exanthemata Flashcards
the 6 classical exanthemata diseases
- measles
- scarlet fever
- rubella-german measles
- fourth diesease aka nothing
- parvovirus B19=slapped cheek disease
- Roseola infantum=exanthemata subitum
what causes measles
mobilivirus
what causes scarlet fever
group a beta haemolytic strep pyogenes
what causes rubella
rubivirius
what causes roseola infanatum
human herpes virus 6
what is a macule rash
can be seen but not felt
what is a papule lesion
can be felt and seen
what is a maculapapular rash
mix of macule and papule so can feel some bits
how is exanthemata dx
serology IgM for all
molecular
-PCR for measles
measles transmission
- droplet spread by respiratory route
- conjunctival contaminaion
v. contaigous
symptoms and timeline of measles
-incubation 7-18 days
-10days to prodrome
-prodrome for 4 days
-at 14 days get a rash
(aka appears on day 4)
clinical features of measles
-prodrome 2-4 days
-day 4 must have fever and BLANCHING maculopapular rash
plus on of 3 c’s
-coryza
-conjunctivits
-cough
also
-koplik spot 2 days before rash
what is the rash in meaasles
- blanching maculopapular rash
- starts behind the ears
- fades leaving capillary staining
- fine desquamation
- soles and palms spared
measles severe manifestation
- pulmonary invovlement- severe chest infection 90% of cases, bronchiolitis and giant cell pneumonia
- encephalitis
- modified and atypical forms in immunocompromised
x-ray of pulmonary measles
hyperinflation and diffuse fluffy infiltrates
when is MMR vaccine given
2 doses 12 months and 3-5 years
severity of rubella
mild illness with few severe manifestations
clinical features of rubella
- rash and illness on same day usually week incubation
- fever
- lymphadenopathy post ear
how long does rash last for rubella
3 days without staining
what are the complications of rubella
- reactive arthritis in adults
- congenital rubella syndrome
- thrombocytopaenia
- guillain barre
- encephalitis
what is congenital rubella syndrome and when is the risk greatest
if the foetus is exposed to rubella
<10 weeks 90% risk
transient features of CRS in foetus
hepatitis jaundice rash thrombocytopaenia anaemia lymphadenopathy
permanent features of CRS in the foetus
classic triad
- patent ductus arteriosus
- cataracts
- senorineural deafness
also neuro eg micropcephaly
developmental features of CRS potenitally
- increased risk of insulin dependent diabetes
- thyroid disease
- progressive hearing or visual loss
prevents of CRS
Immunisation before pregnancy
what does parvovirus cause in adults
arthropathy in adults-reactive arthritis
clinical features of parvovirus in children
- fever then rash
- slapped cheek rash then 1-2 days later get a generalised rash
complications of parvovirus
- infects red cell precursors
- aplastic crisis in patients with pre-existing haemolytic anaemia eg sickkle cell
- chronic infection in immunocompromised
what does parvovirus do to foetus
-foetal anaemia-hydrops fetalis in 5% maternal infection
how does roseola infantum present
-high fever for 4-5 days
-when fever falls get a rash
-scattered maculopapular rash
on chest, back and limbs
spares feet and hands
scarlet fever type of toxin
erythrogenic toxin
clinical onset of scarlet fever
- rash appears 1-2 days after onset of a sore throat
- assoc. to pharyngeal infection
what type of rash is scarlet fever
- face-circumoral sparing
- blanching rash
- elevates around hair follicles-sandpaper
- capillary haemorrhage in skin folds Pastia’s lines
- strawberry tongue
- desquammation
immune complications of scarlet fever
-rheumatic fever
-post strep glomeruloneprhitis
but now rare
what is rheumatic fever
-multi system autoimmune disorder occurring 3 weeks after pharyngeal infection
features of rheum fever
pancarditis arthritis chorea-prepubertal subcutaneous -nodules erythema marginatum
long term complication of rheumatic fever
damage to heart valves cause rheumatic heart disease at risk of endocarditis
strep pyogenes clinical features
- ssti eg erysipelas, cellulitis
- strep throat
- if makes erythrogenic toxin get scarlet fever
treatment of strep pyogenes
antibiotics means rarely develop scarlet fever anymore
