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Infectious Disease > Arbo, Bunya, Arenyaviruses > Flashcards

Arbo, Bunya, Arenyaviruses Flashcards

1
Q

VEE, WEE, EEE, chkungunya all belong to what family of arboviruses?

A

togaviridae: alphavirus

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2
Q

Dengue, yellow fever, japanese encephalitis, west nile, St. Louis, and Russian spring summer encephalitis all belong to what family of arboviruses?

A

flavivirus

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3
Q
  • enveloped RNA viruses
  • positive polatiry
  • 5’ methylated cap but no polyA tail
A

alphavirus and flavivirus

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4
Q

alphavirus vs. flavivirus genomic organization, which has structural then non-structural proteins?

A

alpha: non-structural –> structural
flavi: structural –> non-structural

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5
Q

epidemiology of alpha and flavi virus:

  • who is at risk?
  • geography/season?
  • modes of control?
A
  • people who enter ecological niche of arthropod vector
  • endemic regions determined by habitat of vector, disease more common in summer months
  • mosquito breeding sites should be eliminated, live attenuated vaccine for yellow fever
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6
Q

alpha and flavivirus can be maintained in nature by replication in _______ of mosquitoes

A

salivary glands

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7
Q

dengue virus and urban yellow fever use what transmission cycle?

A

man-arthropod-man, where reservoir may be in man or arthropod vector

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8
Q

Japanese encephalitis, EEE,WEE, Jungle yellow fever use what transmission cycle?

A

animal-arthropod-man, where reservoir is animal other than humans, man becomes infected incidentally

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9
Q

how does encephalitis occur from arbovirus?

A

mosquito bite –> primary viremia –> infect macrophages, liver, spleen, lymph nodes –> secondary viremia –> virus infects endothelial cells to cross BBB –> virus infects neurons resulting in cell death

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10
Q

diseases caused by arboviruses?

A

fever and rash
encephalitis
hemorrhagic fever

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11
Q
  • biggest arbovirus problem in the world today (390 million infections each year)
  • severe cases present with hemorrhagic fever or shock syndrome
  • found in SE Asia, Africa, Caribbean, South america
  • 5 serotypes, transmitted by Aedes mosquitos
  • human-mosquito-human cycle
A

Dengue Fever

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12
Q

phases of Dengue pathogenesis?

A
  1. febrile phase: sudden fever, headache, muscle pain, rash with petechia called breakbone fever
  2. critical phase: fever resolves, plasma leakage leading to fluid in chest and abdominal cavity, bleeding in GI tract, shock
  3. recovery: fluid is reabsorbed, accompanied by severe itching and slow heart rate
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13
Q

Dengue fever:

  • diagnosis made by ______
  • antiviral therapy?
  • prevention depends on __________
A

serology
no therapy
mosquito eradication

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14
Q

risk factors for DHF/DHS:

  • risk greatest for which strain?
  • higher risk with two serotypes circulating simultaneously known as?
  • pre-existing antibodies may lead to ____________ of disease
A
  • DEN-2
  • hyperendemic transmission
  • antibody dependent enhancement
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15
Q
  • found in West Africa and South America
  • urban and jungle forms, where jungle is natural reservoir in cycle involving non human primates and forest mosquitos, urban from transmitted b/w humans by Aedes mosquito
A

Yellow Fever virus

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16
Q
  • Yellow fever presents with chills, fever, and headache, general myalgias
  • after _____ days, more severely ill patients experience bradycardia, jaundice, hemorrhagic manifestations
  • 50% of patients with Frank yellow fever develop fatal disease characterized by?
A
  • 3-4 days

- severe hemorrhage, oliguria, hypotension

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17
Q

diagnosis of yellow fever?
antiviral treatment?
vaccine?

A
  • serology
  • no antiviral treatment
  • live attenuated vaccine for persons living in or traveling to endemic areas
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18
Q
  • 80% of infections in humans asymptomatic
  • 20% of infected humans develop west nile fever
  • less than 1% of infected humans develop West Nile neurologic disease
  • of those with WNND, 40% develop meningitis and 60% develop encephalitis
  • small percent causes polio like acute flaccid paralysis
  • most common in elderly
A

west nile virus

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19
Q
  • causes nonpurulent conjunctivits, facial exanthema, maculopapular rash on the trunk
  • fetal microencephaly
A

Zika virus

20
Q
  • largest family of viruses
  • depend on wild animals for persistence
  • 5 genera
  • human to human transmission generally does not occur
A

bunyaviridae

21
Q
  • enveloped, pleomorphic, have two envelope glycoproteins

- 3 segments of ssRNA, negative

A

bunyaviruses

22
Q
  • perpetuated in rodent populations
  • enveloped ssRNA virus, virions in square grid like structure
  • genome has 3 RNA segments
A

hantaviruses

23
Q

subtypes of Hantavirus that cause disease in humans?

A
  • hantaan, porrogia
  • seoul
  • puumala
  • sin nombre
24
Q

highest mortality rate of hantaviruses?

A

sin nombre

25
Q

hantaviruses: rodents shed virus in _______, trasnmitted to people through _______

A

urine, droppings, saliva

aerosolization

26
Q

5 phases of hantavirus?

A
  1. febrile phase
  2. hypotensive phase
  3. oliguric phase
  4. diuretic phase
  5. convalescent phase
27
Q

febrile phase of hantavirus: abrupt onset of severe flu like illness with erythematous rash after incubation period of?

A

2-3 days

28
Q

hypotensive phases of hantavirus begins at day?

A

5

29
Q

oliguric phase of hantavirus begins at day ____, patient may develop acute renal failure and shock, hemorrhages confined to petechia

A

9

30
Q

diuretic phase occurs between days?

A

12-14

31
Q

convalescent phase of hantavirus may require how long?

A

up to 4 months

32
Q

majority of deaths occur during what 2 phases of hantavirus disease?

A

hypotensive and oliguric phases

33
Q
  • damage to capillaries occur predominantly in lungs rather than kideny
  • shock and cardiac complications may lead to death
  • majority caused by sin nombre virus
  • micrograph: interstitial pneumonitis, intra-alveolar edema
A

hantavirus pulmonary syndrome

34
Q

treatment of HVD and HPS?

A

supportive measures, oxygen if hypoxic, vasopressors

35
Q

effective treatment against HFRS but not HPS?

A

ribavirin

36
Q
  • transmitted by mosquito culex pipens
  • can be spread to umans by contact with tissue or blood, transcutaneous
  • formalin inactivated vaccine, not licensed for humans
  • outbreaks directly correlated with rainfall
A

rift valley fever

37
Q

rift valley fever:

  • incubation period?
  • influenza like illness with abrupt onset of fever and assoc’d symptoms
  • fatal cases experience what symptoms?
A
  • 2 to 6 days

- liver necrosis with hemorrhage, retinitis, meningoencephalitis

38
Q

treatment for rift valley fever?

A

ribavirin

39
Q

sandfly fever:

  • ______ fever
  • incubation? symptoms?
A

phlebotomous

2-6 day incubation, rapid onset fever, complete recovery

40
Q

-enveloped virus, round or pleomorphic, ssRNA genome in 2 segments, ambisense orientation

A

arenaviridae

41
Q

arenaviruses associated with disease?

A

lassa, junin, machupa, guararito, sabia, LCMV

42
Q

small round objects in lasse fever virus are what?

A

ribosomes

43
Q
  • no arthropod vectors, persist in rodent species
  • persist in nature by congenital transmission
  • interhuman transmission rare except with lassa fever
A

arenavirus infections

44
Q

high rate of moratlity in arenaviruses except for?

A

LCMV

45
Q
  • natural reservoir is rat
  • man to man transmission can occur
  • incubation 3-5 days, patchy or ulcerative pharyngeal lesions, severe cases (myocarditis, pneumonia, encephalopathy, hemorrhage, shock)
  • high mortality rate
A

lassa fever

46
Q
  • appears during early convalescence
  • not related to severity of illness
  • occurs in 1/3 cases
  • may be unilateral or bilateral
  • may persist for life
A

sensorineural deficits with lassa fever

47
Q

treatment for lassa virus?

A

ribavirin, must be given early

Infectious Disease (22 decks)

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