For long-term sufferers, any indication of itchy eyes or a runny nose can sound the alarm. Allergy sufferers are well accustomed to the telltale signs of an impending attack and are often armed with a range of prophylactics, from sprays to pills and ointments, to stave off the worst of the symptoms. This can be especially heartbreaking for animal lovers whose families develop allergies to dander (skin cells shed by animals with fur).
Surprisingly, the holy grail is therapy that not only relieves symptoms, but actively helps the sufferer become less allergic. And so recent reports that the Duchess of Cambridge, Kate Middleton, had started a new treatment for her horse allergy sparked interest. According to reports, the Duchess had been treated with sublingual immunotherapy to relieve the allergy.
Does sublingual immunotherapy for animal allergies offer a solution for families who have had to virtually isolate the family pet? Maybe.
“We’ve had treatments for allergies for at least 100 years, but not all have been 100 percent accurate. Some had side effects,” explains Dr. Juan Trujillo, Pediatric Allergy Consultant at Cork University Hospital and Senior Lecturer at UCC, where he is coordinating a new MSc in Allergy and Clinical Immunology.
“The most common form of immunotherapy for allergies – subcutaneous (under the skin) – has been practiced worldwide for about 60 years. Sublingual has been around for 20 or 30 years.
“What is new is that there are two large manufacturers of prescription drugs on the market that have good evidence. That’s not to say these treatments will cure you of allergies, but the evidence shows that immunotherapy can reduce the burden of allergies.”
Sublingual immunotherapy is administered through drops under the tongue. It is part of the field of precision medicine, which means that drugs are customized rather than generic. It gradually desensitizes the patient to the allergy, but is a long-term drug, requiring duration of three to five years, and works best in patients under the age of 30 (in addition, the immune system is less susceptible to changes).
“Sublingual immunotherapy has generally been available in Ireland and the UK since around 2016,” explains Dr. Simon Bull, Medical Specialist at Allergy Ireland. “The newer treatments cover three inhalant allergies, and although pet dander is an inhalant allergy, it is not covered by sublingual immunotherapy. They are limited to subcutaneous immunotherapy, which has not been widely offered since the late 1980’s when there were some concerns about its use in patients with severe asthma. It’s widespread in Europe and America, but not here.”
Allergies are “epigenetic” diseases, meaning they are influenced by our genetic heritage, but not fully inherited. Both ancestry and environment play a role. The presence of an allergy in a parent doubles the likelihood of having a child with this disease. When both parents are present, a child is four times more likely to have an allergy.
While hay fever can be a nuisance in the spring and summer, the house dust mite is a year-round irritant and the world’s most common allergy. They thrive in humid environments between 13 and 27 degrees, making Irish homes particularly hospitable. Shocked families could implement a scorched earth cleaning policy, but a dust mite allergy doesn’t mean an unclean home.
“You have radiators, heaters, and the dust mite will live in there even if you’re extremely clean,” explains Dr. Trujillo. “The dust mite feeds on the dry skin that everyone leaves behind in the sheets, blankets and pillows. So even though we clean everything and try to avoid the dust mite, we will have it.”
The symptoms of so-called inhalant allergens can be similar. Therefore, a correct diagnosis of the specific allergen is essential.
“Inhaled allergens would manifest as allergic rhinitis symptoms,” explains Dr. Bull. “They consist of runny, itchy nose with nasal congestion. Postnasal drip can occur, often predisposing the patient to recurrent episodes of acute sinusitis. This is where the ongoing reaction in your nose has compromised the drainage of ducts leading to your sinuses. The nose has misidentified a substance, such as dander, as a threat and mounted an immune response against it. So you develop a swelling in your nose.”
Skin prick tests introduce a small amount of allergen into the dermis to make the diagnosis. When a dander allergy is suspected, clinics typically test for “cat and dog plus or minus horse or rabbit.” It’s specific,” adds Dr. Bull added.
While tests can accurately diagnose an allergy to pet dander — when performed by a clinician — immunotherapy treatments have “vague” results, says Dr. Trujillo.
“If an adult is allergic to a dog or cat, they usually won’t complain. It’s different with children. In Ireland there is no specific immunotherapy against animal dander, but in some other countries there is. However, the results are somewhat vague. There isn’t a lot of strong evidence to support treating patients.”
So what can you do? First, while there is currently no direct immunotherapy for dander, experts believe it is only a matter of time. Seek a suitably qualified specialist to diagnose the allergy and beware of doctors who may be overly enthusiastic about such a diagnosis.
“Prick testing is an extremely dangerous weapon if not used properly, and all my colleagues agree,” says Dr. Trujillo. “Patients will get tested at places that test everything and that’s not how allergies work. You have to investigate and research the cause of the allergy and choose the right tests as they can give a lot of false positives, especially with cow’s milk allergies.”
Once an allergy is diagnosed, clinicians can coordinate treatment to reduce symptoms. Even when a definitive cure isn’t available, symptomatic relief is necessary as it can help reduce severity over time.
“Virtually whenever someone has an inhalant allergy with nasal congestion, we can achieve profound improvement by following our treatment guidelines, which are quite effective and probably better than you would get from your GP. In addition, the additional measure of immunotherapy would be in consultation with the patient.”
This is a long-term commitment in terms of both time and money. A month’s treatment can cost between €70 and €90. “The investment of three to four years and the costs of the course must be worthwhile. The symptoms would have to be sufficiently obstructive.”
In those under 20, results from immunotherapy are “typically excellent,” but improvements can be made for those in their 50s. It’s undoubtedly a significant investment, but for those unhappy with allergies, it’s probably worth every drop.
For more information on the MSc in Allergy and Clinical Immunology, visit ucc.ie/en/pcaci/. dr Bull practices at Allergy Ireland. See allergy-ireland.ie
https://www.independent.ie/life/health-wellbeing/health-features/could-immunotherapy-be-the-answer-to-kate-middletons-horse-allergy-and-what-other-allergies-can-it-cure-41925653.html Could Immunotherapy Be the Answer to Kate Middleton’s Horse Allergy? And what other allergies can it cure?