Viruses Flashcards
What does arbovirus mean?
Arthropod-borne virus
ie viruses that are transmitted by insects - Usually mosquitos or tics
3 main syndroms of arbovirus
Fever-athralgia-rash
Viral haemorrhagic fever
CNS infection
Key CNS arboviruses
Japanese encephalitis
Enterovirus 71
west nile virus
What does Chikungunya translate to? vector? Key way to differentiate from dengue
‘that which bends you over’
Aedes and culex mosquitos
Severe polyarthropathy
3 main syndroms of arbovirus
Fever-athralgia-rash
Viral haemorrhagic fever
CNS infection
Which is only arbovirus from anopheles mosquitos? key symptom?
o’nyong nyong
Conjunctivitis
ee oo
[Symmetrical O like a pair of eyes 👀]
Interval of how long between exposure and Sx rules out viral haemorrhagic fever
3 weeks
Lassa VHF caused by? Geography? transmission? Human-human? rx?
Arenavirus
West africa
Rodents / human-human
Ribavirn
[2 people riding rats with lasso in an arena]
Ebola / marburg VHF caused by? Geography? transmission? Human-human? rx?
Filovirus
Sub saharan africa
Bats / human-human
No rx
Hanta VHF caused by? Geography? transmission? Human-human? rx?
hantavirus
New and old world
rodents (NO human-human)
ribavirn
Crimean-congo VHF caused by? Geography? transmission? Human-human? rx?
Nairovirus
Europe / Asia / Africa
Hyalomma ticks / livestock / human-human
Ribavirn
[Congo by origin of river nail which travels through lots of countries. LOTS = even Europe. Only trop disease in Europe is tick borne]
Rift valley fever VHF caused by? Geography? transmission? Human-human? rx?
Phebovirus
Africa / middle east
Ades / mosquitos / livestock
Ribavirn
[Rift between You and phoebe because you went to africa and middlr east and she got bit by mosquitos and had to ride livestock ]
Dengue VHF caused by? Geography? transmission? Human-human? rx?
Flavivirus
Tropics
Ades mosquito-
no Human-human
No rx
Yellow fever VHF caused by? Geography? transmission? Human-human? rx?
Flavivirus
Africa / south america
Mosquitos / monkeys. No human
No rx
Key early features to make suspicious for VHF
Pharyngitis with ulcers (eg dysphagia / retrosternal chest pain)
Conjunctival injection - basically pronounced vessels
Petechiae
Prostration - too weak to do anything (lying face down)
Dx VHF ?
PCR
ELISA
IgM
[Need to be undertaken in biosafety level 4 labs]
Which VHF has sensory neural deafness as key complication long term ?
Lassa
[Loud crowd deafening]
Which VHF classically causes renal syndrome and non-cardiogenic Pulm oedema
Hantavirus
-requires Ribavirin
Hantavirus [in Panama like rodrick who’s got a good heart = non cardiogenic pulmonary oedema]
[note all VHF cause a degree of pulm oedema due to capillary leak]
Which VHF is often has a major haemorrhage? vector?
Crimean-congo haemorrhagic fever
ixodid ticks (hyalomma genus)
Generally which VHF are transmitted exclusively by arthropods?
Which by arthropods and Human-human?
which only direct eg animals and humans?
Arthropod only - Dengue and yellow fever
Direct transmission - Lassa, ebola / marburg
Both - crimean-congo, rift valley
Which is only VHF where humans can be hosts?
Dengue
Ades aegypti mosquito
Dengue Ix
Low neutrophils and thrombocytopenia
NS1 antigen (ELISA)
PCR
ELISA for IgM / IgG (false positives from cross-reaction with other flaviviruses)
w
Yellow fever clinical features?
Jaundice
Liver failure
GI bleeding
Which mosquito-borne virus is most rapidly spreading worldwide?
Dengue
Which dengue protein for entry into cell and protects against host immune response
Protein E
Post infection with dengue how long are you immune
Only 2-3 months
Dengue incubation period
4-7 days - Max 2 weeks
Characteristic rash in dengue recovery phase
‘White islands in a sea of red’
Dengue timeline of Temp vs haematocrit vs platelets
How often do you get dengue haemorrhagic fever or dengue shock syndrome
1% of cases
85% Asx/ Mild Sx
Most important risk factor for Severe dengue infection
Previous infection with a DIFFERENT dengue strain
-Keep in mind Infants with primary infection born to dengue-immune mothers
[Non-nutralising antibodies bind to new serotypes and get an excessive immune response…]
Criteria for severe Dengue
[Loss of Plasma, RBCs, Organs]
Severe plasma leakage leading to:
* Shock (DSS)
* Fluid accumulation with respiratory distress
Severe bleeding
-as evaluated by a clinician
Severe organ involvement
* Liver: AST or ALT ≥ 1000 U
* CNS: Impaired consciousness
* Heart and other organs
Who needs to be treated in hospital with denngue
–Any criteria of severe
– Co-existing conditions that may complicate dengue or its management: Infancy, pregnancy, old age, obesity,
diabetes mellitus, renal failure, chronic haemolytic diseases, bronchial asthma
– Live far from health facility
Who can be sent home with dengue
– Tolerate adequate volumes of oral fluids
– Pass urine at least once every 6 hours
– Do not have warning signs, especially when fever
subsides
Who am I
aedes aegypti
Important consideration for someone with confirmed dengue
Prevent them getting bitten by other aedes aegypti mosquitos
Who cant have dengue vaccine
If your dengue naive
-Otherwise risk of worse dengue if you get it again
[Only if previous infection]
Which viruses are we thinking about when fever
+ encephalitis
+ arthritis
+haemorrhage
Chikungunya vector? usual reservoir?
Aedes aegypti or Aedes albopictus (new mutation-> adapted)
Humans - also primate reservoir
Chikungunya pattern of arthritis
Symmetric polyarthralgias /arthritis
Usually: hands and feet >10 joints
Assoc with swelling and tendosynovitis
Blood tests chinkungunya vs dengue
WBC? platelets? haemoconc?
Chicken legs (lymphopenia)
Everything else worse in dengue
Rx athritis chikungunya
Acute -NSAIDs
Chonic (45% at 10 months) - may need steroids / DMARDs
Which alphaviruses cause arthritis - name 3
Chikungunya
O’nyong’nyong
Mayaro
Ross River
Sindbhi
Zika vs Chik vs dengue
Fever? conjunctivitis? Arthritis? rash? myalgia? haemorrhage?
23F Lima Peru with 4 d fever, chills, malaise, myalgias, arthralgias and HA after travel to Iquitos
[No rash, bleeding, jaundice, abdominal pain, cough, SOB, GI] Develops non-purulent conjunctivitis.
Zika
name 2 Key fetal issues with zika
Approx 20% get infected
Fetal loss (miscarrage / still birth)
5% microcephaly - especially in 1st trimester
retinal abnormalities
Small for gestational age
Key complication following zika
Guillian barre
Where should you get sample for zika Dx?
Urine (95% sens)
Serum - only 56%
PCR ideal
NAAT used commonly as cheaper
Most common infective cause of myocarditis
coxsackie B virus
2 examples of Paramyxovirus
Measles
Mumps
high fever, cough, runny nose and conjunctivitis is what?
(diarrhoea in 10%)
Maculopapular rash
Name 3 complications? 1 late comp?
Measles
-Ear infection
-Pneumonia (most common cause of death in kids)
-Encephalitis -> seizures / deafness
-Pregnancy - prematurely, or low-birth-weight baby
Late
Subacute sclerosing panencephalitis (SSPE)
[Koplik spots]
Where does the measles rash usually start?
Behind ears
Measles Rx - Low vs high income?
Low income - Vitamin A (may reduce mortality by 50%)
High income - immune serum
Ribavirin - in immunocompromised
Most common precipitating factor of this progression of vit A deficiency blindness
Measles
The biggest issue with the distribution of the measles vaccine worldwide
Cold chain essential (loses 1/2 potency after 1hr warm)
Measles vaccine then kid comes in after a minor fall with reduced GCS - whats happened? Other complication
Thrombocytopenia - > bleed
[Post-infectious encephalomyelitis
- 50% permanent damage]
Rubella complications
Arthritis - 70% of adult women
Pregnancy - miscarriages, fetal deaths/stillbirths
-Congenital rubella syndrome - cataracts, heart defects, and hearing impairment.
Yellow fever geneotype west africa? East africa? South america?
1a - west africa
1b - south America
2 - central and east Africa
3 types of yellow fever transmission
Sylvatic (jungle) from monkey reservoir - Ades
Savannah - only in Africa - Ades ssp
Urban - Ades aegypti
Yellow fever incubation? How many go on to hemorrhagic fever
3-6 days
only 10% - haemorrhagic
Name a few laboratory findings in yellow fever
Albuminuria
Transaminase elevation - often initially massive due to apoptosis
-Alkaline phosphatase only minimally elevated
Direct bilirubin 5-10 mg/dl
Prolonged PT
ALT / AST >5000
DDx?
Councilman bodies are acidophilic inclusion bodies in the cytoplasm of hepatocytes
- Yellow fever, autoimmune hepatitis, other viral infections
Type of vaccine is YF
Live attenuated virus (17D and 17DD) vaccines
- Cant give to immunocompromised
Mpox name 2 routes of transmission? incubation period?
Entry via broken skin, respiratory tract,
mucous membranes
-Contact with contaminated clothing or
linens
-Direct contact with skin lesions or scabs
-Respiratory secretions
Incubation period: 7-10 days
Mpox clinical Hx? How long are you infective
Invasive phase - 1-5 days
-Fever
-flu-like illness
-Lymphadenopathy
Eruptive phase - infectious while still has skin lesions
Differentiate mpox from chicken pox
MPOX on palms and soles
has lymphadenopathy
Name 3 complications of mpox
Secondary bacterial infections
Sepsis
Encephalitis
Pneumonia
Keratitis -> sight-threatening
Who has very high mortality in Mpox
HIV infection CD4<100 mortality rate 30%
Mpox rx
Mostly supportive
[Brincidofovir, Tecovirimat]
How fast does Mox replicate?
Slowly (large DNA virus)
Orthopoxvirus
2 clades of mpox? which is the 2022 outbreak
I higher mortality, endemic in central African countries
II lower mortality, IIb B.1 2022 outbreak strain.
Varicella - Name 3 congenital complications
chorioretinitis, optic atrophy, pigmented patches of skin but may include hypoplastic limbs, club feet, cataracts, microphthalmos and early death.
Adult T-cell leukaemia/lymphoma (ATLL) due to HTLV-1 infection is sub-divided into four categories:
Acute, lymphomatous, chronic, and smouldering
All the VHFs are what type of virus
Enveloped RNA viruses
All zoonoses
[Filoviruses/Arenaviruses/Bunyaviridae (Hantaviruses/Nairoviruses)]
1/52 Fever, fatigue, headache, joint pains, vomiting, nausea , diarrhoea, abdo pain
Septic shock
West Africa - which VHFs are there
Ebola
Lassa
What is ebola? Incubation? Transmission? Diagnosis?
Filovirus
[important strains - Zaire, Sudan, Bundibugyo]
2-21 days
Fruit bat
Contact with bodily fluids from infected patient e.g tears, blood, diarrhoea, vomit, sweat, semen
RT-PCR
Stages of ebola
1 Dry - flu-like
2 Wet - D&V
3 Haemorrhage / seizure etc
Stages of ebola
1 Dry - flu-like
2 Wet - D&V
3 Haemorrhage/seizure etc
Ebola Rx is mostly flluid / supportive. Could you recognise one of these Drug Rx on an MCQ?
mAb114
RGEN EB3
Marburg is? Incubation? Transmission? Diagnosis?
Filovirus
2-21 days
Fruit bat / bush meat
RT-PCR
No approved treatment or vaccination
Filoviruses (ebola and Marburg) presentation
Fever, DIARRHOEA (with or without blood) vomiting and haemorrhage
Lassa reservoir
Mastomys natalensis
-rodent
Where is lassa geography
West Africa
-Nigeria, sierra leone, liberia and guinnea
Fever, sore throat, vomiting, swollen face? Other key features? Confirm diagnosis?
Lassa
SN hearing loss
PCR
What order are hantavirus? Key pathopysiology? Dx?
Bunyavirales
- Increased capillary permeability (causing vascular leakage)
- thrombocytopenia.
RT-PCR
Old world vs new world hantavirus
Old - haemorrhagic fever with renal syndrome
-Proteinuria, haematuria, AKI- > oliguric
New world - Cardiopulmonary syndrome
Influenza-like illnesses -> rapidly progressing pulmonary oedema caused by pulmonary capillary leak syndrome
38 year old Afghan origin
* Involved in ritual sacrifice at wedding (Kabul)
-Shock, Fever, thrombocytopenia
=?
Transmission?
Incubation?
Crimean-Congo Haemorrhagic Fever (CCHF)
- Tick bite/crushing
- Direct contact (blood/tissues) of infected
animals/humans
1-13 days
2 key Bunyavirales
Hanta
Crimean-Congo Haemorrhagic Fever (CCHF)
Ribavarin used for both
CCHF presentation
Often haemorrhagic early on compared with other VHFs
Name 2 Key risk factors for CCHF
Tick bite/crushing (Hyalomma spp. main vector).
Direct contact (blood/tissues) of infected animals/humans
Living/working in close contact with Livestock (e.g., farmers, shepherds, ranchers, and abattoir workers)
VHF from only south west india and is a biphasic illness
Kyasunar forest disease
Rats, bats, monkeys
[flea born]
Fever/flu-like -> recovery -> menigoencephalitis
Dog rabies presntation
Paralytic ‘Dumb’ 60% - often with high pitched bark
furious 40%
all human-to-human rabies transmission has been?
Organ transplant
Rabies encephalitis 2 presentaitons in humans
Furious - hydrophobic spams
-Often with ++ itching around healed bite site
Paralytic ‘dumb’ - survive longer
- Ascending flaccid paralysis
- no hydrophobia or spasms
Negri bodies by Seller’s stain
Rabies virus in a neurone - diagnostic
Rabies PEP? If immunosupressed?
4 dose IM over 21-28 days,
or 3 or 2 dose multi-site ID over 7 days
- RIG is recommended for severe/high risk exposures
[Eg broken skin]
Immunosuppressed - an additional booster dose at 28/30 days and RIG even for low risk exposure
Rabies PrEP? PEP if you’ve had PrEP
3 doses IM or ID over 21-28 days (boosters only for sustained high risk or check neutralising antibody titre)
2 dose IM over 3 days or multi-site ID on 1 day
