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Virology > VHF > Flashcards

VHF Flashcards

1
Q

Who should be suspected of having VHF?

A

Fever >37.5

Visited affected area where there is VHF outbreak in past 21 days

This should trigger a VHF risk assessment on PHE website. Result should be documents on NNUH VHF risk assessment document

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2
Q

15 viral agents cause VHF.

What are the most common ones?

A

Lassa (arenaviridae)

CCHF (bunyaviridae)

Marburg (filoviridae)

Ebola (filoviridae)

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3
Q

What is geographical spread of following VHF?

Lassa

CCHF

A

Lassa - West Africa

CCHF - Africa/ East Europe/ China

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4
Q

What is geographical spread of following VHF?

Marburg

Ebola

A

Marburg - west and central Africa

Ebola - west and central Africa

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5
Q

Causes of VHF can be divided into arboviruses and non-arbovirus

What are causes of VHF arboviruses?

Flaviviruses

Bunyaviruses (also non-arbovirus)

Reoviruses

A

Flaviviruses

  • mosquito borne - yellow fever
  • mosquito borne - dengue
  • tick borne + dead rodent - Omsk (Russia)
  • tick borne - Kyasanur Forest Disease (India)

Bunyaviruses

  • mosquito borne - Rift valley fever
  • tick borne - CCHF

Reoviruses
- Colorado tick virus

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6
Q

Causes of VHF can be divided into arboviruses and non-arbovirus

What are causes of VHF non-arboviruses?

Filovirus

Bunyaviruses (also arbovirus)

Arena viruses

A

Filovirus

  • ebola - bat sources
  • marburg - bat source

Bunyaviruses (also arbovirus)
- hantavirus - rodent source

Arena viruses

  • lassa fever - rodent source
  • South American VHF - rodent source
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7
Q

What are names of South American VHF Arena viruses?

A

Junin - Argentina

Machupo - Bolivia

Guanarito - Venezuela

Sabia - Brazil

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8
Q

GP phones about suspected VHF

What parts of history suggest VHF?

A

Fever >37.5
Travel to endemic area within past 21 days
Travel to are with outbreak within past 21 days
Visited caves/ mines/ bats/ funerals
Extensive bruising/ bleeding

Raised ALT

Thrombocytopenia

Shock

Oxygen requirement

Malaria negative

If has symptoms - can be low/ high possibility of VHF

If has symptoms, and cared for/ contact with suspected VHF - high possibility

Complete VHF risk assessment record form

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9
Q

After referral from GP, what are next steps?

A

Isolate patient in side room

VHF risk assessment record form by medical team. This is then discussed with virology to see if agree. Then transfer to isolation facility

Routine tests including cultures/ malaria screen should not be delayed

Virologist to contact -

  • Imported Fever Service - Porton Down
  • Infection control
  • Occupational health - trace contacts
  • UKHSA
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10
Q

What are infection control procedures for suspected VHF?

A

Isolate patient on arrival or transfer to high level isolation unit

Patient wear surgical mask

Staff - wear full PPE. Buddy system for donning and doffing
FFP3 mask
Eye protection
Disposable gown or suit
double glove
boots

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11
Q

Arenaviruses are ssRNA

How are they transmitted?

A

Direct contact rodents - mouse/ rat
inhalation of infected excreta

rodents can harbor lifelong, asymptomatic infection

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12
Q

What drugs have been used for treatment of lassa?

What drugs have been used for treatment of ebola?

A

Ribavirin

Ribavirin + remdesevir
ZMapp monoclonal antibody
Inmazeb
ZEBOV vaccine developed may offer protection

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13
Q

Ebola/ marburg are filoviruses.

How are they transmitted?

A

direct contact with fruit bats
contact with bat excreta

infects via mucosa

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14
Q

What is treatment of CCHF?

A

Ribavirin has been shown to have mild efficacy, although controversial

Favipiravir is a nucleoside analogue viral RNA polymerase inhibitor. some efficacy in rodent models. Clinical trials needed

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15
Q

What are management options for Ebola?

A

Ribavirin trialled

Remdesevir

Convalescent plasma - trials underway

ZMapp - cocktain of three human-mouse monoclonal antibodies.No longer used

Inmazeb - 3x monoclonal antibodies

Favipravir - viral RNA polymerase inhibitor. Good results in mice. Await further testing

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16
Q

Ebola vaccination

What options exist?

What is the efficacy?

A

Ervebo vaccine - single dose
Zadbeno - 2x doses
Mvabea - 2x doses

Live attenuated

Effective against Ebola Zaire virus

Vaccine 97% effective from day 10 onwards

17
Q

What preventatitve measures exist for CCHF?

A

Vaccine - Bulgarian exists from 1970s, mouse derived
inactivated
2 doses
mild efficacy - requires booster doses every 5 years

Clothing/ PPE for high risk workers - farmers/ abbatoir/ healthcare worker

Tick control

Quarantine unwell animals

Education

18
Q

What treatments are available for Lassa virus?

A

Ribavirin - some efficacy if given early

Favipiravir - animal models

Monoclonal antibody cocktail

Envelope glycoprotein viral entry inhibitor - in trial

High genetic diversity means difficult to create vaccine

19
Q

Why are VHFs of particular health importance?

A

high case fatality rate

Spread easily between patients/ staff

No effective treatments

20
Q

VHF staff contacts

What to do with:

No contact

Low risk

High risk

A

No contact -
- no direct contact with patient e.g sharing a room, without contact with body fluids
- reassure

Low risk -
- direct contact with patient e.g routine nursing care. But did not directly handle body fluids, and wore PPE
- passive monitoring with fever chart for 21 days

High risk -
- unprotected exposure to infectious body fluid
- active monitoring - fever chart for 21 days, with active reporting daily to the monitoring officer

21
Q

What is evidence of giving ribavirin as PEP for Lassa contacts

A

ribavirin has poor efficacy anyway

some data shows ribavirin just prolongs incubation period of Lassa, rather than stopping infection

not recommended

22
Q

What does term Viral Haemorrhagic fever actually mean?

A

severe multi-organ disease due to damage to the vascular system, with host inability to regulate itself

caused by a virus

23
Q

Which VHFs are Hazard Group 4 pathogens?

A

Arena - Lassa
Bunya - CCHF
Filo - Ebola/ Marburg
Flavi - Kyasanur Forest/ Omsk

Group 3
Yellow fever
Dengue
Rift Valley fever
Hantavirus

24
Q

What percentage of patients infected with Lassa, develop severe symptoms?

A

Estimated 20% develop severe symptoms

Others may have mild symptoms such as a flu-like illness

25
Q

Which VHF can cause long term deafness?

A

Lassa virus has been associated with deafness

26
Q

Vaccine in development for Lassa

How far along is this?

A

2024 Phase 2 trial completed in Nigeria - further results expected in 2025

27
Q

Vaccine in development for Lassa

What is the vaccine based on?

A

Based on recombinant vesicular stomatitis virus, which is already in use for Ebola vaccine Ervebo

Virology (56 decks)

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