Paeds- Derm and Infectious Diseases Flashcards
what is chicken pox?
highly infectious disease caused by the varicella zoster virus VZV
what does reactivation of the dormant VZV lead to?
reactivation of the dormant virus in the posterior root ganglia after a bout of chickenpox leads to herpes zoster (shingles)
explain briefly the pathophysiology of chicken pox
- enters URT
- 4-6 days later- viraemia, 11-21 days- skin lesions
- infective from 4 days prior to rash until all leasions have scabbed
how does chicken pox present clinically?
- temperature 38-39
- headache, malaise, abdo pain
- crops of vesicles appear- itchy- on head, neck and trunk
- redness around lesion- bacterial superinfection
differential diagnosis of chicken pox
- shingles
- generalised herpes zoster/ simplex
- dermatitis herpetiformis
- impetigo
how is shingles differentiated from chicken pox?
- shingles is confined to one dermatome
- occurs upon reactivation of virus in dorsal root ganglion
how is chicken pox diagnosed?
- clinical
- fluorescent antibody tests- IgG/ IgM
complications of chicken pox
- secondary bacterial infection of lesions
- pneumonia
- encephalitis
- arthritis, nephritis, pancreatitis
- disseminated haemorrhage chickenpox
how is chicken pox managed and treated?
management:
- keep cool
- trim nails (less harm fro scratching)
- antihistamines and emollients
- off school for 5 days
treatment:
- Antivarecella-Zoster immunoglobulin and Acyclovir if severe
- if bacterial superinfection- flucloxacillin
what are Exanthems?
Exanthems are eruptive skin rashes associated with a fever or other constitutional symptoms, associated with infectious diseases
which childhood exanthems are notifiable diseases?
- measles
- scarlet fever
- rubella
what are the:
- first disease
- second disease
- third disease
- fifth disease
in childhood exanthems?
1st= measles
2nd= Scarlet fever
3rd= Rubella
5th- slapped cheek syndrome (erythrovirus)
explain the transmission of measles
- acute viral infection
- single stranded RNA morbillivirus
- airborne via respiratory drops/ saliva
- incubation of 7-12 days
- infectivity lasts from prodrome until 4 days after rash disappears
how does measles present clinically?
- rash for at least 3 days
- fever (>40) presenting with at least one of:
a non productive cough, corzya, conjunctivitis
describe the prodrome of measles
4C’S
Cough, coryza, conjunctivitis, cranky
Koplik’s spots on palate- small red spots with a white speck
describe the rash seen in measles
- morbilliform
- first on forehead, neck and behind ears
- spreads to trunk and limbs in 3-4 days
- fades after 3-4 days
- leaves behind a brownish discolouration and fine desquamation
what 2 features may present alongside the rash in measles?
swelling of eyes
photophobia
differential diagnosis of measles
rubella
parovirus B19
enterovirus
scarlet fever
how is measles diagnosed?
Lab
- IgM & IgG +ve
- salivary swab/ serum sample for measles-specific immunoglobulin taken within 6 weeks on onset
- RNA detection in swabs
how is uncomplicated measles treated and managed?
Notifiable disease !
parent must isolate
self limiting- tx is symptomatic- paracetamol, ibuprofen + fluids
what are some potential complications of measles?
- ottitis media
- croup/ tracheitis
- pneumonia (most common cause of death in measles)
- encephalitis (older)
- subacute sclerosing panencephalitis
aetiology of scarlet fever
endotoxin mediated disease arising from a bacterial infection from a toxin-producing strain of strep pyogenes (group A haemolytic strep)
epidemiology of scarlet fever
2-10 years old commonly
how does scarlet fever present clinically?
- 2-4 days incubation
- onset- sudden sore throat and fever, rash follows 12-24 hours later
- scarlatiniform rash
- strawberry tongue
- circumoral pallor
describe the scarlatiniform rash seen in scarlet fever
appears first on chest, axilla and behind ears
affects trunk and legs later
red ‘pin prick’ blanching rash- sandpaper texture
describe the ‘strawberry tongue’ seen in scarlet fever
prominent red papillae seen through a ‘white fur’
describe the prodrome of scarlet fever
- sore throat + tonsilitis
- fever
- headache
- vomiting and abdo pain
- myalgia
give 4 complications of scarlet fever
- syndenhams chorea
- otitis media
- rheumatic fever
- glomerulonephritis
how is scarlet fever diagnosed?
clinically
throat swab and culture
antigen detection kits
strep antibody tests
how is scarlet fever treated?
Pencillin/ azithromycin for 10 days
rest + fluids
ibuprofen and paracetamol
NOTIFIABLE DISEASE !
what virus causes rubella?
RNA virus- rubivirus togaviridae
how is rubella transmitted and what is its incubation period and infectivity window?
- airborne droplets
- incubation of 14-21 days
- infectious for 5 days before and 5 day after rash
Lifelong immunity !
when is rubella a major complication?
maternal infection in early pregnancy
describe the prodrome of rubella
lethargy
low grade fever
headache
mild conjunctivitis
anorexia
describe the rash present in rubella
initially pink, discrete macular rash that coalesce starting behind the ears and face
spreads to entire body
in which lymph nodes is lymphadenopathy present in rubella?
suboccipital
differentials for rubella
contact dermatitis erythema multiforme drug allergy measles scarlet fever Kawasaki
how is rubella diagnosed?
- PCR
- FBC- low WBC with raised lymphocytes and thrombocytopenia
can rubella be treated?
No ! managed with antipyretics + vaccines
what are the complications of maternal rubella infection during early pregnancy?
weeks 1-4- eye anomaly
4-8- cardiac abnormalities
8-12- deafness
what is slapped cheek syndrome and how is it spread?
- paravovirus B19
- transmission via respiratory secretions
- incubation- 4-20 days before rash develops
- droplet spread
describe the prodrome of slapped cheek syndrome
- starts around 1 week after symptom onset
- mild
- headache, rhinitis, sore throat, low-grade fever, malaise
- nausea, diarrhoea, abdo pain, arthralgia
describe the presentation of slapped cheek syndrome after the initial prodrome
- symptom free for 7-10 days
- classic ‘slapped cheek’ rash then appears- malar erythema that SPARES the nose, perioral and periorbital regions
- 1-4 days after facial rash- a new erythematous macular rash develops on limbs (non itchy)
describe the arthralgia seen in slapped cheek syndrome
- symmetrical- hands, wrists, knees and ankles
- usually resolves in a few days
what is a serious complication of slapped cheek syndrome?
aplastic crisis
how is slapped cheek syndrome diagnosed?
- B19 specific IgM
- B19 specific IgG
- PCR
if B19 specific IgM is present, what result is implied?
current/ recent infection with parvovirus B19 (slapped cheek)
if B19 specific IgG is present, what result is implied?
immunity/ past infection
what is impetigo and at what ages does it peak?
contagious superficial infection by staph aureus +/- strep pyogenes
2-5 years
how does impetigo present clinically?
well defined lesions that start around nose and face with honey/ golden coloured crusts on erythematous base
how is impetigo treated?
topical fusidic acid or oral flucloxacillin if severe
explain the science behind meningitis
micro-organisms reach the meninges either by direct extension from the ears, nasopharynx, cranial injury or congenital meningeal defect, or by bloodstream spread
bacterial causes of meningitis
Neiserria meningitides
streptococcus pneumoniae
haemophilus influenza
staph group B
listeria monocytogenes
e.coli
viral causes of meningitis
enterovirus mumps herpes simplex HIV EBC
fungal causes of meningitis
cryptococcus neoformans
candida albicans
risk factors of meningitis?
- immunocompromised
- spinal procedures
- bacterial endocarditis
- diabetes
- alcoholism/ IV drug abuse
- malignancy
- renal and adrenal insufficiency
what is the physiological difference between bacterial and viral meningitis?
bacterial- pia-arachnoid becomes congested with polymorphs- pus layer forms
viral- predominantly lymphocytic inflammatory CSF with no pus formation and no polymorphs
what occurs first in meningitis, septic or meningeal signs?
septic signs !
what are the septic signs of meningitis?
- malaise, fever, temp, rigors, severe headache
- increased pulse and RR, reduced BP
- DIC
- poor feeding
- signs of shock
- petechial non-blanching purpural rash
what are the meningeal signs of meningitis?
- +ve Kernigs sign
- +ve Brudzinski’s sign
- neck stiffness (rare)
- photophobia
- opisthotonus (arched back)
- bulging fontanelle in infants
what is Kernigs sign?
resistance to extending knee when hip is flexed
what is Brudzinski’s sign?
neck flexion results in hip flexion
what are the complications of meningitis and which one is most commonly seen?
SHAPeD
Sepsis Hydrocephalus/ encephalitis Abcess Paralysis Deafness (most common ! )
how is meningitis diagnosed?
- blood- lactate, fbc, glucose, coag
- lumbar puncture
- blood culture
- throat swab
when is a lumbar puncture contraindicated?
meningococcal disease !
how is meningitis treated BEFORE the organism is known?
- immediate- IV cefotaxime ! + supportive therapy (high flow O2, saline etc)
- if <3 months= cefotaxime + amoxicillin
- > 3 months- 18 years= ceftriaxone + dexamethasone
what must a GP immediately give to a pt with suspected meningitis?
Benzylpenicllin (cefotaxime if allergic ! )
causative organisms of meningitis- how are they treated?
Neisseria Meningitis
cefotaxime/ ceftriaxone/ benzylpenicllin
causative organisms of meningitis- how are they treated?
Haemophilis influenzae
ceftriaxone
causative organisms of meningitis- how are they treated?
strep pneumoniae
ceftriaxone/ benzylpenicllin
causative organisms of meningitis- how are they treated?
E.coli
cefotaxime/ gentamicin
causative organisms of meningitis- how are they treated?
Group B haemolytic strep
Benzylpenicllin IV
causative organisms of meningitis- how are they treated?
listeria monocytogenes
IV ampicillin + gentamicin
how is group B haemolytic strep passed to the infant?
via the mothers vagina
what is given as prophylaxis from meningococcal meningitis?
rifampicin and ciprofloxacin
how is viral meningitis treated?
- supportive therapy- analgesia, anti-pyretic, hydration
- acyclovir
give the differences in the:
- appearance
- glucose
- protein
- gram stain
between bacterial and viral meningitis
appearance:
- bacterial- clear-turbid
- viral- clear
glucose:
- bacterial- low
- viral- normal
protein:
- elevated in both
gram stain:
- bacterial- organisms present
- viral- normal
what is Coxsackie’s disease?
hand, foot and mouth disease
viral illness commonly causing lesions involving the hands, feet and mouth
aetiology of Coxsackie’s disease
Coxsackievirus A16
enterovirus 71
how is Coxsackie’s disease transmitted and what is the incubation period?
- faecal-oral route
- 5-7 days
describe the prodrome of Coxsackie’s disease
- low-grade fever
- malaise
- loss of appetite
- sore mouth/ throat
- cough
- abdo pain
how do the mouth lesions present in Coxsackie’s disease?
- buccal mucosa, tongue + hard palate
- initially macular lesions that progress to vesicles and then erode
- yellow ulcers surrounded by red haloes
how do skin lesions present in Coxsackie’s disease?
- palm, soles and between fingers and toes
- erythematous macules that progress to grey vesicles with an erythematous base
differential diagnosis of Coxsackie’s disease
- herpangina
- herpes simplex
- chickenpox
- Kawasaki disease
how is Coxsackie’s disease diagnosed?
- clinical
- swab lesions
- PCR
how is Coxsackie’s disease managed and treated?
- symptomatic !
fluid intake, soft diet, paracetamol
can use lidocaine oral gel if mouth is painful
stay off school if feeling unwell
causes of encephalitis in infants
infective !
HSV, mumps, varicella zoster, rabies, parvovirus, influenza, TB, toxoplasmosis, malaria
immunocompromised
clinical signs of encephalitis
flu-like prodrome
reduced consciousness
‘odd’ behaviour
vomiting
fits/ seizures
raised temp
meningism
how is encephalitis investigated?
CSF, MC&S, PCR, bloods, stool (enteroviruses), urine
which causative organism of encephalitis is most treatable and how is this managed?
herpes simplex encephalitis- acyclovir
when should TB be suspected?
- overseas contact
- HIV +ve
- odd CXR
how does TB present clinically?
anorexia
low fever
failure to thrive
malaise
possible cough
describe the tuberculin test
hypersensitivity test to tuberculin when applied to skin via an injection
how does TB present on a CXR?
consolidation and cavities
Miliary spots (fine white dots)- rare, but grave
how is TB managed?
6-month supervised plan of isoniazid + rifampicin + pyrazinamide
how much does the transmission rate of HIV increase by if the mother breastfeeds?
50%
how is HIV diagnosed in infants?
test at birth, 3 and 6 months:
- HIV viral PCR
- P24 antigen
- specific IgA
- monitor CD4 counts= help stage HIV
give some symptoms which, if present, could indicate HIV
- PUO, lymphadenopathy, hepatosplenomegaly, parotid enlargement
- persistent diarrhoea
- shingles
- reduced platelets
- failure to thrive, recurrent infections that are slow to clear, finger clubbing
when should a non-vertical HIV seroconversion illness be suspected in an infant?
- temp, fatigue rash, pharyngitis, oral ulcers, headache
- lymphadenopathy
- meningism, peripheral neuropathy
- thrush, WL, neight sweats
what is the prognosis for HIV infection in infants?
by 3 years only, those with early opportunistic infection- 50% died
describe HAART
Highly Active Anti-Retroviral therapy
- PENTA regimen
- used in pt’s with AIDS defining conditions/ CD4 <15%
what are the side effects of HAART?
- raised lipids and glucose
- reduced bone metabolism
how is toxic shock syndrome caused?
toxin-producing Staph. Aureus/ group A strep
what is toxic shock syndrome characterised by?
fever >39’c
hypotension
diffuse erythematous, macular rash
what is the main consequence of toxin release?
organ dysfunction- vomiting, diarrhoea, organ impairment, altered consciousness etc
how is toxic shock syndrome managed?
ceftriaxone + clindamycin
surgically debride infected areas
what is vaccinated against at the 8 week mark?
- diptheria, tetanus, pertussis, polio, HiB, Hep B (6- in - 1)
- pneumococcal
- meningitis B
- rotavirus
- gastroenteritis
what vaccines are given at 12 weeks?
6-in-1
rotavirus
what vaccines are given at 16 weeks?
6-in-1
pneumococcal
meningitis B
what vaccines are given at 1 year?
HiB and meningitis C
pneumococcal
MMR
Meningitis B
what vaccine is given each year between 2-8 years?
influenza
what vaccines are given pre-school (around 3 years and 4 months)?
diptheria, tetanus, pertussis and polio (4 in 1)
MMR
what vaccine is given to girls aged 12-13?
HPV- 2 dose given 6-12 months apart
what vaccine is given at age 14 (and which vaccine is specific to men)?
tetanus, diptheria, polio (3 in 1)
Men- ACWY
describe the epidemiology of eczema in children
present in 15-20% of children
presents before 6 months, clears in around 50% by 5 years and 75% by 10 years
how does eczema present in:
- infants
- younger children
- older children
infants- face and trunk
younger- extensor surfaces
older- typical distribution- flexor surfaces and creases of face and neck
how is eczema managed?
- identify and avoid irritants
- emolients- in ratio with topical steroids of 10:1
- severe- we wraps and oral ciclosporin may be used
what is eczema herpeticum, and how is it managed?
severe primary infection of the skin seen more commonly in kids with atopic eczema
common infective organism- HSV
life threatening ! manage with Acyclovir
what is Stevens-Johnson Syndrome?
severe bullous form or erythema multiforme- also involving mucous membranes
how does Stevens-Johnson Syndrome initally present?
Vague upper respiratory tract symptoms 2-3 weeks after starting a drug, a rash will then present 2 days after
describe the clinical presentation of Stevens-Johnson Syndrome
Painful erythematous macules- evolve to form target lesions
severe mucosal ulceration (typically on 2 surfaces- e.g. conjunctiva, oral cavity, urethra, labia)
what drugs can cause Stevens-Johnson Syndrome?
- Sulfonamides
- anti-epileptics
- penicllins
- NSAIDs
how is Stevens-Johnson Syndrome managed clinically?
- ophthalmological assessment
- supportive therapy- protect skin
- avoid steroids- increases infection risk
do not debride skin !!
how does urticaria present clinically?
hives/ flesh coloured wheals or redness
resulting from local vasodilation and increased permeability of capillaries/ venules
itchy !
how does urticaria result into angioedema?
involvement of deeper tissues produces swelling- usually around lips and eyes
what are the 3 classes of utricaria and angioedema?
- acute
- chronic idiopathic
- physical urticarias
describe acute urticaria and angioedema
- resolves in 6 weeks
- triggers- infection, food allergy, drug reaction
- viral infection- last days
- allergen- lasts hours
describe chronic idiopathic urticaria and angioedema
intermittent for >6 weeks, usually non-allergic in origin
causes of physical urticarias
cold, delayed pressure, heat contact, solar
how are urticaria and angioedema managed?
2nd generation, non-sedating antihistamines
what is given in refractory cases of urticaria and angioedema?
omalizumab
what is anaphylaxis?
severe, life-threatening hypersensitivity
causes of anaphylaxis in children
85%- food allergy
IgE mediated reactions
insect stings, drugs, latex, exercise, inhalant allergens
how is anaphylaxis diagnosed?
Airway- swelling, hoarseness, stridor
Breathing- tachypnoea, wheeze, cyanosis SpO2 <92%
Circulation- Urticaria/ angioedema
how is anaphylaxis managed?
ABCDE
- establish airway
- high flow O2
- IV fluid- crystalloid
- early administration of adrenaline IM/ IV
- chlopheniramine- antihstamine
- hydrocortisone
- salbutamol if wheeze
monitor pulse oximetry, ECG, BP
What are the TORCH infections?
Toxoplasmosis Other (syphillis, varicella-zoster, parvovirus B19) Rubella Cytomegalovirus Herpes
In HIV, what is vertical transmission?
term used to describe mother to child transmission
