Thursday, June 23, 2016

Tick Bites and Meat Allergy

People who live in the southern and central United States, areas of the country where bites from the lone-star tick (Amblyomma americanum) are common, are reported to be at risk of developing an allergy to red meat.  The allergy is thought to develop as a result of exposure to a carbohydrate called alpha-gal (galactose-α-1,3-galactose) that is transferred from the tick to humans via their bite.
Alpha-gal is present in several mammals (e.g., cows, pigs, deer, sheep, etc.) but is not naturally present in apes and humans.  Ordinarily, when meat from one of these sources is consumed by humans, the alpha-gal remains in the digestive tract without causing problems.  If alpha-gal is transferred to the blood stream of a human during a tick bite, however, the body recognizes the carbohydrate as a foreign substance and initiates an immune response.

During this immune response, antibodies (IgE) to alpha-gal are produced to protect the body from this carbohydrate which it perceives to be a threat.  IgE antibodies are one of 5 classes of antibodies produced in the body and the one most commonly involved in allergies and allergic reactions. With subsequent consumption of food containing alpha-gal, IgE antibodies are released which bind to the foreign carbohydrate and trigger the release of histamine and other chemicals causing an allergic reaction.

Symptoms of a meat allergy can include:
  • Hives or skin rash
  • Nausea, stomach cramps, indigestion, vomiting, diarrhea
  • Stuffy/runny nose
  • Sneezing
  • Headaches
  • Asthma
  • Anaphylaxis, an allergic reaction that restricts breathing
Alpha-gal-related allergy symptoms characteristically occur 3 to 6 hours after eating red meat, rather than the more typical hour or less common to most other food allergies. A blood test to measure for the presence of alpha-gal IgE antibodies is available, however, this test has not been approved yet by the U.S. Food and Drug Administration and may not be covered by certain health insurance carriers.

At present, treatment of alpha-gal meat allergy involves avoidance of eating meat from mammals.  Should mild symptoms occur despite avoidance efforts, treatment with antihistamines or corticosteroids should help. Anaphylaxis, also known as "anaphylactic shock", is a true medical emergency and requires immediate treatment. Symptoms of anaphylaxis include swelling of the tongue and throat, constriction of the airways, a weak and rapid pulse, and dizziness or fainting. Treatment typically involves administration of oxygen, anti-histamines and injectable epinephrine.  People with meat allergy should consider carrying an epinephrine auto-injector (e.g. EpiPen) in case of a reaction.
Non-mammalian meat (fish, chicken, turkey, etc.) does not contain alpha-gal, but milk and some milk products have been suspected of triggering the allergic reaction.  Gelatin and protein powder with whey may also contain alpha-gal. Although most common in the southeastern U.S., alpha-gal meat allergy could occur in any area of the country where lone-star ticks are present.  Other ticks, including the European Castor Bean Tick and the Paralysis Tick in Australia have also been implicated in the development of meat allergy.

Sources for article:
Researchers Tie Tick Bites to Serious Red Meat Allergy from Medscape
Meat Allergy from the American College of Allergy, Asthma & Immunology

If you have any questions about tick bites, please log into your account and send us your question. We are here to help

Kent Davidson MD - Health Tip Content Editor
Reviewed and Approved by Charles W. Smith MD, Medical Director on 6-22-2016.

Thursday, June 16, 2016

Bursitis, not just a geriatric problem

Many people have heard of the term "bursitis", but few know what a bursa, the structure that is affected in bursitis, actually is.  In the body there are over 150 bursae (the plural of bursa).  A bursa is a small jelly-like sac, which serves as a cushion to decrease pressure between two adjacent structures.  For example, when a tendon slides against a bone in the process of moving a joint, a bursa helps to decreases the friction between these two structures. If a bursa becomes inflamed, a painful condition known as bursitis develops. Let's look at why bursitis may occur and at some of the most common types of bursitis
What causes bursitis?  Bursitis is usually the result of an overuse or a traumatic injury. Repetitive movements, such as throwing a ball, kneeling for prolonged periods, or running, are example of activities that can produce overuse injuries. Trauma, such as a blow to an area of the body overlying a bursa, can also lead to the development of inflammation within the bursa sac.
Which bursae are most commonly affected?  Fortunately, only a few of the bursae in the body are likely to become inflamed. These include the bursa at the side of the hip joint (trochanteric bursa), the one on top of the shoulder (subacromial bursa), a bursa on the front of the kneecap (pre-patellar bursa) and the bursa at the tip of the elbow (olecranon bursa).

Trochanteric bursitis is a common problem that causes pain over the outside of the upper thigh. The trochanteric bursa rests between the bony prominence on the side of the upper hip (the greater trochanter) and a tendon that passes over this bone. Someone with trochanteric bursitis usually reports having hip pain at night, particularly when lying on the affected side. Pain may also be noticed at the outside of the upper hip when getting up from a chair or after prolonged walking, stair climbing, or squatting.

Subacrominal bursitis affects the shoulder, causing pain with movement such as reaching overhead or behind the back. It is part of a broader condition known as "impingement syndrome", one of the most common causes for shoulder pain. With impingement, "pinching" of the rotator cuff tendons and bursa occurs between the humerus (upper arm bone) and the bony arch (acromion) that is situated above. While it is more likely to develop in individuals over the age of 40, it is far from a geriatric problem.  Sports activities, including tennis, swimming, and baseball, can all cause subacrominal bursitis.  Work-related activities, such as overhead assembly work, can also trigger this type of bursitis.

Pre-patellar bursitis affects the bursa on the front of the knee cap (patella). This bursitis is sometimes known as "housemaid's knee", since the repetitive pressure on the front of the knee from kneeling, as when scrubbing a floor, is a typical cause. Pre-patellar bursitis can also be caused by a direct blow or fall on the knee.  In pre-patellar bursitis a fluid filled lump is often visible over the front of the kneecap.

Olecranon bursitis is associated with marked swelling at the tip of the elbow.  Prolonged pressure to the tip of the elbow, as could occur in someone who drives for long distances with their elbow on an arm rest, is an example of an activity that could produce this type of bursitis.  A traumatic injury, such as striking the tip of the elbow in a fall, can also cause olecranon bursitis.

What is the treatment for bursitis?   While there are some differences in treatment among the various types of bursitis, a few treatment principles remain the same for all types. First a period of rest is necessary. This means avoiding activities that led to the development of the bursitis or those that aggravate the problem.   Next, anti-inflammatory medications (e.g. ibuprofen, naproxen, etc.) are typically recommended to help control the inflammation. Intermittent application of ice to the skin overlying the inflamed bursa can also help to diminish inflammation as well as serving to reduce pain. Other measures that can be used in treating bursitis include physical therapy modalities, stretching exercises, cortisone injections, and rarely surgery.

A special circumstance should be mentioned when treatment of bursitis becomes urgent. If the skin overlying the bursa becomes broken, such as with an insect bite or a scrape, bacteria may get inside the bursa and cause an infection. Infected bursae can become markedly swollen with redness and swelling of the overlying skin. Surgery, to incise the bursa and drain accumulated pus, along with antibiotic treatment, is usually necessary.

So, if the doctor tells you that you have bursitis, don't feel like you are necessarily "over the hill". Bursitis is almost as common among younger, active individuals as it is in older folks.

Sources for article:
Hip bursitis from OrthoInfo
Bursitis and Tendinitis from the National Institutes of Health

Thursday, June 9, 2016

Topical (rub on) Pain Medicines

When experiencing joint or muscle aches and pains, many people seek relief from an oral pain medication, such as acetaminophen (e.g. Tylenol) or ibuprofen (e.g. Motrin).  An alternative to this, particularly well suited in someone who cannot tolerate these medications, are topical pain medicines (analgesics).  Topicals, which are applied directly to the skin, come in several preparations including gels, solutions, and sprays. Some of the most common applications for topical analgesics are joint pain associated with arthritis, nerve-related pain, and muscle soreness after physical exertion.

What's in over-the-counter (OTC) topical analgesics?  Several topical are available on an OTC basis. The active ingredients in these fall into a few general categories.
Counterirritants (Icy Hot, Biofreeze, others) These topicals work primarily by creating a burning or cooling sensation that distracts the user from the painful stimulus. The active ingredients in these medications include methylsalicylate, menthol, and camphor. This class of analgesics has no effect on the underlying inflammation associated with arthritis and work primarily at the level of the superficial nerve fibers.

Salicylates  (Aspercreme, Bengay, others)  The most well-known salicylate is aspirin. When absorbed through the skin, however, creams containing salicylates can provide some of the same pain-reducing effect as oral aspirin.  This class of topical analgesics may be particularly beneficial with arthritis pain in the fingers and knees.
Capsaicin  (Zostrix, Capsagel, others)  Capsaicin is the chemical that makes chili peppers hot.  When applied topically, it works by decreasing a chemical in the body (substance P) that is involved in sending pain signals to the brain. Capsaicin analgesics may be used to treat minor pain associated with arthritis or muscle strains.  Topical analgesics of this class also work well for a type of persistent nerve pain following a bout of shingles (post-herpetic neuralgia).

Are prescription topicals available?  Oral medications in a class of drugs known as non-steroidal anti-inflammatory drugs (NSAIDs) are widely used to treat pain and inflammation.  Ibuprofen (Advil, Motrin), naproxen (Aleve, Naprosyn), celecoxib (Celebrex) and indomethacin (Indocin) are examples of drugs in this class.  Taken orally, however, these drugs can produce serious side effects including stomach ulcers, liver or kidney failure, and may increase one's risk of having a heart attack.  In the U.S. a prescription topical that contains the NSAID, diclofenac (Voltaren Gel 1%) has been approved by the Food and Drug Administration for the treatment of osteoarthritis in joints close to the skin's surface, such as the hands and knees. A potential benefit of topical administration of this product is the avoidance of many of the side effects associated with oral NSAIDs.

How well do they work?   At the risk of sounding like a TV ad for a medication--- "your results may vary". Much of the evidence for the effectiveness of OTC topical analgesics is anecdotal, coming from users of the various products. Results of scientific studies evaluating the effectiveness of OTC topical analgesics have generally shown only modest improvements in symptoms.  In regard to a topical containing the prescription medication diclofenac (e.g. Voltaren gel), however, there is stronger data supporting its effectiveness. In an analysis of multiple studies performed by an international body of health experts, topical diclofenac solution was found to be equally effective to that of oral NSAIDs in knee and hand osteoarthritis while producing a lower incidence of gastrointestinal problems.

Are topical analgesics safe to use? Like any other medication, topical analgesics can have side effects or cause allergic reactions.  The most common side effect, particularly with capsaicin-containing products, is a local skin reaction at the site of application. These medicines should not be applied to broken skin or to mucous membranes.  It is important to let your doctor known if you are using any of the OTC products while taking other medications since it is possible for a drug-drug interaction to occur.  Someone taking blood thinners needs to be particularly careful when using a salicylate-containing product since the combination can increase the risk of bleeding.

Sources for article:
Rub-on pain reliever can ease arthritis discomfort from Harvard Health Publications
Topical NSAIDs for chronic musculoskeletal pain in adults from the Cochrane Library
Arthritis pain: Treatments absorbed through your skin from the Mayo Foundation for Medical Education and Research

If you have any questions about topical (rub on) pain medicines, please log into your account and send us your question. We are here to help.

Kent Davidson MD - Health Tip Content Editor
Reviewed and Approved by Charles W. Smith MD, Medical Director on 6-8-2016