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Month: May 2023

Mammalian Meat Allergy Update

Mammalian meat allergy which is also known as alpha-gal syndrome causes an immediate hypersensitivity reaction hours after eating beef, pork, lamb, venison, or any other mammalian meat product. Although the allergy was first described in patients with hives (i.e., urticaria) and severe life-threatening reactions such as anaphylaxis, there is now a new phenotype of mammalian meat allergy that has different presenting symptoms. The new and increasingly recognized phenotype is called gastrointestinal (GI) alpha-gal. Gastrointestinal alpha-gal presents with GI symptoms such as abdominal pain, diarrhea, nausea, and vomiting without the predominant skin, respiratory, or circulatory symptoms.

Individuals with mammalian meat allergy or alpha-gal syndrome have an allergy to the galactose alpha-1,3-galactose, a sugar molecule on the cells of all non-primate mammals which is not present in humans. Lone star ticks can transfer this molecule to humans, by first feeding the mammals, and subsequently biting the humans. Since the galactose alpha-1,3-galactose molecule is foreign to humans, antibodies are formed in order to fight the foreign sugar molecule. When this occurs, the individual becomes sensitized to the molecule. The antibodies produced are called IgE antibodies that are specific towards the galactose alpha-1,3-galactose sugar molecule.

After the sensitization to the galactose alpha-1,3-galactose sugar molecule occurs, if the individual eats mammalian meat which naturally contains the galactose alpha-1,3-galactose (i.e., alpha-gal antigen), the alpha-gal antigen binds to the IgE antibodies present on the mast cells that richly populate the GI tract. As a result of the binding, these mast cells degranulate and release large quantities of histamine and other chemical mediators into the bloodstream. These chemical mediators in turn can act on sensory nerve endings to cause pain, intestinal smooth muscles to cause contractions, and/or mucous glands to cause the secretion of mucous.

When patients seek care for frequent abdominal pain, bloating, cramping, and/or diarrhea, they are often diagnosed as having irritable bowel syndrome (IBS), if no organic cause for these symptoms is identified. Some of these patients could have been previously sensitized to alpha-gal and their symptoms could be an indicator of an allergic reaction. The onset of symptoms could be several hours after the ingestion of the mammalian meat, as opposed to other common immediate type of hypersensitivity reaction (e.g., egg allergy, peanut allergy, seafood allergy), where symptoms usually begin within minutes of the exposure to the food.

A history of awakening up at night from sleep with gastrointestinal distress may suggest alpha-gal given the typical hours delay that occurs in this condition from alpha-gal ingestion to the subsequent reaction. Patients who have a history of tick bites or enjoy outdoor pursuits are at a higher risk for this allergy.


Alpha-gal syndrome or mammalian meat allergy is a clinical diagnosis with supporting laboratory findings (i.e., a positive alpha-gal antibody level in the blood). A diagnosis of alpha-gal syndrome may be made in patients with consistent symptoms and an increased alpha-gal IgE titer whose symptoms resolve or improve after adhering to an alpha-gal–avoidance diet, where mammalian meat is avoided.

The clinical presentation of this syndrome can be highly variable and unpredictable. Many patients who have been are previously sensitized, may not have symptoms every time they consume mammalian meat. At other times however, they can have a severe reaction after consuming even a small quantity of mammalian meat.

It should be noted that the gold standard for diagnosing food allergies typically is by an oral food challenge. In individuals with mammalian meat allergy however, there is usually at least a couple or more hours-long delay time until the allergic reaction occurs. Since the allergic reaction is delayed and may also be inconsistent, an oral food challenge is not reliable and thus not used to diagnose mammalian meat allergy.


The cornerstone of managing alpha-gal syndrome is to eliminate alpha-gal from the diet. Individuals diagnosed with this condition should not eat pork, beef, lamb, venison, rabbit, whale, or any other mammalian meat. In essence, any animal with hair as well as products made from these mammals (e.g., lard, butter, milk) should be avoided. Dairy does contain smaller amounts of alpha-gal, particularly ice cream, cream, and cream cheese, which have a high fat content.

Gelatin is derived from the collagen in pig or cow bones. As such, foods that contain gelatin (e.g., marshmallows, gummy bears, gelatin candies) also may trigger allergic reactions. In addition, processed foods can have small amounts of animal-derived products. Restaurants may cross-contaminate foods with alpha-gal which may be a problem for patients with high levels of sensitivity to alpha-gal.

Fish, shellfish, turkey, chicken, and other fowl are acceptable for patients with alpha-gal.


Alpha-gal–allergic individuals should take measures to avoid further tick bites because additional tick bites may worsen the allergy. Performing regular tick checks, showering soon after activities in grassy and woody areas, creating a barrier at the ankles by pulling up tight mesh socks over the pant cuffs on hikes, and treating clothes and boots with permethrin may all help reduce the likelihood of tick bites.

Certain medications such as cetuximab (i.e., Erbitux) and pancreatic enzymes are derived from pigs and may cause problems in mammalian meat-allergic individuals. A company in Blacksburg, VA developed alpha-gal-free pork, which is FDA-approved but not yet widely available. Another option for alpha-gal allergic individuals is to consume plant-based alternatives to meat commonly found in companies like Beyond Meat or Impossible (e.g., Impossible burger).

All patients diagnosed with alpha-gal allergy should carry a self-injectable epinephrine device (e.g., EpiPen, Auvi-Q, Adrenaclick) for use in case of a systemic reaction following an inadvertent exposure to mammalian meat. If a self-injectable epinephrine device is used, the patient should go immediately to the closest emergency room.

The board certified allergists at Black & Kletz Allergy have been diagnosing and treating food allergies and intolerances as well as mammalian meat allergy (i.e., alpha-gal) for many years. If you or your child suffers from food allergies, food intolerances, eosinophilic esophagitis, hives (i.e., urticaria), swelling episodes (i.e., angioedema) please call us to make an appointment. Alternatively, you can click Request an Appointment and we will respond within 24 hours by the next business day. Black & Kletz Allergy has offices in Washington, DC, McLean, VA (Tysons Corner, VA), and Manassas with on-site parking all 3 locations. Our Washington, DC and McLean, VA locations are Metro accessible and we offer a free shuttle between our McLean, VA office and the Spring Hill metro station on the silver line. We look forward to helping you with all your allergy, asthma, and immunology needs as we have been doing in the Washington, DC, Northern Virginia, and Maryland metropolitan area for more than a half century.

Poison Ivy, Poison Oak, and Poison Sumac Update

It is the Spring now and people will be spending a lot more time outdoors. Activities such as hiking, gardening, landscaping, golf, and picnicking tend to pick up in the Spring when the temperatures are warmer and these activities are generally enjoyed until the late Fall in the Washington, DC, Northern Virginia, and Maryland metropolitan area, when the temperatures become cooler. These outdoor activities as well as other outside happenings may predispose an individual to coming in contact with poison ivy, poison oak, and/or poison sumac. These plants are well known for causing an itchy rash when the plants come in contact with a sensitive individual. The itchy rash can occur from touching any part of the plant including the leaves, berries, flowers, stems, and/or roots, whether the plant is living or dead.  In some individuals, coming in close contact with anything that has touched the plants, (e.g., shoes, sneakers, clothing, garden tools, lawn mowers, fur from animals) can also spread the agent that is responsible for causing the itchy rash.

The agent responsible for causing the itchy rash is a chemical called urushiol. It is important to note that all parts of these 3 plants contain the same oily pale-yellow liquid resin called urushiol.  As stated above, it is this contact with the urushiol that is responsible for causing the rash.  When an urushiol-sensitive individual comes in contact with the urushiol, an allergic reaction takes place. This allergic reaction occurs on the skin which results in an itchy rash. The rash that is caused by poison ivy, poison oak, and/or poison sumac is classified as “contact dermatitis.”

The itching and rash can vary in severity from individual to individual and range from a mild rash to a severe rash. The symptoms of the cutaneous allergic reaction may include itching, linear red streaks (which characteristically follows a straight line pattern where the plant brushed up against the skin), red bumps of varying sizes, and/or blisters filled with fluid. Occasionally, the rash can become secondarily infected, which is usually due to scratching.  Rarely, an individual may be so highly sensitive that angioedema (i.e., swelling) of the throat, face, lips, eyes, and/or neck may occur. If this type of swelling occurs, it can manifest itself as difficulty swallowing and/or difficulty breathing which can be very serious as it may lead to unconsciousness.  Individuals who develop such severe reactions should go immediately to the closest emergency room for treatment.

Usually, the symptoms of poison ivy, poison oak, and/or poison sumac begin between 24-48 hours after contact with the plants.  Occasionally, it may take a longer period of time to develop symptoms, particularly if it is the first time that the individual has a reaction.  The rash typically lasts about 2-3 weeks in duration, but can persist much longer in some sensitive individuals.

A few common fallacies should be pointed out about poison ivy, poison oak, and poison sumac. First of all, this type of contact dermatitis does not actually spread by itself. In order to develop a rash, contact with the urushiol liquid is necessary. Thus, the only way the rash is transported to other areas of the skin would be from spreading the oily urushiol from one area to another by way of one’s fingers. It is actually the urushiol being transported from one area to another that causes the contact dermatitis to be visible in another location. It is not the leakage of the blister fluid that causes other areas of the skin to be involved because there is no urushiol in the blister fluid. One should also keep in mind that there are other skin diseases that may cause blistering. It is advised to see a board certified allergist or dermatologist if you have blistering of any kind.

Identifying the differences between poison ivy, poison oak, and poison sumac is not always that easy and clinically not that important. Poison ivy and poison oak look similar and consist of compound leaves (i.e., multiple leaflets that make up 1 leaf). In the case of poison ivy and poison oak, there a 3 leaflets on each leaf. Poison ivy has 3 glossy almond-shaped leaflets with jagged edges per leaf. In the Spring, the leaves can be red or a mixture of red and green. In the Summer, the leaves are green. In the Fall, the leaves can be bright orange, yellow, or red. Poison oak has 3 fuzzy leaflets per leaf that have uneven and scalloped edges. In the different seasons, the leaves can vary from green to red. Poison oak tends to blend in around the surrounding shrubs which often makes it difficult to spot. Poison sumac has between 7 and 13 leaflets on a reddish stem and resembles a fern. The green leaflets of poison sumac are oval-shaped with a pointy top. These leaflets tend to run in pairs up the stem. It should be noted that all 3 plants may also contain berries.

Prevention of contact with poison ivy, poison oak, and poison sumac is ideally the best way to avoid the contact dermatitis that occurs with these plants. It is advisable to wear long pants, long-sleeved shirts, sleeves, gloves, and closed shoes in order to decrease the probability of contracting the rash. It is also desirable to wash one’s clothes immediately in order to remove any urushiol that may have gotten on one’s clothing from the plants.

The treatment of poison ivy, poison oak, and/or poison sumac is to wash the affected skin with a mild soap and cool water in order to try to remove the oily urushiol. Calamine lotion, zinc oxide ointment, and oral antihistamines are used often to help relieve the annoying symptoms. Occasionally oral corticosteroids and antibiotics may be necessary in more severe and recalcitrant cases and in cases of secondary infections respectively. If the rash persists and or gets worse, it is important to see a board certified allergist or dermatologist.

The board certified allergy specialists at Black & Kletz Allergy have 3 convenient locations in the Washington, DC, Northern Virginia, and Maryland metropolitan region and have been providing allergy and asthma care to this area for more than 50 years. We diagnose and treat both adults and children. Our offices are located in Washington, DC, McLean, VA (Tysons Corner, VA), and Manassas, VA. All of our offices offer on-site parking. For further convenience, our Washington, DC and McLean, VA offices are Metro accessible. In addition, our McLean, VA office location offers a complementary shuttle that runs between this office and the Spring Hill metro station on the silver line. For an appointment, please call one of our offices. Alternatively, you can click Request an Appointment and we will respond within 24 hours by the next business day. If you suffer from poison ivy, poison oak, poison sumac, contact dermatitis, hives (i.e., urticaria) hay fever (i.e., allergic rhinitis), sinus problems, asthma, or immune issues, please contact our office as it is our mission to help alleviate your undesirable symptoms, so that you can enjoy a better quality of life.