Infection and Immunity Flashcards
What is an allergy?
Umbrella term for immune mediated hypersensitivity reaction to an allergen
What is an allergen?
Proteins that the immune system sees as foreign and harmful
What is a type 1 hypersensitivity reaction?
- IgE mediated to a specific allergen
- Immediate
- There is mast cell degranulation and histamine release
E.g. food allergy
What is a type 2 hypersensitivity reaction?
- IgG or IgM mediated
- Activation of the compliment system leading to localised damage
E.g. haemolytic disease of the new-born
What is a type 3 hypersensitivity reaction?
- Due to deposition of immune complexes causing local tissue damage
E.g. RA, SLE, HSP
What is a type 4 hypersensitivity reaction?
- Cell mediated
- T lymphocytes inappropriately activated leading to local tissue damage
E.g. contact dermatitis
How can allergies/ sensitivities be tested for? Describe these methods
Skin prick: drops onto skin and then prick. See if a wheal develops. This is used for allergies
Skin patch: Sticker patches are put on to the skin. This is used for contact dermatitis
R: Looks for IgE in the blood
What is allergic rhinitis and what are the signs and symptoms?
Type 1 hypersensitivity reaction
- Sneezing
- Nasal congestion, discharge
- Eye watering and redness
How is allergic rhinitis managed?
Cetirizine
When and how does cows milk protein allergy present?
Often from 3 months, can be at point of weaning.
- Regurgitation and vomiting
- Diarrhoea
- Urticaria, rash, angioedema
- colic type pain and distress
How should cows milk protein allergy be managed?
- hydrolysed formulae
- amino acid based formulae
If breastfeeding then a maternal cow milk free diet
What are the features of DiGeorge syndrome?
C - congenital heart defect A - abnormal face T - thymus underdevelopment (= T cell non-functional) C - cleft lip and palate H - hypoparathyroidism = hypocalcaemia 22 - deletion of chromosome 22
How is Wiskott-Aldrich inherited? What are the features?
X-linked recessive
- Abnormal T cells
- Thrombocytopenia, neutropenia
- Eczema, recurrent infection
What is SCID and how does it present?
Absent/ dysfunctional T and B cells
- recurrent opportunistic LRTIs
- persistent diarrhoea
- reaction to live vaccines (MMR)
- FTT
How is SCID managed?
sterile environment
haematopoietic stem cell transplant
What is selective IgA deficiency and how does it present?
maturation defect in B cells
- very mild and sometimes not picked up
- frequent respiratory and sinus infections
What is common variable immunodeficiency? How does it present? What are patients more at risk of?
Deficiency in IgA, IgG +/- IgM
- recurrent respiratory infections
- risk: RA and NH lymphoma
What are the signs and symptoms of Kawasaki disease?
Very high fever Strawberry tongue Red and cracked lips Conjunctival redness Red palms and soles Rash over torso - can be desquamating Cervical lymphadenopathy
How is Kawasaki disease managed?
IvIG and aspirin
What is a complication of Kawasaki disease?
Coronary artery aneurysm
Define neonatal conjunctivitis. What organisms most commonly cause it?
Conjunctivitis within the first 28 days
- Neisseria gonorrhoea and chlamydia trachomatis
What are the signs of neonatal conjunctivitis?
Lid swelling Mucopurulent discharge Conjunctival oedema (chemosis)
What causes glandular fever? What are the signs and symptoms?
EBV Sore throat + fever + cervical lymphadenopathy \+/- splenomegaly \+/- palatal petechiae \+/- hepatitis
How is glandular fever diagnosed?
Monospot test in the 2nd week of illness
How does threadworm present and how is it managed?
Itchy bottom and vulva - itching worse at night
Mebendazole for the whole family
How is impetigo managed?
- topical hydrogen peroxide
- topical fusidic acid
Oral flucloxacillin if widespread
What organism causes chicken pox? How does it present?
varicella zoster
Prodromal fever then rash beginning on the torso and progressing in “crops” as follows:
macular to papular to vesicular to crust
How is chicken pox managed?
topical calamine lotion
trimming the nails
VZIg and aciclovir if immunocompromised
What are the complications of chicken pox?
- varicella pneumonia - miliary opacities seen on CXR
- encephalitis
- superimposed infection
Describe the rash seen in Measles
State if there are any associated features of prodromes
Beginning behind the ears it then spreads down the torso becoming blotchy and confluent
+ fever, conjunctivitis prodrome
+ Koplick spots (white) on buccal mucosa
Describe the rash seen in Rubella
State if there are any associated features of prodromes
Pink, maculopapular starts on the face
- occipital lymphadenopathy
- low grade fever
Describe the rash seen in Fifth disease
State if there are any associated features of prodromes
Slapped cheek rash on the face
- rash spreads to arms
- can have lethargy, fever prodrome
Describe the rash seen in Roseola infantum
State if there are any associated features of prodromes
- Extremely high fever +/- febrile convulsions
- Sore throat
- Rash spares the face
Describe the rash seen in Scarlet fever
State if there are any associated features of prodromes
- Sandpaper rash on the torso that spares the palms and soles
- Strawberry tongue
- Fever, tonsillitis, otitis media
Describe the rash seen in Hand, foot and mouth disease
State if there are any associated features of prodromes
- Yellow ulcers with a red halo in the mouth
- Then erythematous macules on palms and soles
What virus causes:
a) rubella
b) 5th disease
c) Roseola infantum
d) Scarlet fever
e) Hand, foot and mouth
rubella: Togovirus
5th: parvovirus B19
Roseola: Herpes virus 6
Scarlet: group A haemolytic strep
HFM: Coxsackie A16
How is scarlet fever managed?
Penicillin
Which childhood rashes/ infections require school exclusion?
Measles
Rubella
Scarlet fever
What is ITP?
type 2 hypersensitivity reaction i.e. autoimmune disorder resulting in reduced platelets
What are the signs and symptoms of ITP?
Bleeding and bruising
- nose bleeds
- menorrhagia
- gum bleeds
Can get intracranial and GI bleeds
When and how is ITP pharmacologically managed?
It is dependant on symptom severity
- prednisolone
- IV Ig
- other immunosuppressing agents
What advice should be given to parents whose child has ITP?
- No contact sports
- Alert medics if involved in trauma eg crash
- Avoid IM injections
- Avoid NSAIDs and aspirin
Which complication of DKA are children particularly at risk of?
cerebral oedema
What can cause congenital hypothyroidism?
Most of the time it is a problem with the thyroid gland.
Can also be thyroid hormone or pituitary or hypothalamus
How may congenital hypothyroidism present?
- Prolonged jaundice
- Poor feeding
- Constipation
- Hypotonia
- Macroglossia
If not treated, what characteristic appearance do children with hypothyroidism develop?
- Wide spaced eyes
- Eyelid oedema
- Narrow palpebral fissure
- Depressed nasal bridge
What is the most common cause of childhood hypothyroidism and how is it diagnosed?
Hashimotos
Anti-TPO antibodies
What are the signs and symptoms of childhood hypothyroidism?
Poor growth
+ same as adults (fatigue, weight gain, brittle hair, constipation)
What are the hormone abnormalities of congenital adrenal hyperplasia? Therefore how is it managed?
Low cortisol
Low aldosterone
High testosterone
Managed with hydrocortisone and fludrocortisone
How does congenital adrenal hyperplasia present in
a) both sexes
b) females
c) males
a) hyponatraemia, low glucose, hyperkalaemia and pigmented skin
b) Ambiguous genitalia if severe. Amenorrhoea, tall, deep voice, facial hair
c) Tall, deep voice, large penis, small testis
