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

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

Flashcards in 5/28- 5 Arboviruses: Toga, Flavi, Bunya, Arena, Filo Deck (92):
1

What three families are comprised in Arboviruses?

- Togaviridae

- Flaviviridae

- Bunyaviridae

2

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

False. Humans are typically dead-end hosts

3

Clinical syndromes of arboviral infections?

CNS disease:

- Encephalitis/meningoencephalitis

- Aseptic meningitis

Febrile illnesses (+/- rash)

"Hemorrhagic diseases"

Asymptomatic (unrecognized infxn)

4

Arthropod vectors

- Mosquitos

- Ticks

- Flies

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

5

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

Q image thumb

Learn

6

Do arboviruses have seasonal fluctuations?

Yes. Early summer/fall when mosquitoes at peak level

7

Symptoms of encephalitis

- Fever, HA, vomiting, confusion, seizures

- Minimally stiff neck (differentiates from meningitis)

- With recovery, a proportion will have residual neurologic damage (varies with virus)

8

Two structural surface glycoproteins of Togaviridae?

E1

E2

9

Two genera of Togaviridae

- Alphavirus (Group A arboviruses)

- Rubivirus = rubella

10

Alphavirus classification by __?

Antigenic

11

Different thypes of antigenic classifications (4)?

- 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

12

New world alphavirus antigenic complexes

- Eastern equine encephalitis virus (EEEV)

- Western equine encephalitis virus (WEEV)

- Venezuelan equin encephalitis virus (VEEV)

13

Old world alphavirus antigenic complexes

- Semliki Forest virus (SFV)

- Middleburg virus (Africa)

- Ndumu virus (Africa)

- Barmah Forest virus (Sindbis virus is old world although in WEEV antigenic complex)

14

Clinical syndromes of new world alphaviruses? old world?

New:

-Encephalitis

- Aseptic meningitis

Old:

- Febrile illness

- Rash

- Arthritis

15

Semilki Forest virus group includes?

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)

16

WEEV group includes?

- Sindbis (Europe, Asia, Africa, Australia)

17

How many people with Chikungunya develop clinical symptoms?

72-97%

18

Incubation period of Chikungunya?

3-7 days (range 1-12 days)

19

Clinical symptoms of Chikungunya?

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

Resolution of acute symptoms with Chikungunya?

Typically resolve 7-10 days

21

Recovery phase of Chikungunya may involve?

- 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

22

Diagnosis of Alphavirus infxn?

- 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

23

Treatment/prevention of alphavirus?

- Supportive (no antiviral therapy)

- Prevent by avoiding/controlling mosquitoes

- Investigational inactivated and live attenuated (e.g. VEE) vaccines for high risk individuals

24

T/F: Rubella is not an arbovirus

True; rubella is spread person-to-person

25

Symptoms of Rubella

- Mild febrile exanthem in children and adults

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26

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

1st trimester especially

- Cataracts

- Deafness

- Cardiac abnormalities

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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?

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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?

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52

Clinical syndromes of Dengue (broad)?

- Undifferentiated fever

- Classic dengue fever

- Dengue hemorrhagic fever

- Dengue shock syndrome (rash)

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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

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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?

Q image thumb

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?

Q image thumb

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