VHF Flashcards
Who should be suspected of having VHF?
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
15 viral agents cause VHF.
What are the most common ones?
Lassa (arenaviridae)
CCHF (bunyaviridae)
Marburg (filoviridae)
Ebola (filoviridae)
What is geographical spread of following VHF?
Lassa
CCHF
Lassa - West Africa
CCHF - Africa/ East Europe/ China
What is geographical spread of following VHF?
Marburg
Ebola
Marburg - west and central Africa
Ebola - west and central Africa
Causes of VHF can be divided into arboviruses and non-arbovirus
What are causes of VHF arboviruses?
Flaviviruses
Bunyaviruses (also non-arbovirus)
Reoviruses
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
Causes of VHF can be divided into arboviruses and non-arbovirus
What are causes of VHF non-arboviruses?
Filovirus
Bunyaviruses (also arbovirus)
Arena viruses
Filovirus
- ebola - bat sources
- marburg - bat source
Bunyaviruses (also arbovirus)
- hantavirus - rodent source
Arena viruses
- lassa fever - rodent source
- South American VHF - rodent source
What are names of South American VHF Arena viruses?
Junin - Argentina
Machupo - Bolivia
Guanarito - Venezuela
Sabia - Brazil
GP phones about suspected VHF
What parts of history suggest VHF?
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
After referral from GP, what are next steps?
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
What are infection control procedures for suspected VHF?
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
Arenaviruses are ssRNA
How are they transmitted?
Direct contact rodents - mouse/ rat
inhalation of infected excreta
rodents can harbor lifelong, asymptomatic infection
What drugs have been used for treatment of lassa?
What drugs have been used for treatment of ebola?
Ribavirin
Ribavirin + remdesevir
ZMapp monoclonal antibody
Inmazeb
ZEBOV vaccine developed may offer protection
Ebola/ marburg are filoviruses.
How are they transmitted?
direct contact with fruit bats
contact with bat excreta
infects via mucosa
What is treatment of CCHF?
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
What are management options for Ebola?
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
Ebola vaccination
What options exist?
What is the efficacy?
Ervebo vaccine - single dose
Zadbeno - 2x doses
Mvabea - 2x doses
Live attenuated
Effective against Ebola Zaire virus
Vaccine 97% effective from day 10 onwards
What preventatitve measures exist for CCHF?
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
What treatments are available for Lassa virus?
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
Why are VHFs of particular health importance?
high case fatality rate
Spread easily between patients/ staff
No effective treatments
VHF staff contacts
What to do with:
No contact
Low risk
High risk
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
What is evidence of giving ribavirin as PEP for Lassa contacts
ribavirin has poor efficacy anyway
some data shows ribavirin just prolongs incubation period of Lassa, rather than stopping infection
not recommended
What does term Viral Haemorrhagic fever actually mean?
severe multi-organ disease due to damage to the vascular system, with host inability to regulate itself
caused by a virus
Which VHFs are Hazard Group 4 pathogens?
Arena - Lassa
Bunya - CCHF
Filo - Ebola/ Marburg
Flavi - Kyasanur Forest/ Omsk
Group 3
Yellow fever
Dengue
Rift Valley fever
Hantavirus
What percentage of patients infected with Lassa, develop severe symptoms?
Estimated 20% develop severe symptoms
Others may have mild symptoms such as a flu-like illness
Which VHF can cause long term deafness?
Lassa virus has been associated with deafness
Vaccine in development for Lassa
How far along is this?
2024 Phase 2 trial completed in Nigeria - further results expected in 2025
Vaccine in development for Lassa
What is the vaccine based on?
Based on recombinant vesicular stomatitis virus, which is already in use for Ebola vaccine Ervebo
