Rabbit Bush (Ambrosia deltoidia), flowering

It’s an unusual name for a weed: Rabbit Bush.  And although it is not clear where the name for this Arizona native variety of ragweed comes from, one thing is clear:  there is a lot of it and it’s a major cause of allergy problems in the spring.  In fact, Rabbit Bush is one of the most prevalent spring allergenic weeds in South Mountain Park and is therefore a significant source of ragweed pollen for Ahwatukee and surrounding areas.   Rabbit Bush (technically Ambrosia (Franseria) deltoidea and also known as triangle bur ragweed or tirangleleaf bursage) comes to life in the spring, particularly if we have had winter rain, producing copious amounts of pollen in the Arizona Sonoran desert from March until  May.   Allergenically,  it is closely related to other varieties of ragweed found throughout the Unities States and will trigger allergy symptoms in patients who have had problems with ragweed before moving to Phoenix.   Other native varieties of ragweed found in the Sonoran Desert include Canyon Ragweed, fond of desert washes, and Desert Ragweed, a smaller but also prevalent ragweed  in the Phoenix area.

Rabbit Bush (Triangular Bursage)

It sounds like science fiction.  A hideous blood-sucking alien creeps into the bedroom of an unsuspecting victim while they sleep.  With razor sharp fangs the monster begins to feed, injecting a cocktail of chemicals to keep the blood flowing. As the fiend’s venom works it’s way through the body, a frightening change takes hold.  Forever transformed, the victim is doomed to live in fear of pleasures he once enjoyed.

As bizarre as it sounds, this scary story (with a few embellishments) is not science fiction but true.  Here are the unsettling details.

The blood sucking alien is Amblyomma americanum – the lone star tick.  The tick is found primarily in the Southeastern part of the United States, although some believe that it’s territory may extend further west.  In some individuals, a bite from the tick triggers the immune system to produce antibodies to a sugar found in the saliva of the tick called galactose-α-1,3-galactose or alpha-gal.   This sugar is also found in meats such as beef, lamb, and pork and so once a victim becomes “immunized” by the tick bite, eating a steak, for example, can cause hives or even more severe allergic symptoms.

Unlike most allergic reactions to foods, the alpha-gal reaction can occur 4-6 hours after eating meat.  And although a blood test for the alpha-gal antibody is available, it may not be ordered if the connection between a patients severe allergic reaction and eating a hamburger six hours earlier is not made. To make matters worse, patients who have become sensitized to alpha-gal by a tick bite can also have severe allergic reactions to cetuximab, a new medication used to treat cancer.

So far, the only treatment for alpha-gal sensitivity and the resulting meat allergy is avoidance.

Maricopa County health officials are continuing to report an alarming increase in cases of whooping cough.  In fact, the number of confirmed cases of whooping cough in 2012  in Maricopa County was more than three times the number in 2011, with 282 confirmed cases by September.

Whooping cough or pertussis, caused by the bacteria Bordetella pertussis, is a very contagious infection that can spread rapidly in a community.  Recent studies have suggested that asthmatics are at even greater risk of contracting the illness.  It can be treated with antibiotics such as azithromycin (Zithromax, Z-pack) although it is most effective when given early in the course of the illness.

Pertussis should be considered in anyone with a cough lasting for more than two weeks.  Diagnosis usually requires a nasal swab and culture and needs to be done before antibiotics are started.

Although the highest attack rate of pertussis occurs in children under one year of age, approximately 60 percent of cases now occur in adults.  For this reason the CDC’s Advisory Committee on Immunization Practices recommends that all adults under the age of 65, including all health care personnel, receive a dose of the pertussis vaccine, Tdap, regardless of the time since their last immunization.

It’s finally starting to feel like fall.  Nighttime and early morning temperatures have dropped below 90 degrees, the monsoon humidity and risk of monster dust storms is on the decline, kids are back in school, and club sports are in full swing.   We are also seeing early signs of the Arizona fall allergy season.   Unlike the Midwest and the South, where fall can bring some of the worst allergy misery of the year, the fall allergy season in the desert can be hit or miss depending on the amount of monsoon rain during the summer.   This year, things are shaping up to be a real hit.  Higher than normal rain fall has produced a bumper crop of allergenic weeds including Russian Thistle (tumble weed), Careless Weed, and Ragweed.  In many parts of the country, ragweed pollen defines the fall allergy season.  In the Phoenix area, ragweed often plays a minor role in the fall allergy season because it is too hot and dry.  On the other hand, ragweed is a major cause of springtime allergy symptoms, particularly when the valley gets sufficient winter rain. This year may be an exception, and residents of Phoenix who usually have allergy problems during the spring may find themselves suffering as much itching, sneezing, and wheezing this September and October as they usually do in March and April.

Bermuda grass, although pollinating throughout the summer, becomes a more serious allergy problem in the fall as children start practicing and playing on bermuda grass sport fields.  Landscapers and homeowners also begin “scalping” and dethatching there bermuda grass lawns in preparation for planting winter rye grass. Scalping a lawn (mowing the grass very close to ground) sends a cloud of bermuda grass dust high into the dry fall air where it can be carried throughout the neighborhood.

All this increase in atmospheric pollen and particulate production is compounded by the phenomenon of temperature inversion.  In the fall, as the nighttime temperatures begin to drop, a layer of cooler air becomes trapped by a layer of warmer air above. Particulates, including dust and pollen, become trapped in this cool air mass close to the ground,  right at nose and mouth level.

Patients with asthma often have a harder time keeping under control during the fall.  This is not only the result of increased fall pollen and air pollution exposure but also because of the fall cold and flu season.  Viral upper respiratory infections are the number one cause of asthma attacks, particularly in school age children.

In sports and other competitive pursuits the saying “whatever does not kill you makes you stronger” seems appropriate and possible even comforting.  To have this applied to the topic of food allergy, particularly in children, seems anything but comforting.   Recent research aimed at understanding the complex problem of food allergy suggests that this principle may not be too far from the truth and underlies a significant paradigm shift in how we approach food allergy prevention.  The result is creating a squeeze felt by families with food allergies as well as the physicians who care for them.

Until recently, the American Academy of Pediatrics recommended that infants who were considered at increased risk of developing food allergy because of their family history should avoid peanuts during the first three years of life,  milk for the first year, egg until age two, and tree nuts and fish until three years of age. Also,  it was suggested that mothers avoid peanuts and other allergenic foods during pregnancy and breast-feeding.

Recently, however, these recommendations were withdrawn by the American Academy of Pediatrics because of a lack of current evidence supporting the assumption that delaying introduction of allergenic food helps to reduce the occurrence of food allergy and other allergic disease.  Also noted was a lack of evidence supporting dietary restrictions during pregnancy and breast feeding.  Even the World Health Organization’s strategy to prevent allergy by recommending exclusive beast-feeding for the first six months of an infants life has come into question.  Although breast feeding until four months of age is still recommended, evidence seems to suggest that prolonging breast feeding beyond 4 months of age may acutely increase the likelihood that a child will develop allergies!

So what options are available to parents and physicians to determine if a child is at risk of a serious food allergy because of a family history or other concerns and how can we prevent or reduce the likelihood of a serious food allergy from developing?

The “dual-allergen exposure hypothesis” is a new theory that may shed light on these questions .  This theory suggests that infants come into contact with small amounts of food through the skin as they explore the environment and as a result of this cutaneous contact, become sensitized.  Sensitization is the process of developing allergic antibodies to something in the environment.  These allergy causing antibodies can be detected on an allergy skin test or blood test.

Sensitization does not always lead to clinical allergy.  Why not?  Because between sensitization and allergy symptoms is a third factor:  tolerance.  Tolerance is our bodies way of reining in the inappropriate allergic response, preventing inflammation that we experience as symptoms.  We want tolerance: it’s natural and very effective, and without it, we would be at risk of reacting to many of the foods that we require for adequate nutrition.

The second part of the dual-allergen exposure hypothesis states that, although sensitization may occur through the skin, tolerance occurs through oral exposure.  In other words, eating the food helps to prevent allergies from developing.  The timing and balance of cutaneous and oral exposure determines whether a child at risk will develop adequate tolerance or else develop harmful adverse reactions because of allergy.

The dual-allergen exposure hypothesis has important implications for the use of allergy blood tests in children.  The use of blood tests to diagnose food allergy in children may in fact be causing more severe allergy problems because parents are frequently told to restrict from the diet foods that show up on a blood test (indicting sensitization but not necessarily allergy) and in the process, push the child from sensitization to true food allergy.

There is always some risk when a child is exposed to a food for the first time (as there is with taking their first step or attending their first day of school), but in spite of the risk of a few bumps along the way, early oral exposure to a food may in the end make the child stronger and less vulnerable to more serious food allergies in the future.

The following instructional videos will help you learn the proper use of asthma inhalers, a spacer, and nebulizer

How to Use the Nebulizer Machine – Demonstration

How to Use a Metered Dose Inhaler – Demonstration

How to Use a Diskus for Asthma Relief – Demonstration

How to Use the Pulmicort Flexhaler

How to Use an Inhaler with a Spacer ACP Foundation

Asthma Inhaler at 11 months old, Delaney can do it!!!

Palo Verde is one of the most common trees of the Sonoran Desert and is found throughout southern Arizona and southeastern California.  Starting in April, the Palo Verde produces a brite yellow flower that stands in contrast to it’s characteristic  green trunk and branches.  In late spring it is common to see the Palo Verde covered in yellow blossoms with a blanket of yellow at it’s base from dropped flowers.  It is this fact that makes the Palo Verde a bit of an allergy enigma.

As a general principle, plants that produce conspicuous and fragrant flowers do so to attract insects such as bees to distribute their pollen.  In addition, the pollen is typically heavy and sticky so that it sticks to the insects rather than being wasted blowing in the wind.  Wind pollenated plans on the other hand produce copious amounts of light pollen that easily catches a ride in a breeze, and often finds it’s way to the nose and eyes of allergy sufferers.   Palo Verde, although an insect pollenated tree, can cause allergy problems just because of the huge volume of flowers that fall to ground, dry, and then picked up by the wind

“If you wish to converse with me,” said Voltaire, “define your terms”.

In my practice as an allergy specialist, I find the principle of first defining terms before beginning a discussion with a patient to be key.  Particularly the term “allergy”.   “Allergy” is a very common word, frequently used in general conversation, therefore its definition should be fairly clear.  But this may not always be the case, and subtleties of variance in how we define this term can lead to significant misunderstanding.

From an immunologist’s point of view, a scientific definition of allergy could go something like this:

“Allergy is a  hypersensitivity disorder of the immune system which occurs when a person’s immune system reacts to normally harmless substances in the environment. These reactions are acquired, predictable, and rapid. Allergy is one of four forms of hypersensitivity and is formally called type I (or immediate) hypersensitivity. Allergic reactions are distinctive because of excessive activation of certain white blood cells called mast cells and basophils by a type of antibody called Immunoglobulin E (IgE). This reaction results in an inflammatory response which an range from uncomfortable to dangerous”.

In this definition there are a few key points.  Allergy is reaction to specific substances involving a class of antibodies call IgE,resulting in symptoms.

A more conventional, laymen definition of allergy might look like this:  “An allergy is a reaction of the body to something that you eat, drink, breath or come into contact with that makes you itch, sneeze, wheeze, break out in a rash, get a stomach ache, or swell up”.

There are several medical problems that clearly meet this definition of allergy but in fact, are not allergy at all.  An example of this is lactose intolerance.   This is a problem with mammalian milk (cow, goat, even human) which is caused by the lack of an enzyme which is required to digest milk sugar.    Without this enzyme to turn the big lactose sugar molecule into its much smaller and absorbable bits, drinking milk will cause uncomfortable intestinal bloating, gas, and pain.  Although this a clear reaction to a food, no antibodies are involved,  so it is not an allergy.

Another example is Celiac disease.  In  this rare condition, patients become very ill with abdominal cramping, diarrhea, and even severe weight loss when exposed to even small amounts of gluten in their diet.  This difficult condition is definitely caused by an antibody reaction to a particular food, although the antibody is IgA, not IgE, and is therefore by definition, not an allergy.

Allergy has also been defined in terms of a result on a laboratory test  as well as in terms of symptoms.  For example, if a patient has a laboratory blood test that looks for IgE antibodies to food, any positive result might be viewed as proof of a food allergy.   However,  our definition of  allergy also  requires the presence of symptoms.     When a patient shows evidence of IgE antibodies to a food on an allergy test, we use the term “sensitization”.    A blood test for food allergy may show multiple sensitivities, but unless there is a history of adverse symptoms caused by a particular food, there is no allergy.    This means that you could be “sensitized” to something without being “allergic”, but you cannot be allergic if you are not sensitized.   Essential to the diagnosis of food allergy is the presence of symptoms caused by exposure to a food and laboratory evidence (skin test or blood test) of anti-food IgE antibodies.

Sensitivity, the antibody response on a laboratory test for allergy,  is an important definition to keep in mind when we discuss other tests for food allergy, such as the IgG test.  This test is commonly used in Naturopathic  Medicine, a form of alternative medicine, that places a strong emphasis on the role of diet  and food allergy in health and well being. IgG, like IgE, is a class of antibodies produced by our immune system.  Unlike IgE, IgG’s primary job is to defend against infections such as viruses and bacteria.  When you get a flu shot you are boosting the bodies production of anti-flu virus IgG antibodies.  When the real flu tries to invade and make you sick, the anti-flu IgG antibodies are ready to squash them.    Results of these IgG tests for food allergy frequently return a long list of positive reactions, and patients, upon seeing this list, frequently ask the question, “so what am I supposed to eat if I am allergic to all these foods”.

It does seem strange that our bodies would produce antibodies to a food if there is not a problem of some kind. Why would our immune system react to a food unless it had an issue with it, even if I am not aware of a problem or what that issue is?  Naturopaths use this line of reasoning to suggest that some foods cause “hidden allergy” and can be a source of inflammation.  This inflammation could lead to a variety of chronic conditions such as fatigue, headaches, weight gain, depression, mental fogginess, and many others.  However, this assumption is often a misunderstanding.  Some experts believe that the IgG antibody response occurs to the foods we eat the most and may play a role in the proper development of tolerance.  Tolerance is a good thing. Therefore the IgG food allergy test may simply reflect the foods that we eat most commonly, rather than being harmful.  For this reason, most experts agree that the IgG test for food  allergy is unhelpful and may in fact lead to excessive and dangerous food restriction diets.

A bit of bad news if you live in Tempe, Arizona, particularly if you live in or near Warner Ranch,  and are allergic to Ash pollen.

Arizona Ash is a medium to large deciduous tree, growing to 30-50 ft and found natively in Arizona around the Mogollon Rim at an elevation of 2000-6000 ft.  In contrast to the more common varieties of desert trees, such as Mesquite and Palo Verde, that to some look more like large bushes trimmed to look like a tree, the Arizona Ash provokes memories of the kind of stately shade trees found in the Midwest or Northeast, where many migrants to Arizona grew up.

I have heard that homeowners originally buying into the equestrian homesites in Warner Ranch (between Elliot and Ray Road and east of Ahwatukee) in the 80s were strongly encouraged, if not required, to plant an Arizona Ash tree.  The result is an area filled with mature Ash Trees.  The Ash trees began to pollenate around the first of February, a bit early this year, likely because of the warm, sunny weather. When the wind blows there will beenough Ash pollen in the air to affect the surrounding areas of Tempe, Chandler, and Ahwatukee for several weeks to come.

Cough is one of the most common symptoms prompting patients to see a doctor in the United States with an estimated 30 million trips to the doctor for this problem each year. More than 40% of the patients seen in our allergy and pulmonary practice between November and February complain of cough.

Cough is classified as acute, sub acute or chronic depending on how long the symptom has been present.   Acute cough lasts for less than three weeks and is most commonly the result of an acute respiratory tract infection. Other more serious causes of acute cough include pneumonia and in our clinic in Arizona, coccidiomycosis infection or valley fever.

A cough associated with typical cold symptoms may be called bronchitis, particularly when symptoms last for more than a week. Acute bronchitis is most often caused by a viral infection although other respiratory infections besides viruses, including Mycoplasma pneumoniae, Chlamydophila pneumoniae, and Bordetella pertussis may be involved.  Although most viral infections cause symptoms lasting less than 2-3 weeks, some patients with viral or other upper respiratory tract infections will continue to cough for more than eight weeks after the acute infection.  This persistent cough may be the result of a type of airway injury.  Although the source of the infection is gone, the injury remains and takes time to heal.

Another important cause of acute cough in children in adults is pertussis (whooping cough).  Pertussis is a very contagious disease caused by the bacteria Bordetella pertussis. Before the advent of vaccinations in the 1940s, pertussis was a major cause of severe illness and death among infants and children.  Although cases of pertussis decreased by more than 99% after the introduction of pertussis vaccine, it remains a cause for concern, in part because of the incomplete protection provided by the vaccine and the increasing numbers of children that are never vaccinated.  In fact, pertussis is the only vaccine-preventable disease that is associated with increasing deaths in the United States.  In 2010, more than nine thousand cases of whooping cough were reported in California. At least ten infants died from the infection prompting the health authorities to declare a pertusis epidemic.

Pertusis infection usually begins with symptoms similar to the common cold although after several weeks, frequent and often violent coughing begins. The illness is most severe in infants and young children, particularly in those that have not been immunized. In adults, the only symptoms may be a persistent cough.

In a recent study published in The Journal of Allergy and Clinical Immunology (JACI), the risk of adults and children with asthma developing whooping cough was 1.7 times higher than those without asthma, suggesting that asthma significantly increased risk for whooping cough.

A cough lasting more than 4-6 weeks without a clear history of acute respiratory infection is considered chronic and is most likely the result of one of three conditions: asthma, rhinitis/sinusitis and gastroesophageal reflux disease.

Asthma and rhinitis/sinusitis are frequently the result of allergies and so a history of allergies or a positive allergy evaluation strengthens the likelihood that one of these conditions is behind the cough.

Gastroesophageal reflux disease (GERD) and laryngopharyngeal reflux disease (LPR) are conditions associated with the leakage of stomach contents into the esophagus.  In GERD, stomach acid refluxes into the lower esophagus causing irritation and damage.  Exposed nerves in the esophagus can cause cough as well as pain (heartburn).  In LPR, stomach contents may reach to the top of the esophagus causing direct irritation of the throat and possible sinuses.  The throat and upper airway are lined with cells that produce mucous as well as cells that have hair-like projections or cilia that sweeps the mucous to the back of the throat where it is swallowed.  Acid and protein-destroying enzymes in the refluxed stomach contents inflame and  damage the hair cells, hindering the ability to clear mucous.  The result is pooling of mucous in the back of the throat and recurrent cough to clear it.  It is estimated that 50% of patients with LPR have no other symptom of their condition other than cough and is therefore frequently missed.   GERD and LPR should be suspected if an evaluation for allergies, asthma, and sinus disease is negative and the cough fails to respond to conventional treatment.