Final exam (advanced micro) Flashcards
(276 cards)
1
Q
Epidemiology
A
The study of the occurence, distribustion, and causes of health and disease in a population
2
Q
Population
A
Members of a city, country, region, or all members of a species
3
Q
Goals of epidemiology
A
Identify cause of a disease and its transmission
4
Q
Where do infectious diseases cause more deaths
A
Non-developed countries
5
Q
What accounts for nearly half of deaths in developing countries
A
Infectious disease
6
Q
Who challenged the idea of the cholera miasma
A
John Snow (english physician)
7
Q
What year did John Snow figure out the cause of cholera
A
1854
8
Q
Cause of cholera
A
Contaminated drinking water (not a miasma)
9
Q
Who is the pioneer in the field of epidemiology
A
John Snow
10
Q
Survaillance
A
Epidemiologists rely on this. The obervation, recognition and reporting of diseases as they occur
11
Q
Epidemiologists trace the spread of disease to identify its _____ and _____
A
Origen and mode of transmission
12
Q
What promotes the rapid spread of microbes today
A
Globalization
13
Q
Incidence
A
Number of new cases of a disease in a given period of time
14
Q
What is incidence used to predict
A
Risk of disease for an individual
15
Q
Prevalence
A
Total number of new and existing cases in a population in a given time
16
Q
What is prevalence used to measure
A
“total disease burden” in a population
17
Q
Epidemic
A
Occurs in an unusually large number of people in a population at the same time
18
Q
Pandemic
A
Widespread, usually worldwide (global)
19
Q
Endemic
A
Disease is constantly present in a population but usually at low incidences (not very virulent and many are immune)
Low but persistant number of cases
20
Q
Reservoirs
A
Individuals that are infected with a pathogen that causes endemic disease
21
Q
Sporatic disease
A
Occurs one at a time in geographically separated area, suggesting that the cases are not related
22
Q
Outbreak
A
Occurs when a number of cases of a disease are reported in a short period of time in an area previously experiencing only sporatic of endemic disease
23
Q
Subclinical infections
A
Diseased individuals who show no or mild symptoms (carriers), may be in the incubation period of the disease
24
Q
Can carriers spread the infection
A
Yes
25
Virulence
Relative ability of a pathogen to cause disease
26
What must a pathogen do to cause disease
Replicate and grow inside a host
27
How does a well adapted pathogen survive
Lives in balance with its host, takes what it needs but does not kill its host
28
Chronic infections
Host and pathogen survive
29
Example of chronic infection
Tuberculosis
30
Acute infections
Result in rapid and severe disease with a relatively quick return to health
31
Examples of acute infections
A new strain of influenza, food poisoining
32
Infection
The organism invades, colonizes and grows in the host
33
Incubation period
The time between infection and onset of symptoms
34
What is the incubation period determined by
Inoculum size, virulence, generation time of pathogen, resistance of host
35
Acute period
The disease is at its height with overt symptoms and signs
36
Decline period
Disease symptoms are subsiding
37
Convalescent period
Patient regains strength and returns to normal
38
Mortality
Incidence of death in a population
39
Morbidity
Incidence of disease, including fatal and nonfatal diseases
40
What is a better indicator of the health of a population, mortality or mrbidity? Why
Morbidity
| Not all diseases have a high mortality rate
41
Example of high morbidity infections with low mortality
the common cold, acute respiratory infections, acute digestive disorders
42
Example of low morbidity but high mortality
Ebola (mortality is 70% but number of cases are few)
43
What are mortality and morbidity used to indicate
Severity of a pathogen
44
Disability adjusted life year (DALY)
Measures disease burden (quality of life) in terms of lost years due to the disease, disability due to disease, and premature death
45
Herd immunity
Resistance of a group to infection due to immunity of a high proportion of the group
46
How do immunized people protect nonimmunized people
The pathogen cannot be passed on and the cycle of infectivity is broken
47
How are pathogens classified
By their mechanism of transmission
48
Mechanisms of transmission stages
- Escape from host
- Travel
- Entry into new host
49
Modes of pathogen transmission
- Person to person transmission
- Transmission via an inanimate object called a fomite
- Transmission via a living vector (ex: bugs)
50
Infectious disease reserviors
Sites in which infectious agents remain viable and from which individuals can become infected
51
Zoonosis
Disease the primarily infects animals but is occasionally transmitted to humans
52
Ex of zoonosis
Rabies
53
Can nonliving matter serve as a reservoir
Yes
54
Nonliving matter as reservoir example
Soil is a reservoir for clostridium tetani, the cause of tetanus
55
Types of epidemics
Common-source
| Host-to-host
56
Common-source epidemic
Usually arises from contamination of water or food that all affected individuals have ingested
57
What are common-source diseases typically
Intestinal diseases
58
Example of common source disease
Cholera
59
How do common source diseases occur
Pathogen exists in host fecal material which contaminates food or water supply. It enters the GI tract of the recipient
60
Mechanism of host-to-host epidemic
Slow progessive rise and gradual decline
61
Examples of host to host
Influenza and chicken pox
62
What leads to fairly rapid decline of new disease cases
Quick identification of the disease vehicle
63
How can distribution of an infectious disease change
Chnanges in pathogen, environment or the host
64
Emerging diseases
Diseases that suddenly become prevalent, includes diseases new to host and re-emerging
65
Borrelia burgdorferi disease and symptoms
Lyme disease
| Rash, fever, neurological and cardiac abnormalities, arthritis
66
Borrelia burgdorferi mode of transmission
Bite of infective lxodes tick
67
Borrelia burgorferi cause of emergence
Increase in deer and human populations in wooded area
68
Mycobacterium tuberculosis disease and symptoms
Tuberculosis
| Cough, weight loss, lung lesions
69
Mycobacterium tuberculosis mode of transmission
Sputum droplets (exhaled through cough or sneeze) from a person with active disease
70
Mycobacterium tuberculosis cause of emergence
Antimicrobial drug resistance as multidrug resistant and extensively drug resistant tuberculosis
71
Vibrio cholerae disease and symptoms
Cholera
| Severe diarrhea, rapid dehydration
72
Vibrio cholerae mode of transmission
Water contaminated with the feces of an infected persons, food exposed to contaminated water
73
Vibrio cholerae cause of emergence
Poor sanitation and hygiene, carried to non-endemic areas via infected travelers and commerce
74
Dengue symptoms
Hemorrhagic fever
75
Dengue mode of transmission
Bite from infected mosquito (Aedes aegypti)
76
Dengue cause of emergence
Poor mosquito control, increased urbanization in tropics, increased travel and shipping
77
Filovirus disease and symptoms
Marburg, Ebola
| Fulminant, high mortality, hemorrhagic fevers
78
Filovirus mode of transmission
Direct contact with infected blood, organs, secretions and semen
79
Filovirus cause of emergence
Contact with vertabrae reservoirs
80
Influenza H5N1 (avian) symptoms
Headache, fever, cough, pneumonia, high mortality
81
Influenza H5N1 mode of transmission
Direct contact with infected animals or humans, not easily spread via respiratory aerosols
82
Influenza H5N1 cause of emergence
Danger of animal-human virus reassortment, antigenic shift
83
Zika symptoms
Asymptomatic or fever, rash, muscle and joint pain, headache
84
Zika mode of transmission
Bite of an infected mosquito (aedes aegypti), mother to fetus, sexual contact, blood transfusion
85
Zika cause of emergence
Poor mosquito control, increased urbanization in tropics
86
Candida disease and symptoms
Candidiasis
| Fungal infections of the GI tract, vagina and oral cavity
87
Candida mode of transmission
Member of the endogenous microbiota becomes an opportunistic pathogen, contact with secretions or excretions from infected persons
88
Candida cause of emergence
Immunosuppression, medical devices (catheters), antibiotic use
89
Emergence factors
1. Dense urban populations
2. Economic development and changes in land use
3. Failure of sanitation measures
4. International travel and commerce
5. Changes in pathogens
6. Breakdown in public health measures
7. Decline in vaccination and inadequate public vaccination programs
8. Changes in weather patterns
9.
90
Dengue fever type of infection
Viral
91
Where is the dengue fever endemic to
Originally: SE Asia
Now: Puerto Rico, Brazil, Texas
92
How many types of dengue fever
4
93
Transmission of dengue fever
Two types of mosquito (aedes aegypti and aedes albopictus)
94
Is dengue passed from person to person
No
95
Early symptoms of dengue
High fever, headache, prosteration (decline in strength)
96
Later symptoms of dengue
Sharp pains in joints and sensations like bones are breaking (breakbone fever). Some have severe eye pain and rash
97
How long does dengue fever last
A week (immune response resolves infection)
98
Complactions in dengue fever
Unusual, unless one of 3 other types enters the body later
99
Why is infection with one of the other 3 dengue strains later worse
Immune system reacts to memory of first dengue infection allowing subsequent infections to replicate unchallenged
100
Resulting condition of new strain of dengue infection
Dengue hemorrhagic fever
101
Symptoms of dengue hemorrhagic fever
Bleeding from nose, gums, feces, and vomit
| Intense abdominal pain, respiratory diseases, decrease in blood pressure, coma
102
Treatment for dengue
Only therapy
103
Prevention of dengue
Insecticides and draining standing water, vaccines are in clinical trials
104
2. Economic development and changes in land use can promote spread of disease example
Lyme disease, residential reforestation and changes in land use
105
How does reforestation increase lyme disease
Reforestation increases deer habitat and consequently lyme-infected deer ticks
106
First lyme disease outbreak year
1975
107
Type of microorganism of borrelia burgdorferi
Bacterium (spirochete)
108
Lyme disease vector
Deer tick
109
Are deer resovoirs for lyme disease
No, only reproductive hosts
| Cannot be transmitted from deer to deer, deer to human or human to human
110
Asymptomatic resovoirs of lyme disease
Small rodents and birds (domestic animals can become ill)
111
Stages of untreated lyme disease
- Early localized stage
- Early dissemination stage
- Late stage
112
Early localized stage
3-31 days incubation peirod
- Bullseye rash (75%) at site of tick bite within 1 week
- Systemic infection resulting in chills, fever, aches, pains and flu-like symptoms
113
Can early localized stage of lyme disease be treated
Yes with antibiotics
114
Early dissemination stage
Weeks to months later
| - Can spread to heart (meningitis, irregular heart beat), nervous system, and joints
115
Late stage
Months to years later
| - Chronic arthritis and swelling in limbs and joints, weakness in limbs, vision problems and facial muscle problems
116
Is there a vaccine for lyme disease
Yes but removed from market because of poor sales, immunity wanes over time
117
3. Common source foodbourne disease epidemics when sanitation fails example
2009 e-coli 0157-H7 sickened and killed people in 8 US states due to a single meat processing plant that had contaminated ground beef
118
4. International travel spread of pathogens examples
- TB from infected individual to 34 passangers on flight from Russia to NYC
- Spread of West Nile infection in the US
119
Mycobacterium tuberculosis characteristics
Small, aerobic, nonmotile rod with waxy coating that enhances resistance to disinfectants and many antibiotics
120
Transmission of TB
Air droplets
121
Target tissue of TB
Aleveoli
122
Distinguishing symptoms of TB
Cough, weight loss, fatigue, fever, breathing pain, night sweats
123
Primary TB infection
Pathogen enters alveloi
124
Test for primary TB infection
Positive tuberculin reaction but negative x-ray and sputum test
125
How tubercles visible in chest x-ray are formed
Macrophages ingest bacterium but cannot destroy them, bacteria multiply inside white blood cells. Lymphocytes and fibroblasts surround mass in lung forming hard nodule
126
What percent of primary TB cases progress to latent (dormant) TB
90%
127
Latent TB
Tubercules heal and undergo fibrosis and calcification. Asymptomatic but chest x-ray is positive. 90% do not develop active disease and will not be infectious
128
What will TB in weakened immune system
Secondary active TB
129
How common is secondary active TB
10%
130
Secondary active TB
Reactivation of bacilli (rupture from tuburcles, multiply and spread),
131
Secondary active TB symptoms
result in symptoms such as chronic cough, chest pain, high fever, expel sputum, positive tuberculin reaction, chest x-ray and sputum test
132
Can bacteria spread in secondary active TB
Yes, through blood and lymph to other organs like the liver, meninges, and bone
133
Milinary/disseminated TB
Active tubercles develop throughout the body, seen in AIDS patients
134
Leading cause of death in AIDS patients
TB
135
Are toxins produced in TB
No
136
How does TB kill
No toxins but growth is unrelenting, body tissue is literally consumed
137
Treatment of TB
Multiple antibiotics for 6-9 months and vaccine (BCG)
138
MDR-TB (multidrug resistance TB)
5% of new cases
139
XDR-TB (extensively drug resistant TB)
Resistant to almost all drugs (very few treatment options remain, prognosis depends on severity and patient's immune system)
140
Detection of TB
1. Injection of purified protien derivative under skin
2. Chest x-ray
3. sputum test
141
Evidence TB is a population wiper
Found in 4,400 y/o egyptian mummies
142
Where does TB result in more deaths than any other infectious disease
Developing nations
143
How many new cases of TB each year and how mant deaths
10 million new cases
| 3 million deaths
144
TB incubation period
About 8 weeks (generation time is 8 hours)
145
Who first isolated mycobacterium tuberculosis and when
Robert Koch in 1882
146
5. Changes in pathogens - what causes changes
- Horizontal gene transfer
- Mobile genetic elements
(enhance virulence and multidrug resistance)
147
What types of viruses mutate rapidly
RNA viruses (influenza and hemorrhagic fever viruses)
148
What do RNA virus mutations change
Surface antigens (viral proteins). Immunity to old viral antigens does not protect against new mutated strains
149
6. Breakdown in public health measures disease example
Cholera
150
How to prevent cholera
Effective sewage and water treatment
151
Cholera outbreak in Haiti
2010, caused by earthquake- contaminated water supply
152
Main symptom of cholera
Extensive diarrhea (leads to dehydration)
153
What causes shock and coma in cholera
Body cannot retain fluids so blood is thickened (sluggish bloodflow to brain)
154
When does death occur due to cholera if untreated
Within 24 hours
155
V. cholerae characteristics
Gram -, motile, curved rod
156
Ingestion of small amounts of cholera
Destroyed by stomach acid
157
Ingestion of millions of cholera
Cells survive and colonize intestines
158
Does cholera secrete a toxin
Yes (enterotoxin)
159
Cholera treatment
Tetracycline, intravenous injections of salt solutions (or sugar/electrolyte)
160
Prevention of cholera
Immunization with dead C. cholerae cells
161
7. decline in vaccination or inadequate public vaccination programs disease caused
Pertussis
162
Common name of pertussis
Whooping cough
163
Causative agent of whooping cough
Bordetalla pertussis
164
Bordetalla pertussis characteristics
Gram -, aerobic, bacillus with pili
165
Whooping cough target tissue in host
Aggregates on cilia of epithelial cells in mouth and throat. Exotoxin paralyzes cilia and impairs mucus movement. Disintegrating cells and mucus accumulate and cause labored breathing (pneumonia)
166
Symptoms of whooping cough
Prolonged and spastic coughing that often ends in a characteristic gasp (whoop)
167
Whooping cough treatment
Antibiotics (erythromycin)
168
Prevention of whooping cough
Vaccination (protection wanes over time, adolescents and adults are suseptable)
169
What is the whooping cough vaccine
Part of DTaP vaccine (diptheria and tetanus toxoids plus acellular pertussis chemical extracts)
Tdap booster for adolescents and adults
170
Nickname for whooping cough
100 day cough
171
Why are the number of cases of whooping cough increasing
Increased virulence of bacteria
172
8. Changes in weather patterns
- Changes migration of mosquitos (dengue fever is now in US)
- Mild and rainy winter led to increase in rodents with hantavirus
173
How to contain an outbreak
Isolation, quarentine and immunization
174
Acute LRT infection
Influenza
175
Influenza family
Orthomyxoviridae
176
Influenza genome
-ssRNA (8 helical segments each surrounded by a capsid), additional structural protein surrounds RNA segments
177
Influenza capsid structure
2 types of spikes
178
Types of spikes
Hemagglutin (80%)
| Neuraminidase (20%)
179
Hemagglutin
(H) helps the virion attach and penetrate host cells, determines hot range (key)
180
Neuraminidase
(N) helps release virions from the host cell after replication and assembily (sword)
181
Envelope in influenza?
Yes
182
First recorded influenza epidemic
1510
183
How many recorded pandemics of influenza
31
184
How many types of influenza are there
3
185
Types of influenza
A, B and C
186
Influenza A
Strikes every year and causes most epidemics
187
Hosts for influenza A
Birds, pigs and humans
188
What are subtypes of influenza A based on
17 antigenically different types of H spike proteins (H1-17) and 10 different N spike proteins (N1-N10)
189
Incubation period of Influenza A
1-4 days
190
How long until influenza A resolves
7-10 days
191
Influenza B
Strikes every year but is less common than type A
192
Hosts of influenza B
Humans only
193
Influenza C
Mild respiratory illness but not epidemics
194
Why is there a new flu vaccine every year
New flu strain evolves every year
195
Complications of flu
Pneumonia or secondary infections (infants, elderly and immunocompromised) --> accounts for most seasonal flu deaths
196
Guillian-Barre
Occurs when the body "mistargets" the infection and damages its own peripheral nerve instead (muscle weakness and possible paralysis)
197
Guillian-Barre occurance rate
1 case per 100,000
198
Reye syndrome
Occurs in children who take aspirin to treat pain and fever
199
Reye syndrom symptoms
Nausea, vomitting, mental confusion, delirium
200
Who do DNA viruses have a lower rate of mutation
Ability of cell to proofread and correct errors that have occurred during replication (cells have DNA proofreading mechanisms)
201
Why do RNA viruses mutate more
No RNA proofreading mechanism in cells
202
Antigenic drift
Results in small changes to protein spikes and suble change in shape
203
Cause of antigenic drift
Minor point mutations that occur during replication of the viral RNA genome
204
What is responsible for new seasonal strains of the flu
Antigenic drift
205
True or false, immunity is complete in antigenic drift
False
206
What creates new strains
Genetic recombination
207
Gene swapping
In influenza pieces of RNA genome of 2 separate viruses that infect the same cell become associated, changes surface antigens
208
Antigenic shift
Major abrupt change in structure of influenza A (H and N spikes) due to gene swapping
209
Cause of pandemics
Antigenic shift
210
Where do human and avian viruses often reassort
Pigs
211
Is there immune recognition after antigenic shift
No
212
Antigenic drift changes to spike protein
Subtle, individuals may have partial immunity
213
How often do influenza pandemics occur
Every 10-40 years
214
Most devestating influenza pandemic year
1918
215
How many people infected and dead from 1918 flu
Half billion infected
| 50 billion dead
216
Strain of flu in 1918
H1N1
217
Most recent flu pandemic
March 2009
218
March 2009 flu pandemic
Began in Mexico, spread to almost every country within 6 months
219
How many infected and dead in 2009 flu
60 million in US infected
| 3400 dead
220
Cause of 2009 flu
Hybrid strain of H1N1 (genes from bird, swine and human influenza viruses)
221
Where was H5N1 originally found
Birds in Hong Kong, from chicken to duck to human
222
Outbreaks of H5N1 location
Egypt, Indonesia, Cambodia, Bangledesch, China
223
Number of cases and deaths from H5N1 in 2014
638 cases, 379 deaths (mortality rate of 60%)
224
Poliovirus family
Picornaviridae
225
Genome of polio
+ssRNA (immediately translated)
226
Symmetry of polio
Icosahdral with no envelope
227
Target tissue of polio
CNS
228
Where does polio enter
Mouth
229
Where does polio multiply
Intestines and throat
230
What does polio target after entering the bloodstream
Motor neurons and CNS
231
What animals can polio infect
Humans only
232
How is polio spread
Person to person contact, very contagious (contact with feces, sneeze and cough). Can contaminate food and water
233
When can disease be spread by infected person
Immediately before onset of symptoms and 1-2 weeks after symptoms
234
How many strains of polio
3
235
Type 1 polio
Causes most epidemics (sometimes paralysis)
236
Type 2 polio
Less frequent (causes paralysis)
237
Type 3 polio
Remains in GI tract
238
Poliomyelitis
Paralytic disease, only people with paralytic infection have the disease
239
Subclinincal polio infections
Most people asymptomatic (72 of 100) but can still pass to others
240
Symptoms of polio nonparalytic infection
Sore throat, fever, tiredness, nausea, headache, and stomach pain (flu like)
241
How long does it take symptoms to resolve on their own in nonparalytic polio
2-5 days
242
How many people deveop meningitis from polio
1 in 25
243
How mant people develop paralysis or weakness in arms and legs from polio
1 in 200
244
Paralytic bulbar polio
Affects medulla of the brain
245
How many people with paralytic polio die from respiratory paralysis
2-10 of 100
246
Post polio syndrome (PPS)
May affect polio survivors 15-40 years after recovery form initial infection
247
PPS health problems
Muscle weakness, fatigue, pain from joint deterioration
248
PPS frequency
Affects 25-40 out of 100 polio survivors
249
Is PPs life threatening
No but it affects quality of life
250
Is PPS contagious
No
251
Vaccines to prevent polio
Inactivated polio virus vaccine (IPV)
| Attenuated oral poliovirus vaccine (OPV)
252
Jonas Salk
Produced first polio vaccine in 1955 by inactivating virus with formaldyhyde
253
Albert Sabin
Produced live but attenuated vaccine, oral administration
254
Which vaccine is used in United states
Only IPV
255
Where is OPV used
Throughout the world (volunteers administer)
256
Trivalent OPV and IPV protect against...
Types 1,2 and 3
257
Bivalent OPV targets...
Types 1 and 3
258
Switch to bOPV
tOPV can lead to paralysis
259
Vaccine associated paralytic poliomyelitis (VAPP)
Polio caused by OPV
260
Circulating Vaccine Derived Poliovirus (cVDPV)
Mutated versions of OPV which can cause paralysis and spread from person to person. Almost all are type 2
261
When was wild poliovirus eradicated globally
1999
262
Does IPV cause VAPP or cVDVP
No
263
When should children be vaccinated for polio
4 times: 2 months, 4 months, 6-18 months and booster at 4-6 years
264
What ages are most affected by polio
Under age 5
265
What percent of people with paralytic polio die
5-10%
266
How many people used to become infected with paralytic polio per year
350,000
267
What percent have polio case numbers decreased by
99%
268
Countries where polio is endemic
Afghanistan, Nigeria and Pakistan
269
Why is polio endemic in these countries
Insecurity, weak health systems, poor sanitation
270
When was type 3 polio last seen
2012
271
Partners of polio eradication
```
WHO
Rotary international
CDC
UNICEF
Gates foundation
```
272
How many children have been immunized against polio
20 billion
273
When and where was the last polio paralysis
India 2011
274
When was SE Asia declared polio free
2014
275
When did polio outbreaks increase in frequency in the US
1940s-50s
276
How many people did polio cripple in the US each year
35,000
