The first two patients came in around midnight, both with burning eyes and trouble seeing.
The two didn’t know each other, but emergency department staff at Aria Health-Torresdale Campus in far Northeast Philadelphia discovered that both had attended a cheerleading competition at a local high school that day.
“I said, ‘Where were you sitting?’ I thought maybe somebody sprayed something,” recalled Annahieta Kalantari, the physician in charge. Then more people arrived in the ER with red eyes, irritated eyes, tearing. A few reported shortness of breath, which led Kalantari to wonder whether she faced “a mass exposure casualty sort of thing.” She ordered the hazmat tent erected outside the ER and emergency responders alerted.
By the time Steve Alles arrived at the gym in the morning, fire, police, hazmat, emergency operations, and others had swarmed the gymnasium. Swabs for chemical powder were negative. Ditto air monitoring for radioactivity, volatile organic compounds, hazardous gases.
Alles, who led the city health department’s response, took his laptop to the ER to interview patients; about two dozen had come in during the night; half were still there.
Shortness of breath turned out to be uncommon, perhaps caused by stress. About 1,000 people had attended the Dec. 4, 2011, competition, and a quarter of them eventually had eye pain. But the Sunday event went for nine hours, with hardly anyone seeking help until late at night.
“A chemical [reaction] should be seconds to minutes. An infection would be days. The fact that it was hours, a half-day, was a head-scratcher,” Alles said.
Steve Alles, the physician who manages the city health department’s bioterrorism and public health preparedness unit, had worked on plenty of epidemiological investigations before – tracking back, through the activities of people who are ill, the sources of food poisoning or whooping cough or influenza.
Though causes often can be easily determined, sources are tougher. Foodborne illness caused by norovirus, for example, has a well-defined set of symptoms, yet locating the restaurant where a sick worker handled the produce may be impossible.
This time, the source of the red and inflamed eyes – often known as pinkeye or conjunctivitis – clearly was the cheerleading event at Father Judge High School. It was the cause that was unknown.
“Epi” investigations typically rely on responses to questionnaires that are unique to every outbreak. Based on his interviews with patients in the ER, Alles spent much of the day preparing a questionnaire to be sent through coaches of the more than 20 competing teams to everyone who had attended – mainly families of the cheerleaders, age 5 to 16, from around Northeast Philadelphia.
Meanwhile, Alles used a tool that physicians of all stripes, from oncologists to public health investigators, rely on every day: a literature search.
He went to databases that contain millions of medical journal articles, and started searching for such key phrases as eye burning and school gymnasium.
Up popped a few articles describing large numbers of people seeking treatment for burning eyes after attending events at school gymnasiums. The culprit: metal halide lamps with broken outer envelopes.
The lamps produce an electric arc that travels through mercury and metal halide gases, creating intense white light. The glass outer shells protect against harmful ultraviolet wavelengths. In gyms they occasionally get hit by errant basketballs or volleyballs, breaking the protective envelope even as the light keeps shining.
Exposure causes a temporary condition called photokeratitis. Snow blindness is a version of this, as is eye damage from looking directly at a solar eclipse, although that can be permanent.
Alles called the fire department. The bulb at Father Judge was too high to see from the ground but upon climbing a ladder the break was obvious. The bulb was replaced with a newer version that is designed to self-extinguish when broken.
Alles went ahead with his questionnaire, a 33-page document that asked families that attended the competition everything from what each person saw (flash of light?), smelled (fumes?), and ate to what they wore (mascara? glitter? tanning spray?) and where they sat and when, as well as medical symptoms they might have experienced.
Given the size of the event and the 75 percent response rate, the survey turned up a wealth of information. A total of 242 people of all ages had developed photokeratitis, half of them serious enough to seek treatment.
Those who spent at least two hours sitting in the bleachers were two-thirds more likely to report burning eyes than those who spent less time there. And people who wore eyeglasses or contacts were one-third less likely to have symptoms than those who did not.
It’s unclear how often broken metal halide bulbs cause such outbreaks. The U.S. Centers for Disease Control and Prevention recently published a case study about the Philadelphia event, coauthored by Alles, in its Morbidity and Mortality Weekly Report. The MMWR often highlights public health risks that are not well-known.
The report included a second event here two years later, in 2013, when people complaining of burning eyes sought emergency treatment after as little as 30 minutes playing basketball in the Kingsessing Recreation Center gym. It took several days to realize a broken bulb was the culprit in eye pain for 20 people that lasted from three hours to more than a week.