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Virology > Arboviruses > Flashcards

Arboviruses Flashcards

1
Q

In the US, what is the major spreading cycle of Arboviral

A

From mosquitos to birds to mosquitos to birds

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2
Q

In regards to Arboviral, infections of humans are considered _______

A

incidental

-Humans are a ‘dead-end-host’
-This is b/c humans can’t spread the disease back to a mosquito or other people
-This is NOT an urban cycle, no matter the number of infected birds or humans

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3
Q

What is the urban cycle of spread of Arboviral

A

-From human to mosquito to human to mosquito
-In this type of spread, the infection is not circulating through a different animal and several things must be in place to spread the disease

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4
Q

What is needed for an urban cycle of spread?

A

-The virus has to be able to infect urban mosquitos
-There has to be high enough virus levels in the infected person’s blood to infect a mosquito
-There must be high enough levels of mosquitos to sustain the spread of the disease
-There has to be high enough density of people susceptible to infection

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5
Q

So far, which 4 different arboviruses have high enough virus levels in a person’s blood to infect a mosquito?

A

Yellow fever
Dengue
Zika
Chikungunya

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6
Q

Describe the general characteristics of West Nile Virus

A

West Nile Virus is a Flavivirus, +ssRNA, enveloped virus

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7
Q

Which arbovirus has the most cases in the US?

A

West Nile Virus

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8
Q

Is West Nile Virus (asymptomatic/symptomatic)?

A

Asymptomatic

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9
Q

How is West Nile Virus transmitted?

A

-It is NOT transmitted through urban spread
-The mosquito vector is not the same vector that spread Zika, dengue, and chikunguna.
-The vector for West Nile Virus (WNV) prefers to feed on birds and bites mostly from dust to dawn

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10
Q

What age group is affected by West Nile Virus?

A

It can occur at any age

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11
Q

What are the post-infection symptoms of Wet Nile Virus?

A

Many can have lingering problems with fatigue (some also report motor defects)

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12
Q

The older you are, the more likely you will get the _________ form of WNV

A

neuroinvasive

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13
Q

Of those infected with neuroinvasive WNV, about 50% have _________ and recover completely

A

meningitis

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14
Q

The remaining 50% of those infected with neuroinvasive WNV have more serious complications like….

A

-Encephalitis and/or acute flaccid paralysis
-This is where the deaths more likely to occur
-Survivors can have long-term complications like memory loss, muscle weakness, fatigue, and difficulty doing daily activities

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15
Q

Describe the structure of Yellow Fever

A

Yellow Fever is a Flavivirus, +ssRNA, enveloped virus

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16
Q

What type of vaccine is the yellow fever vaccine?

A

An attenuated-live vaccine that, with just one shot, gives 99% protection for life

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17
Q

Which is the first arbovirus known to have an urban cycle?

A

Yellow Fever

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18
Q

Several countries in __________ are endemic for Yellow Fever

A

Africa and South America

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19
Q

Half of the yellow fever infections are asymptomatic; describe the symptoms of the other 50% of infections

A

-Some will have severe disease
-About 1/2 of them will die
-Jaundice is a common complication of severe disease, hence yellow fever and hemorrhaging

20
Q

How does Yellow Fever spread?

A

-By the same mosquito that spreads Zika, dengue, and chikungunya.
-For this reason, if you live in an area endemic for yellow fever, most countries require proof of vaccination before entry

21
Q

What is the number one arbovirus worldwide?

A

Dengue

22
Q

How many serotypes does dengue have?

A

4

23
Q

What happens the first time you are infected with dengue?

A

You usually don’t get the severe form of dengue disease

24
Q

What type of virus is Dengue?

A

Another Flavivirus with a high number of asympotomatic infections

25
Q

If you are infected again with a different serotype of dengue, now you are at risk of ______

A

More severe disease, Dengue Hemorrhagic Fever or Dengue Shock

-Death from more severe forma is much more likely without tx

26
Q

T/F: In most endemic areas, several dengue serotypes circulate at the same time

A

True

27
Q

Let’s say you are infected with Dengue serotype 1 and recover. What do you have now?

A

Lifelong immunity to serotype 1 but not any other dengue type

28
Q

If now you are infected with a different serotype, like 3, what happens to the antibodies from type 1?

A

The antibodies to type 1 will bind to the type 3 viruses from the new infection

29
Q

Instead of neutralizing the type 3 viruses, the bound antibody is recognized by _________ on monocytes, and the type 3 receptor is internalized into the monocyte. What does this aid in?

A

the Fc receptor;

This aids the virus in infecting the monocyte leading to more efficient infection, high viral loads, and more severe disease

30
Q

Why has it been so hard to make a vaccine for dengue?

A

Because of the fact that antibodies to one serotype can aid in the infection of another serotype and lead to more severe diseases

-The fear was that the vaccine would lead to more dengue hemorrhagic fever/dengue shock, not stop it

31
Q

_____ has symptoms similar to dengue, with most asymptomatic

A

Zika

32
Q

What type of virus is Zika?

A

Flavivirus

33
Q

Problems associated with Zika are ___________ and congenital abnormalities.

A

Guillian-Barre Syndrome

(Zika is rarely fatal)

34
Q

What are the symptoms of Zika?

A

Fever
Rash
Joint pain
Conjunctivitis

35
Q

What has Zika virus been linked to?

A

Congenital abnormalities

36
Q

The same risk for congenital Zika syndrome if the maternal infection is _________

A

symptomatic or asymptomatic

37
Q

When is there a risk for congenital Zika syndrome during pregnancy?

A

During any trimester of maternal infection

38
Q

What can Zika virus affect in a fetus?

A

Can affect brain development in the fetus, leading to microcephaly, damage to the brain, slight and hearing problems, and movements of limbs

39
Q

How can Zika be spread?

A

Through sexual contact from both symptomatically and asymptomatically infected people

40
Q

What type of virus is Chikungunya?

A

A togavirus

41
Q

How is Chikungunya spread?

A

-By the same mosquitos that spread yellow fever, dengue, and Zika
-It also has an urban cycle of spread

42
Q

What happens to most people who get infected with Chikungunya?

A

-Most people DO get sick
(Relatively few are asymptomatically infected)

43
Q

What are the symptoms of chikungunya?

A

The symptoms overlap with dengue and zika, but there is much more severe joint pain

44
Q

What is the problem with Chikungunya infection?

A

That about 1/4 of infected people will have lingering joint pain for months to years

45
Q

What is the vaccine for Chikungunya?

A

There is no vaccine, but infection can afford lifelong protection from reinfection

46
Q

All of the arboviruses are _____________ infections

A

systemic/generalized

Virology (17 decks)

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