This past spring was one of the worst allergy seasons on record in Houston. The unusually long cold season delayed some trees from blooming and, consequently, led to an usually high peak in the number of trees blooming at one time. Oak pollen is especially highly allergenic. Over the last four years, the highest pollen counts ranged from 2,062 to 2,669 grains per cubic meter. This year, the oak pollen counts topped 6,000 grains per cubic meter.


CONSTANT THREAT

The Houston allergy “season” starts with tree pollen in January and extends to September because of our area’s short winters. The common tree pollen producers in Houston include cedar, elm, pine, oak, ash, hackberry, pecan and cedar elm.

The final allergy season of the year is ragweed, which starts in mid-August and extends until the cool weather sets in.


IT'S THE HUMIDITY

Thanks to the high humidity, Houstonians are exposed not only to the typical pollens and ragweed allergy seasons, but also must deal with relatively higher fungal exposure than other areas. Molds can be highly allergic and have been shown to trigger sinus and asthma disease.

The molds common to Houston include cladosporium, ascomycetes, alternaria and various dermatiaceous or pigmented fungal species. The mold counts are related to the moisture in the environment, with higher counts associated with increased rainfall. This summer’s rainstorms caused total mold counts in Houston to skyrocket to just under 10,000. For comparison, the maximum mold count in June last year was only 7,698.


UPWARD TREND

The overall prevalence of allergic rhinitis has been trending higher worldwide over the last several decades, and more so in developing countries. Allergies are more common in the developed world, including the U.S. It is estimated that one in five people suffer from allergic rhinitis in the U.S.

There remains no clear explanation for the upward trend, but a popular reasoning is the hygiene theory, which purports that limiting exposure to bacteria during early childhood can make the immune system more reactive to typically innocuous agents such as pollen or dust mites later in life. The practice of adding anti-bacterial agents to everything from wipes to hand soap has significantly reduced everyday bacterial exposure.


SYMPTOMS AND TREATMENTS

Allergic rhinitis is defined by symptoms consisting of running nose, sneezing, nasal congestion and watery eyes. Many people often complain of fatigue, difficulty thinking and overall difficulty performing at work or school during exacerbation of allergy symptoms. Allergic rhinitis is also commonly associated with respiratory ailments such as sinus infections and asthma.

Although generally difficult to accomplish, avoidance of allergens is typically recommended for the initial management of symptoms. But there are currently no studies that have demonstrated clear benefit with avoidance-only measures. Most people seek help with symptoms through medical therapy. Antihistamines are readily available without a prescription.

Antihistamines block the histamine that is released from inflammatory cells during an allergy response from its receptor. The newer generation anti-histamines are characterized by their nondrowsy benefit.

Unlike first generation antihistamines, such as diphenhydramine (Benadryl), the second generation formulations do not cross the blood-brain barrier. Antihistamines can be very effective for rhinorrhea, sneezing and itchy eyes/ears/nose and throat, but less effective in relieving nasal congestion.

To relieve the nasal congestion, intranasal steroids are often recommended concurrently with an antihistamine. Itranasal steroids allow topical delivery of steroids to the nasal mucosa. Generally, the intranasal steroids suppress the inflammatory response. Several formulations are available, but unlike the antihistamines, all require a prescription.

Other medical therapy options include topical antihistamines, leukotriene antagonist, local cromones, oral and intranasal decongestants and oral steroids, although the data supporting the benefits of these options is not completely clear.

If medical therapy has failed, immunotherapy has proven to be effective in altering the immune system. These allergy shots require a commitment by the patient and treating physician, as shots are generally given on a regular basis for three to five years.

Allergy and Asthma Care of Houston
Dr. Joseph Perez
14090 Southwest Freeway, Ste. 306, Sugar Land, 77478
281-645-6401 • Aachou.com

Vital Allergy and Asthma Center
Dr. Carlos Vital
Park Plaza Professional Building
1213 Hermann Dr., Ste. 480, Houston, 77004
713-538-1240 • Vitalallergy.com

Ear, Nose, Throat and Allergy Clinic
Dr. Harold James Wall
4140 Southwest Freeway Houston, 77027
713-621-2556

Allergy and Asthma Care of Houston
Dr. David Engler and Dr. Alnoor Malick
1200 Binz, Ste. 180, Houston, 77004
713-522-9911



AMBER LUONG, MD, PH.D., is an assistant professor with the University of Texas Medical School at Houston. She has co-authored more than 10 articles and book chapters. Her primary research interest focuses on understanding the pathophysiology of allergic fungal rhinosinusitis.