Category Archives: Allergy

Latex allergy

The name for pure natural rubber. Found all over the place – foam (mattresses), condoms, balloons, seals, adhesives. In hospitals, BP cuffs, elastic bandages, catheters and ET tubes, pulse oximeters… Not so often in surgical gloves now. Can cause mild and severe (anaphylaxis) reactions, plus delayed (non type 1) allergy. Allergy first described in 1979, became epidemic in 1980s.

The rubber tree Hevea brasiliensis is not the same as “rubber plants” (Ficus) you get as pot plants, although you can be allergic to those too, of course.

About half of latex allergic patients also have fruit allergies, especially avocado, banana, kiwi, melon but also chestnut and tree nuts.

Certain high risk groups:

  • Spina bifida
  • Health care workers

Atopic or irritant dermatitis may also be caused by rubber chemicals rather then latex itself.

Diagnosis

  • Blood IgE test – as with other IgE tests, potential for false positives esp with grass/fruit allergy.
  • Skin prick test with standardised latex
  • Prick through suspected glove! Needs latex free environment, of course. Potential for reaction to powder, rather than latex…
  • Glove test – wet hand! Risk of anaphylaxis.

Risk of Anaphylaxis

As with other allergies, seems to vary between individuals. And previous reactions do not reliably predict future reactions.

With health care, difficult. First on surgical list. Label patient. Latex free environment, as far as possible. Reports of probable reactions from IV fluids and needle puncture of bungs in IV sets.

Need for careful occupational advice.

Allergy and mental health

Evidence that having a peanut allergy has worse quality of life for a family than having diabetes… Mostly due to fear of unexpected severe reaction, and restrictions on social activities particularly eating out, parties and holidays.

Allergic patients can feel embarrassed or even ridiculed for declaring their allergy. Allergy is often mocked in the media (Cobra Kai, the Box Trolls, Peter Rabbit).

School and nursery are a particular area of concern, whether the right foods will be served, whether teachers or other children might bring allergens into school (food is sometimes used in classes, for example making bird seed balls), whether reactions will be managed appropriately, school trips. Children have died in school (Nasar Ahmed, Mohammed Ismaeel Ashraf).

Mums tend to be more concerned by limitations in the child’s own social life, dads seem to care more about limitations in the whole family’s social life. [Stensgaard, Clin Exp Allergy 2017]. Mums are the ones most studied. There probably are significant differences between mums and dads. In some studies, parents overrate their child’s quality of life, but in others (particularly with teenagers) parents can be seen as over anxious. Teenagers tend to take on the perspective of the parent of the same sex.

How bad previous reactions have been, interestingly, does not in itself contribute significantly to quality of life – in some cases, not having ever had a reaction can make families more anxious, because they don’t know what to expect! In one study, having multiple allergies and having an adrenaline pen was associated with worse quality of life. [Protudger, Clin Transl Allergy 2016]

Parents can feel guilty if their child has a reaction, a failure of their duty to protect. Mums can feel guilty about having “caused” their child’s allergy, either through their own medical history or what they ate or didn’t eat in pregnancy (even there is no good evidence for this being a factor).

Better quality of life is seen in allergic families with greater self efficacy for food allergy management, and lower perceived likelihood of a severe reaction [Knibb, Pediatric Allergy & Immunology. 27(5):459-464, August 2016].

APPEAL-1 study

8 European countries, questionnaire study of adults and children with peanut allergy

Only a minority remembered getting any training in future emergencies or use of medication, after their initial reaction. There was a low rate of satisfaction with AAI training! 

43% reported bullying, and a third of these described it as severe. 

65% confident in ability to recognize a reaction, but only 45% confident about knowing when to use an AAI and 59% how.  62% say the carry AAI all the time.

25-30% said it was not easy (or rarely easy) to talk to friends or family about their allergy, although most felt confident talking to new people about their allergy. Friends and family were generally seen as “believing there is too much concern over allergy” even though overall they were seen as having a good awareness and understanding of allergy (cf other people, where this was seen as the opposite).

Dutch respondents had lowest rates of uncertainty and stress around activities, and for feeling anxious.  At same time, they had the highest rates of confidence around knowing when and how to use AAI.  France had highest rate of being made to feel different in a negative way, and feelings of isolation.

NB – likely to be the most affected families who participated.

[Dunngalvin, Allergy 2020]

Wheat allergy

Talking here about type 1 IgE mediated wheat allergy. Not coeliac disease, which is an autoimmune process triggered by gluten.

Only 10% persists to adulthood, equivalent to milk/egg.  Max IgE over 20 has median resolution age of 7, rises to 16 if max over 50. Unusually, IgE often remains positive even when tolerance has developed! But trend still useful for individual patient.

Wheat allergens – most commonly LMW glutenin, alpha and gamma gliadins, NOT omega. Technically gluten is found only in wheat, and is a complex of gliadin and other proteins, similar prolamins in other cereals have different names eg zein (rye), avenin (oat), hordein (barley)! 

Level of omega 5 antibodies correlates with clinical severity of exercise induced anaphylaxis! Not specific though – Omega 5 antibodies are present in 80% with anaphylaxis to wheat (non-exercise induced) and 20-30% of wheat allergic with eczema. Useful for predicting anaphylaxis??

Note that those with grass pollen allergy often have non clinically significant IgE to wheat.

[Nutrients 2017 – doi: 10.3390/nu9010035]

Lots of different names for wheat versions/products – Bulgar wheat, couscous, durum wheat, freekeh, einkorn, emmer, farola, kamut, malted wheat, semolina, spelt, triticale, wheat bran, wheat germ.

Presence of wheat starch in gluten free products (can be useful for producer) means the low level permitted for coeliac disease may still cause reactions if sufficient amount eaten, so avoid wheat based gluten free products if type 1 allergy.

But glutens present in non-wheat grains are not usually a problem for type 1 wheat allergy, so excessively restrictive to follow gluten free labels on things not made with wheat, eg oats!

Testing often suggests cross reactivity between different cereals but when you actually challenge, majority only react to one, and non wheat allergies pretty rare. Oat, rye, barley allergy uncommon. Maize allergy seen more with Southern European fruit allergy syndromes.

And strange how aeroallergy so rarely translates to food allergy and vice versa [(J ALLERGY CLIN IMMUNOL 1995;96:341-51]

So I would say no need to avoid or test unless symptomatic.

Cross contamination (as in coeliac) a big issue – crumbly! Toasters, butter, surfaces etc.

Hydrolysed vegetable protein sometimes comes from wheat, has to be declared as allergen but little evidence that it is still allergenic.

Reports of allergy to deamidated wheat (“wheat protein isolate”), where tolerant to normal wheat. Found in cosmetics too.

Hay fever

=allergic rhinoconjunctivitis due to seasonal triggers, typically grass and/or tree pollen. First described by John Bostock in 1819! More likely if born in early months of year!

So itchy, swollen, watery eyes, runny and/or blocked nose, sneezing. Often itchy throat and ears too. Cobble stone appearance can be seen at the back of throat.

Not dangerous, but can seriously affect quality of life: poor sleep, poor concentration (exams usually at worst time of year), embarrassment about snot. One study showed children in England were less likely to get their predicted exam grades if they had hay fever, especially if prescribed sedating antihistamines. Moderate to severe hay fever also associated with worse, uncontrolled asthma. London study found hospital admissions for asthma 50% higher 3 days after high grass pollen levels (inconclusive for tree pollen). [Int J Biometeorol. 2017] Brussels study found similar, compounded by air pollution. Treatment of hay fever with intranasal steroids or class 2 antihistamines reduced admissions by up to 80%. [asthma res and pract 2015]

Associated with other atopic conditions, such as food allergy and asthma. Under recognized as trigger for asthma exacerbations – pollen is too large to trigger the lower airways directly, rather, pollen exposure in the upper airways trigger inflammation that travels down (probably over a period of weeks) to the lower airways. An exception is when pollen grains are fragmented, as seen in thunder storm asthma where one night in Melbourne, 2016, several thousand acute respiratory presentations came to ED (up over 400%), ambulance service was overwhelmed, hospitals ran out of inhalers. 10 deaths implicated. [Australia, Clin Exp Allergy. 2018;48:1421‐1428]. Complex though, rain/moisture probably contribute to pollen grain rupture, and atmospherics bring surges of pollen down to ground level.

There are many different species of grass, but if allergic to one you tend to be allergic to all of them. Trees on the other hand vary, you tend to be allergic to specific groups of trees. In Europe the most important are birch (northern Europe) and olive (Southern Europe). Birch is related to alder, hazel, beech and oak.  Olive is related to ash.  Weeds belong to various unrelated families.

Hazel trees can start producing pollen in January! Weeds such as nettle can continue producing pollen through September! Moulds seem more associated with asthma than hay fever. Cypress blooms in winter! 

Pollen seasons in Scotland – University of Worcester Pollen Lab

It’s not just pollen count – the amount of allergen carried by the pollen (“pollen potency“) varies too. Correlates pretty closely but varies by time and place, 4-5 fold difference geographically (especially grass). France has the highest yearly average grass pollen potency, 7-fold higher than Portugal. Olive pollen from two locations 400km apart varied 4-fold in their allergen potency – in Portugal there are times when pollen from Spain probably more of a problem for triggering hay fever than pollen from “local” trees! [Health Impacts of Airborne Allergen Information Network (HIALINE project)]

Management

Watch the pollen count, and choose activities inside or outside accordingly. There are apps that can help with this. But note that the time of day is important too – for grass pollen, the risk is greatest in the first half of the morning and again from about 4pm in the afternoon, until late evening. But can persist into the early hours if temperatures remain high, this effect is particularly noticeable in the cities of the south of England. For tree pollen, the risk is usually during daylight hours only.

Closing windows, or at least not sitting near windows should help. Wash your hair more regularly. Don’t dry clothes outside. Pollen barrier balms available (evidence?). Big, wrap around sunglasses?

Choose when and where you are going on holiday carefully, so you get away during the worst period. North of Scotland and the islands have a short, late grass season (late June, early July). Coastal areas likely to be best (although often there are fields just back from the coast, so it may depend on the wind direction!). For tree pollen, season is earlier for most (see above), and there are parts of Scotland (Orkney, Lewis, Caithness, Sutherland) with very few trees. For holidays abroad, see World pollen data.

Antihistamines – oral or nasal. Various, some people find one works better than another Sedating antihistamines eg Chlorphenamine should be avoided except at night. Nasal steroids useful if used correctly. Combination steroid/antihistamine available. Leukotriene receptor antagonist licensed for hay fever in children with asthma.

Short courses of oral steroids might be justified for special occasions.

Immunotherapy available – deaths reported in asthmatics with poor control.

Sublingual – age not important cf ability to hold in mouth for 2 minutes. Not approved by SMC in Scotland yet. Combined grass and house dust mite coming.

[Sian Ludman, St Mary’s]

For symptoms all year round (perennial), triggers such as house dust mite and pets are more likely.

Tree nut allergy

Group of nuts that includes hazelnut, almond, brazil nut, cashew, pecan, pistachio, walnut and macadamia. Definition of nut is actually a bit complicated, to do with whether the shell comes off spontaneously or not, but I stick to those defined by food labelling law.

Does not include peanut (a legume), coconut, pine nut, chestnut or tiger nut.

You can be allergic to just one, a couple or the whole lot. Risk of allergy to peanut is higher than if you weren’t allergic to anything.

Hazelnut and cashew allergies are common. Almond rare.

Hazelnut allergy goes along with fruit allergy and oral allergy syndrome.

Cashew allergy goes with pistachio allergy. Cashew allergy is particularly associated with anaphylaxis, even more so than peanut (but less common as allergy and allergen so less well known).

Pecan allergy goes with walnut allergy.

Hazelnut allergy

One of the tree nuts. One of the most common food allergens in the UK. Adults seem to get less severe reactions than children. Anaphylaxis rare compared with peanut and other tree nuts.

Hazel tree is related to birch, and indeed hazelnut allergy can be associated with tree pollen allergy (hay fever), as well as fruit allergies.

Cor a 1 is the least likely to cause systemic reactions, and then only with raw cf roast.  But pretty much everyone tests positive for it, so not v helpful unless it is the only thing that is positive. You are usually also positive for rBet v 1/2, the birch pollen antigens. Cor a 8/9/14 associated with systemic, although 8 is LTP so may only be local (and likely fruit allergy too) – probably seen more often in Mediterranean populations. The others are storage proteins so more likely to cause severe reactions.

Cor a 9 and 14 seem most useful  – >1kU/l and/or >5 respectively give specificity of >90% and sensitivity of 83% in kids for “allergy with objective symptoms” viz more than just a tingle/itch, so more likely to have severe reactions. That translates to a negative predictive value of about 93% (PPV not given). [Dutch study, JACI 2013;132(2):393]

German study found  Cor a 14 had best AUC (0.89, cf 0.71 for whole hz).  Level of 0.35 gave 85% sensitivity with 81% specificity.  PPV doesn’t hit 90% until 47.8 though…

Bell pepper allergy

The names get confusing!

Bell peppers or sweet peppers (capsicum) come in red, yellow and green varieties.  The colour just tells you how ripe it is, they are the same thing! 

They are related to potato, tomato, aubergine, latex (the nightshade family).  You are not automatically allergic to all of these things, but you may have a higher risk if you are already allergic to one or more of them.

Chilli peppers are closely related to bell pepper.  There are lots of different ones, both red and green eg bird’s eye, Scotch bonnet, jalapeno, chipotle. 

Chilli powder, paprika, cayenne, pimento are all spices made from these plants, so if you are allergic to the vegetable there’s a good chance you will react to these spices too. These get used to make pepperoni, salami, chorizo sausage and others.

Black and white pepper are completely unrelated! You do not need to avoid these.

Cross contamination can be a big problem, since in restaurants, the same knife and chopping board will get used for chopping bell peppers and all other vegetables.  Chargrilled food is also a risk if cooked on the same surface as roast peppers! Ask restaurants to use separate knives, chopping boards, frying pan etc.

Ketchup, baked beans, BBQ sauce, crisp flavourings, stock cubes, soups are all potentially a problem, as are most ready meals, you will need to look closely at the ingredients label.

Paprika extract is used as red/orange colouring in lots of things.

You might need to avoid anything with unidentified ‘spices’ or ‘flavourings’ until you can get further details from the manufacturer.

You may not react if the amount of spice used is very low, but this is hard to predict and you may find that one time you don’t react but another time you do react to the very same thing. 

Abroad, food can be very different and you need to be much more careful.  In Serbia and Croatia, for instance, there is a traditional tomato sauce ajvar that often gets served on the side of meals, which is made with red peppers.

(With thanks to Julia Marriott)

Celery Spice Mugwort syndrome

An allergy syndrome, where there is cross reactivity between mugwort (a pretty nondescript weed, pollen can cause hay fever and trigger asthma) and a wide range of foods, including:

  • Fruit – esp apple, melon, peach, orange, watermelon
  • Tomato
  • Vegetables – esp  celery, carrot, green pepper, onion, parsnip
  • Spices – eg mustard, paprika, pepper, coriander, basil, dill, oregano, parsley, thyme, anise, caraway, fennel, tarragon
  • Chamomile
  • Sunflower seeds

You are not automatically allergic to everything, just be aware that you are at higher risk of being allergic to something else on the list if you are allergic to one or more things.