Allergy/Immunology

Question 1

Define Anaphylaxis

Answer 1

A severe, life-threatening, generalised or systemic hypersensitivity reaction characterised by a rapidly developing airway and/or breathing and/or circulation problems, usually associate with skin and mucosal changes.

Question 2

True or false, angio-oedema secondary to an ACE inhibitor, is an example of allergic angio-oedema?

Answer 2

False. It is a non-allergic drug reaction

Question 3

True or false, angio-oedema and anaphylaxis both involve histamine and/or bradykinin?

Answer 3

True

Question 4

What is the best initial approach for assessing patients with suspected anaphylaxis?

Answer 4

ABCDE approach

Question 5

What is the best management for rapidly developing angio-oedema without anaphylaxis?

Answer 5

Slow IV or IM chlorphenamine
+ Hydrocortisone
+ Emergency admission

Question 6

What is the best management for stable angio-oedema without anaphylaxis?

Answer 6

Remove underlying cause if known
Non-sedating antihistamine
Consider short course of oral corticosteroid if severe
Refer to immunology or dermatology if cause of angio-oedema is not known

Question 7

How do you manage anaphylaxis?

Answer 7

Call an ambulance (medical emergency)
IM adrenaline 1:1000 (dose based on age)
Repeat adrenaline after 5 minutes if no improvement
Continue to give every 5 minutes if no improvement
[Refractory anaphylaxis protocol will be required involving IV fluid bolus, high flow O2, and adrenaline infusion in secondary care]

Question 8

Where is adrenaline injected in anaphylaxis?

Answer 8

Anterolateral aspect middle third of thigh
(Change site of injection on each repeated dose)

Question 9

What are the doses of adrenaline based on age?

Answer 9

Adult / Child > 12 years - 500mcg (0.5ml 1:1000)
Child 6-12 300mcg (0.3ml 1:1000)
Child 6 months - 6 years 150mcg (0.15ml 1:1000)
Child <6 months 100 - 150mcg (0.1 - 0.15ml 1:1000)

Question 10

A patient in anaphylaxis is unconscious, what is the best position to put them in?

Answer 10

Recovery position

If patient remains conscious then lying flat or sat up are preferred. Lying flat can help if hypotensive.

Pregnant women should lie on their left side to prevent caval compression

Question 11

When placing pregnant women in the recovery position, how should they be positioned?

Answer 11

On their left side to prevent caval compression

Question 12

What is the best after-care following an episode of anaphylaxis?

Answer 12

Refer to specialist allergy service
2x adrenaline auto-injectors + instruction on how to use
General information on anaphylaxis

Question 13

What are the three diagnostic criteria for anaphylaxis?

Answer 13

Sudden onset or rapid progression
Life-threatening airway, breathing, circulation problems
Skin or mucosal changes

Question 14

Name a non-sedating antihistamine

Answer 14

Cetirizine
Loratadine
Fexofenadine

Question 15

What is the best antihistamine to use in pregnancy or breast feeding mothers?

Answer 15

Loratadine

Oral antihistamines should be avoided where possible in pregnancy, especially during the 1st trimester due to risk of congenital abnormalities (poor evidence of this in reality but manufacturers advise caution). However, if one is required, then loratadine is the safest. Cetirizine could also be considered as a 2nd line alternative.

Question 16

True or false, HI antihistamines are associated with reduced milk production in breast feeding mothers?

Answer 16

True.

Non-sedating antihistamines can still be prescribed but mild caution is advised. Loratadine is the safest choice. Cetirizine can also be considered.

Question 17

Why are “non-sedating” antihistamines less sedating?

Answer 17

They do not cross the blood brain barrier as easily, and so have less of a sedating effect. They can still cause sedation however at higher doses. The sedating effect is worse with alcohol.

Question 18

What are the three types of Cow Milk Protein Allergy?

Answer 18

Immune mediated (IgE) - immediate onset (within 2 hours)
Non-IgE mediated - delayed onset (2-72 hours)
Mixed IgE and non-IgE

Question 19

True or false, almost all cases of cow milk protein allergy present before 1 year of age?

Answer 19

True

Question 20

Which resolves faster, IgE-mediated CMPA or non-IgE mediated CMPA?

Answer 20

Non-IgE Cow Milk Protein Allergy tends to resolve faster

Question 21

How do you manage CMPA?

Answer 21

Refer to specialist allergy clinic if suspected IgE mediated (faltering growth, rapid onset, atopic signs).
If suspected non-IgE mediated (delayed) then no need to refer to allergy clinic.

Skin prick testing or Serum specific IgE testing if IgE mediated CMPA is suspected.

Consider referral to paediatric dietitian to monitor growth and nutrition + hypoallergenic formula advice

Advise elimination of all cow’s milk from mother’s and infant’s diet (if breast feeding) for trial of 2-4 weeks if suspect non-IgE mediated. Then reintroduce to see if improves symptoms.

Cow milk free diet for mother and infant until 9-12 months old / at least 6 months. Following this can reintroduce to test for tolerance using a “milk ladder” (step-wise reintroduction guide).

Question 22

How does the “milk ladder” work with CMPA?

Answer 22

It is a gradual reintroduction of cow milk protein into the diet after 9-12 months of age or 6 months of being CMP free.

It is conventionally used for non-IgE mediated CMPA (delayed) but is also used with caution in IgE mediated CMPA (immediate)

Starts with baked milk e.g. biscuits, cakes etc where the protein is denatured and therefore is relatively safe. Then progresses to uncooked milk products.

Question 23

True or false, Amino acid formulas (AAFs) are first-line hypoallergenic infant formulas for children with mild-moderate CMPA?

Answer 23

False.

AAFs are reserved for children with severe symptoms or a history of anaphylaxis.

Extensively hydrolysed formulas (eHFs) are usually the first line in mild-moderate cases.

Question 24

True or false, soya milk is not recommended for children under 6 months?

Answer 24

True. They contain trace isoflavones which may have an oestrogenic hormonal effect on the reproductive system. They may be used after 6 months if there is no evidence of soya allergy.

NB: 60% of Non-IgE mediated CMPA are allergic to soya
14% of IgE mediated are allergic to soya

Question 25

True or false, almond, oat, rice and coconut are suitable alternatives for a 6 month year old with CMPA?

Answer 25

False. These milks have poor nutritional value compared with cow's milk, and are therefore not recommended as an infant's main drink under 1 year of age.

Question 26

True or false, rice milk is safe for a 1 year old to drink?

Answer 26

False. Rice milk contains natural inorganic arsenic and is not advised under 4.5 years of age.

Question 27

True or false, lactose-free formulas are safe for children with CMPA?

Answer 27

False. Lactose free formulas still contain intact cow's milk protein and therefore should not be used in suspected or confirmed cow's milk protein allergy.

Question 28

True or false, alternative mammalian milks (sheep, goat etc) are safe alternatives if a child has CMPA?

Answer 28

False. These milks are not recommended in children with CMPA. There is a high risk of cross-reactivity.

Question 29

Define urticaria. What is the difference between acute and chronic forms? What are the common causes?

Answer 29

Superficial swelling of the skin (epidermis and mucous membranes) that results in red, raised, itchy rash. Acute (< 6 weeks) Chronic (>6 weeks) Causes: 1) Chronic inducible: caused by physical stimuli e.g. UV light, cold, heat, dermatographism, vibration etc 2) Autoimmune (IgG autoantibodies targeting IgE receptors) 3) Spontaneous: No clear cause e.g. drugs, infection, stress etc

Question 30

What is the treatment for urticaria?

Answer 30

Acute is likely self-limiting and will resolve with the removal of the cause e.g. infection, medication etc. If significant or chronic symptoms, then antihistamine for 3-6 months (regular or as prophylactic) Symptom diaries can be useful Urticaria Activity Score (UAS7) or quality of life assessment (Chronic Urticaria Quality of Life Questionnaire CU-Q23oL) can also be used Antipruritic agent e.g. calamine lotion to relieve itch Short course oral corticosteroid e.g. prednisolone 40mg OD 7 days can be considered if severe. Refer to paediatrics if patient is <16 years old. Sedating antihistamine e.g. chlorphenamine at night if sleep disturbed Refer to dermatology if chronic, severe, or not responsive to treatment. Especially if urticaria is painful as may be vasculitic urticaria.

Question 31

What is the difference between Type A and Type B adverse drug reactions?

Answer 31

Type A: Pharmacological/Augmented - an exaggeration of a drug's normal pharmacological action when given at usual therapeutic dose. (Most common ~ 80% of ADRs) Type B: Bizarre/Idiosyncratic - Cannot be predicted from the known pharmacology of the drug. NB: ~6-7% of hospital admissions are due to ADRs.

Question 32

Where are adverse drug reactions reported?

Answer 32

Yellow Card Scheme For: 1) Serious, medically significant, or resulting in harm 2) Associated with black triangle products (including non-serious ADRs) (Underpins pharmacovigilance in the UK)

Question 33

What are "black triangle" drugs?

Answer 33

A label given to drugs or vaccines which are: 1) New medicines 2) New route of administration 3) New drug-delivering system 4) Established medicine being used un a new patient population Any ADR (even non-serious) occurring with a black triangle product, should be reported on the yellow card scheme.

Question 34

True or false, Yellow Card reports can be made for electronic cigarettes?

Answer 34

True. Yellow Card reports for adverse drug reactions can be made for any drug, vaccine or product which causes serious harm, or even non-serious harm in black triangle products. This includes fake medicines, e-cigarettes, and medical devices.

Question 35

What are the 4 types of hypersensitivity reaction? Give an example of each

Answer 35

Type I - immediate (minutes) IgE/histamine (degranulation of mast cells) mediated e.g. Anaphylaxis Type II - IgG / IgM mediated Cytotoxic reaction (hours-days) e.g. Haemolytic disease or Goodpasture's. Type III - Antigen-Antibody immune complex mediated (hours - days). Typically IgM and IgG bind the antigen e.g. SLE, serum sickness, RA, and post-streptococcal glomerulonephritis Type IV - Delayed Hypersensitivity. T cell mediated. e.g. Contact dermatitis, tuberculin skin test (Mantoux test). Involves sensitisation of T helper cells.

Question 36

In Goodpasture's syndrome, what is attacked by the auto antibodies?

Answer 36

A Type 2 hypersensitivity reaction (cytotoxic) where alpha-3 chain of type IV collagen in basement membranes is attacked. This predominantly affects the lungs and the kidneys.

Question 37

True or false, Goodpasture's syndrome is associated with cigarette smokers?

Answer 37

True. Goodpasture's (Type 2 hypersensitivity) affects the alpha-3 chain of type IV collagen in the basement membranes of the lungs and kidneys. It is associated with cigarette smokers and certain genes HLA-DRB1 and DR4).

Question 38

True or false, all patients newly registering to a practise should have an HIV test?

Answer 38

False. It depends on the local prevalence. If the prevalence is > 2 in 1000, then newly registered patients should be tested.

Question 39

Give two risk factors for HIV

Answer 39

MSM Coming from high prevalence areas IVDU

Question 40

What is the typical course of HIV infection

Answer 40

Primary HIV infection aka seroconversion illness usually 10 days to 6 weeks. Mild - Severe flu-like symptoms. Develops in 60% of those infected. Fever, weight loss, maculopapular rash, genital or perianal ulcers, myalgia etc. Long-standing HIV may be asymptomatic for up to 10 years. May present with certain cancers e.g. Kaposi's sarcoma (the most common in HIV), fungal infections e.g. oral candidiasis, or respiratory infections such as pneumocystis pneumonia (PCP).

Question 41

What is the most common cancer associated with HIV infection? How does it typically present?=

Answer 41

Kaposi's sarcoma Purple, painless lesions on the skin, typically the mouth

Question 42

How is HIV tested?

Answer 42

CD4 and viral load are checked CD4 reflects the degree of immunosuppression. Normal is > 500 cells per microliter. Viral load reflects rate of viral replication (measured using PCR test). A rising viral load may suggest non-adherence to Antiretroviral therapy (ART) or drug resistance. Viral load less than 20-50 copies is "undetectable"

Question 43

Below what CD4 count are patients with HIV highly susceptible to opportunistic infections and cancers?

Answer 43

<200 cells per microliter Risk of infections and cancers increases with CD4 <500 but significant risk is < 200.

Question 44

True or false, HIV mutates as it replicates?

Answer 44

True. This is why combination therapies are used to minimise the risk of drug resistance.

Question 45

What contraceptive advice is given to sexually active patients with HIV?

Answer 45

Advised not to use oil based lubricants with latex condoms as increases risk of splitting Condoms lubricated with spermicide nonocinol-9 (N9) should not be used as these increase the risk of genital lesions and therefore HIV transmission. Condoms should still be used if ART is taken, viral load is suppressed and the person's partner is HIV positive (prevent drug resistant strains from spreading). Condoms should ideally be used with an additional contraceptive method.

Question 46

With respect to HIV, what is PrEP?

Answer 46

Pre-exposure prophylaxis A combination of 2 antiretroviral drugs taken before and after sex to reduce the risk of HIV acquisition. It is offered to HIV negative people who are at high risk and who do not always use condoms. Sign post to sexual health clinic for specialist advice.

Question 47

What is PEP and when is it used?

Answer 47

Post-Exposure Prophylaxis After an HIV negative individual has had sexual contact with an HIV positive individual with ART adherence/resistance issues or active viral load. PEP is no longer used in cases where the HIV positive individual is compliant with ART or has a sustained undetectable viral load.

Question 48

True or false, oral contraceptive may have reduced effectiveness with antiretroviral therapy?

Answer 48

True

Question 49

True or false, the copper coil is safe to use as emergency contraception in patients with HIV and a CD4 count <200?

Answer 49

False. The risk of infection post procedure is too high if CD4 is <200.

Question 50

True or false, people with HIV can receive BCG vaccinations?

Answer 50

False. Individuals with HIV should not usually receive live vaccinations such as BCG, cholera or oral typhoid immunisations.

Question 51

True or false, HIV screening is offered to all pregnant women as part of routine antenatal care?

Answer 51

True

Question 52

What is the window period with respect to HIV testing?

Answer 52

The time between exposure and reliable detection of HIV infection depends on the test. Point of care testing: 90 days to detect 3rd generation antibody test: 60 days 4th generation antibody/antigen (Ab/Ag): 45 days (6 week window) If test is negative within the window period then a second test to confirm, is indicated.

Question 53

How many weeks for the 4th generation antibody/antigen HIV test to be 99% accurate?

Answer 53

6 weeks (99% identified) If tested negative within 6 weeks of exposure, then a repeat test should be done after 6 weeks.

Question 54

True or false, patients suspected of having pneumocystis pneumonia should be referred into hospital?

Answer 54

True. PCP an indicator condition of HIV, needs to be referred to secondary care as can be fatal if left too late.

Question 55

What is the estimated risk of HIV infection for: 1) Needle stick injury with contaminated blood 2) Blood transfusion with contaminated blood 3) Pregnancy without preventative measures 4) Pregnancy with preventative measures 5) Vaginal sex 6) Injecting drug use

Answer 55

Needlestick: 1 in 435 (0.23%) Blood transfusion: 9 in 10 (92.5%) Pregnancy w/out measures: 1 in 4 (22.6%) Pregnancy with measures: 1 in 715 (0.14%) Vaginal sex: 1 in 1000 (0.08%) Injecting drug use: 1 in 158 (0.63%)

Question 56

True or false, the risk of HIV transmission with vaginal sex without condom use, if the patient has an undetectable viral load is 0%

Answer 56

True

Question 57

True or false, the risk of vertical transmission of HIV from an HIV positive mother on optimal treatment is 0%?

Answer 57

False. There is between a 0 and 0.5% risk

Question 58

What is pollen food syndrome?

Answer 58

Pollen food syndrome (oral allergy syndrome) is a hypersensitivity reaction to fruits, vegetable, nuts and latex (plant foods) which causes a mild, irritation or itching of the mouth and throat. It affects 2% of the population.

Question 59

True or false, latex allergy is an example of an oral allergy syndrome aka Pollen food syndrome?

Answer 59

True. Latex is an organic product.

Question 60

How do you differentiate the tests for Hepatitis B?

Answer 60

Hepatitis B surface antigen (HBsAg) - Indicates active infection Hepatitis B e antigen (HBeAg) indicates high levels of viral replication and therefore higher infectivity Antibody to HBeAg (Anti-HBe) - indicates control of viral replication and predicts resolution of acute infection IgM to core antigen (anti-HBc IgM) - recent infection within 6 months. Helps distinguish acute from chronic infection. IgG antibody to core antigen (anti-HBc IgG) persists and indicates past infection Antibody to HBsAg (Anti-HBs) indicates immunity to HBV. If Anti-HBs without anti-HBc this suggests immunisation

Question 61

A patient is positive for anti-HBs but negative for anti-HBc, what does this imply?

Answer 61

Positive antibodies to Hepatitis B surface antigen Negative antibodies to Hepatitis B core antigen Suggests immunity to HBV as a result of immunisation (rather than infection). Core is from the infection, surface is from immunisation.