The Correlation Between House Dust Mite and Shellfish Allergies

Over the past decades, food allergies have become more frequent on both the West and East side of the globe. The presentation pattern of food allergy is slightly different in the Asian group of patients in comparison to the Western populations. While fish and peanut allergies are generally uncommon in Asian population, seafood/shellfish allergy is common in Asian patients experiencing food allergy. 

Shellfish food allergy affects approximately 5% of the teenagers in Singapore. Shellfish allergy is one of the leading reasons of food allergy associated anaphylaxis in Asian countries such as Singapore, Hong Kong, Thailand and Taiwan.  There is also unique pattern seen in the Asian clinical manifestation of shellfish allergy- intriguingly the allergic symptoms tend to be milder with localised reaction over the oral cavities.

The tropical weather with high humidity in Asia is conducive for house dust mites to thrive and they are practically ubiquitous everywhere we go in Asia. House dust mite allergy remains one of the most common airborne related allergens in Asian patients. House dust mite allergy is associated with a myriad of nuisance symptoms that can affect a person’s quality of life ranging from rhinitis, asthma, to incessant itch, hives and chronic eczema.

In this article, we want to understand the association between house dust mite and shellfish allergies, importantly whether treating the former can exacerbate or improve the latter.

House Dust Mite Allergy Symptoms

House dust mite allergies are mainly associated with respiratory allergic symptoms, though one can experience abnormal skin symptoms. Symptoms can be acute, occurring within seconds to minutes or less acute, occurring over hours to days after exposure to house dust mite allergens.

Following sensitisation to house dust mites, one may experience 

Respiratory symptoms such as

• Watery and snuffly nose
• Itchy and watery lacrimation of the eyes
• Throat itching
• Shortness of breath
• Wheezing
• Cough

Skin symptoms such as

• Eye swelling
• Facial swelling
• Lip or tongue swelling
• Hives
• Eczema

Shellfish Allergy Symptoms

Shellfish allergy can occur within seconds to minutes upon exposure to shellfish allergens following direct contact of the allergen onto the skin, inhalation of the allergen or consumption of the allergen into the gut system.

Mild allergy symptoms involve localised presentation

• Itching of the mouth, throat, and tongue
• Mouth and tongue swelling
• Facial swelling

One can present with severe abdominal symptoms involving

• Acute abdominal pain
• Nausea
• Vomiting
• Diarrhea

In life life-threatening condition, one may develop anaphylaxis from shellfish allergy. This is a dangerous medical emergency where one experiences a full-blown allergic reaction – with closing of the airway, facial swelling, inability to breathe, blackout, drop in blood pressure, and widespread body rashes. Immediate medical treatment can reverse and treat such dire situation, however, delay of allergy treatment can result in death.

As the majority of patients with shellfish allergy in Asia tend to present with milder and more stable symptoms, one may even mistake shellfish allergy as gastrointestinal infection, skin inflammatory conditions or other medical conditions.

The Link between House Dust Mite and Shellfish- Tropomyosin

The main allergen that triggers an allergic reaction in shellfish allergy is tropomyosin, a protein that is involved in contracting muscles in invertebrates. In the shellfish family, tropomyosin can be seen in crustaceans such as shrimp, crabs, lobsters and mollusks such as squid and snail. Interestingly, a highly similar tropomyosin protein is also found in house dust mites, cockroaches. 

In view of the presence of similar protein in these living invertebrates, allergy cross-reactivity between house dust mite and shellfish (or even cockroaches) is expected and well documented in clinical literatures. In layman's terms, this means that a person can have house dust mite and shellfish allergies (and cockroaches) concurrently.

Shellfish Sensitisation Following House Dust Mite Sensitisation

As house dust mite can be found in abundance in tropical humid places, it is postulated that the exposure to environmental allergens such as house dust mite and cockroach triggering the first sensitisation to tropomyosin in an allergic person via inhalation of the allergens. Further recognition and sensitisation of the immune system against tropomyosin particles occur in subsequent exposure to shellfish during consumption of the seafood leading to eventual food allergies.

This can be a comparable version of ‘oral-allergy syndrome’ that is commonly seen in the Europe whereby a person who has birch pollen-allergy, may also have cross-reactive allergies when consuming certain fruits and nuts.

House Dust Mite Specific Immunotherapy – Will It Harm or Benefit Those with Concurrent Shellfish Allergy?

Immunotherapy targeting house dust mite has become the game changer in managing atopy conditions associated with dust mite allergies. By re-education and re-challenged of the immune system against dust mite proteins, immunotherapy has proven clinically effective and safe in managing dust mite allergies- in particularly those associated with respiratory allergic symptoms.

The question arises here whether immunotherapy against dust mite allergens can possibly sensitize cross-reactive allergens such as shellfish allergies. Concerns of exacerbation of food allergy following house dust mite immunotherapy treatment due to sensitisation of tropomyosin is also a valid concern.

Hitherto, thankfully clinical studies show no proven new sensitisation of tropomyosin or worsening of shellfish allergy symptoms following dust mite immunotherapy. In fact, there are case studies suggesting potential benefits of food (shrimp) allergy following immunotherapy against dust mites.

How Can I Screen for House Dust Mite or Shellfish Allergies?

Diagnosis of house dust mite and shellfish allergies can be made from a careful and thorough medical history correlating the exposure of the allergens and presentation symptoms. Skin prick tests and blood RAST test can be useful in confirming both house dust mite and shellfish allergies.

What Have I Learnt Today?

• House dust mites and shellfish allergies are two common allergies seen in tropical Asian countries.
• House dust mite allergies can involve both respiratory and dermatological systems.
• Shellfish allergies tend to be milder and localised in clinical symptoms in Asian patients, though one can develop more severe gastrointestinal symptoms or even anaphylaxis requiring immediate medical support.
• There is allergy cross-reactivity between house dust mites and shellfish due to tropomyosin proteins found in both invertebrates.
• Sensitisation of tropomyosin occurs following inhalation of house dust mites or consumption of shellfish proteins.
• House dust mite immunotherapy is effective and safe in managing dust mite allergies.
• There is no sufficient evidence to show worsening or sensitisation of shellfish allergy during treatment of dust mite allergies with immunotherapy.
• Allergy testing can be useful in confirming house dust mite and shellfish allergies.

If you're experiencing symptoms and wondering whether they're related to dust mites or shellfish, our team at Dr. Ben Medical Clinic is here to support you. Book a consultation to better understand your condition and explore treatment options so you can manage your symptoms effectively.

References:

1. Wong L, Huang CH, Lee BW. Shellfish and House Dust Mite Allergies: Is the Link Tropomyosin? Allergy Asthma Immunol Res. 2016 Mar;8(2):101-6. 
2. Pevec B, Pevec MR, Markovic AS, Batista I. House dust mite subcutaneous immunotherapy does not induce new sensitization to tropomyosin: does it do the opposite? J Investig Allergol Clin Immunol. 2014;24:29–34.
3. Pevec B, Pevec MR, Markovic AS, Batista I. House dust mite-specific immunotherapy and tropomyosin sensitizations: harm or benefit for patients? FAAM. 2013;3(3):44.
4. Klaewsongkram J. High prevalence of shellfish and house dust mite allergies in Asia-Pacific: probably not just a coincidence. Asian Pac J Allergy Immunol. 2012;30:247–248. 
5. Cortellini G, Spadolini I, Santucci A, Cova V, Conti C, Corvetta A, et al. Improvement of shrimp allergy after sublingual immunotherapy for house dust mites: a case report. Eur Ann Allergy Clin Immunol. 2011;43:162–164.
6. Santos AB, Chapman MD, Aalberse RC, Vailes LD, Ferriani VP, Oliver C, et al. Cockroach allergens and asthma in Brazil: identification of tropomyosin as a major allergen with potential cross-reactivity with mite and shrimp allergens. J Allergy Clin Immunol. 1999;104:329–337.