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Microbiology 455 > Ch 15 - Disease & Epidemiology > Flashcards

Ch 15 - Disease & Epidemiology Flashcards

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Biology 101 flashcards
1
Q

Epidemiology

A

The science that evaluates occurrence, determinants, distribution, and control of health and disease in a defined human.

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2
Q

John Snow

A

First epidemiologist

Studied cholera in London

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3
Q

Epidemiologists Determine

A
  • Causative Agents
  • Sources and/or reservoirs of disease agents
  • Mechanisms of transmission
  • Host and environmental factors that facilitate development of diseases within defined populations
  • Control Measures
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4
Q

Measuring Infectious Frequency

A

To determine an outbreak, epidemic, or pandemic, epidemiologists measure disease frequency at a single time over time

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5
Q

Morbidity Rate Formula

A

Rate of new cases

(# new cases during specific time/total population size) x100%

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6
Q

Prevalence Rate Formula

A

Total number of cases

(# of cases in a population/total population size) x100%

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7
Q

Mortality Rate Formula

A

Rate of deaths

(# deaths due to specific disease/total population size with the disease) x100%

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8
Q

Factors in classifying infectious diseases

A
  • Disease occurrence
  • Disease severity/duration
  • Host involvement
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9
Q

Incidence

A

The number of new people who develop a disease during a particular time period. Indicates how fast the disease spreads (new cases/year)

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10
Q

Prevalence

A

The number of people who develop the disease at a specified time, regardless of when it first appeared. Accounts for old & new cases (number infected/year) and indicates how long the disease occurs in a population

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11
Q

Patterns of incidence terms

A
  • Sporadic Disease
  • Endemic Disease
  • Epidemic Disease
  • Pandemic Disease
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12
Q

Sporadic Disease

A

Occurs only occasionally

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13
Q

Endemic Disease

A

Constantly present in a population

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14
Q

Epidemic Disease

A

Unexpectedly acquired by many people in a given area in a short time (political implications)

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15
Q

Pandemic Disease

A

Worldwide epidemic

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16
Q

HIV Disease Stats

A

From 1983-95 HIV was epidemic in US
Now HIV is endemic in US
The incidence in 1995 was >70,000
The Prevalence from 1979-1995 was 500,000

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17
Q

Acute Disease

A

Symptoms develop rapidly but the disease only lasts a short time (ex. influenza)

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18
Q

Chronic Disease

A

Symptoms develop slowly (ex. tuberculosis)

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19
Q

Subacute Disease

A

Intermediate between acute and chronic

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20
Q

Latent Disease

A

Causative agent is inactive for a time but then activates and produces symptoms (ex. herpes virus)

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21
Q

Herd Immunity

A

Immunity in most of a population

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22
Q

Factors to host involvement

A
  • Extent of host body affected (local or systemic)
  • State of host resistance (resistant, susceptible, or compromised)
  • Predisposing conditions (gender, age, lifestyle)
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23
Q

Extent of host body affected

Local Infection

A

Pathogens are limited to a small area of the body (ex. respiratory infection)

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24
Q

Extent of host body affected

Systemic (generalized) Infection

A

An infection throughout the body (ex. measles)

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25
Q

Extent of host body affected

Focal Infection

A

Systemic infection that began as a local infection

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26
Q

Extent of host body affected

Sepsis

A

Toxic inflammatory condition from the spread of microbes, especially bacteria or their toxins, from a focus of infection

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27
Q

Extent of host body affected: systemic

Septicemia

A

“blood poisoning”

growth of pathogens in the blood

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28
Q

Septicemia

Bacteremia

A

Bacteria in the blood

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29
Q

Septicemia

Viremia

A

Virus in the blood

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30
Q

State of host resistance

Subclinical Disease

A

No noticeable signs or symptoms. Healthy, resistant host.

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31
Q

State of host resistance

Primary Infection

A

Acute infection that causes initial illness. Healthy, but susceptible host.

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32
Q

State of host resistance

Secondary Infection

A

Opportunistic infection after a primary infection. Compromised & susceptible host. (ex. HIV patients contract pneumonia)

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33
Q

Predisposing Factors

A

Factors that make the body more susceptible to disease.

  • Gender (ex. UTIs are more common in women)
  • Inherited Traits (ex. Sickle Cell allele)
  • Climate/Weather (ex. flu in the winter)
  • Fatigue
  • Age
  • Lifestyle (ex. drinking, smoking, workout, drugs)
  • Poor nutrition
  • Chemotherapy
34
Q

People to know

John Snow (1848-1849)

A

Mapped the occurrence of cholera in London

35
Q

People to know

Joseph Lister (1850’s)

A

Used phenol as a disinfectant during surgery to lower post-operative wound infections

36
Q

People to know

Florence Nightingale (1858)

A

Showed that improved sanitation decreased the incidence of epidemic typhus

37
Q

2 Types of disease transmission

Noncommunicable/Common source spread

A

Results from single common contaminated source (ex. food poisoning)

38
Q

2 Types of Disease Transmission

Communicable/Propagated Spread

A

Results from the introduction of a single infected individual into a susceptible population which is propagated to others

39
Q

3 Types of common source epidemics (noncommunicable)

Point Source Spread

A

Occurs for a short period of time (ex. bad batch of food)

40
Q

3 Types of common source epidemics (noncommunicable)

Continuous Common Source Spread

A

Infection occurs for an extended period of time (ex. bad water)

41
Q

3 Types of common source epidemics (noncommunicable)

Intermittent Common Source Spread

A

Infection occurs of a period, stops, then begins again (ex. water is contaminated during floods)

42
Q

Sources of Infection

Human Reservoirs

A
  • Some pathogens exist only in humans

- Carriers may have inapparent infections or latent diseases (ex. whooping cough)

43
Q

Sources of Infection

Animal Reservoirs

A
  • Many pathogens move between species & genera

- Zoonoses are diseases transmitted from animals to humans (ex. influenza virus)

44
Q

Sources of Infection

Nonliving Reservoirs

A
  • Some pathogens are acquired from our environment

ex. cholera is from contaminated water

45
Q

Types of disease transmission

Contact Transmission

A

Disease is transmitted upon contact with a surface or substance that contains the disease. Types: Direct, Indirect, Droplet

46
Q

Types of disease transmission

Vehicle Transmission

A

Disease that is transmitted through something that people often come in contact with. Types: Waterborne, Foodborne, Airborne, Bloodborne.

47
Q

Types of Disease Transmission

Vector Transmission

A

Disease that is transmitted via another living creature. Types: Mechanical and Biological

48
Q

Types of contact transmission

Direct Contact Transmission

A

Requires close association between the infected and susceptible host (ex. person-to-person transmission)

49
Q

Types of contract transmission

Indirect Contact Transmission

A

Spreads to a host by a nonliving object called a fomite (contaminated surfaces/objects, used needles, door knobs)

50
Q

Types of contact transmission

Droplet Transmission

A

Transmission airborne droplets <1 meter (ex. mucous) Not considered airborne over short distances.

51
Q

Types of vehicle transmission

Waterborne

A

Disease transmitted via water. (ex. sewage contaminated water)

52
Q

Types of vehicle transmission

Foodborne

A

Disease transmitted via food (ex. poorly handled foods, contaminated food supply)

53
Q

Types of vehicle transmission

Airborne

A

Disease transmitted via air. Persistent droplet nuclei or dust over a large area. (ex. pollution)

54
Q

Types of vehicle transmission

Bloodborne

A

Disease transmitted by transfusion or direct exposure to blood

55
Q

Vector Transmission

A

Disease spread via another species (ex. arthropods, fleas, ticks, mosquitoes)

56
Q

Types of vector transmission

Mechanical Transmission

A

Arthropod carries pathogen on its feet (ex. a fly walks on dog poop then walks on your food)

57
Q

Types of vector transmission

Biological Transmission

A

Pathogen reproduces in the vector and is transmitted via bites or feces (ex. malaria, heartworms)

58
Q

3 Types of Control Measures

A
  1. Eliminate/reduce source/reservoir of infection
  2. Break the connection between source of infection and susceptible individuals
  3. Reduce number of susceptible individuals
59
Q

Healthcare-Associated Infections (HIAs)

A

aka. nosocomial infections
Acquired while receiving treatment in a health care facility. Affect 1 in 25 hospital patients (incidence rate is increasing)

60
Q

HAIs result from

A

Microbes in the hospital
Compromised hosts
Chains of transmission

61
Q

HAIs result from

Microbes in the Hospital

A

Normal flora and Horizontal Transfer of R plasmids

62
Q

HAIs result from

Compromised Host

A

Broken skin/mucous membrane
Resistance to infection is impaired by disease, therapy, or burns
Altered breathing

63
Q

HAIs result from

Chains of transmission

A

Direct from staff & other patients
Indirect from fomites
Airborne from ventilation systems

64
Q

Controlling HAI

Reduce the number of pathogens

A

Handwashing, disinfecting tubs used to bathe patients, cleaning instruments scrupulously, using disposable bandages and intubation

65
Q

Controlling HAI

Infection Control Committees

A

Dedicated epidemiologists, coordinate staff, regular inspections, spot checks

66
Q

Types of Epidemiological Investigations

Observational Stuides

A

Involves data from affected population

67
Q

Observational Stuides

Descriptive Epidemiology

A

Collection and analysis of data

68
Q

Observational Studies

Analytical Epidemiology

A

Collection and analysis of data from a select group

69
Q

Observational Studies: Analytical

Retrospective Studies

A

Uses data from previous cases

70
Q

Observational Studies: Analytical

Prospective Studies

A

Use date from current cases to monitor disease progress

71
Q

Observational Studies: Analytical

Case-control Studies

A

Use data from previous cases compared to healthy

72
Q

Observational Studies: Analytical

Cross-sectional Studies

A

Use data from random, current individuals to monitor disease progress

73
Q

Types of Epidemiological Investigations

Experimental Studies

A

Involves a hypothesis & controlled experiments. Very hard to do with people.

74
Q

Notifiable Infectious Diseases

A

Diseases in which physicians are required to report occurrence

75
Q

Notifiable Infectious Diseases

Morbidity Rate

A

Number of infections from a disease in relation to the population in a given time period

76
Q

Notifiable Infectious Diseases

Mortality Rate

A

Number of deaths from a disease in relation to the population in a given time

77
Q

Morbidity and Mortality Weekly Report (MMWR)

A

Publication from the CDC

78
Q

Organizations

CDC

A

Collects & analyzes epidemiological information in the US

79
Q

Global

Centers of Disease Control and Prevention in Atlanta, GA

A

Functions as national focus for:

  • Developing and applying disease prevention and control
  • Environmental Health
  • Health promotion and health education activites
80
Q

Global

World Health Organization

A

Worldwide public health organization in Geneva, Switzerland

81
Q

Emerging Infectious Diseases

A

Disease that are new, increasing in incidence, or showing a potential to increase in the near future. Most are zoonotic, of viral origin, and likely to be vector-borne

82
Q

Contributing Factors

A
  • Genetic Recombination (Escherichia coli O157 & avian influenza H5N1)
  • Evolution of New Strains (Vibrio cholerae O139)
  • Widespread use of Antibiotics and Pesticides (antibiotic-resistant strains)
  • Changes in weather patterns (hantavirus in dry, hot conditions)
  • Modern Transportation
  • Ecological disaster, war, and expanding human settlement
  • Animal Control Measures (Lyme disease in deer populations)
  • Public Health Failure (Diphtheria, cholera)

Microbiology 455 (7 decks)

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