viruses Flashcards
distinguish those numbered diseases…
first = measles
second = scarlet fever = strep. pyogenes
third = rubella
fourth = ?SSSS
fifth = parvo = erythema infectiosum
sixth = roseola infantum = HHV6
specific rashes
- parvo
- measles
- rubella
- congenital rubella
- measles
parvo = slapped cheek, rash worse with sun/heat, and LACY rash!
rubella = pinpoint petechiae on soft palate
congenital rubella= blueberry muffin rash
measles = koplik spots, maculopapular cephalocaudal rash
which viruses can be reactivated with a transplant
hhv6 (latency in monocytes and macrophages)
EBV
CMV
HSV
VZV
adenovirus
parvovirus: when infectious
days prior to rash/arthropathy - those are immune mediated in response to infection
parvovirus: main complications
- transient aplastic crisis - goes to bone marrow and affects erythroid progenitor»_space; chronic haemolytic anaemia
- arthropathy
- hydrops fetalis
- neurological e.g. GBS
HHV6: higher rate of what??
1/3 feb covulsion
complex seizures inc. post ictal paralysis
HHV8 causes what??
Kaposi sarcoma = multifocal angiogenic lesions in skin/mucous membranes
rubella vaccinations
Given at 12 months (MMR) and 18 months (MMR-V)
- Not given to immunocompromised patients
complications of rubella (non-congenital)
arthralgia
encephalitis ** RARE, but severe
thrombocytopaenia
measles: main complications
it suppresses the immune system for up to 6 weeks so can get:
1) OM (most common)
2) pneumonia
3) encephalitis
4) a decade later: subacute sclerosing panencephalitis
Warthin Finkeldey giant cells = what disease???
measles
public health things about measles
vaccinate contacts within 72h of exposure
- exclude school for 14 days if vax declined
90% household contacts will get it
2 vax - 12mo and 18mo
classic lymphadenopathy pattern rubella
post-auricular and suboccipital lymphadenopathy.
measles vax vs flu vax can be given to which people?
measles can given with egg allergy!
mumps: main complications
- parotitis
- SNHL
- orchitis/EO
- meningitis
features of congenital varicella
- Cicatricial skin scarring
- Limb hypoplasia
- neuro stuff e.g microcephaly, seizures
- Eyes – chorioretinitis, microphthalmia, cataracts
shingles - explain
herpes zoster = shingles:
varicella dormant in dorsal root ganglia
if IC/aging
reactivates > travels to dermatome
post-herpetic neuralgia = pain in dermatoma which can last up to 3 months
why is aspirin CI in VZV / influenza
Reye syndrome = rapidly progressive encephalopathy with hepatic dysfunction esp a/w VZV/influenza
exposure during the foetal/neonatal period for varicella - what to do?
For mum:
past infection / immunisation - no action
If seronegative:
i. Exposure <= 96 hours earlier = ZIG
ii. Exposure >= 96h = no ZIG, consider oral aciclovir PEP
For foetus:
<28/40 = VZIG
>28/40 = VZIG if no maternal Ab
<1 week old = VZIG if from mum. If not from mum, VZIG if no maternal Ab
what is ramsay hunt syndrome?
herpes zoster oticus:
reactivation of VZV in geniculate ganglion > facial nerve palsy, deafness and vertigo with vesicles and pain in the auditory canal
HSV1 vs HSV2
HSV 1
- oral infection, can cause genital
- decreased risk of recurrent infection
HSV2
- Genital infection, can cause oral
- Increased risk of recurrent infection
where does HSV lie latent?
trigeminal or sacral ganglia
clinical manifestations possible with HSV (outside of neonates)
- gingivostomatittis
- encephalitis
- eyes: keratoconjunctivitis, branching dendritic lesion on cornea
- skin: herpes labialis (cold sores), herpes whitlow
- genital herpes
PCR vs serology: what is the more useful test in detecting CMV acute infection, and why?
PCR:
- MOST of the population is IgG positive
- IgM only develops after 4-16 weeks
- Avidity of IgG is typically LOW for the first 4-5 months following infection
treatment of varicella contacts
1mo-1yo: if complications, VZIG.
>1yo: VZV vax within 5 days (prevents and modifies disease)
acute EBV illness i.e. mono: clinical signs/symptoms
- Fever 1-2 weeks
- pharyngitis / tonsillitis
- Lymphadenopathy (particularly epitrochlear + posterior cervical LN)
- fatigue
- Hepato-splenomegaly
- Eyelid edema (MCQ)
- palatal petechiae
complications of EBV infection
- splenic rupture
- lymphoproliferative disorders: HLH, PTLD
- malignancy: burkitt’s, hodgkin’s, leiomyosarcoma, nasopharyngeal
- in immunocompromised: Oral hairy leukoplakia and Lymphoid interstitial pneumonitis
lab test for EBV
MONOSPOT – tests for Heterophile antibody (made by infected B cell), usually +ve after 2-9 weeks after infection
younger kids: EBV specific Abs (EBNA = latent infection, IgM VCA)
two common reasons for false negative monospot
- too early (25% neg in first week)
- too young (<4yo, B cell won’t make the heterophile Ab)
what is the only respiratory virus with a mAb to treat? when to treat?
RSV and palivizumab (monthly injections);
1. CLD
2. Congenital heart disease if < 2
3. Extremely premature < 28 weeks
RSV most often co-infects with what virus
human metapneumovirus
unlike influenza, what can RSV not do?
no antigenic shift!
most common cause of a common cold in a child?
rhinovirus!
major clinical manifestations of adenovirus to know about
- resp - bronch, pneumonia
- eyes - conjunctivitis (pink eye)
- GI - diarrhoea
- haemorrhagic cystitis
- disseminated
what are the 4 enteroviruses?
PEEC:
polio
echo
entero
coxackie
the major clinical manifesatations of enteroviruses, and which ones are implicated
- non-specific viral
- HFM = coxsackie A16 (+ enterovirus 71)
- herpangina = Coxsackie A and enterovirus 71
- Acute haemorrhagic conjunctivitis = enterovirus 70 + coxsackie virus A25
- Myocarditis/ pericarditis = coxsackie B
- meningitis = enterovirus 71, coxsackie B
- polio = coxsackie A7, poliovirus, enterovirus 71
coxsackie A vs B generally affect what?
coxsackie A = skin stuff (HFM, conjunctivitis)
coxsackie B = internal stuff (pericarditis, myocarditis, gastro, encephalitis, aseptic meningitis)
enterovirus 71 causes what important things
HFM
herpangina
aseptic meningitis
paralytic poliomyelitis
most common viral cause of viral meningitis
enterovirus - most coxackie B / echo
incidence of paralysis with polio infection
1/1000
prognosis of polio virus infection
dependent on type
a. Abortive polio + aseptic meningitis = usually benign
b. Severe bulbar poliomyelitis = mortality rates up to 60%
which polio vax causes vaccine derived polio virus?
OPV i.e. Sabin (therefore we prefer Salk)
antigenic shift vs antigenic drift
antigenic shift = point mutation = variant “shift = seasonal”
antigenic drift = sudden new HA subtype +/- NA = no recognition by immune response = PANDEMIC (e.g. H1N1) - only happens with flu A
what are the surface proteins we care about for influenza
- haemagluttinin
- neuraminidase = releases virus from cells
- membrane channel protein M2
oseltamivir MOA
neuraminidase inhibitor
human metapneumovirus vs paraflu - more bronch or croup?
human metapneumo: bronch > croup
paraflu: croup > bronch
rotavirus vax - major rare side effect
intussusception - in first 3 weeks post vax. Risk increases if doses are delayed
hpv cause what cancers, and which types cause what manifestations
- Genital warts and laryngeal papillomatosis (types 6, 11)
- Cervical cancer (types 16, 18); vulval and vaginal cancer
how can HIV be transmitted
- vertical (intra-uterine, intra-partum, post-partum breastfeeding is not common in industrialised nations)
- blood transfusion
- sexual transmission
rotavirus vaccine efficacy
85% only
how does HIV infect?
-targets CD4 T cells
-binds to the T cell using gp120. needs to bind to the T cell co-receptors (CXCR4 or CCR5) for entry
-RNA reverse transcribes > DNA moves into host nucleus and integrates into host DNA
natural history of HIV
- primary infection with seroconversion: like mono
- clinical latency by 12 weeks - but virus replicating and T cells reducing
- 200-500 cell count: constitutional symptoms, candidiasis, leukoplakia, lymphadenopathy
- <200 adults; <1500 in <1yo: AIDS
what is wasting syndrome?
- Persistent weight loss >10% of baseline OR downward crossing of 2 or more major centile lines
- an AIDS defining condition
when to treat HIV positive children
treat at any CD4 count
all <1yo
all infants also need PJP prophylaxis
Meds for HIV - the 4 MOA
- prevent viral entrance
- gp41 binder = enfuvirtide
- CCR4 receptor blocker = maraviroc - reverse transcriptase inhibitor
- NRTI
- NNRTI - protease inhibitor
- inhibit integration of virus into human DNA
classic side effects of NRTIs
lactic acidosis + hepatic steatosis (zidovudine also causes lipodystrophy)
how do you manage BK induced transplant nephropathy
reduce immunosuppression
human t lymphotrophic virus
i. Myelopathy
ii. Arthropathy
iii. Uveitis
iv. (adult) T cell leukaemia/ lymphoma
v. Hairy cell leukaemia
exams: rabies = ?? symptoms
aerophobia
hydrophobia
compare the 5 maculopapular rashes of childhood
- VZV: itchy AF. 1-3d prodrome fever. vesicles.
- roseola: not itchy, but high as fuck fever
- measles: not itchy, but got them 3C’s and koplick spots with cephalocaudal rash.
- rubella: itchy. starts on face. can get blueberry muffin.
- parvo: usually not itchy. fever 3 days prior to rash. slapped cheek. aplastic crisis/fetal hydrops.
