Virology, Immunology, and Epidemiology Flashcards
1
Q
Non-specific immune defenses
A
- physical and chemical (skin and mucous membranes)
- inflammation/fever
- natural killer cells
- protective proteins (interferons)
2
Q
Specific immune defenses
A
immunity created by white blood cells
3
Q
Phagocytes
A
engulf and destroy pathogens; 2 kinds
1) neutrophils
2) macrophages
4
Q
Neutrophils
A
type of phagocyte that remains in the blood
5
Q
Macrophages
A
type of phagocyte that leaves blood and enters tissues and organs
6
Q
Lymphocytes
A
recognize, destroy, and remember pathogens; 2 kinds of
1) B Cells
2) T Cells
7
Q
B Cells
A
make antibodies that bind to unique antigens displayed in foreign pathogens; “patrol” in blood
8
Q
Antibodies
A
1) neutralization - block binding sites on virus so they can’t bind and invade own cells
2) clumping - antibodies can bind multiple antigens, clumping pathogens together
3) signal to phagocytes and lymphocytes to destroy clumps
9
Q
T Cells
A
3 kinds:
1) helper
2) killer
3) suppressor
10
Q
Helper T Cells
A
recognize antigens; signal to other white blood cells to attack
11
Q
Killer T Cells
A
destroys infected cells
12
Q
Suppressor T Cells
A
stops the immune response
13
Q
Major histocompatability complex (MHC)
A
- proteins on the surface of every cell in the body
- are unique to each individual
- serve as signals by which the body recognizes self from non-self
- important in organ transplants
14
Q
Antigens
A
- any substance that can stimulate the body to mount an immune response
- they are the “markers” on the surface of a pathogen (virus, bacteria, etc.) which allow the body to identify it as not belonging
- same concept as MHC
15
Q
Recognition
A
foreign antigens are recognized in 2 ways:
1) when they bind to antibodies in our bloodstream
2) when phagocytes “eat” pathogens and display the antigens on the surface of their cells
16
Q
Types of antibodies
A
- IgG
- IgA
- IgM
- IgE
17
Q
Presence of antibodies (meaning)
A
if antibodies are present in the body, it means one of 3 things:
1) you are currently sick
2) you were previously sick and recovered
3) you were vaccinated
18
Q
IgG
A
- most common antibody in the bloodstream and can cross the placenta
- binds to pathogens, activates phagocytes
19
Q
IgA
A
- found in saliva and breast milk
- prevent pathogens from attaching to body cells in the digestive tract and respiratory tracts
20
Q
IgM
A
- found in bloodstream
- help immobilize pathogens so they can’t move through the bloodstream (clumping)
21
Q
IgE
A
- found on mast cells primarily
- responsible for allergic reactions
22
Q
Specificity
A
WBC bind to foreign antigens which then produce a receptor that is specific to each antigen shape
23
Q
Diversification of WBC
A
humans encounter millions of different antigens in their lives that all require unique/diverse B and T cells for each one
24
Q
Memory (function)
A
after an immune response, there are B and T cells which remain and circulate through the body which have “memorized” that particular disease and antigen so if that pathogen invades again, the immune response with be so quick and strong that it one doesn’t realize they’re sick
25
Memory (weakness)
only works with viruses or bacteria which do not mutate (chicken pox doesn’t mutate, but the cold virus mutates quickly)
26
Early notions of what causes disease
- punishment from God
- demons (because of foul odors)
27
Modern understanding of what causes disease
disease is caused by microorganisms such as bacteria and viruses
28
What makes something a virus?
- unicellular (not considered living)
- cannot divide on their own, grow on their own, or move on their own
- can only replicate inside a host cell
- composed of nucleic acid (DNA or RNA) and capsid (protein coating)
29
Lytic Cycle (viral reproduction)
virus invades cell and destroys cell's DNA and the virus takes over the metabolism of the cell in order to replicate the virus, enzymes in the virus cause the cell to lyse, releasing virus particles that can infect new cells
utilized by: polio, cold, etc
30
Lysogenic Cycle
the virus may enter through a lytic stage and destroy the host cell OR enter into a new dormant phase where the cell keeps replicating with the virus's DNA floating in the cytoplasm
utilized by: herpes, HIV, etc
31
Epidemiology definition
the study of disease in a population (bacterial or viral)
32
Sporadic
disease occurs occasionally in a small population
ex: West Nile virus in Florida, Hepatitis A in a particular city
33
Endemic
diseases that are constantly present in a population
ex: common cold, malaria
34
Epidemic
many people in a given area that are infected in a relatively short time
ex: ebola virus in Africa
35
Pandemic
an epidemic disease that occurs worldwide
ex: influenza, smallpox, bubonic plague, COVID-19
36
Direct Transmission
- biting, sneezing (directly in someone's face), coughing, sexual contact
- contact is direct from one PERSON to the next
37
Indirect Transmission
- vehicle borne
- vector borne
- airborne
38
Vehicle-borne
- non-living
- spoiled food or contaminated water
39
Vector-borne
- living
- on or in an insect, rodent, or other non-human
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Airborne
- aerosols
- sneezing (a sneeze from across the room that travels by air)
41
Emerging Infectious Disease (EID)
a new or changing disease that shows an increase in occurrence
42
Factors contributing to EID
- widespread use of antibiotics and pesticides
- global warming may increase survival rates of viruses
- modern transportation (extreme travel over a short period of time)
- natural disasters (disturbances in the earth)
- war (soldiers become exposed to foreign diseases)
- rising numbers of some animals
- poor vaccination efforts by poor or uneducated populations
- cutting down rainforests or invading other natural areas of the environment
43
Influenza (transmission)
Direct and airborne transmission through saliva
44
Influenza (symptoms)
- 100-104 fever
- body aches
- fatigue
- cough
- congestion
45
Influenza (prevention/treatment)
Annual flu vaccine is based on previous year's 3-5 most common strains seen in Asia in the spring
46
Influenza (information)
- hundreds of types
- mutates very quickly
- human can be infected by pig, bird, or human strains
- 2 types of antigens on surface of virus (Hemagglutinin and Neuraminidase) which are used to name the strain
47
1918 Spanish Influenza Pandemic (1918)
In March of 1918 in Camp Funston, Kansas, 1100 soldiers out of 56000 recruits were hospitalized within 3 weeks; severe illness in 20% of cases in Europe and the US; lungs filled w/ fliud causing chest pain and bleeding; some died within 12 hours of symptoms
48
1918 Spanish Influenza Pandemic (2005)
Virus particles were recovered from the lung tissue of a dead body found in Alaska from 1918; virus was found to be H1N1 (of avian origin)
- virus levels were 39000 times greater than normal flu
- caused cytokine storm
- lethality 100x greater than other flu
- no other human influenza viruses have shown this level of virulence in mice
49
Why to large pandemis occur every 10-20 years?
The virus undergoes antigen shifts; every 10-20 years there is a genetic change that is so radical that the human immune system can't identify it as an influenza virus
50
Avian Influenza A (transmission)
Humans got the virus via bird feces (vehicle borne indirect transmission)
51
Avian Influenza A (source)
- found in migratory aquatic birds
- first emerged in China in 1996
52
Avian Influenza A (information)
- highly pathogenic (almost 100% mortality rate in birds)
- no known cases of human to human transfer
- creates a cytokine storm
- would have been worst flu pandemic if airborne transmission was possible
53
What make a virus most effective?
1) airborne transmission
2) long incubation period/slow to show symptoms
3) mutates frequently
4) survives for long periods in environment
5) jumps species
6) high transmission rate
7) causes a cytokine storm
8) high mortality rate
54
Rabies (transmission)
Vector transmission
- animal bite where saliva is transferred to an open wound
- worlwide, dogs are most common carrier
55
Rabies (symptoms)
- frothing at the mouth and hydrophobia
- headache, fever, and nausea
56
Rabies (prevention/treatment)
- vaccine, but prior to symptoms
- Fond du Lac girl was the first to have survived with no vaccine treatment
57
Rabies (information)
Infects the nervous systems and salivary glands
58
West Nile Virus (information)
- infects various areas involving the nervous system
- most infections are mild
59
West Nile Virus (transmission)
Vector transmission by mosquito
60
West Nile Virus (symptoms)
- most patients have malaise, loss of appetite, eye pain, and vomiting
- few patients develop paralysis, inflammation of brain and/or heart muscles
61
West Nile Virus (prevention/treatment)
- use bug spray with DEET
- don't allow atanding water to prevent mosquitoes from having habitats to hatch
- IV fluids and rest
- respirator in extreme cases
62
Polio (information)
Infection of brain and spinal cord
63
Polio (transmission)
Vehicle borne transmission by water or food
- humans are the only known reservoir of polio
- virus can remain in water or food for a long time
64
Polio (symptoms)
- paralysis
- fever, back pain, and muscle spasms
65
Polio (prevention/treatment)
- infant vaccination
- 2 vaccines (Salk - dead virus, and Sabin - weakened, but alive virus with rare risk of disease from vaccine)
66
Hepatitis (information)
Inflammation of the liver
67
Hepatitis A
- most common
- doesn't cause chronic sickness
- transmitted via fecal-oral route (common in restaurants)
- doesn't cause permanent liver damage
68
Hepatitis B
- more severe than A
- 10% become chronically sick
- transmitted via blood and bodily fluids
69
Hepatitis C
- most severe
- 50% become chronically sick
- transmitted via blood
- causes permanent liver damage
70
Hepatitis (symptoms)
- jaundice
- nausea, diarrhea, abdominal pain, lack of appetite
71
Hepatitis (prevention/treatment)
- no cure
- vaccine as preventative for type A and B
72
Smallpox (transmission)
Airborne or direct transmission
73
Smallpox (symptoms)
- severe rash
- infects internal organs first and then displays on the skin
74
Smallpox (prevention/treatment)
- first disease to have a vaccine
- only 2 living sources DOCUMENTED in the world (in the US at the CDC, in Russia at Vector)
75
Smallpox (information)
- no animal host
- in the middle ages, 80% of the population of Europe caught it
- 20% mortality rate but scars horribly
76
Hantavirus (information)
- cardiovascular virus
- found mostly in desert areas
77
Hantavirus (transmission)
Vector transmission by rodent feces or urine
78
Hantavirus (symptoms)
- victim has trouble breathing and drowns in own blood
- flu-like symptoms and a few days later, symptoms get worse and include severe iritation of the lungs caused by leaking capillaries
79
Hantavirus (prevention/treatment)
- no prevention/treatment
- 70% mortality rate in the worst viral strain which was found first in the Four Corners region of the US
80
Measles (transmission)
Airborne or direct transmission
- transmission rate of 18 (the highest of all viruses)
81
Measles (symptoms)
- cold-like for a few daysand then rash starts 8-10 days later
- contagious the whole time
- can be deadly in infants and elderly populations
- often causes blindness
82
Measles (prevention/treatment)
Can be prevented by the MMR vaccine
83
How do vaccines work?
- can be made from type of antigen or cells from a virus or bacteria
- vaccine is then injected into the bloodstream where an immune response starts
- the immune response results in the formation of memory cells
84
Edward Jenner (Scottish doctor in the 1700s)
- discovered that cows got a disease called cowpox - similar to smallpox
- farmers that got cowpox were immune to smallpox
- invented the first vaccine
- VACCA = COW in latin
85
Types of Vaccines
1) Kill Organism/Use ONLY Antigen
2) Weaken the Organism
3) Use Toxins
4) mRNA
86
Kill Organism/Use ONLY Antigen
- kills the pathogen or use only the antigen and inject
- only a mild immune response
- may require a booster later on
- safe for immunosuppressed patients
87
Kill Organism/Use ONLY Antigen (examples)
1) Rabies
2) Polio
3) Influenza
4) Hepatitis B
88
Weaken the Organism
- age the pathogen or alter its growth conditions
- pathogen is still able to replicate (not as virulent) so they cause a strong immune response
- may be able to mutate back to a strong (virulent) form
89
Weaken the Organism (examples)
1) MMR
2) Chicken pox (varicella)
90
Use Toxins
- toxins are very strong... too strong and are often treated with aluminum to decrease harm
- use a toxin (harmful product that actually causes disease) produces by the germ
- create immunity to parts of the germ itself
- immune response targeted to toxin instead of the whole germ
- causes a low level immune response (need boosters)
- often administered with an "adjuvent" to increase the response
91
Use Toxins (examples)
1) DPT (pertussis as an adjuvent)
92
mRNA Vaccine
- a person receives mRNA that encodes the viral protein
- the injection of the genetic instructions causes the muscle cells to translate them to make the viral protein directly in the body
- this approach mimics what the SARS-CoV-2 does in nature
- only codes for the critical fragment of the viral protein
- this gives the immune response a preview of what the real virus looks like without causing disease
- gives the immune system time to design powerful antibodies that can neutralize the real virus if the individual is ever infected
93
Herd Immunity
- helps to protect vulnerable populations in society (young, elderly, immuno-compromised, etc)
- when the entire population gets vaccinated against disease, it essentialy takes the virus out of the equation
- lowers the the number of people prone to be infected and then pass it on (lowers the spread of a disease)
94
Basic Reproduction Number (R0)
- the number of new infections originating from a single infectious person among a total susceptible population
- measures how many people would be infected by one person if no one had immunity and there was no intervention
- the greater the R0, the larger the expected epidemic is among a given population
95
3 Prerequisites for a Pandemic
1) New influenza virus emerges from animal reservoirs/viral mutation
2) capable of causing disease/illness in humans
3) easily spread from person to person
