[Public Health] Attacking Asthma

Conventional wisdom in the 1980s and ’90s equated children’s asthma symptoms primarily with allergen triggers such as dust mites, cats and dogs. But in this new century, researchers are finding that exposure to cockroach and mouse allergens is just as effective in triggering asthma attacks.

WHAT IS ASTHMA? According to the World Health Organization, asthma “is a disease characterized by recurrent attacks of breathlessness and wheezing, which vary in severity and frequency from person to person. This condition is due to inflammation of the air passages in the lungs and affects the sensitivity of the nerve endings in the airways so they become easily irritated. In an attack, the lining of the passages swells, causing the airways to narrow and reducing the flow of air in and out of the lungs.”

There is no cure for asthma, but a combination of medicine and reducing exposure to allergen triggers can help control symptoms.

STUDY FINDINGS. One researcher involved in ongoing asthma studies is Dr. Ginger Chew, an assistant professor of environmental health sciences at the Mailman School of Public Health of Columbia University in New York City.

She cites a study conducted in 2005 with children from a major East Coast city’s inner-city community. All the children had asthma, and underwent allergen skin testing. In this procedure, the arm is pricked with multiple needles containing allergens from various sources, including dust mites, cats, dogs and tree pollen, as well as cockroach and mouse allergens. The arm is observed to see which allergens produce welts and the severity of those welts. Results were conclusive: The cockroach allergen was a huge trigger, even more so than dust mites, cats or dogs.

“That made me a firm believer,” said Chew, “that if children with asthma have cockroaches in their environment, PCOs need to eradicate them.” She warns, however, that PCOs need to be careful in their choice of treatment, because some pesticides also can exacerbate asthma symptoms.

One of the first allergy intervention studies was conducted in 1999 with the participation of 38 families. However, only 11 families engaged in pre-study allergen eradication steps, and overall, “the study did not have good participation or buy-in from the families,” Chew said. Level readings of cockroach allergen were determined at two, six and 12 months from the onset of the study. The level had decreased, “but it didn’t decrease enough to be lower than the thresholds that would trigger children’s asthma symptoms,” she added.

A second attempt focused on measuring particulate matter, trying to decrease cockroach allergen through intervention. Again, no significant decrease in cockroach allergen was detected. However, an improvement in the children’s symptoms was determined. With this study, the findings showed that $492, the amount spent on allergen intervention per home, was needed to decrease symptoms (an amount far cheaper than an ER visit after an asthma attack).

Another study, conducted by North Carolina State University, found that more participants dropped out of their study as time progressed. Many cited the intrusion and bother of the researchers coming into the home, asking questions and taking samples. So the researchers fine-tuned their study, only going into the home and applying pesticides. More families remained in the study. “This can be good for future studies,” Chew said.

MORE PERSONALIZED STUDIES. An article appearing in a 2004 issue of the New England Journal of Medicine dealt with an inner-city asthma study. Prior to the study, children were tested to determine their allergies, and each child received personalized allergen avoidance techniques. Cost ranged from $750 to $1,000 per child, and allergy symptoms decreased for up to one year.

Each of these studies focused on the child’s home, ranging from single-home dwellings to multi-use buildings (i.e., restaurants or shops on bottom floors, with apartments above) to high-rise apartment buildings. One interesting fact about mouse allergen emerged: the higher the story, the less exposure to mouse allergen. “Mice will climb a few stories, but they really don’t like living up high,” Chew said.

She wanted to get a reading on exposure in the other prominent area in children’s lives: their schools. After obtaining permission from the New York City Board of Education, she conducted a study on mouse and cockroach allergen exposure. Focusing on 11 schools, her goal was to determine the proportion of allergen exposure from home and school. Interestingly, the level of mouse allergen in nine of the 11 schools was greater than the threshold for developing mouse allergies. The cockroach allergen in most of the schools, however, was below the sensitization threshold level.

STUDY METHODOLOGIES. Currently, Chew said, epidemiologists are conducting studies on a shoestring budget. Three main areas are used: questionnaires, dust sampling and air sampling. Families are asked if they’ve seen mice or cockroaches in their homes and they’re questioned about children’s asthma symptoms.

“We’re trying to standardize dust sampling as much as possible,” Chew said. Now they demarcate certain areas to vacuum, including mattresses, floors, chairs and sofas. The dust sampling can measure cumulative effects of the allergen exposure.

Air sampling, on the other hand, measures short-term exposure. The smaller the particle size, the deeper the particle can lodge in the respiratory system. This is particularly true with cat allergen. Cockroach allergen, however, has larger particle size, and settles out of the air quickly. With the current technology for air sampling, it’s difficult to get a true reading on allergen exposure.

Chew said researchers are working on better methods for air sampling. One involves an in-nose filter that would more closely determine what is being inhaled.

NEXT STEPS. PCOs can play a large role in helping control allergy triggers by using Integrated Pest Management procedures in homes and schools. By decreasing cockroach and mouse allergen exposure, children with asthma can breathe easier.

The author is a frequent contributor to PCT magazine.

Startling Statistics

What’s all the fuss about asthma anyway? According to the American Academy of Allergy Asthma & Immunology Web site, here are the facts:

• Asthma and allergies strike one out of four Americans.
• Nine million U.S. children under 18 have been diagnosed with asthma.
• More than 70 percent of people with asthma also suffer from allergies.
• Asthma rates in children under the age of five increased more than 160 percent from 1980 to 1994.
• Asthma accounts for one-quarter of all emergency room visits in the U.S. each year, and two million emergency room visits in 2001.
• Children five to 17 years of age missed 14.7 million school days due to asthma in 2002.
• Every day in America, 40,000 people miss school or work, 30,000 people have an asthma attack, 5,000 people visit the emergency room, 1,000 people are admitted to the hospital and 11 people die due to asthma.