Exanthemata Flashcards
(13 cards)
List the 6 classical exanthemata
Six classical exanthemata
- Measles Paramyxovirus, genus: Morbillivirus, ss(-) RNA
- Scarlet fever Group A, beta-haemolytic strep, strep. pyogenes
- Rubella Togaviridae, genus: Rubivirus, ss(+) RNA
- “Fourth disease” Duke’s disease – probably scarlet fever
- Parvovirus B19 Parvovirus, genus Erythovirus, ss DNA “slapped cheek”
- Roseola infantum HHV6
What infections cause a macula-papular rash?
Measles
Rubella
Parvovirus
What infections cause a vesicular rash?
VZV
Herpes
Paracox
Measles
- how is it transmitted?
- when is someone infectious?
- incubation period?
- clinical features
- diagnosis
- management
- prevention
- droplet spread by resp. route, and conjunctival contamination
- infectious from just before onset of symptoms to 4 days after appearance of rash
- incubation: 7-18 days
Clinical features
- fever, rash and at least 1 of the C’s (conjunctivitis, coryza, cough)
- Koplik’s spots (white spots on side of cheek - opposite molars)
- Rash - on day 2-4; blanching; starts behind ear and spreads south; fine desquamation; sole and palms not involved
Diagnosis
- confirm all cases serologically and report to public health without waiting for results of diagnostic test
- PCR viral throat swab
- serology - Anti-measles IgM and IgG; isolation of measles virus or identification of measles RNA
- histologic evaluation of skin lesions or respiratory secretions - may show syncytial keratinocytes giant cells
Management
- uncomplicated = self limiting (10-12 days)
- supportive
Prevention
- live attenuated vaccine - MMR
- UK schedule - 12 months, 3-5 years
- 99% effectiveness after 2 doses
Measles
- Name two severe manifestations
- what would be seen on investigations
Severe manifestations
- pulmonary involvement - 90% of severe cases; bronchiolitis and giant cell pneumonia; hyperinflation and diffuse fluffy infiltrates on CXR; worse in immunocompromised and malnourished
- Encephalitis - rare but severe
Someone has been exposed to measles. What can be done?
prophylactic MMR vaccine within 72 hours of exposure
Rubella
- what virus causes it? what type of virus is this?
- presentation
- when are individuals infectious?
- complications?
- prevention?
Rubivirus - SS+ve RNA
Mild illness with few severe manifestations
- Frequently asymptomatic
Clinical presentation
- Rash - fades in 3 days without staining;
- fever
- lymphadenopathy – usually mild; Post auricular
- Arthritis in adults
- Occasional thrombocytopenia, Guillain-Barré, encephalitis
Infectious for 1 week before onset of rash, which usually occurs on first day of illness in children
Infection during pregnancy can cause congenital rubella syndrome (CRS)
Prevention: immunization (age 13-14) & screening pre-pregnancy (in high incidence settings)
Congenital rubella syndrome
- what is the risk of this occurring?
- features
Risk depends on stage of pregnancy
- < 10 weeks: 90%
- 11-12 weeks: 30%
- 13-20 weeks: <10%
- > 20 weeks: very low risk
Features of CRS are:
Transient
- Child born with features suggesting current viral infection
- Hepatitis & jaundice, rash, thrombocytopenia, anaemia, lymphadenopathy
Permanent
- Classic triad: Patent ductus arteriosus, cataracts and sensorineural deafness
- Other cardiac defects (e.g. PA stenosis), ophthalmic (e.g. retinopathy, corneal defects, glaucoma) or neurological (e.g. microcephaly)
Developmental
- Increased risk of insulin dependent diabetes (20% by 35y)
- Thyroid disease
- Progressive hearing or visual loss
Slapped cheek disease
- what viruses causes this infection?
- incubation?
- when most infectious?
- modes of transmission
- who is most at risk of infection?
- Presentation
- management
- complications
- Parvovirus B19
- Most infections - asymptomatic and unrecognised
- Incubation: 1-2 weeks
- most infectious before onset of rash
Modes of transmission
- Resp. tract secretion, percutaneous exposure to blood or blood products and vertical transmission from mother to foetus
Epidemiology
- Children 4-10 yrs old, but can affect all ages
- Tends to occur in epidemics (school outbreaks in late winter and early spring)
- Secondary spread among susceptible household members common, with infection occurring in ~ 50% of susceptible contacts
In most communities, ~ 50% of young adults and often more than 90% of elderly people are seropositive
Presentation
- Prodrome: low-grade fever, malaise, headache, pruritus, coryza, myalgias, joint pain (more common in adult women)
- Fever then rash
- Initially on face – bright red cheeks - followed 1-2 days later by generalized rash on trunk/extremities with characteristic lacy appearance (dantelle, pizzo, merletto)
- Can precipitate arthritis – esp. in adults
- No specific treatment for uncomplicated infection
- Supportive therapy - fatigue, malaise, pruritus, and arthralgia
- Generally resolves after 5-10 days, but can reoccur for months upon exposure to sunlight, hot temperature, exercise, bathing, and stress
Complications - as it infects red cell precursors so may cause:
- Aplastic crisis in patients with pre-existing haemolytic anaemia (e.g. sickle cell)
- If immunocompromised - chronic erythroid hypoplasia with severe anaemia
- Chronic infection and anaemia in immunocompromised (e.g. HIV)
Pregnancy
- 5% infections → hydrops fetalis (foetal anaemia / condition in fetus = accumulation of fluid/oedema in at least 2 fetal compartments), intrauterine growth retardation, pleural and pericardial effusions, and death.
- Risk highest in first trimester
- Risk of foetal death: 2% -6.5%
- If pregnant women has been in contact with children who were in incubation period of infection or in anaplastic crisis, inform her of small risk of infection and offer the option of serologic testing.
- Foetal ultrasonography can be useful.
Papular purpuric gloves and socks syndrome
- what virus causes this?
- presentation?
Rare presentation of Parvo B19
Painful and pruritic papules, petechiae, and purpura of hands and feet, often with fever and enanthem (oral erosions).
Unlike typical rash of erythema infectiosum, patients with this presentation are viraemic and contagious (they should not be around those at risk).
Roseola
- another name for this infection?
- what virus causes this?
- mode of transmission?
- who is most at risk?
- prevention?
- presentation?
- prognosis
- treatment
Exanthema subitum
Acute infection by HHV-6; less commonly HHV-7
HHV-6 infection in children results in:
- Subclinical infection
- Acute febrile illness without rash
Seroprevalence of HHV-6 in the adult population is greater than 95% BUT Reactivation in immunocompromised hosts may cause significant morbidity
Mild illness
Unknown mode of transmission – possibly from nasopharyngeal secretions
Children 6 months – 4 years
- Most common exanthema before age 2
No vaccine, infection results in immunity
Presentation
- High fever for 4-5 days
- When fever falls, rash comes - Seen in 20% of infected children
- Rash = Scattered pink maculopapular 1-5mm, surrounded by white halos; Begins on trunk, spreads to neck and proximal extremities; Spares hands and feet; Lasts 1-3 days
- Prodrome: High fever (39-40°C), palpebral oedema, cervical lymphadenopathy, mild upper respiratory symptoms. Child appears well. As fever subsides, exanthem appears (“exanthema subitum” means “sudden rash”).
Prognosis & treatment
- Usually benign and self-limited
- HHV6 known to cause febrile seizure in children with infection, often without rash
Treatment may be necessary for atypical cases with complications and in immunosuppressed patients
Scarlet fever
- what causes this?
- presentation
- complications
- treatment
Group A beta-haemolytic streptococcus (syn. Streptococcus pyogenes)
- Erythrogenic toxin resulting in delayed-type skin reactivity
Cause either (1) Soft tissue infection (erysipelas, cellulitis) or (2) Acute pharyngo-tonsillitis (“strep throat”)
- Usually associated with pharyngeal infection
- Rash appears 1-2 days after onset of sore throat - Starts on face – circumoral sparing - not around mouth; Blanching rash with elevations around hair follicles (“sandpaper” papier de verre, carta vetrata); Rash is followed by desquamation - skin peels
- Capillary haemorrhage in skin folds – Pastia’s lines
- Strawberry tongue
Frequency & severity have declined
Immune complications
Rheumatic fever
- Multi-system auto-immune disorder occurring 3 weeks after pharyngeal streptococcal infection
- Pancarditis (peri-, myo- and endocarditis)
- Arthritis (large joints, migratory)
- Chorea (“St Vitus’ dance) - prepubertal females
- Erythema marginatum
- Subcutaneous nodules
- Scarlet fever; streptococcal toxic shock syndrome; acute glomerulonephritis; Paediatric autoimmune neuropsychiatric disorder associated with group A streptococci (PANDAS)
- Patient may be left with damaged heart valves = rheumatic heart disease
- Damaged valves at risk of bacterial infection = infective endocarditis
- Often caused by alpha-haemolytic streptococci (e.g. viridans group – strep. Mitis, mutans salivarius)
Post streptococcal glomerulonephritis
- May follow pharyngeal or skin infection
Treatment
Oral penicillin V = agent of choice for treatment of GAS pharyngitis (10 days)
- reduced duration & severity of clinical signs/symptoms incl suppurative complications
- increased incidence of nonsuppurative complications (eg, acute rheumatic fever)
- reduced transmission to close contacts by reducing infectivity
Rheumatic fever
- what is it?
- clinical features
-
Multi-system auto-immune disorder occurring 3 weeks after pharyngeal streptococcal infection
Features:
- Pancarditis (peri-, myo- and endocarditis)
- Arthritis (large joints, migratory)
- Chorea (“St Vitus’ dance) - prepubertal females
- Erythema marginatum
- Subcutaneous nodules
Scarlet fever; streptococcal toxic shock syndrome; acute glomerulonephritis; Paediatric autoimmune neuropsychiatric disorder associated with group A streptococci (PANDAS)
Patient may be left with damaged heart valves = rheumatic heart disease
May progress in terms of valve function without further infection
Damages valves at risk of bacterial infection = infective endocarditis
Often caused by alpha-haemolytic streptococci (e.g. viridans group – strep. Mitis, mutans salivarius)
