Infectious disease Flashcards
What is Kawasaki disease
a systemic medium-sized vessel vasculitis
(aka mucocutaneous, lymph node syndrome)
Describe the epidemiology of kawasaki disease
- affects young children u5, peak incidence at 1yr
- mc in Japanese children
- mc in boys
Give 6 clinical features kawasaki disease
- Persistent high fever for over 5 days
- Non-purulent conjunctivitis
- Red (strawb) tongue and cracked lips
- Cervical lymphadenopathy
- widespread maculopapular rash
- Peeling of fingers and toes (later sign)
What is a major complication of kawasaki disease
coronary artery aneurysm
How is kawasaki disease investigated
- Clinical diagnosis
- ECHO - rule out aneurysms
How is kawasaki disease managed
- IV immunoglobulins - reduce risk of CA anueyrsms
- High dose aspirin
- ECHO at 6 weeks
Why is aspirin given to children with kawasaki disease
reduce the risk of thrombosis
What is the major route of HIV infection in children
mother-child (vertical) transmission during pregnancy (intrauterine), at delivery (intrapartum), or through breastfeeding
How is HIV diagnosed in children over 18 months
HIV antibody screen: detects antibodies against the virus
How is HIV diagnosed in children less than 18 months
HIV DNA PCR
Why is the presence of antibodies against HIV in children under 18 months not diagnostic of the illness
- Children <18 months who are born to
infected mothers will have transplacental maternal HIV antibodies - at this age a positive antibody test confirms HIV exposure but not HIV infection.
Presentation of children with mild and moderate immunocompromise in HIV
- Mild: may have lymphadenopathy or parotid enlargement
- Moderate: recurrent bacterial infections, chronic diarrhoea and lymphocytic interstitial pneumonitis
Clinical features of severe AIDS in children
- Pneumocystis jirovecii pneumonia
- severe faltering growth
- encephalopathy
How is HIV managed in children
- Antiretroviral therapy should be started in all infants and some older children depending on clinical status/ HIV load and CD4 count
- Don’t delay routine immunisations (except BCG)
- MDT and Regular follow up: weight, development and clinical signs of disease
- Prophylactic co-trimoxazole
Co-trimoxazole is given as a prophylaxis to some children with HIV.
a) what infection is this against
b) what circumstances is it prescribed (2)
a) pneumocystis jirovecii pneumonia
b) all infants who are HIV-infected and older children with low CD4 counts
Give 4 ways vertical transmission is reduced in HIV
- Positive mothers should be on antiretroviral drugs to reduce viral load at time of delivery
- Post exposure prophylaxis given to infant after birth (zidovudine)
- avoid breastfeeding
- C-sections in all women with > 400 copies / ml
- IV zidovudine should be given during the caesarean if the viral load is unknown or there are > 10000 copies / ml
What testing is done in children to HIV positive parents and at what age is each test done (2)
- HIV viral load at 3m - if -ve, child has not contracted HIV during birth and will not develop HIV unless they have further exposure
- HIV Abx test at 24m - to assess whether they have contracted HIV since their 3 month viral load, for example through breast feeding
What causes scalded skin syndrome
caused by a type of staphylococcus aureus bacteria that produces epidermolytic toxins
Describe the clinical presentation of scalded skin syndrome
- fever and malaise
- red rash with wrinkled tissue
- typically starts on face and flexural regions then spreads
- after the rash, large fluid-filled blisters form
- widespread erythema and tenderness
- Nikolsky sign
Describe Nikolsky sign
- The epidermis separates and creates an erosion when the skin is gently rubbed
- Large areas of skin blister and peel away, leaving red, wet, and painful areas
How is scalded skin syndrome managed
- IV anti-staph Ab e.g. flucloxacillin
- Analgesia
- monitor hydration and fluid balance
What causes toxic shock syndrome
Toxin-producing staph aureus and group A streptococci
Characteristics of toxic shock syndrome
- Fever over 39
- hypotension
- diffuse erythematous, macular rash
- desquamation of rash, especially of the palms and soles
Toxic shock syndrome causes organ dysfunction. Give 5 examples of this
- Mucositis - oral and genital mucosa
- GI dysfunction - vomiting/ diarrhoea
- Liver impairment
- renal impairment
- Clotting abnormalities and thrombocytopenia
How is toxic shock syndrome managed
- IV fluids
- areas of infection should be surgically debrided (removed)
- IV antibiotics - flucloxacillin + clindamycin
- IVIg to neutralise circulating toxins
What is measles
Highly infectious disease caused by measles virus
Features of measles
- Prodrome: fever, conjunctivitis, irritability
- koplik spots - typically develop before the rash, white spots on the buccal mucosa
- discrete maculopapular rash becoming blotchy & confluent
- rash begins behind the ears and spreads to the whole body
How is measles diagnosed
- ELISA (blood test) - measles-specific IgM and IgG serology
- clinical
How is measles managed
- supportive treatment
- avoid school 5 days after initial rash
- Notify public health
- vitamin A supplements
How is measles prevented in the UK
Immunisation - 2 doses of MMR vaccine
Give 3 complications of measles
- otitis media - mc
- febrile convulsions
- encephalitis
- subacute sclerosing panencephalitis (rare, years after infection)
- pneumonia
How long after measles infection does subacute sclerosing panencephalitis typically manifest
7 years
What causes subacute sclerosing panencephalitis
variant of the measles virus which persists in the CNS
What is chickenpox
- common virus spread by respiratory droplets
- Highly infectious during viral shedding
What virus causes chickenpox
varicella zoster
Describe the presentation of chickenpox
- Fever initially
- itchy, rash starting on head/trunk before spreading. Initially macular then papular then vesicular
- itching may lead to permanent scars/ secondary infection
How is chickenpox managed
- keep cool, trim nails
- calamine lotion
- Immunocompromised kids - aciclovir
- avoid school until lesions are dry and have crusted over
Give 4 complications of chickenpox
- secondary bacterial infection of the lesions
- generalised encephalitis
- pneumonitis
- disseminated haemorrhagic chickenpox
What severe complication can occur in a small number of chickenpox patients with bacterial infections?
Invasive group A streptococcal soft tissue infections, potentially leading to necrotizing fasciitis.
What causes scarlet fever
group A, beta haemolytic streptococcus - strep.pyogenes
Scarlet fever is most common between what ages
2 - 8 years old
Describe the presentation of scarlet fever
- Fever : typically lasts 24 to 48 hours
- headache, N+V, malaise
- sore throat
- sandpaper like maculopapular rash initially on trunk then spreads (spares area around mouth)
- flushed cheeks
- strawberry tongue
- cervical lymphadenopathy
How is scarlet fever managed
- 10 days course of phenoxymethylpenicillin (penicillin V)
- penicillin allergy: clarithromycin (10d), azithromycin (5d)
- pregnancy - erythromycin 10d
- notify public health
- can return to school 24h after starting antibiotics
When are outbreaks of rubella more common
winter and spring
What is the incubation period of rubella
14-21 days
When are individuals with rubella infectious
individuals are infectious from 7 days before symptoms appear to 4 days after the onset of the rash
features of rubella
- prodrome, e.g. low-grade fever
- rash: maculopapular, initially on the face before spreading to the whole body, usually fades by the 3-5 day
Give 3 complications of rubella
- arthritis
- encephalitis
- myocarditis
What causes diphtheria
Corynebacterium diphtheriae (gram positive bacillus)
How may diphtheria present
- neuritis
- heart block
- sore throat with a grey, pseudomembrane on the posterior pharyngeal wall
- bulky cervical lymphadenopathy
What causes slapped cheek syndrome
parvovirus B19
(aka erythema infectiosum)
Describe the presentation of slapped cheek syndrome
- may be asymptomatic
- fever, headache and myalgia
- characteristic rose-red rash on face which may spread to the trunks and limbs
- aplastic crisis in children with haemolytic anaemia
What is impetigo
superficial bacterial skin infection usually caused by either Staphylcoccus aureus or Streptococcus pyogenes
Describe the features of non-bullous impetigo
- usually occurs around the nose or mouth
- exudate from lesions dries to form a golden crust
- no systemic symptoms, will not be unwell
Describe the features of bullous impetigo
- always caused by s. aureus
- fluid filled vesicles form and then burst leaving golden crust
- fever and malaise
How is impetigo managed
- Localised, non-bullous: hydrogen peroxide 1% cream or fusidic acid
- widespread, non-bullous: 5 days topical fusidic acid or mupirocin
- widespread or bullous: 5 days flucloxacillin or clarithromycin (if penicillin allergy)
- children should be excluded from school until the lesions are crusted and healed or 48 hours after commencing antibiotic treatment
Give 3 complications of impetigo
- cellulitis
- Staphylococcal scalded skin syndrome
- scarring
What commonly causes hand, foot and mouth disease
coxsackie A16 and enterovirus 71
Describe the presentation of hand, foot and mouth disease
- mild systemic upset: sore throat, fever
- oral ulcers
- followed later by vesicles on the palms and soles of the feet
How is hand, foot and mouth disease managed
- symptomatic treatment only: general advice about hydration and analgesia
- children do not need to be excluded from school
- highly contagious: advice about measures to avoid transmission
