Tick You Very Much/No Beef For You!

There has been a lot of discussion and awareness raised about Lyme Disease lately and for good reason. What was just a few decades ago a rare, little-known infectious disease primarily seen in the Northeast United States, has exploded both in number of cases and geographical distribution. Lyme Disease is caused by a spiral bacterium called Borellia burgdorferi and trans-mitted by the bite of an infected deer tick. The bacteria triggers a rash and fever in the short-term, but if not diagnosed accurately and treated properly with antibiotics, the disease can progress to cause serious joint, neurological and cardiac symptoms that last for months or even years. The number of cases has surged both due to increased aware-ness, including several celebrities who have been diagnosed with the disease and spoken out about their experiences, but also due to the spread of deer ticks, which in the past couple decades has moved from the Northeast and Mid-Atlantic states to now cover almost the entire eastern and Midwest U.S.

Despite all the attention paid to Lyme Disease, there are other afflictions caused by tick bites that are not as well-known, such as Rocky Mountain Spotted Fever, babesiosis and Powassan Fever. However, there is one very unique condition that I had not heard about until this week when I read an article in The Buffalo News titled, "It's High Time for Ticks, Which Are Growing in Number as They Spread Disease Further" (printed on July 25, 2017 and written by Aneri Pattani of The New York Times). The article mentions the surge of tickborne diseases, including newly discovered pathogens such as the Heartland virus and Bourbon virus, as well as the spread of not just deer ticks, but also lone star ticks, which are native to Texas and the Deep South, but has now been found in 39 states as the arachnids move north- and westward.

The latter section of the article introduced a strange medical condition known as alpha-gal syndrome, an allergy to red meat engendered by lone star tick bites. "Alpha-gal is a sugar molecule carried by the lone star tick. When the tick bites a human, it activates the immune system, which starts producing alpha-gal antibodies. The body becomes wired to fight alpha-gal sugar molecules, which are abundant in red meat. Eating red meat can then trigger allergic reactions, from an itchy rash to anaphylactic shock."

So how does this happen? Well, drawing on my knowledge of immunology, there is a rather simple answer. White blood cells known as B lymphocytes act as sentinels in the bloodstream. Each B cell has a receptor on its surface that recognizes a portion of a protein or sugar molecule found on the surface of bacteria, viruses, fungi, parasites, transplanted tissues, tumor cells or food particles, called an antigen. When a B cell encounters a specific antigen, it recognizes that protein or sugar molecule as foreign to the body (and possibly harmful) and becomes activated. The B cell secretes a substance known as interleukin, which stimulates other immune cells called T lymphocytes to commence an immune response. The B cell itself transforms into a specialized cell called a plasma cell, which is basically an antibody-producing factory. It churns out large amounts of antibodies specific for that antigen. The antibodies then bind to the protein or sugar molecule, thus targeting those foreign substances for destruction by the body's immune system.

In some cases, rather than merely destroying the antigen, the recognition of a protein or sugar molecule as foreign, can trigger an allergic reaction. There are other cells found in the bloodstream known as mast cells. These cells have a protein on their surface similar to antibodies called immunoglobulin E (antibodies in the blood are made from IgG or IgM, while antibodies secreted in saliva, tears, breast milk, etc. consist of IgA). The IgE on the surface of mast cells are constantly on the lookout for foreign antigens. When IgE comes across and binds to a specific antigen, it activates the mast cell to release histamine, which attracts other mast cells to the area, and is responsible for the varied symptoms associated with allergic reactions- from the runny nose and red, watery eyes of pollen-induced hay fever, to hives, to anaphylactic shock caused by a massive release of histamine that causes blood vessels to dilate, leading to a dramatic drop in blood pressure and vital organs suffering damage from inadequate blood flow. The latter is often seen in severe food allergies, such as from peanuts and shellfish, that can cause an overwhelming allergic response that can be fatal in minutes if not counter-acted with an injection of epinephrine (EpiPen).

In the bizarre case of alpha-gal syndrome, the bite of a lone star tick injects alpha-gal molecules into the bloodstream of the victim, which then prime the immune system by activating B cells and mast cells that specifically recognize that sugar molecule. A large number of these alpha-gal fighters develop just waiting to encounter this antigen again, much like a soldier at a military outpost scanning the horizon with binoculars, looking for members of the enemy. When a person then eats some red meat- beef, veal, pork, lamb- the food gets broken down by that individual's digestive tract into its basic molecular contents- fatty acids, polypeptides and simple sugars- before being absorbed across the lining of the intestines and enters the bloodstream. There the B cells and mast cells are waiting for the alpha-gal molecules, and when they encounter this antigen, the mast cells release their pre-produced histamine, triggering an allergic response. So now a person who had the bad luck of being bitten by a lone star tick suffers from the inability to enjoy a delicious beef/veal/pork/lamb dinner without the consequences of an allergic reaction. What a bummer! Well, at least the lone star tick does not rob anyone of their enjoyment of poultry, fish or seafood.

#LymeDisease #deerticks #Borelliaburgdorferi #RockyMountainSpottedFever #babesiosis #PowassanFever #Heartlandvirus #Bourbonvirus #lonestarticks #alphagalsyndrome #Blymphocytes #Tlymphocytes #plasmacell #antibodies #antigen #mastcells #immunoglobulinE #histamine #hayfever #anaphylacticshock

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© 2017 by Peter McNeela.