Flashcards in Arboviruses Deck (93):
What is an arbovirus?
arboviruses are not a family of viruses, they include alpha viruses (member of togaviridae) and flaviviruses (member of flaviviridae) and members of bunyaviridae that can undergo zoonotic transmission
What are the major characteristics of arboviruses? (ss/ds, DNA/RNA, pos/neg, env/non-env)
What is the reservoir of arboviruses?
vertebrates serve as reservoirs
blood sucking arthropods are the vectors
What is a reservoir vs. vector vs. dead-end host?
Reservoir = virus present in the bloodstream
Vector = virus acquired during a meal and the vector then transmits the virus
Dead-end host = does not maintain high enough viremia to ensure that a vector can acquire it
What are the major alphaviruses?
EEE -- eastern equine encephalitis virus
WEE -- western equine encephalitis virus
VEE -- Venezuelan equine encephalitis virus
What family do alphaviruses belong to?
What animals do the alphaviruses cycle between?
rodents and mosquitos, and then humans and horses are dead-end hosts
What are clinical symptoms of alphaviruses?
- mild flu-like disease
- can also cause a systemic viremic phase that invades the CNS and causes encephalitis
What is Chikungunya?
An alphavirus first isolated in Tanzania in 1952 that causes fever, rash, and arthralgia
What does the word "chikungunya" mean?
"that which bends up" referring to the stooped posture of the patients
What are the clinical symptoms of chikungunya?
fever, petechial or maculopapular rash, and arthralgia affecting multiple joints
the arthralgia can be debilitating
How do we treat Chikungunya?
no effective treatments
Do we have a vaccine against Chikungunya? If so, what type?
Alphaviruses are arboviruses, so what are their major characteristics?
Flaviviruses are arboviruses, so what are their major characteristics?
Name some important flaviviruses.
- Zika virus
- Dengue virus
- Yellow fever virus
- West Nile virus
- Japanese encephalitis virus
- 3 more types of encephalitis spread by ticks
Zika virus is in what family of viruses?
It is flaviviridae and is an arbovirus
What is the history of Zika virus?
1947: discovered in Uganda
1952: first human cases
2007: first outbreak outside of Afric and Asia on the island of Yap in Micronesia
2013: Virus spread to other pacific islands
2015: spread to south america/brazil, researchers tied it to neurologic disorders
2016: Puerto Rico and Florida
Clinical symptoms of Zika infection?
- most cases are asymptomatic
Other common s/s:
- mild fever
- skin rashes
- muscle and joint pain
How does Zika cause congenital defects?
the virus can be passed from pregnant women to the fetus and can cause:
- microcephaly, then later
- developmental delay
- intellectual disability
- movement/balance problems
- feeding problems
- hearing loss
- vision problems
How do we treat Zika virus?
Do we have a vaccine, and if so, what type?
How is Zika transmitted?
Most data shows mosquito-borne transmission, but some cases acquired through sexual transmission, laboratory transmission, and unknown route person-to-person
What is Dengue virus?
A member of flaviviridae and an arbovirus, causes hemorrhagic fever, 100 million infections each year
How many people are at risk of contracting Dengue virus each year?
2.5 billion people are at risk, 100 million get infected, and 300,000 get the dengue hemorrhagic fever
How is Dengue virus transmitted?
What is the difference between first and second infection of dengue virus?
First infection results in dengue: a febrile disease
Second infection results in dengue hemorrhagic fever
Dengue vs. Dengue hemorrhagic fever?
Dengue is a febrile illness from the first infection of dengue virus
Dengue hemorrhagic fever results from a second infection of dengue virus
What are the clinical symptoms of dengue?
febrile disease with petechial rash, headache, myalgia, usually self-limiting
What are the clinical symptoms of dengue hemorrhagic fever?
fever, petechial rash, GI hemorrhage, thrombocytopenia, liver enlargement, and shock
Why does a second infection cause a worse dengue disease?
antibody from a primary dengue virus infection binds to a viral particle in subsequent infection but cannot neutralize it
instead, the Ab-virus complex attaches to the Fc receptors on circulating monocytes and facilitates the infection of FcR cell types in the body
How do we diagnose dengue?
How do we treat dengue?
Is there a vaccine to dengue? If so, what type?
Who is the host of Dengue virus? (not the vector)
humans and monkeys
Who is the host of VEE? (not the vector)
Rodents and horses
Who is the host of EEE and WEE? (not the vector)
Who is the host of Chikungunya? (not the vector)
humans and monkeys
Who is the host of yellow fever? (not the vector)
humans and monkeys
Who is the host of japanese encephalitis? (not the vector)
pigs and birds
Who is the host of west nile? (not the vector)
birds, humans are dead-end hosts
What is yellow fever virus?
Mostly found in Africa and South America, causes fever, chills, headache, backache, vomiting
Severe toxicity causes jaundice with GI hemorrhaging
How many people are affected every year by Yellow fever virus?
200,000 are infected
30,000 are killed
Name the two forms of yellow fever virus. What's the difference?
Urban Yellow Fever
Jungle Yellow Fever
The difference is in the transmission. Urban yellow fever virus goes between humans and mosquitos.
Jungle yellow fever goes between primates and mosquitos with some spillover to humans.
What is a viscerotropic virus?
A virus with tropism for the visceral organs.
In the case of yellow fever, this means that it causes liver damage and jaundice, GI hemorrhage
What is the path of yellow fever virus in the human body?
The virus multiplies first in the region of the lymph nodes nearest to the site of the mosquito bite.
Then viremia and dissemination.
The liver becomes damaged and there are GI hemorrhages
What are the clinical symptoms of yellow fever virus?
Fever, chills, headache, backache, vomiting.
Also severe toxicity and jaundice with extensive GI hemorrhaging, causing bloody or "black vomit" and shock
Do we have a vaccine for yellow fever virus? If so, what type?
live-attenuated vaccine, used often for travelers
How do we try to prevent yellow fever transmission?
Mosquito eradication programs
What are the names of the two severe complications of yellow fever virus and who do they happen to?
YF-associated neurotropic disease (infants)
YF-associated viscerotropic disease (elderly)
What is West Nile Encephalitis Virus?
Virus transmitted by mosquitos from birds to humans
Can cause fever, headaches, fatigue, lymphadenopathy, myalgia, and sometimes a rash
What family does west nile virus belong to?
flaviviridae (it is also an arbovirus)
What family does Zika virus belong to?
Flaviviridae (it is also an arbovirus)
What family does Dengue fever virus belong to?
Flaviviridae (it is also an arbovirus)
What are the major characteristics of West Nile virus? (it is flaviviridae and an arbovirus)
What are the major characteristics of Dengue fever virus? (it is flaviviridae and an arbovirus)
What are the major characteristics of Yellow Fever virus? (it is flaviviridae and an arbovirus)
What are the clinical symptoms of west nile virus?
80% of those infected have no symptoms
20% get West Nile Fever with:
- body aches
- swollen lymph glands
- severe neurologic disease in less than 1%
What is a severe complication of West Nile virus?
severe neurologic disease with headache, high fever, neck stiffness, stupor, disorientation, coma, tremors, convulsions, muscle weakness, and paralysis
Where is West Nile Virus usually located?
It was first in Africa, but now it is endemic to the US
How do we treat WNV?
supportive care, respiratory support, management of cerebral swelling, prevention of secondary bacterial infection
How do we diagnose WNV?
Detect IgM specific WNV antibodies in CSF and serum
How do we prevent WNV?
avoid exposure to mosquitos
Is there a vaccine against WNV? If so, what type?
Who is the host of St. Louis encephalitis virus? (not the vector)
birds, humans are dead-end hosts
What is the St. Louis encephalitis virus? What does it cause?
A flavivirus located in the US, usually asymptomatic, but occasionally leading to encephalitis
What are the major characteristics of St. Louis encephalitis virus? (it is flaviviridae and an arbovirus)
How many cases of St Louis encephalitis virus are there each year?
It fluctuates widely.
1967: 2 cases
Usually an average of 102 cases/year
What are the clinical symptoms of St. Louis encephalitis virus?
Illness that does develop includes:
Spontaneous recovery can occur after that.
Can occasionally have CNS invasion leading to encephalitis, coma, or death
How is St. Louis encephalitis virus transmitted?
From birds through mosquitos to humans
How do we treat St. Louis encephalitis virus?
What is Japanese encephalitis virus?
A flavivirus (and an arbovirus) originally found in Japan, now large-scale epidemics occur in Asia
What are the major characteristics of Japanese encephalitis virus? (it is a flavivirus and an arbovirus)
What are the clinical symptoms of Japanese encephalitis virus?
most human infections are subclinical
Life-threatening encephalitis can occur
Do we have a vaccine for Japanese encephalitis virus? If so, what type?
Yes, an inactivated vaccine
How do we treat Japanese encephalitis virus?
Name the four families in the arbovirus classification.
Bunyaviridae, Flaviviridae, Togaviridae, Reoviridae
Are all viruses in the bunyaviridae family arboviruses?
No, genus orthobunyaviruses are (like La Crosse), but genus hantaviruses are not (like hantavirus)
What are the major characteristics of LaCrosse Encephalitis virus? (it's bunyaviridae)
What is different about bunyaviridae from the other arbovirus families? (flaviviridae and togaviridae (and reoviridae?))
other arboviruses are enveloped (+)ssRNA, whereas bunyaviridae is (-)ssRNA
What is LaCrosse (California) Encephalitis virus?
A virus endemic to US that can cause encephalitis but is usually subclinical, more prevalent in the summer
How is LaCrosse (California) encephalitis virus spread?
The hosts are rodents, small mammals, birds, and mosquitos are the vector
What is the path of the LaCrosse (California) encephalitis virus through the body?
- The virus first multiplies in the vascular endothelial cells closest to the mosquito bite
- Then the pt becomes viremic
- Then it targets the CNS
What are clinical symptoms of LaCrosse encephalitis virus?
Most infection are subclinical
- abdominal pain
- encephalitis (about 150 cases/year in the US)
Is there a vaccine for LaCrosse Encephalitis virus? If so, what type?
How do we treat LaCrosse Encephalitis Virus?
Why are we talking about hantavirus in this flashcard slideshow?
Because hantavirus is from the bunyaviridae family, which also contains some arboviruses, but hantavirus is not an arbovirus
How is Hantavirus transmitted?
What is the host/reservoir of hantavirus? (not the vector)
Rodents (deer mice)
What is Hantavirus?
a virus not originally thought to be in the US that can cause severe hemorrhagic fever with renal syndrome
What are the clinical symptoms of hantavirus pulmonary syndrome?
- fever, chills, myalgia, sweats
- GI symptoms
- SOB, dizziness
- back/chest pain
- respiratory distress with pulmonary edema
- can lead to respiratory failure and death
How do we diagnose Hantavirus?
serologic confirmation, RT-PCR, or IHC