Block 11 - L12-L13 Flashcards
1
Q
What are arboviruses?
A
Group of RNA viruses classified together based on their mode of transmission by insects and arthropod vectors
2
Q
What are vectors?
A
The animals/insects (arthropods) that transmit a virus
3
Q
What are reservoirs?
A
The hosts in which a prolonged viremia allows the natural cycle to continue
4
Q
Why aren’t all “viremic” viruses transmitted by mosquitos?
A
The virus from the blood meal must infect the mosquito itself, which transmits viral particles in its saliva
5
Q
True or false - arboviruses multiply in both vertebrates and arthropods.
A
True
6
Q
Describe the four major cycles by which arboviruses are transmitted.
A
- Jungle cycle - virus cycles between an arthropod and a mammalian host with man (or horses?) usually a dead-end host infected by the arthropod
- Urban cycle - virus cycles between man and an arthropod species (usually caught from an arthropod who was previously in a jungle cycle)
- Insect -> goat -> insect -> rodent -> insect -> man (dead end); man can also get this from the goat’s milk
- ?
7
Q
List the three clinical syndromes associated with arbovirus infection.
A
- Undifferentiated/rash fever (high fever, headaches, myalgias, arthralgias, malaise - 3-10 days, resolve without sequelae)
- Encephalitis (fever, headache, stiff neck, altered consciousness, seizures, strokes, can have permanent neurologic sequelae)
- Hemorrhagic fever (#1 + profuse bleeding into the skin and GI tract secondary to DIC, hypotension, shock, and leukopenia)
8
Q
Discuss the pathogenesis of arbovirus infection.
A
The mosquito introduces the virus directly into the bloodstream. There is a prodrome, followed by severe or life-threatening disease (if the immune system does not mount a sufficient response)
9
Q
How is arbovirus infection detected?
A
RT-PCR or serology
10
Q
How is arbovirus infection prevented and controlled?
A
- Breakage of transmission cycle (eradicate vector with insecticides)
- Avoidance of endemic areas
- Immunization (yellow fever)
11
Q
What type of virus causes Yellow Fever?
A
Positive strand RNA, enveloped virus: Flavivirus
12
Q
How is Yellow Fever usually transmitted?
A
Vector - insect
Reservoir - monkeys
Humans can serve as a reservoir for urban cycle
13
Q
How is Yellow Fever typically diagnosed?
A
Clinical diagnosis by common presentation and travel history. Confirmation by serology (detect NS1 protein with ELISA) by the public health department
14
Q
What is the pathogenesis of Yellow Fever?
A
Viremia resulting in extensive viral replication in the liver
15
Q
How do you treat a patient with Yellow Fever?
A
Supportive care
16
Q
Is there a vaccine currently available for Yellow fever?
A
Live-attenuated vaccine (YF17D)
17
Q
Are there any major consequences to Yellow Fever infections?
A
Long-term immunity and fatality
18
Q
What are the primary symptoms of Yellow Fever?
A
Fever and jaundice
19
Q
What is the most severe manifestation of disease associated with Dengue virus?
A
Hemorrhagic fever/break bone fever (headache, backache, fever, pains, in joints, muscles, eyeballs, maculopapular eruptions)
20
Q
How is Dengue virus usually transmitted?
A
Vector - mosquito
Reservoir - monkeys
Humans can serve as a reservoir for urban cycle
21
Q
In places endemic with Dengue virus, what is the laboratory test of diagnosis?
A
ELISA of serum for NS1
22
Q
What is the pathogenesis of Dengue?
A
Immunopathogenesis causing fever and rash
23
Q
Are there any effective therapies against Dengue virus?
A
No
24
Q
Is there an effective vaccine currently available for Dengue virus?
A
No vaccines are currently available; development of a live-attenuated tetravalent vaccine is ongoing
25
Are there any major consequences to Dengue virus infections?
Ab dependent enhancement of disease if infected with another serotype
26
What type of virus causes Dengue fever?
Flavivirus, positive enveloped single stranded RNA
27
What is the most common cause of epidemic encephalitis in the USA?
West Nile Virus
28
How is West Nile virus usually transmitted?
Mosquito vector with marsh bird reservoir; humans can serve as a reservoir for urban cycle
29
How is West Nile Virus typically diagnosed?
Serology and/or RT-PCR
30
What is the pathogenesis of West Nile Virus?
Viremia leading to infection of the CNS
31
Are there any effective therapies against West Nile Virus?
No
32
Is there a vaccine currently available for West Nile virus?
No; vaccine is in development (chimeric vaccine with YF17D, envelope proteins of WNV - subunit vaccine)
33
What population is most likely to exhibit severe disease after West Nile virus infections?
Adults over 50 y/o
34
What type of virus causes WN encephalitis?
Flavivirus, positive enveloped single stranded RNA
35
What are the symptoms of Zika infection?
Fever, headaches, conjunctivitis, ganglion cysts, rash, joint and muscle pain
36
How is Zika transmitted?
Mosquitos to humans, can be transmitted from mother to baby during pregnancy (can cause microcephaly); can also be transmitted in semen
37
What is the second most common cause of epidemic encephalitis in the US?
St. Louis Encephalitis Virus (second to WNV)
38
What is the family and genome of St Louis Encephalitis Virus?
Single stranded positive RNA Flavivirus
39
What is the reservoir for St Louis Encephalitis Virus?
Vector - mosquito
Reservoir - marsh bird
Man can serve as a reservoir for urban cycle
40
How is St Louis Encephalitis Virus typically detected?
Serology and/or RT-PCR
41
What is the pathogenesis of SLEV?
Viremia leading to infection of the CNS
42
Are there any effective therapies against St Louis Encephalitis Virus?
No
43
Is there a vaccine currently available for St Louis Encephalitis virus?
No
44
Are there any major consequences to St Louis Encephalitis virus infections?
Long-term immunity
45
What is the family and genome of Eastern Equine Encephalitis Virus?
Single stranded positive RNA Togavirus
46
How is EEE virus usually transmitted?
Mosquito vector with a marsh bird reservoir; man and horses are a dead-end host (short viremia)
47
What is the current laboratory test for diagnosis of EEE Virus?
Serology and RT-PCR by the Public Health Department
48
What is the pathogenesis of EEE viral infection?
Viremia leading to infection of the CNS
49
Are there any effective therapies against EEE Virus?
No
50
Is there a vaccine currently available for EEE virus for humans?
No
51
Are there any major consequences to EEE viral infections?
Fatality or long-term immunity
52
What is the most striking manifestation of Chikungunya virus infection compared to other arboviruses?
Arthralgia
53
How is Chikungunya virus usually transmitted?
Insect vector (mosquitos)
Reservoir - bird
Man can serve as reservoir for urban cycle
54
How is Chikungunya Virus typically diagnosed in the United States?
Serology and PCR by the public health department
55
What is the pathogenesis of Chikungunya virus infection?
Viremia leading to polyarthralgia and rash
56
Are there any effective therapies against Chikungunya Virus?
No
57
Is there a vaccine currently available for Chikungunya virus?
No
58
Are there any major consequences to Chikungunya viral infections?
Polyarthralgia can last weeks to months
59
What is the family and genome of the LaCross and California Encephalitus Virus?
Bunyaviridae, negative segment RNA, enveloped
60
How is the LaCross virus transmitted?
Vector - mosquitos
Reservoir - small mammals (squirrel and chipmunk)
Humans are dead end hosts
61
Compare the geographical distribution of Eastern Equine, St. Louis, and LaCrosse viruses.
EE - East, Gulf Coast, South
SL - Central, West, South
LC - Central, East
62
Compare the affected age group of Eastern Equine, St. Louis, and LaCrosse viruses.
EE - children
SL - adults > 50 y/o
LC - children
63
Compare the mortality of Eastern Equine, St. Louis, and LaCrosse viruses.
EE - 50-75%
SL - 2-20%
LC - <1%
64
Compare the sequelae of Eastern Equine, St. Louis, and LaCrosse viruses.
EE - 80% of survivors have sequelae
SL - 20% of survivors have sequelae
LC - low risk of sequelae
65
Compare the symptoms of Eastern Equine, St. Louis, and LaCrosse viruses.
EE - headache, altered consciousness, seizures (fulminant)
SL - headache, N/V, disorientation, stupor, irritability
LC - seizures, paralysis, focal weakness
66
What are the common symptoms when infected with Colorado Tick Fever Virus?
Fever and myalgia
67
How is Colorado Tick Fever usually transmitted?
Tick bite
68
What Laboratory test is used to diagnose Colorado Tick Fever?
Serology by the public health department
69
What is the pathogenesis of Colorado Tick Fever?
Viremia resulting in inflammation and rash followed by recovery
70
Are there any effective anti-viral therapies for Colorado Tick Fever Virus?
No
71
Is there a vaccine currently available for Colorado Tick Fever Virus?
No
72
Are there any major consequences to Colorado Tick Fever infections?
Long-term immunity
73
Colorado tick fever virus belongs to what viral family?
Reoviridae
74
What is the most common manifestation of disease associated with Ebola virus?
Hemorrhagic fever
75
How is Ebola usually transmitted person to person?
Direct contact with infected blood or body fluids
76
How is Ebola typically diagnosed in the United States?
RT-PCR from the sera
77
What is the best way to describe the pathogenesis of Ebola?
Viremia resulting in extensive viral replication and cell death and organ failure
78
How do you treat a patient with Ebola?
Supportive care
| Compassionate use of non-FDA approved anti-virals or neutralizing monoclonal Ab
79
Is there a vaccine currently available for Ebola?
No
80
Are there any major consequences to Ebola infections?
Fatality, persistent infection, or recovery with long-term immunity
81
What family of viruses does Ebola belong to and how does it appear on EM?
Filovirus, negative strand RNA, shepherd's hook
82
What are the likely reservoir of filoviruses?
Bats
83
What are the symptoms of SARS (Severe Acute Respiratory Syndrome)?
Fever and atypical pneumonia
84
How is SARS-CoV transmitted?
Bats to humans; respiratory droplets (human to human)
85
How is MERS-CoV (Middle East Respiratory Syndrome) transmitted?
Camels to humans
86
What is the most common manifestation of disease associated with existing human Coronavirus infections?
Common cold or gastroenteritis
87
How are Coronaviruses usually transmitted?
Respiratory spread through close contact
88
How are Coronaviruses currently diagnosed?
Film array PCR
89
What is the best way to describe the pathogenesis of a Coronavirus infection?
Viral replication leading to inflammation
90
Are there any approved anti-virals against coronaviruses?
No
91
Is there a vaccine currently tested and available for Coronaviruses such as SARS?
No
92
Are there any major consequences to emerging coronavirus infections?
Pandemic diseases such as SARS and MERS
93
The Nipah virus belongs to what family of viruses?
Paramyxovirus (negative strand RNA w/envelope)
94
What animals was the Nipah virus associated with?
Pigs; flying-foxes (bats)
95
What is the most common disease associated with Hantavirus?
Pulmonary syndrome
96
How is Hantavirususually transmitted?
Zoonotic infection from inhalation of urine or feces from infected deer mice
97
What is the current laboratory test for diagnosis of Hantavirus?
Serology performed by the public health department
98
What is the pathogenesis of Hantavirus?
Viral replication in the respiratory tract, inflammation and pneumonia
99
Are there any effective anti-viral therapies available for Hantavirus Pulmonary Syndrome?
No
100
Is there a vaccine currently available for Hantavirus?
No
101
Are there any major consequences to Hantavirus Pulmonary Syndrome?
Long-term immunity, fatality
102
Describe the differences between active and passive immunization.
Active - stimulate an individual to develop an immunologic defense IN ADVANCE of a challenge (live-attenuated, killed, or subunit vaccine)
Passive - supply preformed Ab to provide TEMPORARY treatment or protection to individuals already exposed/about to be exposed to an infectious agent
103
State the advantages and the potential problems associated with using a live,
attenuated virus compared to a killed virus for vaccination.
Live, attenuated - "best" vaccines because they replicate in humans and elicit the "appropriate" immune response; reversion to virulence is possible
Killed virus - good for generating a serum Ab response, but sometimes do not provide life-long immunity
104
Describe how smallpox was eradicated.
1. Disease is severe and worthy of eradication
2. Smallpox is strictly human, with no known animal or inanimate reservoirs; outcome for an infected individual was either death or permanent recovery
3. Accurate diagnosis is relatively easy (always presents with visible pustular lesions)
4. Disease spreads slowly
5. Only one worldwide serotype
6. Virus is resistant to inactivation by physical and chemical agents (vaccine could be used in many settings)
7. Presence of a scar indicates successful vaccination
105
Describe how poxviruses may be engineered and used as a vaccine vector.
1. Poxvirus replicates entirely in the cytoplasm.
2. Poxvirus encodes its own DNA-dependent DNA and RNA polymerases.
3. Poxvirus encodes proteins that are synthesized and released during viral infection which block interleukins and inhibit the immune response from efficiently clearing viral infections.
106
Describe how chimeric Yellow Fever 17D vaccine is being used to develop vaccines
for West Nile virus and Zika virus.
To date, the most successful vaccine for any arbovirus is the live-attenuated Yellow
Fever virus strain 17D (YF17D) that was developed by passaging the wild type virus in
cell culture. The molecular basis for the attenuation of YF17D is not fully understood.
However, many laboratories have taken the approach of replacing the structural protein
region of YF17D with the structural proteins of West Nile virus or Zika virus and thus
generating a chimeric virus. Experiments are in progress to determine if the chimeric
virus 1) is attenuated so that it does NOT cause disease (including transmission to the
fetus in the case of Zika virus); 2) DOES elicit protective immunity.
107
Where is smallpox infections still a prevalent disease?
Nowhere, it has been eradicated
108
How was Smallpox virus usually transmitted?
Respiratory
109
How would Smallpox virus be diagnosed?
Clinical presentation, confirmed by sequencing by Homeland Security
110
What was the pathogenesis of Smallpox virus infection?
Replication in the respiratory tract, viremia leading to characteristic rash
111
Are there any effective anti-viral therapies against Smallpox Virus?
No
112
Is there a vaccine currently available for Smallpox virus?
Live-attenuated vaccine; currently administered to military personnel
113
Are there any major consequences to Smallpox being eradicated?
1. Hope that eradication of other viral diseases is possible
2. Vaccinia may serve as a possible vaccine vector for other viruses
3. Not needing continued vaccinations saves the health care system millions of dollars/year
114
Are there any major consequences to Smallpox being eradicated?
1. Hope that eradication of other viral diseases is possible
2. Vaccinia may serve as a possible vaccine vector for other viruses
3. Not needing continued vaccinations saves the health care system millions of dollars/year
115
Smallpox virus is a ___ DNA, ___-shaped virus.
Double-stranded; brick
116
What are complications associated with vacinia virus vaccination?
1. Death ~1/million
| 2. Vaccine-induced diseases (encephalitis, generalized vaccinia, eczema vaccinatum)
