Paediatric Infection and Immunity - Allergies, Conjunctivitis, Impetigo and Chickenpox Flashcards
What is an allergy?
Immunological hypersensitivity leading to a variety of disease
May or may not be IgE mediated
What is an allergen?
Substance that stimulates the production of IgE or cellular immune response
What is sensitisation?
Production of IgE antibodies after repeated allergen exposure
Asymptomatic
What is required for something to be an allergy?
Symptoms + specific IgE rise
Give examples of atopic disease
Allergic rhinitis Allergic conjunctivitis Asthma Atopic dermatitis (Eczema) Urticaria Insect, food and drug allergy
How does urticaria present and when is it not allergic?
Maculo-papular pruritic rash
If chronic >6weeks, not allergic
What are the hypotheses for increasing allergies?
Hygiene hypothesis
Dual allergen hypothesis
Vitamin D hypothesis
What is the hygiene hypothesis?
Microbiological exposure low in developed environment so immune system development is suppressed
What is the dual allergen hypothesis?
Exposure through skin may lead to allergy
However, consumption will lead to tolerance
What is the vitamin D hypothesis?
Need high levels of Vit D to regulate the immune system
What can you do to reduce risk of allergy onset?
Good skin hygiene
Microbial exposure - pets
Vitamin D
Early weaning - varied diet
What are the types of allergic rhinitis?
Seasonal - hayfever
Persistent - dust mites, pets
Occupational - flour, wood dust
What is the pathophysiology of allergic rhinitis?
IgE mediated inflammation of the nasal mucosa
Mast cells release histamines - increase epithelial permeability
Inflammatory cell migration
Acute and late phase response
What happens in the acute phase response?
Sneezing followed by secretions
What happens in the late phase response?
6-12 hours after –> nasal congestion
What symptoms does allergic rhinitis present with?
Bilateral nasal congestion Itching Sneezing Discharge Watery, red eyes
How is allergic rhinitis assessed?
Diagnosis from history
Can do skin prick or IgE testing via ELISA
How is allergic rhinitis managed?
Avoid allergen
Cetirizine
>5yo - try topical nasal antihistamines PRN
Nasal steroids if nasal blockage predominant symptom
How can food allergies be split up?
Immunological - IgE mediated and Non-IgE mediated
Non-immunological
What symptoms would all immunological food allergies present with?
Pruritis
Diarrhoea
Abdo pain
What symptoms of food allergy would be indicative it is IgE mediated?
Urticaria Angio-oedema Oral itching Sneezing SOB and wheeze Signs of anaphylaxis
What symptoms of a food allergy would indicate it is a non IgE mediated immunological allergy?
Eczema
GORD and colic
Bowel changes
Poor growth
What symptoms would indicate a food allergy is non immunological?
Take hours - days to occur Headache Fatigue Bowel changes Urticaria
How are IgE mediated food allergies investigated?
Food diary
Physician supervised oral food challenge
Skin prick
Allergen specific IgE measurements via ELISA
How is a non IgE mediated food allergy investigated?
Trial elimination diet
How are immunological food allergies managed?
Food avoid
Dietician referral
Antihistamines
Adrenaline
How are non-immunological food allergies managed?
Food avoidance
Dietician referral
What commonly causes lactose intolerance?
Post-viral gastroenteritis lactase deficiency
What is the pathophysiology of lactose intolerance?
Lactase normally decrease with age
If accelerated - lactose intolerance
Lactose pass into colon and fermented - diarrhoea and bloating
How can cows milk protein allergy present?
With other food allergies Colic Oesophagitis Constipation Acute colitis
How are infants with cows milk protein allergy fed?
Hydrolysed formula first
Then wean onto cows milk protein free diet
What organisms commonly cause conjunctivitis?
Adenovirus
Staph
Strep pneumoniae
H Influenzae
How does conjunctivitis present?
Generalised red eye
Irritated gritty feeling
Vary depending on bacterial or viral
History of close contact
What symptoms are indicative of bacterial conjunctivitis?
Purulent discharge
Eyes stick together
What symptoms are indicative of viral conjunctivitis?
Serous discharge
Recent URTI
Periauricular lymphadenopathy
How is viral conjunctivitis managed?
Self limiting - resolve in 2 weeks
Lubricant eye drops, warm water
No school exclusion but don’t share towels etc.
How is bacterial conjunctivitis treated?
Antibiotics if severe - Chloramphenicol
Prescribing can be delated - 3 days with no improvement
What is impetigo?
Superficial skin infection by staph aureus or strep pyogenes
What are risk factors for impetigo?
Poor hygiene
Break in skin - eczema, bites
How does impetigo present?
Usually around a month Tiny vesicles which crust into honey coloured plaques Rapidly spreading Some itching No erythema or oedema Regional lymphadenopathy
How is impetigo investigated?
Swab for culture if lesion widespread or MRSA suspected
How is impetigo managed?
Keep area clean - soap and water Avoid sharing towels, dummies etc No school until lesions crusted or antibiotics for 48hrs Fusidic acid - topical Oral fluclox if widespread or bullous
What are the complications associated with impetigo?
Cellulitis
Staph scaled skin syndrome
What is bullous impetigo?
Thin roofed lesions which rupture seen on top of other lesions
Where is bullous impetigo most commonly seen?
Face, trunk and buttocks
Who is bullous impetigo most commonly seen in?
Neonates
What organism causes chicken pox?
Varicella zoster
What is a key property of chicken pox?
Infectious!
How and when does chicken pox spread?
Via respiratory route from someone who has chicken pox or shingles
4 days before rash –> 5 days after rash appear
How long is the incubation period for varicella zoster?
10-21 days
How do children with chicken pox present?
38-39 degrees for up to 4 days
Itchy rash on head and trunk
What is the progression of the chicken pox rash?
Macular –> papular –> vesicular –> crust
What complications are associated with chicken pox?
Bacterial infections of lesion
Pneumonia
Encephalitis
How is chicken pox managed non pharmacologically?
Calamine lotion
Trim nails
Exclude from school - 5 days after rash onset
How is chicken pox managed pharmacologically?
Varicella zoster immunoglobulin for immunocompromised and newborns exposed to it
Aciclovir if contract chicken pox
What can be seen on chest X-ray with varicella pneumonia?
Miliary opacities
What are each of the HHV’s and what disease do they cause?
HHV1 - herpes simplex 1 - oral infection and encephalitis
HHV2 - herpes simplex 2 - neonatal and genital infection
HHV3 - varicella zoster - chickenpox and shingles
HHV4 - Epstein Barr virus - glandular fever
HHV5 - Cytomegalovirus - congenital & immunocompromised
HHV6/7 - Roseola
