent by specific acquired immunity which may be obtained naturally or artificially. Questions 25-31 are based on situations leading to acquired immunity:
An infection confers which kind of immunity?
a) Natural active
b) Artificial active
c) Natural passive
d) Artificial passive
e) General resistance
a) Natural active
101
Host resistance to disease is influenced to the greatest extent by specific acquired immunity which may be obtained naturally or artificially. Questions 25-31 are based on situations leading to acquired immunity:
An antitoxin confers which kind of immunity?
a) Natural active
b) Artificial active
c) Natural passive
d) Artificial passive
e) General resistance
d) Artificial passive
102
Host resistance to disease is influenced to the greatest extent by specific acquired immunity which may be obtained naturally or artificially. Questions 25-31 are based on situations: The administration of convalescent serum confers which kind of immunity?
a) Natural active
b) Artificial active
c) Natural passive
d) Artificial passive
e) General resistance
d) Artificial passive
103
Associations that can be established either between a disease and the personal characteristics of patients and/or factors in the patients' environment are:
a) Of little practical use in epidemiology
b) Useful in identification of sources and modes of transmission
c) Conclusive evidence for cause and effect relationships
d) The responsibility of attending physician
e) Of greatest use in investigation of food borne disease
b) Useful in identification of sources and modes of transmission
104
Factors affecting the risk of acquiring an infection from a contaminated object or vehicle include all but which one of the following?
a) Presence of a suitable reservoir
b) Presence and concentration of the aetiologic agent
c) Presence of an appropriate means of transmission and portal of entry
d) Variations in host susceptibility
e) Nature of contact with that object or vehicle
a) Presence of a suitable reservoir
105
Human diseases that occur more frequently in rural areas than in urban areas usually belong to:
a) The zoonoses
b) The parasitic diseases
c) The contact diseases
d) The respiratory diseases
e) None of the above
a) The zoonoses
106
The purpose of disease surveillance is:
a) Prevent/control disease
b) Collect and analyse health data
c) Identify causal factors
d) Inform health officials of the status of specific diseases in the population
e) All of the above
e) All of the above
107
The importance of morbidity reports is that they:
a) Help to discover source of infection
b) Help to establish endemic levels
c) Help to discover additional unreported cases
d) Help to evaluate progress in disease control
e) All of the above
e) All of the above
108
Primary determinants are:
a) Predisposing, enabling or reinforcing factors
b) Those individuals or animals who, after experiencing acute illness, continue to be infectious
c) Factors whose variation exerts a major effect in inducing disease
d) Always intrinsic determinants
e) Always extrinsic determinants
c) Factors whose variation exerts a major effect in inducing disease
109
A vaccine is used to control a disease if:
a) The incidence of disease is small
b) The vaccine needs to be tested
c) The farmer insists
d) The vaccine interferes with disease detection
e) None of the above
e) None of the above
110
Incidence is:
a) Another name for prevalence
b) The amount of disease occurring in a particular population during a specified period of time
c) The number of new cases of disease occurring within a particular population during a specified period of time
d) The ability of an agent to infect a host
e) B and C
c) The number of new cases of disease occurring within a particular population during a specified period of time
111
Prevention of disease is the responsibility of:
a) Veterinary Services
b) The consumer council
c) Private practitioners
d) The farmer
e) All of the above
e) All of the above
