We’re all familiar with allergies — in the US, approximately 30% of adults and 40% of children suffer from them, and they are unfortunately getting worse for many.
These reactions are triggered by immune system responses to substances that are generally considered harmless. Symptoms range from itchy eyes and runny noses to skin hives to life-threatening, throat-closing anaphylaxis.
Most people are aware of common allergens like pollen, peanuts, dogs, and cats. But allergy and immunology specialists sometimes encounter more mysterious allergies.
Here are some of the strangest and rarest allergies doctors encounter — and how patients with these conditions try to cope.
Red meat: People bitten by infected Lone Star ticks can develop an allergy that makes them unable to consume mammalian meat like beef, pork, or lamb.
Something in the ticks' bite can make people allergic to a sugar compound called alpha-galactose that exists in meat.
This allergy is becoming more common as the tick that delivers the infected bite expands its range. Some people become more allergic to meat than others do, but reactions can be quite severe. Unlike most other allergies, symptoms often take hours to kick in.
No one knows whether the allergy goes away with time or if it can be treated, but scientists think that both additional tick bites and meat consumption might worsen the condition.
Water: People who suffer from aquagenic urticaria, also known as 'water allergy,' develop hives and itchiness shortly after their skin is exposed to water.
This condition, considered a rare disease, mostly affects women and can develop during puberty. The underlying cause is unknown, and experts think it could be caused either by allergens dissolved in water (in which case water wouldn't really be the cause) or by interactions between a person's skin and water that create a substance that triggers hives.
There is limited data on successful treatments, but for some patients, antihistamines -- which are often used to counteract allergic reactions -- help. Some other medications, light therapy, and sodium bicarbonate have been found to be helpful as well.
Semen: Certain unlucky individuals have experienced an allergic reaction to semen -- even their own.
Semen allergies are rare, but they're actually one of the more common on this list. People with this condition experience burning, itching, and swelling after coming into contact with seminal fluid. This condition more frequently affects women but can be found in men. Doctors have even found men who are allergic to their own semen.
There are various treatment options, but most often people are simply advised to avoid the substance -- either completely or with protective barriers like condoms. Some also try gradual exposure to build up a tolerance. Women with this condition who want to become pregnant may need to undergo in vitro fertilization, or may need to be provided with sperm that has certain proteins washed off. Severe cases may require an EpiPen.
Hidden parasites in fish: Certain parasites that are becoming more common can start to trigger allergy symptoms in people who consume them.
An allergic reaction after a fish dinner may make someone think they're allergic to fish, but sometimes the culprit is an organism hidden inside the food. The Anisakis simplex parasite, found in temperate waters around the globe, can infect a number of kinds of fish or squid, and has also been found in chicken meat.
An Anisakiasis infection alone can be severe, causing abdominal pain, vomiting, diarrhoea, and symptoms that mimic Crohn's disease. But people can also develop immune reactions to these parasites that manifest as asthma or severe allergies (with symptoms like hives or anaphylaxis). It's even possible to develop these allergies if fish is well cooked or even via regular contact with fish, as has happened with factory workers.
Treatment options are limited but include antihistamines or emergency adrenaline.
Cold: Sudden drops in temperature can trigger reactions with potentially life-threatening throat swelling in some rare cases.
Sudden drops in temperature are rarely pleasant, but for certain people they can be deadly. Sufferers of cold urticaria are most frequently young adults. A sudden change in temperature is usually responsible, especially in situations where it affects the whole body, like jumping into water.
The condition is not well understood, but it can go away naturally in a few months or years. Patients are told to be careful before engaging in activities like swimming. Antihistamines can help block certain severe reactions.
Exercise: In a small number of people, physical exercise can trigger hives or even life-threatening anaphylaxis.
This condition has been described in medical literature since at least the 1970s. Researchers think the reaction could be triggered by consuming certain foods or medications before exercise. Potential triggers include seafood, celery, wheat, or cheese; medical drugs that may lead to this reaction include NSAIDs and Aspirin.
For treatment, doctors tell patients to avoid exercise after consuming certain substances and to work out with a partner who can administer life support if needed.
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