Lec 20: Epidemiology Flashcards
(93 cards)
1
Q
define epidemiology
A
the study of when and where diseases occur and how they are transmitted
2
Q
what are two types of diseases?
A
-communicable/contagious/infectious diseases
-non-communicable diseases
3
Q
what are communicable diseases? examples?
A
can be spread between hosts.
Examples:
-chickenpox
-measles
-TB
-Covid-19
4
Q
what are non-communicable diseases? examples?
A
Cannot be spread between hosts.
Examples:
-diabetes
-heart disease
-cancer
5
Q
what do epidemiologists study?
A
they study diseases in populations - they gather, organize, and analyze data to prevent their incidence and spread.
6
Q
what is a reportable disease?
A
A disease that, when diagnosed, requires health providers (usually by law) to report to state or local public health officials.
7
Q
are certain diseases reportable to public health agencies? what are examples?
A
Yes -
Alameda County Public Health Department (ACPHD)
California Department of Public Health (CDPH)
Centers for Disease Control and Prevention (CDC)
World Health Organization (WHO)
8
Q
what is the #1 cause of death in developed countries?
A
non-communicable diseases
(heart disease, stroke)
9
Q
what is the #1 cause of death in developing countries?
A
communicable diseases
(pneumonia, diarrhea, TB)
10
Q
what is a morbidity rate?
A
the rate of illness during a specific time
11
Q
what is an incidence rate?
A
the number of mew cases
12
Q
what is a prevalence rate?
A
the total number of cases
13
Q
what is a mortality rate?
A
the rate of deaths during a specific time frame
14
Q
what is a sporadic disease?
A
a disease that appears in population and then leaves
15
Q
what is an endemic?
A
expected low-level amount of disease in a population
16
Q
what is an epidemic?
A
greater than expected levels of disease in a population
17
Q
what is the high line (a) in the graph?
A
the epidemic threshold (if the #’s go above this threshold, it is epidemic)
18
Q
what is the low line (d) in the graph?
A
endemic baseline
19
Q
study the graph on page 6
A
20
Q
what is the chain of infection?
A
The chain of infection tells us what needs to happen for the spread of a disease and is made of various links
21
Q
how can we stop a disease from the chain of infection?
A
we can stop the disease by breaking any of the links:
-using masks: we are trying to break the portal of exit/entry for SARS-CoV-2
-development of a COVID-19 vaccine; we are trying to break the susceptibility of hosts to SARS-CoV-2
22
Q
what are the 5 chains of infection?
A
- Reservoir of infectious agent
- Portal of exit
- Transmission
- Portal of entry
- Susceptible host
23
Q
what are virulence factors?
A
traits of a microbe that allow it to cause a disease ex: capsule (protection from phagocyte), toxins
24
Q
what is an infectious dose?
A
the number of microbes needed to cause an infection
25
what is the infectious dose for Shigella and Salmonella enterica?
Shigella: 10-100 cells causes shigellosis
Salmonella enterica: 100,000 cells cause salmonellosis.
26
what is a reservoir? what are the 3 types?
where pathogens are present -
it can be humans, animals, and the environment.
27
what is an example of a human reservoir?
smallpox
28
what is an example of an animal reservoir?
HIV, COVID-19, Ebola
29
what is an animal reservoir called?
zoonoses
30
what are examples of environment reservoirs?
valley fever, cholera
31
what type of disease is Ebola?
zoonotic disease
32
what are the portals of exit?
-Nose: sneeze
-Mouth: cough, spit
-Anus: diarrhea
-Urogenital tract
-Skin: flakes off
-Blood
33
what are the two types of transmission of diseases?
1. Vertical
2. Horizontal
34
what is vertical transmission?
-When pathogens get transferred from the mother to the baby
35
what are examples of vertical transmission pathogens? what is the mnemonic?
TORGH
-Toxoplasma gondii
-Others (Treponema, pallidum, Zika virus)
-Rubella virus
-Cytomegalovirus
-Herpes simplex virus
36
what is horizontal transmission of pathogens? what are the 3 different subtypes?
From one host to another
Direct: direct, indirect, droplet
Vehicle: food, water, air
Vector: mechanical, biological
37
what are the subtypes of direct horizontal transmission?
-Direct: touch, kiss, sex
-Indirect: (fomites) inanimate objects, ex: surfaces, smallpox, blankets
-Droplet transmission
38
what are the different types of droplet transmissions:
>100 um: bigger droplets that can't travel, they land on fomites.
5-100 um: medium-sized droplets that can travel up to 6 ft; enter hosts or land on fomites
<5 um: small droplets that can travel beyond 6ft and linger in the air for several minutes to hours (airborne)
39
what are the different types of vehicle horizontal transmission?
contaminated food, water, air
40
what is an example of contaminated food for horizontal transmission?
e. coli and salmonella
41
what is an example of contaminated water for horizontal transmission?
cholera
42
what are examples of contaminated air for horizontal transmission?
fungal spores, endospores, <5 um droplets
43
what are vectors for horizontal transmission?
carriers of a pathogen - different from a spillover event
44
what are mechanical vectors for horizontal transmission?
they carry the pathogen on their body surface, ex: a fly
45
what are biological vectors for horizontal transmission?
-they carry the pathogen inside their body.
-the pathogen undergoes a part of its life cycle in a vector.
-ex: Anopheles mosquito in malaria
46
what are the 4 portals of entry?
1. Respiratory tract: the most common (eyes, nose, throat)
2. Digestive tract
3. Genitourinary tract
4. Parenteral route
47
what is the most common portal of entry? what is the second most common?
The first most common portal of entry is the respiratory tract, followed by the digestive tract
48
what is the portal of entry of the parenteral route?
It is the entry into tissues beneath the skin or mucous membranes due to a wound or puncture. Eg: IV, catheter.
49
how can being immune make a host no longer susceptible?
If they gain immunity through:
-Natural immunity: infection
-Acquired immunity: vaccination
50
how can general health help make a host no longer susceptible?
If they are eating well, exercising well, less stressed, they will have a stronger immune system and be less susceptible
51
what behaviors can cause a host to be more susceptible?
eating raw fish, drinking raw milk, and smoking
52
how can age make a host more susceptible and what is an example?
A weaker immune system in kids and older people can cause them to be more susceptible.
An example is an incidence of tetanus
53
how can sex cause a host to be more susceptible?
UTIs are more common in women, which cause them to be more susceptible
54
how can genetics make patients less susceptible?
-The CCR5 gene mutant can make people resistant to HIV
-Sickle cell people are more resistant to malaria
55
what can we do to prevent the chain of infection of zika virus?
1. Mosquito control
2. Vaccine
3. Wash hands
4. Wear a mask
1. Mosquito control
56
what are 3 trends in disease?
1. Reduction or Eradication
2. Emerging and re-emerging diseases
3. Healthcare-associated infections (HAIs)
57
what are examples of how we can reduce/eradicate diseases?
Sanitation, Reservoir/vector control, Antibiotics, and Vaccination
58
how can sanitation reduce/eradicate diseases?
Community:
-Better disposal of trash and feces
-Wastewater treatment
Personal hygiene:
-Handwashing
59
how can reservoir/vector control reduce/eradicate disease?
-Control rodents: to prevent the plague
-Control mosquitos: to prevent malaria, dengue, zika
60
what are some vaccinations that reduce/eradicate diseases?
Smallpox
Polio
61
what are emerging diseases and what is an example?
Emerging diseases are seen for the first time. An example is COVID-19
62
what are reemerging diseases and what are 2 examples?
Reemerging diseases are coming back after being gone for a long time.
Examples are measles and polio.
63
what are examples of things that can affect emerging/reemerging diseases?
-Microbial evolution
-Fears about vaccines
-Changes in human society/technology
-Population expansion and movements
-Mass distribution/importation of food
-Climate change
64
how does microbial evolution affect emerging/reemerging diseases?
it can cause:
-antibiotic-resistant strains
-spillovers from animals to humans
65
what about vaccines can cause emerging/reemerging diseases?
complacency or fears about vaccines
66
how can changes in human society/technology affect emerging/reemerging diseases?
-Daycares: facilitate the spread of disease
-Processed foods: if machines are contaminated, the food gets contaminated.
67
how does population expansion and movements affect emerging/reemerging diseases?
Through travel and expansion into areas inhabited by wild animals.
68
how can mass distribution/importation of food affect emerging/reemerging diseases?
It facilitates spread
69
how can climate change affect emerging/reemerging diseases?
it affects the distribution of vectors like mosquitos and ticks.
70
what percentage of patients develop HAIs/nosocomial infections?
5-15%
71
what are the reasons that patients develop HAIs?
if they are:
-Immunocompromised
-Around sick people harboring pathogens
-Around healthcare workers who are maybe healthy carriers
-In an environment that is a reservoir of pathogens, ex: pathogens
-Invasive devices (ventilators and catheters) and surgical procedures introduce new portals of entry.
72
how many HAIs are present annually in the US, and how many deaths?
722,000 infections and 75,000 deaths annually in the US according to the CDC study of acute care hospitals in 2011
73
what are the most common types of HAIs?
the most common HAIs are respiratory and surgical site infections
74
what is a UTI (what type of infection)? what is it due to?
UTIs are a type of HAIs and are due to the use of urinary catheters
75
what are common pathogens of HAIs?
1. E. coli and other intestinal bacteria (normal GI flora).
-Causes UTIs, wound, surgical site, and blood infections.
2. S. aureus (direct contact and asymptomatic carriers)
-Causes pneumonia, wound, and blood infections.
3. Other Staphylococcus spp. (normal skin flora)
-S. epidermidis can cause blood infections
4. C. difficile (fecal-oral)
5. Pseudomonas aeruginosa (moist environments)
-Grows in catheters and ventilators
-Causes UTIs, pneumonia, wound, and burn infections
76
what are two preventions of HAIs?
1. Infection control committee with hospital epidemiologist or infection control practitioners.
2. Standard Precautions (CDC)
77
what are standard precautions from the CDC to percent HAIs?
-hand hygiene!!
-personal protective equipment
-respiratory hygiene/cough etiquette
-patient placement - v. sick patients get quarantined
-equipment and instruments/devices: keep them clean
-care of environment - keep it clean
78
Name the emerging HAI:
A bacterium that spreads via endospores, causing a disease referred to as "antibiotic-associated diarrhea", which can be difficult to treat (although fecal transplantation can be used).
1. E. coli
2. Pseudomonas aeruginosa
3. Clostridioides difficile
4. Staphylococcus aureus
3. Clostridioides difficile
79
study the graph on the practice questions
80
Which mode of transmission of typhoid fever was seen in the case of “Typhoid Mary?”
1. Droplet transmission
2. Contaminated food
3. Vector-borne
4. Through the air
5. Via fomites
2. Contaminated food
81
A parenteral portal of entry is most likely in the case of:
1. A urinary tract infection
2. The common cold
3. A sexually transmitted disease
4. Food poisoning
5. A needlestick injury
5. A needlestick injury
82
Urinary tract infections that are acquired in the hospital setting are most often caused by:
1. E. coli
2. Staphylococcus aureus
3. Streptococcus pyogenes
4. Pseudomonas aeruginosa
5. Clostridium difficile
1. E. coli
83
Smallpox has been eliminated from the human population through:
1. Improved sanitation
2. Vector control
3. Vaccination
4. Antibiotic therapy
5. Control of animal reservoirs
3. Vaccination
84
Healthcare-associated infections (HAIs) AKA nosocomial infections are a big issue in today’s hospitals. As future health care professionals, please provide:
A definition of HAI
A list of reasons why HAI’s are common
Ways to prevent their occurrence
A healthcare-associated infection (HAI) is an infection acquired during the course of hospitalization or care in other healthcare settings. About 5-15% of hospitalized patients will develop an HAI and some may even die as a result. Some reasons why HAIs are so common include: 1) presence of pathogens (some of which are antibiotic resistant) in patients, medical devices and the environment, 2) crowding together of sick, immunocompromised people, 3) suppression of normal flora due to antibiotics or disease, 4) invasive procedures such as catheterization and surgery which open up new portals of entry to pathogenic bacteria and even normal flora, and 5) healthcare workers acting as healthy carriers of potentially pathogenic organisms. In order to prevent spread of HAIs, hospitals have an infection control committee with a hospital epidemiologist or infection control practitioner on staff. This person researches outbreaks and tries to trace their source. Potential reservoirs of infection include: other patients, healthcare workers, hospital environment and normal flora. Healthcare workers should follow Standard Precautions (including hand hygiene) as a minimum of infection control. More specific actions depend on the results of each specific investigation.
85
Which of the following is a possible origin of the organisms that cause healthcare-associated infections?
1. All of the answer choices are correct.
2. The patient's normal microbiota
3. Other patients
4. Medical personnel
5. Healthcare environment
1. All of the answer choices are correct.
86
In 1918-1919, an influenza virus infected about 500 million people worldwide, killing at least 50 million of them. This disease is best described as a(n) ________.
1. epidemic
2. endemic
3. sporadic
4. outbreak
5. pandemic
5. pandemic
87
A fly that walks on feces and picks up E. coli O157:H7 then lands on food and transfers the microorganisms, is considered a
1. fomite.
2. mechanical vector.
3. mechanical OR biological vector.
4. biological vector.
5. cross-contaminator.
2. mechanical vector.
88
Select the sequence that indicates the steps that occur in the chain of infection.
1. Transmission.
2. Susceptible host.
3. Reservoir of infectious agent.
4. Portal of exit.
5. Portal of entry.
3, 4, 1, 5, 2
89
Which of the following pathogens/diseases would be the easiest to eradicate?
1. A pathogen that causes disease in both animals and humans.
2. A pathogen that mostly infects animals but also sometimes causes disease in humans.
3. A pathogen that only infects humans and causes obvious signs and symptoms.
4. A disease that is asymptomatic and is carried by a large number of people in a population.
5. A pathogen that only infects humans and rarely causes signs and symptoms.
3. A pathogen that only infects humans and causes obvious signs and symptoms.
90
Which infectious disease was spread by Mary? What is the etiology of the disease?
The disease spread by Mary was Typhoid fever. It is caused by the Gram negative rod-shaped bacterium Salmonella serotype Typhi.
91
What are the symptoms of this disease typhoid?
Fever, Weakness, Stomach pain, Headache, Diarrhea or constipation, Cough, Loss of appetite.
92
How did Mary transmit the disease typhoid?
Fecal-oral route.
93
How could Mary have prevented the spread of the disease typhoid?
By washing her hands after using the bathroom.
