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MicroBio > Module 6 Chapter 16 > Flashcards

Module 6 Chapter 16 Flashcards

1
Q

What is epidemiology?

A

A field that concerns the geographical distribution and timing of infectious disease occurrences and how they are transmitted and maintained in nature with the goal of recognizing and controlling outbreaks.

  • Includes: etiology and investigation of disease transmission
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2
Q

What is etiology?

A

The study of the causes of disease

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3
Q

What is morbidity?

A

The state of being diseased
- Morbidity or total morbidity is expressed in numbers of individuals without reference to the size of the population

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4
Q

How can morbidity rate be expressed?

A

As the number of diseased individuals out of a standard number of individuals in the population such as 100 000 or as a percent of the population

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5
Q

What are the two aspects of morbidity that are relevant to an epidemiologist?

A
  • A disease’s prevalence
  • A disease’s incidence
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6
Q

What is Prevalence?

A

O the number or proportion of individuals with a particular illness in a given population at a point in time.

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7
Q

What is incidence?

A

The number or proportion of new cases in a period of time

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8
Q

Mortality

A
  • Death
  • A mortality rate can be expressed as the percentage of the population that has dies from a disease or as the number of deaths per 100,000 persons (or other suitable standard number).
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9
Q

What are sporadic diseases

A

Disease that are seen only occasionally and usually without geographic concentration

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10
Q

What are some examples of sporadic diseases

A
  • Tetanus
  • Rabies
  • Plague
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11
Q

What are endemic diseases

A

Diseases that are constantly present (often at a low level) within a particular geographic region
ex. malaria is endemic to some regions of Brazil, but is not endemic to the United States

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12
Q

What are epidemic diseases

A

Diseases for which a larger than expected number of cases occurs in a short time within a geographic region
- Ex. influenza
These seasonal increases are expected, so it would not be accurate to say that influenza is epidemic every winter; however, some winters have an usually large number of seasonal influenza cases in particular regions, and such situations would qualify as epidemics

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13
Q

What is a pandemic disease?

A

An epidemic that occurs on a worldwide scale
- Ex. HIV/AIDS

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14
Q

What is a etiologic agent or causative agent?

A
  • Determinate the cause of the disease
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15
Q

What was Robert Koch the first scientist for?

A

Demonstrate the causative agent of a disease (anthrax)

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16
Q

Koch developed what?

A

4 criteria, now known as Koch’s postulates, which had to be met in order to positively link a disease with a pathogenic microbe. Without him the golden age of Mircrobio would not have occured.

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17
Q

Between 1876 and 1905, What happened?

A

many common diseases were linked with their etiologic agents, including cholera, diphtheria, gonorrhea, meningitis, plague, syphilis, tetanus, and tuberculosis.

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18
Q

What do we now use the molecular Koch’s postulates for?

A

Can be used to establish a link between the disease state and virulence traits unique to a pathogenic stain of a microbe.

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19
Q

What is the CDC

A
  • The centers for disease control and prevention in America
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20
Q

What does the CDC do?

A

Charged with protecting the public from disease and injury

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21
Q

What does the National Notifiable Disease Surveillance System (NNDSS) do?

A

Monitors diseases considered to be of public health importance on a national scale

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22
Q

What are notifiable diseases or reportable diseases?

A

Diseases considered to be of public health importance on a national scale because all cases must be reported to the CDC

ex. physician must submit report cases with a notifiable disease such as HIV, measles, West Nile virus

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23
Q

What are notifiable diseases tracked by?

A

By epidemiological studies and the data is used to inform health-care providers and the public about possible risks

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24
Q

What does the CDC publish?

A

Morbidity and Mortality Weekly Report (MMWR), which provides physicians and health-care workers with updates on public health issues and the latest data pertaining to notifiable diseases

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25
Q

John Snow

A
  • Determined the source of Broad Street cholera epidemic in London
  • Proposed that cholera was spread through a fecal-oral route of transmission and that a microbe was the infectious agent
  • Investigated the epidemic in two ways
  • Suspected that contaminated water was the source of the epidemic
  • Identified the course of water for those infected
  • Found high frequency of cholera cases among individuals who obtained their water from the River Thames downstream from London. This water contained the refuse and sewage from London and settlements upstream
  • Noted that brewery workers did not contract cholera and on investigation found the owners provided the workers with beer to drink and stated that they likely did not drink water
  • He also mapped the incidence of cholera and found a high frequency among those individuals using a particular water pump located on Broad Street.
  • Local officials removed the pump’s handle, resulting in the containment of the Broad Street cholera epidemic
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26
Q

What is common source spread of infectious disease?

A

When there is a single source for all of the individuals infected

27
Q

What is point source spread of infectious disease? (type of common source spread)

A

The common source operates for a short time period. Less than the incubation period of the pathogen

ex. single contaminated potato salad at a group picnic

28
Q

What is continuous common source spread of infectious disease? (type of common source spread)

A

The infection occurs for an extended period of time, longer than the incubation period

29
Q

What is intermittent common source spread of infectious disease? (type of common source spread)

A

When infections occur for a period, stop, and then begin again. This might be seen in infections from a well that was contaminated only after large rainfalls and that cleared itself of contamination after a short period

30
Q

What is propagated spread?

A

Occurs through direct or indirect person-to-person contact

-No single source for infection; each infected individual becomes a source for one or more subsequent infections

  • Unless spread is stopped immediately infections occur for longer than the incubation period
  • period. Although point sources often lead to large-scale but localized outbreaks of short duration, propagated spread typically results in longer duration outbreaks that can vary from small to large, depending on the population and the disease (Figure 16.6). In addition, because of person-to-person transmission, propagated spread cannot be easily stopped at a single source like point source spread.
31
Q

Florence Nightingale

A
  • Nurse during war
  • Kept records regarding the causes of illness and death during the war
  • Her records showed most death during war was not wounds but preventable infectious diseases
  • These diseases occurred because of poor sanitation and lack of access to hospital facilities
  • Led to many reforms in the British military’s system
  • Her analysis of the data she collected was published in 1858. In this book, she presented monthly frequency data on causes of death in a wedge chart histogram
32
Q

What are reservoirs and what are they needed for?

A

Reservoirs are needed for pathogens to persist over long periods of time, where they normally reside. They can be living organisms or nonliving sites.

These may naturally harbor the organism because it may grow in that environment. These environments may also become contaminated with pathogens in human feces, pathogens shed by intermediate hosts, or pathogens contained in the remains of intermediate hosts.

33
Q

Nonliving resevoirs examples

A

Soil and water in the environment,

34
Q

How do pathogens survive in nonliving environments?

A

May have mechanisms of dormancy or resilience that allow them to survive( but typically not to reproduce) for varying periods of time in nonliving environments

35
Q

Clostridium Tetani

A

Survives in soil and in the presence of oxygen as a resistant endospore

36
Q

Are humans acting as a reservoir for a pathogen always capable of transmitting the pathogen?

A

It depends on the stage of infection and pathogen.

37
Q

What is a carrier?

A

An individual capable of transmitting a pathogen without displaying symptoms

38
Q

What is a passive carrier?

A

Contaminated with the pathogen and can mechanically transmit it to another host; however a passive carrier is not infected

39
Q

What is an active carrier?

A

An infected individual who can transmit the disease to other. May or may not exhibit signs or symptoms of infection

40
Q

What are asymptomatic carriers?

A

Active carriers who do not present signs or symptoms of disease despite infection

41
Q

What is a definitive host

A

In a parasitic infection, this is the parasite’s preferred host

42
Q

What is an intermediate host

A

This is the host or hosts that a parasite may infect

43
Q

What does contact transmission include and what is it?

A

Direct contact or indirect contact.

  • First, transmission from the reservoir to the individual must occur. Then, the individual must transmit the infectious agent to other susceptible individuals, either directly or indirectly. Pathogenic microorganisms employ diverse transmission mechanisms.
44
Q

What is person-to-person transmission?

A
  • A form of direst contact transmission
  • Agent is transmitted by physical contact between two individuals through actions such as touching, kissing, sex, or droplet sprays
45
Q

What is vertical direct contact transmission?

A

Occurs when pathogens are transmitted from mother to child during pregnancy, birth, or breastfeeding

46
Q

What is horizontal direct contact transmission

A

Other kinds of direct contact transmission

47
Q

Other info about direct transmissions:

A

Often, contact between mucous membranes is required for entry of the pathogen into the new host, although skin-to-skin contact can lead to mucous membrane contact if the new host subsequently touches a mucous membrane. Contact transmission may also be site-specific; for example, some diseases can be transmitted by sexual contact but not by other forms of contact.

48
Q

What is droplet transmission?

A

Refers to droplet transmission of a pathogen to a new host over distances of one meter or less

49
Q

What is airborne transmission?

A

Transmission over distances greater than one meter

50
Q

What is indirect contact transmission?

A

Involved inanimate objects called fomites that become contaminated by pathogens from an infected individual or reservoir

  • For example, an individual with the common cold may sneeze, causing droplets to land on a fomite such as a tablecloth or carpet, or the individual may wipe her nose and then transfer mucus to a fomite such as a doorknob or towel.
  • Transmission occurs indirectly when a new susceptible host later touches the fomite and transfers the contaminated material to a susceptible portable of entry
  • Fomites can also include objects used in clinical settings that are not properly sterilized such as syringes, needles, catheters, and surgical equipment
51
Q

What is vehicle transmission?

A

Refers to the transmission of pathogens through vehicles such as water, food, and air

52
Q

What leads to waterborne transmission of disease?

A
  • Water contamination through poor sanitation methods
53
Q

What leads to foodborne transmission of disease?

A

Food contaminated through poor handling or storage

54
Q

What facilitates the airborne transmission of disease?

A

Dust and fine particles known as aerosols, which can float in the air, can carry pathogens that facilitate the airborne transmission

55
Q

What is vector transmission?

A

Diseases can also be transmitted by a mechanical or biological vector, an animal (typically an arthropod) that carriers the disease from one host to another.

56
Q

What is mechanical transmission?

A

Transmission facilitated by a mechanical vector, an animals that carrier a pathogen from one host to another without being infected itself
- Ex. fly may land on fecal matter then transmit bacteria from feces to food that it lands on, then human eating that food can become infected

57
Q

What is biological transmission?

A

Occurs when the pathogen reproduces within a biological vector that transmits the pathogen from one host to another

  • Arthropods main vectors responsible for this
  • Ex. mosquitos, lice, chickens
  • Rabies, typhus (through lice), rabies
58
Q

Nosocomial infections

A
  • Also called healthcare-associated infections (HAI)
  • Infections acquired in health-care facilities
  • Often connected with surgery or other invasive procedures that provide the pathogen with access to the portal of infection
  • Patient must have been admitted to the heath-care facility for a reason other than the infection to get an HAI
  • patients suffering from primary disease are often afflicted with compromised immunity and are more susceptible to secondary infection and opportunistic pathogens.
59
Q

Provide some example of the activities of international public health organizations such as WHO and CDC

A
60
Q

Distinguish between emerging and reemerging infectious diseases

A
61
Q

What does WHO do?

A
  • World Health Organization
  • Monitors and reports infectious disease
  • Develops and implements strategies for their control and prevention
  • Runs programs to reduce illness and mortality that occur as a result of violence, accidents, lifestyle-associated illnesses such as diabetes, and poor health-care infrastructure
  • Maintains a global alert and response system that coordinates information from member nations
  • In case of public health emergency or epidemic it provides logistical support and coordinates international response to the emergency
62
Q

What does the CDC do?

A
  • Carriers out international monitoring and public health efforts, mainly in the service of protecting US public health in an increasingly connected world
  • EU does the same thing
63
Q

What is an emerging infectious disease?

A
  • New to human population or has shown an increase in prevalence in the previous 20 years
  • Could be new or conditions have changed to cause an increase in frequency, its status as emerging implies the need to apply resources to understand and control its growing impact
  • Ex. Ebola

MicroBio (8 decks)

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