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ID II > arboviral dz > Flashcards

arboviral dz Flashcards

1
Q

What are arboviruses

A

Viruses maintained in nature in cycles involving hematophagous arthropod vectors and susceptible vertebrate hosts

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2
Q

arbovirus vectors and hosts

A

vectors: Primarily mosquitoes, but also ticks, biting flies. Hosts: 1.Those that serve as main sources of infections for vectors (reservoirs): may or may not develop disease 2.Those that do not serve as reservoirs, but in which overt disease may occur. Humans are dead end hosts for most arboviruses

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3
Q

Which arboviruses can maintain the transmission of viruses via human-vector transmission

A

dengue virus, urban yellow fever virus, Ross river virus, Chikungunya virus

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4
Q

arbovirus clinical outcomes

A

asymptomatic (90% of dengue virus/ WNV, 15% of chikungunya virus). Fever, chills, muclse pain. Neuro dz: encephalitis, meningitis, AFP. Arthritis: Fever, intense pain in peripheral joints, inflammation in joints, tendons, skeletal muscle, Development of chronic disease is common. Hemorrhagic fever: Damage to the vascular system, loss of platelet function. Signs of bleeding under skin, internal organs, mouth, eyes. Shock, seizures, and mortality

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5
Q

list the three most important arboviruses

A

Bunyaviridae, flaviviruses, togaviridae (alphaviruses)

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6
Q

structure of Bunyaviridae, flaviviruses, alphaviruses

A

Bunyavirus: segmented, Negative sense RNA. Flaviviruses: Single-stranded, Positive sense RNA. Alphaviruses: Single-stranded, Positive sense RNA

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7
Q

List the Flaviviruses

A

Dengue viruses, Yellow fever virus, Japanese
Encephalitis virus, West Nile virus, St. Louis Encephalitis virusDengue viruses, Yellow fever virus, Japanese
Encephalitis virus, West Nile virus, St. Louis Encephalitis virusDengue viruses, Yellow fever virus, Japanese
Encephalitis virus, West Nile virus, St. Louis Encephalitis virus

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8
Q

major global arboviruses

A

Yellow Fever virus (YFV), Dengue viruses (DENV), Japanese encephalitis virus (JEV), West Nile virus (WNV), Chikungunya virus (CHIKV)

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9
Q

major arboviruses in US

A 
West Nile virus (WNV)
St. Louis encephalitis virus (SLEV)
La Crosse virus
Eastern equine encephalitis virus
Colorado Tick Fever virusWest Nile virus (WNV)
St. Louis encephalitis virus (SLEV)
La Crosse virus
Eastern equine encephalitis virus
Colorado Tick Fever virusWest Nile virus (WNV)
St. Louis encephalitis virus (SLEV)
La Crosse virus
Eastern equine encephalitis virus
Colorado Tick Fever virus
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10
Q

Yellow fever clinical

A

Nonspecific syndrome (fever, headache, nausea, vomiting) followed by Remission (1-2 days). 15% of cases progress: Jaundice, Hemorrhagic manifestations, shock, multisystem organ failure. 20-50% of cases with jaundice are fatal

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11
Q

yellow fever treatment/ prevention

A

supportive only. Live attenutaed vaccine- Not recommended for very young (< 9 mos.), elderly (> 60 yo), immunocompromised. Assoc. with rare, but serious, adverse events

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12
Q

Where is Yellow fever most common

A

South America and central africa

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13
Q

yellow fever virus transmission

A

transmitted from monkeys to mosquitos (Aedes aegypti) then to humans and back to mosquitos and back to humans

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14
Q

Dengue virus associated diseases

A
  1. Dengue Fever (DF- 25%):An acute febrile illness characterized by headache, muscle and joint pain, and rash. 2. Dengue hemorrhagic fever/dengue shock syndrome (DHF/DSS- 75%): Characterized by thrombocytopenia, capillary leakage, damage to liver. Fluid loss in tissue spaces can lead to hypovolemic shock and death (DSS)
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15
Q

Dengue severity classifications

A

Dengue without warning signs (dengue fever) > dengue with warning signs > severe dengue. Warning signs include abd pain, persistent vomiting, fluid accumulation. Mucosal bleeding, lethargy, liver enlargement, increased HCT with decreased platelets. Severe dengue: severe plasma leakage, severe hemorrhage or severe organ impairment

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16
Q

Where is Dengue virus most common

A

central America, northern part of South America, Asia, parts of Africa. High temp and precipitation

17
Q

Factors contributing to dengue re-emergence

A

population growth, air travel, urbanization (crowding, poor waste management), lack of mosquito control

18
Q

Dengue transmission

A

mosquito borne (Aedes aegypti, Aedes albopictus). Maintained in human-mosquito-human transmission cycle

19
Q

Risk factors for dengue fever/ dengue hemorrhagic fever

A

A second dengue infection by a different serotype, Age (under age 15), Host genetic background, Viral genotype, Each of the 4 DENV serotypes is composed of several genotypes

20
Q

pathogenesis of increased dengue fever risk with second infection

A

With first infection, Antibody response protects from re-infection with homologous DENV serotype (neutralizing antibodies) and due to cross reaction, initially protects from second infection with a different DENV serotype. Over time these cross reactive Abs decline to subneutralizing levels. Following 2nd infection with different serotype Cross-reactive subneutralizing antibodies generated during the first infection mediate enhanced infection of specific cells via FcγRs. Leads to increased viral replication and immune activation (increased cytokines etc.)

21
Q

Who gets dengue hemorrhagic fever

A
  1. Children and adults with a second infection by a different serotype. 2. Infants with primary DENV infection born to dengue-immune mothers. DENV is rare in infants < 3 months. Occurs primarily 4-12 month infants.
22
Q

Challenges with Dengue vaccine development

A

Antibodies play both protective and pathologic roles. Need to provide balanced and lasting responses to all 4 serotypes. Must be tetravalent. Waning of protection over time may put people at risk for severe disease

23
Q

Why is Dengue so rare in USA today?

A

air conditioning, increased income, piped water, window screens

24
Q

List the alpha viruses

A

Chikungunya virus

25
Q

Chikungunya virus clinical

A

fever, symmetrical joint pain, muscle pain, rash, difficulty ambulating. fingers, wrists, elbows, toes, ankles, and knees most commonly affected. symptoms are incapacitating. symptoms may persist for months to years, sometimes fluctuating. Clinically mimics seronegative RA, unless initial fever, rash, and travel history are revealed

26
Q

Chikungunya virus treatment/ prevention

A

No vaccines or therapies. Vaccines are in development (live attenuated vaccine)

27
Q

chikungunya virus locations

A

US, Africa, Asia

28
Q

List reoviruses

A

Colorado Tick Fever

29
Q

colorado Tick fever vector and reservoir

A

tick vector. Reservoir included squirrels, chipmunks, porcupines

30
Q

West nile virus vectors/ hosts

A

Birds are hosts, mosquitos are vectors. Humans, horses and vertebrates are dead end hosts

31
Q

West Nile locations

A

Every continent except Antarctica

32
Q

West nile virus clinical

A

80% are asymptomatic. 20% have fever, headache, fatigue. 1% have neuroinvasive dz: Fever, headache, altered mental status, neck stiffness. Typically manifests as encephalitis (63%), meningitis (33%), or acute flaccid paralysis (3%). Most cases occur in elderly people and those with impaired immune systems. Long term neurological sequelae are commo

33
Q

West nile virus pathogenesis

A

Replicates in keratinocytes and dendritic cells at site of inoculation > infected cells migrate and spread virus to lymph nodes > primary viremia > virus gains access to CNS (cytokines/ proteases increase endothelial cell permeability) > MNV directly infects neurons > neuronal injury in brain stem, hippocampus, cortex, cerebellum spinal cord

34
Q

West Nile virus treatment/ prevention

A

supportive therapy. No vaccine currently

35
Q

Alternative modes of transmission of WNV

A

solid organ transplant, blood transfusion

36
Q

which arboviruses have vaccines

A

yellow fever (live attenuated), japanese encephalitis virus (inactivated vaccine, chimeric live attenuated, and live attenuated),

ID II (21 decks)

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