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Term 5: Infectious Disease > 5/28- 5 Arboviruses: Toga, Flavi, Bunya, Arena, Filo > Flashcards

5/28- 5 Arboviruses: Toga, Flavi, Bunya, Arena, Filo Flashcards

1
Q

What three families are comprised in Arboviruses?

A
  • Togaviridae
  • Flaviviridae
  • Bunyaviridae
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2
Q

T/F: Once arboviruses are spread to humans by arthropods (e.g. mosquitos), they can be transferred human-to-human

A

False. Humans are typically dead-end hosts

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3
Q

Clinical syndromes of arboviral infections?

A

CNS disease:

  • Encephalitis/meningoencephalitis
  • Aseptic meningitis

Febrile illnesses (+/- rash)

“Hemorrhagic diseases”

Asymptomatic (unrecognized infxn)

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4
Q

Arthropod vectors

A
  • Mosquitos
  • Ticks
  • Flies

Most viruses are spread most efficiently by 1/limited number of insect species (but may be spread by others)

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5
Q

Worldwide Distribution of Major Arboviral Encephalitides: know the North American and then Japanese Encephalitis (vaccine preventable)

A

Learn

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6
Q

Do arboviruses have seasonal fluctuations?

A

Yes. Early summer/fall when mosquitoes at peak level

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7
Q

Symptoms of encephalitis

A
  • Fever, HA, vomiting, confusion, seizures
  • Minimally stiff neck (differentiates from meningitis)
  • With recovery, a proportion will have residual neurologic damage (varies with virus)
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8
Q

Two structural surface glycoproteins of Togaviridae?

A

E1

E2

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9
Q

Two genera of Togaviridae

A
  • Alphavirus (Group A arboviruses)
  • Rubivirus = rubella
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10
Q

Alphavirus classification by __?

A

Antigenic

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11
Q

Different thypes of antigenic classifications (4)?

A
  • Antigenic complex: very closely related but distinct
  • Species level: individual agents, antigenically related but easily separable (>4x diffs between homo/hetero titers of both sera)
  • Antigenic serotypes: (>4x diffs between homo/hetero titers of one but not both sera)
  • Antigenic varieties- special tests to distinguish
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12
Q

New world alphavirus antigenic complexes

A
  • Eastern equine encephalitis virus (EEEV)
  • Western equine encephalitis virus (WEEV)
  • Venezuelan equin encephalitis virus (VEEV)
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13
Q

Old world alphavirus antigenic complexes

A
  • Semliki Forest virus (SFV)
  • Middleburg virus (Africa)
  • Ndumu virus (Africa)
  • Barmah Forest virus (Sindbis virus is old world although in WEEV antigenic complex)
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14
Q

Clinical syndromes of new world alphaviruses? old world?

A

New:

  • Encephalitis
  • Aseptic meningitis

Old:

  • Febrile illness
  • Rash
  • Arthritis
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15
Q

Semilki Forest virus group includes?

A

Chikungunya = important one

(Africa and Asia; now also in C/S America and Florida) (pic B)

Also:

  • SFV (Africa/Asia)
  • O’nyong-nyong (Africa)
  • Mayaro (Central/South America)
  • Ross River (Australia/Oceania)
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16
Q

WEEV group includes?

A
  • Sindbis (Europe, Asia, Africa, Australia)
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17
Q

How many people with Chikungunya develop clinical symptoms?

A

72-97%

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18
Q

Incubation period of Chikungunya?

A

3-7 days (range 1-12 days)

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19
Q

Clinical symptoms of Chikungunya?

A

Mainly fever and polyarthralgia

  • Fever: abrupt onset, typically > 39’C (>102.2’F)
  • Joint pain: sever, debilitating, multiple joints, bilateral, symmetric, most common in hands/feet

Also:

  • Headache
  • Myalgia
  • Arthritis
  • Conjunctivitis
  • Nausea/vomiting
  • Maculopapular rash
  • Mortality rare (occurs mostly in older adults)
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20
Q

Resolution of acute symptoms with Chikungunya?

A

Typically resolve 7-10 days

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21
Q

Recovery phase of Chikungunya may involve?

A
  • Some pts may have relapse of rheumatologic symptoms (polyarthralgia, polyarthritis, tenosynovitis, Raynaud’s) in months following acute illness
  • Persistent joint pain for months to years in some
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22
Q

Diagnosis of Alphavirus infxn?

A
  • Epidemiology (travel/exposure)
  • Serology is primary means for New World (ELISA)
  • Viremia in some old world viruses (e.g. Chikungunya) so isolation during initial illness
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23
Q

Treatment/prevention of alphavirus?

A
  • Supportive (no antiviral therapy)
  • Prevent by avoiding/controlling mosquitoes
  • Investigational inactivated and live attenuated (e.g. VEE) vaccines for high risk individuals
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24
Q

T/F: Rubella is not an arbovirus

A

True; rubella is spread person-to-person

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25
Q

Symptoms of Rubella

A
  • Mild febrile exanthem in children and adults
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26
Q

Infection when in pregnancy commonly results in congenital Rubella? Symptoms?

A

1st trimester especially

  • Cataracts
  • Deafness
  • Cardiac abnormalities
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27
Q

Treatment/prevention of Rubella?

A

Vaccine preventable

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28
Q

What is the composition of Flaviviridae envelope?

A

Lipid

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29
Q

Three genera of Flaviviridae?

A
  • Flavivirus
  • Pestivirus
  • Hepacivirus
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30
Q

Clinical syndromes of flavivirus?

A
  • CNS dz (encephalitis, aseptic meningitis)
  • Fever, arthralgia, rash
  • Hemorrhagic fever
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31
Q

Flavivirus tick-borne viruses

A
  • Kyasanur Forest dz (Haemaphysalis ticks)
  • Omsk Hemorrhagic fever (Dermacentor ticks; also Culex, Aedes mosquitoes)
  • Powassan virus (Ixodes ticks)
  • Tick-borne encephalitis (Ixodes ticks)
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32
Q

Flavivirus mosquito-borne viruses

A
  • Japanese encephalitis virus group
  • Dengue virus group
  • Yellow fever virus group
  • Others
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33
Q

Flavivirus with no known arthropod vecto

A

Rio Bravo group

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34
Q

Japanese Encephalitis Virus Group includes?

A
  • JEV
  • Murray Valley encephalitis virus
  • St. Louis encephalitis virus
  • West Nile virus
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35
Q

When is the peak of Japanese Encephalitis virus?

A

Late summer/early fall

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36
Q

What is the age distribution of JEV infxn?

A

Bimodal: young and old

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37
Q

Incubation period of JEV?

A

4-14 days

38
Q

What percentage of JEV infected show symptoms? Mortality of JEV?

A

1:300 symptomatic to non 10-35% mortality

39
Q

Diagnosis of JEV

A

IgM ELISA

40
Q

Prevention of JEV?

A

Inactivated vaccine

41
Q

West Nile spread in US (2014)

A

Human infxn everywhere but Maine, Vermont, New Hampshire

Non-human infxn everywhere but Maine

42
Q

How many infected with West Nile are asymptomatic?

A

70-80% subclinical with West Nile

43
Q

How many infected develop West Nile fever? Sx?

A

20%

  • Headache
  • Arthralgias
  • Vomiting
  • Body aches
  • Rash
  • Diarrhea
44
Q

How many infected with West Nile develop encephalitis/meningitis? Sx?

A

< 1%

  • Aseptic meningitis
  • Encephalitis
  • Poliomyelitis- syndrome
45
Q

Endemic areas of yellow fever?

A
46
Q

Symptoms of yellow fever?

A

Undifferentiated febrile illness (resembles many other fevers)

Classic yellow fever:

  • Fever, vomiting, epigastric pain
  • Prostration, dehydration
  • Scleral icterus
  • Renal and hepatic abnormalities
  • Hemorrhagic tendency GI bleeding- black vomitus
47
Q

Phases of clinical yellow fever

A

Phase 1: nonspecific febrile illness

  • Viremic pt but diagnosis difficult

Period of Remission

  • Brief clinical improvement
  • 3-4th day after onset

Phase 2: “intoxication”

  • Hepatic and renal dysfunction
  • Bleeding
48
Q

Mortality rate for severe yellow fever?

A

50%

49
Q

Prevention of yellow fever?

Efficacy?

Risks?

A

Live attenuated vaccine (17D strain)

  • Grown in embyronated chicken eggs
  • Protective immunity in > 90% at 10 days, > 99% at 30 days
  • Very safe, but rare cases of yellow fever-like syndrome, post-vaccinal encephalitis, death (avoid in immunocompromised) Mosquito eradication, prevention of biting
50
Q

How many serotypes of Dengue virus?

A
  • 4 serotypes (possibly 5) of Dengue fever can cause severe and fatal dz
  • Each serotype provides lifetime immunity and short-term cross-immunity
  • Genetic variation within serotypes
  • Some genetic variants within each serotype appear to be more virulent/have greater epidemic potential
51
Q

Worldwide distribution of Dengue fever?

A
52
Q

Clinical syndromes of Dengue (broad)?

A
  • Undifferentiated fever
  • Classic dengue fever
  • Dengue hemorrhagic fever
  • Dengue shock syndrome (rash)
53
Q

Vector of Dengue fever?

A

Aedes aegypti mosquito

54
Q

Diagnosis of Flavivirus?

A
  • Serology (primary)
  • RT-PCR
  • Culture
55
Q

Prevention/Treatment of Flavivirus?

A

Supportive (except Hep C…) Prevention:

  • Vector control
  • Vaccination (JEV, yellow fever, others not licensed in US)
56
Q

T/F: Bunyaviridae is non-segmented?

A

False; it is tripartitie (3 segments)

57
Q

Structural proteins of Bunyaviridae?

A

2 external glycoproteins:

  • G1
  • G2

Nucleocapsid protein (N)

Large transcriptase protein (L)

58
Q

Four human genera of Buyaviridae?

A
  • Bunyavirus
  • Hantavirus
  • Nairovirus
  • Phlebovirus
59
Q

Byunavirus genus includes? Geography?

A

California serogroup (Aedes triseriatus)

  • California encephalitis (W. US, Canada)
  • La Crosse (MW/E. US)– especially pediatric pops
  • Jamestown Canyon (N. America)
  • Tahyna (Europe)

Bunyamwera

60
Q

Incubation period of California serogroup (Aedes triseriatus)?

A

3- 7 days

61
Q

What does Nairovirus cause?

A

Crimean- Congo Hemorrhagic Fever

  • Febrile illness followed by multi-organ failure
62
Q

What is the vector for Nairovirus? Geography?

A

Tick-borne (Hyalomma)

Africa/Middle East/E Europe/Asia

63
Q

Incubation of Nairovirus?

A

3-6 days

64
Q

What does Phlebovirus cause?

A

Rift Valley fever

  • Fever, myalgia, malaise encephalitis
65
Q

Vector for Phlebovirus? Geography?

A

Sandfly fever viruses Endemic in sub-Saharan Africa

66
Q

Transmission of Phlebovirus?

A

Potential for nosocomial spread

(aerosol; direct contact?)

67
Q

Incubation of Phlebovirus?

A

2-6 days

68
Q

Hantavirus causes what?

A

Hemorrhagic fever with renal syndrome (HFRS)

  • Hantaan fever
  • Seoul virus Hantavirus pulmonary syndrome (HPS)
  • Sin nombre virus
  • Flu-like illness followed by cap leak syndrome
  • Most frequent: fever, myalgia, nausea/vomiting, cough
  • Other: dizziness, arthralgia, SOB (later in course)
  • Rare: rhinorrhea, sore throat
  • Seen on chest x-ray: bilateral interstitial infiltrates (mod-rapid progression), bilateral alveolar infiltrates, or pleural effusion (hemorrhage not a major part of clinical syndrome)
69
Q

Transmission of Hantavirus?

A
  • 2ndary aerosols, mucous membrane contact, skin breaches…
  • Virus present in aerosolized rodent excreta, particularly urine
  • Horizontal transmission of infxn by intraspecific aggressive behavior
  • Chronically infected rodent
70
Q

New World Hantaviruses with geographic distribution

A
71
Q

Diagnosis of Hantavirus

A

- Serologic (ELISA, HAI, Neutralization)– primary

  • Antigen detection
  • Culture (RVF, CCHF)
72
Q

Prevention and treatment of Hantavirus

A
  • Vector avoidance
  • Vaccine (RVF- indicated, not licensed)
  • Treatment is supportive (Ribavirin in HFRS, possibly in CCHF)
73
Q

Arenaviridae unique genetic feature?

A

Ambisense

74
Q

T/F: Arenaviridae is non-segmented

A

False; it is bipartite (2 segments- L and S)

75
Q

Is Arenaviridae DNA or RNA?

A

RNA

76
Q

Two serologic groups of Arenaviridae?

A
  • Old world: LCM, Lassa fever
  • New world: Junin fever, others
77
Q

What is this?

A

Lass virus

78
Q

What are the important Arenaviridae viruses associated with human dz?

A

- Lassa

- LCMV

(Also: Junin, Machupo, Guanarito, Sabia, LCMV)

79
Q

Transmission of Arenavirus?

A
  • Natural infxn of rodents
  • Aerosolization of rodent excretions
  • Nosocomial spread by contact with blood/body fluids
  • Solid organ transplants
80
Q

Symptoms of LCM?

A

Hemorrhagic fever

  • N/V/D
  • Pulmonary edema
  • Capillary leak/bleeding
81
Q

Endemic areas for Lassa fever?

A
  • West Africa (Nigeria, Liberia, Sierra Leone, Guinea)
82
Q

Infections and deaths due to Lassa fever?

A

300,000-500,000 infxns/year 5,000 deaths

83
Q

Transmission of Lassa fever?

A
  • Rodent-to-human (“multimammate rat, Mastomys species-complex)
  • Secondary human-to-human transmission with the potential for nosocomial outbreaks with high cast fatality
84
Q

Diagnosis and Treatment and Prevention of Lassa fever?

A

Diagnose:

  • Serology
  • Antigen detection
  • RT-PCR
  • Culture

Treatment:

  • Ribavirin for lassa fever
  • Convalescent serum also used

Prevention:

  • No vaccines
  • Rodent control
85
Q

Two genera of Filoviridae?

A
  • Marburgvirus
  • Ebolavirus
86
Q

Species of ebola?

A
  • Zaire
  • Sudan
  • Bundibugyo
  • Tai Forest
  • Reston
87
Q

What is this?

A

Ebola virus

88
Q

Transmission of Filovirus?

A

Reservoir is fruit bats Infection seen after contact w/ infected primates or infected persons

89
Q

What dz does Filovirus cause? time frame?

A

Hemorrhagic fever

Acute onset (typ 8-10 days after exposure, range 2-21 d)

  • Fever, chills, myalgia, malaise, weakness
  • GI Sx: vomiting, diarrhea, abdominal pain
  • Miscarriage
  • Hemorrhage is late sign (<50% of cases)
90
Q

Diagnosis of Filovirus?

A
  • Antigen detection (primary)
  • EM
  • Cell culture (BSL-4 agent)
  • Serology
  • RT-PCR
91
Q

Treatment of Filovirus?

A
  • Supportive
  • Vaccines under development
92
Q

Sequelae in survivors of Filovirus?

A
  • Arthralgia/myalgia (frequent, severe, persistent)
  • Prolonged asthenia
  • Malnutrition
  • Mental health issues
  • Hearing loss
  • Cardiac injury (e.g. myocarditis)
  • Hearing loss
  • Cerebral complications (e.g. seizures, encephalopathy)
  • Ocular problems

Term 5: Infectious Disease (18 decks)

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