Viruses Flashcards
Alphavirus Example
EEE, WEE, Venezuelan EE, RRV, Chikungunya
Flavivirus Example
Dengue, Zika, JEV, MVE, West Nile, Yellow Fever, St Louis Encephalitis
Bunyavirus Example
California encephalitis, La Crosse, Rift Valley Fever
Rabies Transmission
Terrestrial mammals (99% dogs), Bats (Americas only), rare reports of tissue/organ transplant
Rabies Virology
Bullet-shaped RNA wrapped in five proteins - matrix, envelope, nucleo, phospho and RNA polymerase
Rabies Pathogenesis
Exposure -> centripetal retrograde axonal transport to brain along motor neurons, evades immune surveillance > CNS transynaptic spread, replication, inclusion (Negri) body formation, neurons intact but dysfunctional > centrifugal neuronal transport to salivary glands (viral excretion) carried to skin, heart, muscle tongue, but no viraemia
Rabies Natural history
Once clinical signs evident, there is no treatment or survival
Rabies Deaths per annum
60,000 (21,000 India)
Rabies Furious rabies
80% cases - brain stem, cranial nerves, limbic system higher centres
Rabies Paralytic rabies
20% cases - medulla, spinal cord, spinal nerves
Rabies Prodromal symptom
Pruritus
Rabies Clinical furious
Phases of arousal and lucid, CN II, VII, VIII, autonomic sitmulation, arrhythmia, priapism, survive <7d
Rabies Hydrophobic spasm
Provoked by drinking > Inspiratory spasm, becomes more severe, can cause oesophageal tears and pneumothorax
Rabies Clinical paralytic
Ascending paralysis (?GBS) loss of reflexes, bulbar sx, survive <30d
Rabies Differential diagnosis
Post-vaccinal, paralytic polio, Flavivirus, Herpes B virus
Rabies Clinical care
Palliative, barrier nursing (low evidence, but improves anxiety), vaccination of staff and household, inform public health authorities
Rabies Diagnosis
Nuchal biopsy - immunofluorescence rabies Ag on innervation of hair follicle; saliva PCR (variably released); viral tissue culture; brain biopsy Negri bodies (inclusion in cytoplasm of Purkindje cells)
Rabies Treatment
Only if American bat virus, early Ab response, ICU available - Milwaukee protocol discredited
Rabies Pre-exposure vaccination
Endemic area, rabies lab worker, endemic animal handlers, travelers to dog rabies enzootic areas (esp children), HCW looking after rabies pt - at least 2 (WHO) ideally 3 (UK) vaccines
Rabies Vaccine administration
IM deltoid (NOT gluteal), intradermal improves availability, accessibility and affordability in LMIC
Rabies Post-exposure management
Cat 2+ Scrub with soap and water 15min, avoid suturing, give vaccine x2 (RIG and vax x4 if cat 3 AND unvaccinated)
Rabies Category 1 exposure
Touching or feeding animals. Licks intact skin, includes drinking milk from rabid cow
Rabies Category 2 exposure
Nibbling of uncovered skin, minor scratches or abrasions without bleeding, treat as cat 3 if bat exposure, bites on head/neck/face/hands/genitals (highly innervated) - stop Rx if animal well after 10d/proven negative
Rabies Category 3 exposure
Single or multiple transdermal bites/scratches, contamination of mucous membranes or broken skin with saliva, exposures due to bats, includes raw meat of rabid animal - stop Rx if animal well after 10d/proven negative
Rabies Immunosuppressed
PrEP x3, Ab response 2-4w later, PEP x5 and RIG for cat 2+
Rabies Prevention
Mass dog vaccination (IM or oral), educate children, vigorous washing of all bites, vaccination
Rabies PEP
RIG up to 1y after, but not if vax given >7d ago
JEV Outcome
1/3 die 1/3-1/2 longterm disability
JEV Epi
Asia/Pacific
JEV Transmission
Arbovirus, Flavivirus
JEV Amplifying host
Pigs, Water birds also involved, vaccination will not eradicate due to animal reservoir
JEV Symptoms
> 99% asymptomatic, acute meningoencephalitis syndrome with seizures, Parkinsonism (basal ganglia predilection)
JEV Diagnosis
Goldstandard seroneutralisation - paired, and not available outside large reference centres, ELISA available poor spec in serum, also perform on CSF
JEV Vaccination
Ixiaro (UK), Imojev (Aus)
HPV WHO 2030 Targets
90% fully vaccinated by 15y, 70% women screened by 35-45, 90% CaCx receive treatment and care
HPV Genotype
CaCx 16/18, Anogenital warts 6/11
HPV Epidemiology
Most infections will clear within 8m
HPV Ab response
50% women develop no measurable Ab response following infection
HPV HIV co-infection
Increase CaCx x6, Anal cancer x10, increased anogenital warts, HPV is RF for HIV acquisition, HIV decreases HPV clearance
HPV CaCx diagnosis
Visual inspection (VIA) and HPV diagnostics have lower sens/spec in WLHIV compared with general population
HPV WHO HPV screening
General HPV DNA from 30 every 5-10y; WLHIV HPV DNA from 25 every 3-5y
HPV WHO Vaccine recommendation
2 doses from 9yo, option for 1-dose 9-20yo - aim before sexual debut
