VHF Flashcards
What questions are included in a VHF risk assessment?
History of feverishness?
Symptoms within 21 days of leaving VHF endemic country?
Contact with animals/samples/fluids of VHF of suspected VHF case?
Travel to area where there is a VHF outbreak?
Lived or worked in basic rural conditions where Lassa cases occur?
Visited caves/mines, contact with primates, antelopes or bats in a Marburg/Ebola endemic area?
Travel to area where CCHF is endemic AND sustained tick bite/crushed tick/animal slaughter
Extensive bruising or active bleeding?
Who performs the initial VHF risk assessment? What PPE do they wear?
Senior member of the medical team looking after patient and should include input from infection specialist.
Standard infection prevention and control precautions and transmission based precautions are adequate
What actions are taken if a patient is considered at ‘minimal risk of VHF’?
Isolate in a side room with ensuite
Minimise contacts
Urgent malaria investigation
Local blood tests and blood cultures
Samples - handle as usual
PPE - SICPs and TBPs
If no improvement after 72 h, malaria negative and no alternative diagnosis - consider ‘At risk of VHF’
What actions are taken if a patient is considered ‘At risk of VHF’?
Immediately isolate in a side room with ensuite
HCID assessment PPE ensemble required
Urgent malaria testing - if malaria negative, discuss with IFS (or if malaria positive and returning from a country experiencing a current VHF outbreak - consider dual infection and discuss with ID/IFS)
Local blood tests and blood cultures
Samples - inform labs that samples are enroute so they can store securely pending IFS result
If IFS agree to testing then inform local HPT
What actions are taken if a patient is confirmed to have a VHF?
Lead clinician to contact NHS England emergency Preparedness
Transport to specialist HLIU for management
Full public heath action launched
Compile list of staff accessing patient and ensure this is limited to trained staff only
Notify IPC
Notify labs so they can discard waste as Cat A
What is required for cleaning a room of a patient:
Minimal risk of VHF
At risk of VHF
Terminal clean following confirmed VHF
Standard infection control precautions, cleaning and decontaminating procedures
Both ‘At riks of VHF’ and confirmed VHF:
Cleaning staff wear HCID PPE
Cleaning procedure validated for decontamination of VHF
Blood spills treated with 10,000 ppm bleach and 2 mins
Terminal clean of confimred VHF - fumigation with hyrdrogen peroxide
How should ?VHF samples be sent to RIPL/Lothian for testing?
Decision to be made by IFS as whether to send Category A or Category B
How should ‘At risk of VHF’ samples be delivered to the lab for testing?
Not via pneumatic tube system!
Transport samples to the lab in sealed containers
What labelling is required for Cat A and Cat B transport? What is the difference?
UN2814 = Category A infectious
UN2900 = Category A (animals only)
UN3373 = Category B infectious
The courier requires a specific licence to carry Cat A pathogens, and the rigid packaging has higher strength requirements
How should healthcare and laboratory waste be disposed of in confirmed VHF?
Category A waste disposal
Leakproof primary container
Secondary leak proof container with absorbent material
Rigid outer UN certified bin/drum - yellow in colour and labelled with Cat A waste and biohazard label.
Sent for incineration by licensed contractor
Which viruses cause haemorrhagic fever?
Ebola
Marburg
Lassa
CCHF
Rift Valley Fever
Dengue
Chikungunya
Hantavirus
And other Arenaviruses and Flaviviruses
Why are VHFs considered such a significant public health concern?
Spread within hospital setting and the community
Difficult to recognise
High case fatality rate
Transmission via contact > capable of person to person transmission
What are the classical symptoms of VHFs?
Initial ‘dry symptoms’ > fever, cough, myalgia, fatigue
Progressing to ‘wet symptoms’ > diarrhoea, vomiting, bleeding/bruising
What are HLIU and where are they located?
High Level Isolation Units
2x contact HCIDs at Royal Free and Newcastle
5x airborne HCIDs at Royal Free, Guys & St Thomas, Newcastle, Liverpool, Sheffield
Negative pressure patient bed isolator within negative pressure suite - no HCID PPE required
Negative pressure isolation suite with no bed isolator - HCID PPE required
What accidental exposures from a ?VHF patient require urgent attention?
What would be your actions?
Percutaneous injury/contact with unprotected intact or broken skin/contact with mucous membranes
Wash area with soap and water
Encourage bleeding by gently squeezing
If mucous membrane splash then immediately irrigate with splash bottles
Contact IFS for advise incl. PEP
Consider follow up BBV testing
Report to HSE under RIDDOR
What are SICP? TBPs? And additional precautions for AGP in a patient at ‘minimal risk of VHF’?
SICPs = hand hygiene, gloves, plastic apron
TBPs = fluid repellent surgical face mask and eye protection
For AGPs = FFP3 respirator and eye protection (unlikely airborne transmission of VHF but can’t rule out)
What does the HCID assessment ensemble PPE consist of?
FFP3 respirator
Hood
Long length visor
Long rear fastening fluid resistant surgical gown tied to the side
Medium thickness apron
Inner gloves
Middle gloves taped to the gown
Outer gloves
Wellington boots
How should samples from patient ‘At risk of VHF’ be processed in the lab?
Primary sample tubes stored securely for disposal if testing VHF positive
Auto analysers can be used
Ensure buckets used for centrifugation
POC blood gas analysers shouldn’t be used
Malaria films to be made in MSC and disposed of in dedicated sharps bin
Surfaces cleaned with 1000 ppm bleach
Spills cleaned with 10,000 ppm bleach
What family and genus are:
CCHF
Lassa fever
Ebola
Marburg
RVFV
Nairoviridae > Orthonairovirus
Arenaviridae > Mammarenavirus
Filoviridae > Ebolavirus
Filoviridae > Marburgvirus
Phenuviridae> Phlebovirus
What are the risk factors for CCHF transmission?
Travel to affected region (Turkey, Afghanistan, Pakistan, Iraq, Iran, Africa, Balkans, Spain, Russia)
Animal slaughter (inc. slaughterhouse workers, Eid celebrations)
Tick bite or crushing ticks
Funeral practices
Case fatality rate of CCHF?
30% in hospitalised cases
What is vector of CCHF? Which species is the principal vector in Europe?
Hyalomma genus of hard shell tick
Hyalomma marginatum
Incubation of CCHF?
2-7 days (range 1-14d) - shorter than Lassa/Ebola/Marburg
What are typical symptoms in CCHF in:
Ruminants
Birds
Children
Ruminants are source of infection for humans but they do not get sick
Birds don’t get sick but are responsible for spreading infected ticks to new geographical locations
Children very rarely get severe disease
What are the three phases of disease in CCHF, when do they occur and what are the symptoms?
Febrile phase (2-4 d post infection): sudden onset fever, headache, myalgia, photophobia, back pain, confusion
Critical (haemorrhagic) phase (4-5 d after sx onset): rash, bruising, bleeding (earlier than other VHF) epistaxis, vaginal bleeding, cytokine storm and vascular permeability. MOF and shock
Recovery phase
What treatment is used in CCHF infection and PEP?
Supportive (fluids, electrolytes, FFP, platelets, oxygen and blood pressure)
No licensed antivirals but ribavirin ad favipiravir have been used
Ribavirin has shown a benefit as PEP
What vaccines are available for CCHF?
Live attenuated vaccine available in Bulgaria only
ChAdOx1 vaccine trials in progress
What are the 6 species of Ebola virus and which are pathogenic in humans?
Zaire
Sudan
Tai Forest
Bundibungyo
Reston (Asia - pathogenic in pigs and primates, infects humans but no disease)
Bombali (bats only)
Natural host of Ebola virus?
Fruit bats (Pteropodidae)
Risk factors for Ebola virus acquisition?
Travel to affected region (DRC, Sudan, Gabon, Liberia, Uganda, Ivory Coast, Guinea, Sierra Leone)
Contact with possible infection (incl sexual)
Bushmeat (primates, bats, antelope)
Funeral practices
What is the fatality rate of Ebola?
25-90%
When do Ebola victims become infectious?
Very low infectivity at prodromal phase, become infectious at onset of D&V
Blood, vomit and diarrhoea are they most infectious bodily fluids
Incubation period of Ebola?
2-21 d (8-10 d ave)
Symptoms of Ebola infection?
Sudden onset: fever, headache fatigue, myalgia, sore throat
Followed by diarrhoea and vomiting
Patients may develop: rash, cough, SOB, red eyes, hiccups, renal and kidney failure, internal and external bleeding
Diagnosis of Ebola?
RT-PCR in blood (and urine) - blood may be negative up to 48 h post symptom onset
Treatment of Ebola
Supportive (fluids, electrolytes, FFP, platelets, oxygen and blood pressure)
Convalescent plasma has been used and works well due to high neutralising Ab titres
mAbs to Zaire strain available - WHO recommend their use in all confirmed cases, suspected cases in neonates and under 7 d old infants born to infected mothers
REGN-EB3 (Inmazeb)
mAb114 (Ebanga)
After convalescence - where can Ebola virus still be found in some circumstances?
Immune privileged sites including testes, interior of the eye, placenta, CNS
What are the risks of Ebola virus in pregnancy?
Increased risk of fetal loss, pregnancy associated haemorrhage
Most infants born to infected mothers will die
Transplacental transmission does occur
RNA still found in amniotic fluid and breast milk in recovered pregnant women
Neonates should be given mAbs at birth
What is a Cat 3 exposure to Ebola and what are the PH precautions required
Direct contact with Ebola case
Sexual contact with Ebola case (up to 3 months post recovery)
Clinical care of Ebola case (even with PPE)
Lab staff in non-assured labs
NSI etc
For 21 days post exposure:
Private accommodation only
Take temp twice daily and report it to designated official
No patient contact
No air travel (short public transport only)
No unprotected sex/sharing toothbrush/razor/no healthcare unless urgent
What is the reservoir for Marburg?
Fruit bats (Rousettus aegyptii)
Incubation period of Marburg?
3-21 d (ave 10) - rarely up to 28 d?
Risk countries for Marburg?
Uganda, Kenya, Tanzania, Rwanda, DRC, Equatorial Guinea, Ghana, Guinea, Angola
Name the
1) Old World Arenaviruses causing VHF
2) New World Arenaviruses causing VHF
3) Other Arenaviruses not causing VHF or disease in humans
1) Lassa and Lujo
2) Junin, Machupa, Chapare, Guanarito, Sabia, Whitewater Arroyo
3) Flexal and Tacaribe virus (New World) causing febrile illness in lab workers. Lymphocytic chorioemeningitis virus causing CNS disease worldwide
What are the reservoir hosts of all Arenaviruses?
Rodents
What is the reservoir host of Lassa fever?
Mastomys natalensis (multimammate mouse)
Where does Lassa most commonly occur?
Rural areas of West and Central Africa - mostly Guinea, Liberia, Nigeria and Sierra Leone
Risk of person-to-person transmission of the following:
1) Ebola
2) CCHF
3) RVFV
4) Lassa
1) Very high
2) Uncommon
3) Not documented
4) High
Transmission routes of Lassa
Contact with infected rodent excreta (direct, inhaled or ingested)
Person to person transmission via infected bodily fluids
Incubation period of Lassa?
7-10 d (max 21)
When is the infectious period of Lassa?
Onset of symptoms
Virus shed in urine for 3-9 weeks post onset and in semen for up to 3 months
What % of cases of Lassa are 1) asymptomatic/mild 2) fatal
1) 80%
2) 1-3% (20% in hospitalised patients)
What is the most common sequale of Lassa infection?
25% of patients have sensoneuronal hearing loss
Clinical symptoms of Lassa?
Gradual onset of fever, shivering, headache, fatigue, generalised pain, sore throat
Nausea, vomiting and cough
Severe cases include respiratory distress, persistent vomiting, facial swelling, neurological impairment, haemorrhage
Treatment and PEP of Lassa
Supportive therapy - fluid and electrolyte balance, blood transfusion, organ support
IV ribavirin (little evidence)
Broadly neutralizing human mAbs Arevirumab-3 have been studied as PEP
How long should unprotected sex be avoided after VHF?
3 months (up to 12 months for Ebola/Marburg)
Which countries are a risk of RVFV?
Eastern and Southern Africa, Saudi, Yemen and most of Sub Saharan Africa
What is the mortality rate of RVFV?
1% (50% in haemorrhagic disease)
Transmission routes of RVFV?
Mostly via contact with bodily fluids of infected ruminants
Also directly via mosquito
No human to human transmission
What are the vectors of RVFV?
Aedes and less commonly Culex
What is the incubation period of RVFV?
2-6 d
Clinical symptoms of RVFV?
Majority asymptomatic
Mild febrile illness
Severe disease includes hepatitis, encephalitis, haemorrhagic fever, ocular infection
What is the most common severe manifestation of RVFV?
Ocular infection including retinitis, uveitis, blurred vision and permanent blindness
Risk associated with RVFV in pregnancy
Vertical transmission can occur and IgM is detected in symptomatic neonates
What vaccines are available for RVFV?
Livestock vaccine - live attenuated MP-12
No licensed human vaccine but ChAdOx1 in development
What is required for a disease to be classified as an HCID?
FARRTS
Fatality rate - high
Acute infectious disease
Recognition is difficult in early stage
Response - enhanced population and systematic approach
Treatment - none
Spread - in community and healthcare
Name the 8 contact HCID
Junin
Machupo
CCHF
Ebola
Marburg
Lassa
Lujo
SFTSV
Name the 10 airborne HCIDs
Andes hantavirus
Avian influenza H5N1 and H5N6
Avian influenza H7N7 and H7N9
MERS
SARS
Mpox (clade 1 only)
Nipah
Yersinia pestis
Name the 11 WHO priority diseases
COVID
CCHF
Ebola
Marburg
Lassa
MERS
Nipah
Hendra
RVFV
Zika
Disease X
Risk of Lassa infection in pregnancy and babies
90% case fatality rate in infected mothers in 3rd trimester
Breastfeeding contraindicated as source of infection
Infection in babies can result in ‘swollen baby syndrome’ with odema, abdo distension, bleeding and high mortality rate
