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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

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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
Symptoms of Rubella
- Mild febrile exanthem in children and adults
26
Infection when in pregnancy commonly results in congenital Rubella? Symptoms?
**1st trimester** especially - Cataracts - Deafness - Cardiac abnormalities
27
Treatment/prevention of Rubella?
Vaccine preventable
28
What is the composition of Flaviviridae envelope?
Lipid
29
Three genera of Flaviviridae?
- Flavivirus - Pestivirus - Hepacivirus
30
Clinical syndromes of flavivirus?
- CNS dz (encephalitis, aseptic meningitis) - Fever, arthralgia, rash - Hemorrhagic fever
31
Flavivirus tick-borne viruses
- Kyasanur Forest dz (Haemaphysalis ticks) - Omsk Hemorrhagic fever (Dermacentor ticks; also Culex, Aedes mosquitoes) - Powassan virus (Ixodes ticks) - Tick-borne encephalitis (Ixodes ticks)
32
Flavivirus mosquito-borne viruses
- Japanese encephalitis virus group - Dengue virus group - Yellow fever virus group - Others
33
Flavivirus with no known arthropod vecto
Rio Bravo group
34
Japanese Encephalitis Virus Group includes?
- JEV - Murray Valley encephalitis virus - St. Louis encephalitis virus - West Nile virus
35
When is the peak of Japanese Encephalitis virus?
Late summer/early fall
36
What is the age distribution of JEV infxn?
Bimodal: young and old
37
Incubation period of JEV?
4-14 days
38
What percentage of JEV infected show symptoms? Mortality of JEV?
1:300 symptomatic to non 10-35% mortality
39
Diagnosis of JEV
IgM ELISA
40
Prevention of JEV?
Inactivated vaccine
41
West Nile spread in US (2014)
Human infxn everywhere but Maine, Vermont, New Hampshire Non-human infxn everywhere but Maine
42
How many infected with West Nile are asymptomatic?
**70-80% subclinical** with West Nile
43
How many infected develop West Nile fever? Sx?
20% - Headache - Arthralgias - Vomiting - Body aches - Rash - Diarrhea
44
How many infected with West Nile develop encephalitis/meningitis? Sx?
**\< 1%** - Aseptic meningitis - Encephalitis - Poliomyelitis- syndrome
45
Endemic areas of yellow fever?
46
Symptoms of yellow fever?
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
Phases of clinical yellow fever
**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
Mortality rate for severe yellow fever?
**50%**
49
Prevention of yellow fever? Efficacy? Risks?
**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
How many serotypes of Dengue virus?
- **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
Worldwide distribution of Dengue fever?
52
Clinical syndromes of Dengue (broad)?
- Undifferentiated fever - Classic dengue fever - Dengue hemorrhagic fever - Dengue shock syndrome (rash)
53
Vector of Dengue fever?
Aedes aegypti mosquito
54
Diagnosis of Flavivirus?
- **Serology (primary)** - RT-PCR - Culture
55
Prevention/Treatment of Flavivirus?
Supportive **(except Hep C...)** Prevention: - Vector control - Vaccination (JEV, yellow fever, others not licensed in US)
56
T/F: Bunyaviridae is non-segmented?
**False**; it is tripartitie (**3 segments**)
57
Structural proteins of Bunyaviridae?
2 **external glycoproteins:** - G1 - G2 **Nucleocapsid protein (N)** **Large transcriptase protein (L)**
58
Four human genera of Buyaviridae?
- Bunyavirus - Hantavirus - Nairovirus - Phlebovirus
59
Byunavirus genus includes? Geography?
**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
Incubation period of California serogroup (Aedes triseriatus)?
**3- 7 days**
61
What does Nairovirus cause?
**Crimean- Congo Hemorrhagic Fever** - Febrile illness followed by multi-organ failure
62
What is the vector for Nairovirus? Geography?
Tick-borne (Hyalomma) Africa/Middle East/E Europe/Asia
63
Incubation of Nairovirus?
**3-6 days**
64
What does Phlebovirus cause?
**Rift Valley fever** - Fever, myalgia, malaise encephalitis
65
Vector for Phlebovirus? Geography?
**Sandfly** fever viruses Endemic in sub-Saharan Africa
66
Transmission of Phlebovirus?
Potential for nosocomial spread (aerosol; direct contact?)
67
Incubation of Phlebovirus?
**2-6 days**
68
Hantavirus causes what?
**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
Transmission of Hantavirus?
- 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
New World Hantaviruses with geographic distribution
71
Diagnosis of Hantavirus
**- Serologic** (ELISA, HAI, Neutralization)-- primary - Antigen detection - Culture (RVF, CCHF)
72
Prevention and treatment of Hantavirus
- Vector avoidance - Vaccine (RVF- indicated, not licensed) - Treatment is supportive (**Ribavirin** in HFRS, possibly in CCHF)
73
Arenaviridae unique genetic feature?
Ambisense
74
T/F: Arenaviridae is non-segmented
**False**; it is bipartite (**2 segments- L and S**)
75
Is Arenaviridae DNA or RNA?
RNA
76
Two serologic groups of Arenaviridae?
- **Old world**: LCM, Lassa fever - **New world:** Junin fever, others
77
What is this?
Lass virus
78
What are the important Arenaviridae viruses associated with human dz?
**- Lassa** **- LCMV** (Also: Junin, Machupo, Guanarito, Sabia, LCMV)
79
Transmission of Arenavirus?
- Natural infxn of rodents - Aerosolization of rodent excretions - Nosocomial spread by contact with blood/body fluids - Solid organ transplants
80
Symptoms of LCM?
**Hemorrhagic fever** - N/V/D - Pulmonary edema - Capillary leak/bleeding
81
Endemic areas for Lassa fever?
- West Africa (Nigeria, Liberia, Sierra Leone, Guinea)
82
Infections and deaths due to Lassa fever?
300,000-500,000 infxns/year 5,000 deaths
83
Transmission of Lassa fever?
- **Rodent-to-human** ("multimammate rat, Mastomys species-complex) - **Secondary human-to-human** transmission with the potential for nosocomial outbreaks with high cast fatality
84
Diagnosis and Treatment and Prevention of Lassa fever?
**Diagnose:** - Serology - Antigen detection - RT-PCR - Culture **Treatment:** - Ribavirin for lassa fever - Convalescent serum also used **Prevention:** - No vaccines - Rodent control
85
Two genera of Filoviridae?
- Marburgvirus - Ebolavirus
86
Species of ebola?
- Zaire - Sudan - Bundibugyo - Tai Forest - Reston
87
What is this?
Ebola virus
88
Transmission of Filovirus?
Reservoir is **fruit bats** Infection seen after contact w/ infected **primates** or infected persons
89
What dz does Filovirus cause? time frame?
**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
Diagnosis of Filovirus?
- **Antigen detection** (primary) - EM - Cell culture (BSL-4 agent) - Serology - RT-PCR
91
Treatment of Filovirus?
- Supportive - Vaccines under development
92
Sequelae in survivors of Filovirus?
- 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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