Which came first: the chicken or the egg?
❓The (almost) eternal debate on what came first has persisted through decades.
🌆Countless evenings have been spent around a table, with a 🍷wine glass (or plenty more), with people throwing arguments against or in favour of one of the answers.
🤔Despite all thoughts, in reality, the answer is relatively simple.
⚠️The first animals to lay eggs were the dinosaurs.
🥚𝐒𝐨 𝐭𝐡𝐞 𝐞𝐠𝐠 𝐜𝐚𝐦𝐞 𝐟𝐢𝐫𝐬𝐭!🐣
🇺🇲A discovery made in 1990 in North America showed a nest of eggs from a carnivore dinosaur called “Maniraptoran”.
🦕This dinosaur is believed to be the animal from which birds came to develop into new species.
✅Some suggest the new question: What came first, the dinosaur or the egg?
But we will leave that one for another time…
𝐂𝐡𝐢𝐜𝐤𝐞𝐧 𝐌𝐞𝐚𝐭 𝐀𝐥𝐥𝐞𝐫𝐠𝐲 and 𝐁𝐢𝐫𝐝 𝐄𝐠𝐠 𝐒𝐲𝐧𝐝𝐫𝐨𝐦𝐞
❓How many times have I been asked if children should avoid chicken if they are allergic to eggs?
❗Not as often as parents telling me their child is allergic to chicken meat or start sneezing when there is either cooked eggs or cooked chicken around.
⁉️Can this really happen?
✔Actually, it can, but we need to understand that 𝘢𝘭𝘭 𝘢𝘳𝘦 𝘳𝘦𝘭𝘢𝘵𝘪𝘷𝘦𝘭𝘺 𝘳𝘢𝘳𝘦.
Chicken Allergy can be primary or secondary; this one often called Bird Egg Syndrome.
✳But let us take this into the several aspects that might cause any of the above symptoms.
➡️The main difference between the two types is that the primary kind is associated with a protein called 𝘎𝘢𝘭 𝘥 𝟽 and the second called 𝘎𝘢𝘭 𝘥 𝟻.
What does it mean?
✴𝐆𝐚𝐥 𝐝 𝟕 is 𝘩𝘦𝘢𝘵 𝘴𝘵𝘢𝘣𝘭𝘦 (long term allergy), and 𝐆𝐚𝐥 𝐝 𝟓 is 𝘩𝘦𝘢𝘵 𝘥𝘦𝘨𝘳𝘢𝘥𝘢𝘣𝘭𝘦 (very likely to outgrow the egg or chicken meat allergy).
🔻The symptoms vary, according to age group:
▶️In adults, the signs are usually respiratory associated (asthma or wheeze) or affect the eyes or nose (rhinoconjunctivitis).
▶️In children, it will mainly affect the gastrointestinal tract or leading to breathing problems.
👫Children with egg allergy and respiratory symptoms related to bird egg syndrome, tend to either acquire tolerance later or not outgrow it.
𝘜𝘴𝘶𝘢𝘭𝘭𝘺, 𝘴𝘺𝘮𝘱𝘵𝘰𝘮𝘴 𝘴𝘵𝘢𝘳𝘵 𝘭𝘢𝘵𝘦𝘳 𝘪𝘯 𝘵𝘩𝘦𝘪𝘳 𝘭𝘪𝘷𝘦𝘴.
⛔As with egg allergy, be aware of the cross-reactivity between chicken meat and turkey meat.
🚫But there can also be reactions to duck or goose meat, 𝘵𝘩𝘰𝘶𝘨𝘩 𝘵𝘩𝘦 𝘳𝘦𝘢𝘤𝘵𝘪𝘰𝘯𝘴 𝘵𝘦𝘯𝘥 𝘵𝘰 𝘣𝘦 𝘮𝘪𝘭𝘥𝘦𝘳.
So you will need to avoid all those meats until a proper diagnosis is made.
🎄So it is 🎅Christmas, and how many of you are 🍰 baking with 🥚eggs?
‼️This is probably one of the seasons where we should be cautious with this type of allergy!
In what comes to allergies in children, and due to the nature of baby´s weaning, egg sits almost at par with 🥛cow’s milk as the most prevalent form of allergy. This is closely followed by 🥜peanut allergy.
⚠️Up to now, it was believed roughly 50% of children would outgrow their egg allergy by 3 years of age, with that percentage increasing to roughly 66% at 5 years of age. But it seems those percentages are decreasing with time.
❓The reason for that is unknown still.
✅So the earlier a diagnosis and intervention is made, the higher will be the chances for children to outgrow their allergy.
➡️The initial step is to perform skin prick tests, eventually followed by an open food challenge to baked egg.
😊If the child passes this step, they will have roughly 95% chance of outgrowing their egg allergy.
😔As you might imagine, failing that challenge will give them less than 5% of outgrowing the allergy.
▶️If you suspect your child has an egg allergy, don’t give up or become demoralized.
▶️There is a pretty good chance he/she will outgrow it.
⛔Exclude egg and peanut from their diet, exception if already eating peanut.
⚕Ask for a Paediatric Allergy referral and see if their department will also involve a Paediatric Allergy Dietitian.
✳Very important to understand that when we speak about removing chicken eggs from the diet, we also talk about removing eggs from other birds due to cross-reactivity.
🚫The birds’ eggs you should also exclude are 🦃turkey, 🦆duck, 🦢goose, seagull and quail.
🥚Some children who are allergic to egg can eat small amounts of egg that is well baked (in cakes and biscuits, for example).
❗Often they will not tolerate raw egg, whole egg or lightly processed such as mayonnaise or meringue.
⚠️𝐂𝐡𝐢𝐥𝐝𝐫𝐞𝐧 𝐰𝐡𝐨 𝐜𝐚𝐧 𝐞𝐚𝐭 𝐛𝐚𝐤𝐞𝐝 𝐞𝐠𝐠𝐬 𝐚𝐫𝐞 𝐦𝐨𝐫𝐞 𝐥𝐢𝐤𝐞𝐥𝐲 𝐭𝐨 𝐨𝐮𝐭𝐠𝐫𝐨𝐰 𝐭𝐡𝐞𝐢𝐫 𝐚𝐥𝐥𝐞𝐫𝐠𝐲.
😔Unfortunately, those children who cannot tolerate baked egg are less likely to grow out of their egg allergy.
✅It is important to know that egg may be found in a wide range of foods, including:
➡️𝘉𝘢𝘵𝘵𝘦𝘳𝘦𝘥 𝘰𝘳 𝘣𝘳𝘦𝘢𝘥-𝘤𝘳𝘶𝘮𝘣𝘦𝘥 𝘧𝘰𝘰𝘥𝘴
➡️𝘚𝘰𝘮𝘦 𝘪𝘤𝘦 𝘤𝘳𝘦𝘢𝘮𝘴
✅Also, food labels with the below items may suggest the presence of egg so look out for:
➡ ️𝘈𝘭𝘣𝘶𝘮𝘪𝘯 , which suggests the presence of egg;
➡️𝘓𝘺𝘴𝘰𝘻𝘺𝘮𝘦, which is an enzyme derived from egg;
➡️𝘌𝘨𝘨 𝘓𝘦𝘵𝘤𝘪𝘵𝘩𝘪𝘯, (𝘌𝟹𝟸𝟸), which may, in rare cases, be made from egg; It works as emulsifiers and often is in trace amounts. Though trace amounts are not common to cause an egg allergy.
➡️𝘌𝘨𝘨 𝘸𝘩𝘪𝘵𝘦, in some bread it is used as a washing agent. In wine, alcohol-based drinks, coffee drinks and soup stocks (and sometimes along with eggshells) it might be used as a clarifying agent.
✴Resolution of egg allergy tends to occur in stages, starting with tolerance to baked egg.
▶️Further steps will involve cooking the egg so that the protein causing the allergy will be less degraded.
▶️It will end on the last step, which is raw egg.
(𝘧𝘰𝘳 𝘰𝘵𝘩𝘦𝘳 𝘰𝘱𝘵𝘪𝘰𝘯𝘴 𝘰𝘯 𝘦𝘢𝘤𝘩 𝘴𝘵𝘦𝘱 𝘰𝘧 𝘵𝘩𝘦 𝘭𝘢𝘥𝘥𝘦𝘳, 𝘢𝘴𝘬 𝘺𝘰𝘶𝘳 𝘋𝘪𝘦𝘵𝘪𝘵𝘪𝘢𝘯 𝘧𝘰𝘳 𝘢𝘥𝘷𝘪𝘤𝘦)
✔The suggestion is to have an initial dose of ¼ of the age-appropriate dose the child would have in one day.
✔From then double the dose every other day and aim to give it 2 to 3 times per week.
‼️Remember to always be guided by your Paediatric Allergy Team, which should include a Paediatric Allergy Dietitian.
‼️A common source of debate, misconception and confusion is "𝘤𝘢𝘯 𝘮𝘺 𝘤𝘩𝘪𝘭𝘥 𝘣𝘦 𝘷𝘢𝘤𝘤𝘪𝘯𝘢𝘵𝘦𝘥 𝘪𝘧 𝘩𝘦/𝘴𝘩𝘦 𝘩𝘢𝘴 𝘢𝘯 𝘦𝘨𝘨 𝘢𝘭𝘭𝘦𝘳𝘨𝘺?".
Especially now with the circulating Pfizer and AstraZeneca (Oxford) COVID19 vaccines, many have asked me about their safety.
But let's start with the basics.
❓𝐒𝐨 𝐰𝐡𝐲 𝐢𝐬 𝐢𝐭 𝐭𝐡𝐚𝐭 𝐦𝐨𝐬𝐭 𝐨𝐟 𝐭𝐡𝐞𝐦 𝐮𝐬𝐞 𝐡𝐞𝐧𝐬' 𝐞𝐠𝐠𝐬?
🦠The process of growing a virus in an egg leads to that virus becoming less infectious to the human being, but still leading to a protective effect against potential infections in the future.
After a virus is injected, the egg will be sealed with gelatine. This is normally made from pork protein.
🥚On the process of collecting the grown virus from the egg, a small amount of protein will come along as well. This can potentially lead to an allergic reaction.
▶️Studies have shown that this vaccine may contain from no amount to 1ng per 0.5ml of egg protein.
▶️Food challenges done on egg-allergic patients showed most people would react to amounts of 50-100mg, with some as low as 2mg of egg protein.
▶️This means the amount on the vaccine is too small to cause an allergic reaction.
⚠️Saying this, other components might lead to allergic reactions.
The ones I am referring to are 𝐆𝐞𝐥𝐚𝐭𝐢𝐧𝐞 (𝐩𝐨𝐫𝐤 𝐨𝐫𝐢𝐠𝐢𝐧) and 𝐍𝐞𝐨𝐦𝐲𝐜𝐢𝐧.
Both have higher concentrations than Ovalbumin.
➡️𝘛𝘩𝘦 𝘚NIFFLE 𝘴𝘵𝘶𝘥𝘪𝘦𝘴 have shown the safety of the Nasal Flu vaccine.
Several studies have shown that the LAIV (Live Attenuated Influenza Vaccine) that contain less than 0.12μg/mL (so 0.06 μg for a 0.5 mL dose) is safe for patients with an egg allergy.
To produce this vaccine, the virus is grown on chick embryonic fibroblast cells.
In case a patient with an egg allergy needs this vaccine, there two other options that can be used, as they do not contain egg:
1️⃣Human Diploid Cell Vaccine (HDCV)
2️⃣Purified Vero Cell Rabies Vaccine (PVRV)
✅𝐘𝐞𝐥𝐥𝐨𝐰 𝐟𝐞𝐯𝐞𝐫 𝐯𝐚𝐜𝐜𝐢𝐧𝐞
The virus for this vaccine is also grown on chick embryos.
If a patient needs this vaccine, there is only one potential option.
What I am referring to is a graded vaccination programme done in a hospital.
As with the MMR vaccine, the Yellow Fever and the Rabies vaccines one also contain Gelatine.
So extra caution needs to be had in this case.
✅Finally, the COVID19 vaccines:
1️⃣"There is no egg or egg-related component of the Pfizer RNA vaccines.
2️⃣ The Oxford AstraZeneca vaccine is produced in genetically modified human embryonic kidney (HEK) 293 cells.
This means both vaccines are safe to be used in egg-allergic children.
The only children who need to be vaccinated in a hospital are those with an allergy to eggs, with previous anaphylaxis to egg or who had a cardiorespiratory reaction needing admission to Intensive Care or those with coexisting active, chronic asthma.
Dr Costa is a Consultant Paediatrician and fellow of the Royal College of Paediatrics and Child Health.