From the news report:
"Every asthmatic should be tested. A common form of skin testing, sometimes called the prick-puncture test, is conducted by making a series of small pricks on the back to expose the patient to trace amounts of allergens, such as pollen, mold and dust mites.
Corbett likens it to “taking a toothpick and just poking on your back a little bit,” then waiting about 15 minutes to see if the skin reacts."
References:
Allergy testing could pinpoint what ails you