The Philadelphia area has been identified as a hot spot for a lung disease that resembles tuberculosis. It strikes a very specific group of people, and local doctors are trying to figure out why.
Rebecca Kwait carries a tote bag full of tools as she buzzes into an elegant apartment building on the Main Line.
Kwait, a registered nurse, and Lankenau Medical Center pulmonologist Dr. Leah Lande arrive at an upstairs apartment and are greeted by Betty, an 84-year old patient suffering from a respiratory infection.
"Not quite a year ago I came to [Dr. Lande]," Betty said. "I had a cold really, and the cold just lingered on."
Betty had a nagging cough that brought up mucous and wouldn't go away, and she was tired all the time.
"I don't feel like doing things," said Betty, whom Dr. Lande asked to be identified by first name only due to the stigma attached to patients with TB-like diseases.
On this visit, Lande and Kwait aren't at Betty's apartment to treat her. They are trying to track down the cause of her illness.
Betty's lung infection is caused by a group of bacteria called Mycobacterium avium complex, or MAC. The infection is particularly puzzling because of whom it typically strikes: otherwise healthy, post-menopausal, thin, white women. They're often tall and often of higher-than-average socioeconomic status.
Dr. Leah Lande said the bacteria is common in soil and water, so it's a mystery why only certain people come down with MAC.
"Why are these women that are otherwise healthy doing everything right, living very healthy lifestyles, coming down with this chronic respiratory infection?" Lande said.
Philadelphia area a hot-spot for MAC infection
An NIH-funded study this fall confirmed what local doctors have long thought: that the greater Philadelphia area is a hot spot for MAC diagnoses. It's not clear if that is just because doctors such as Lande are more familiar with the diagnosis, or if there really are more infections here. Lande, for one, thinks the infection is on the rise nationwide.
Locally, researchers at Lankenau Medical Center are looking at whether hormone levels in post-menopausal women might play a role in susceptibility to MAC. Others across the country have looked at links between the infection and genetic mutations. Right now, Lande is focusing on where in the home infections are coming from, so women can try to prevent recurrence or take preventive measures.
Medical detectives making house calls
That's why, shortly after greeting Betty in her apartment, nurse Rebecca Kwait headed straight for her bathroom.
The registered nurse dragged a step stool into the shower and pulled out a big pair of pliers. She struggled with the shower head for a moment, then removed it, using a test tube to capture some of the water that had been stored up there since the last shower.
"And so now we have access to the actual pipe that comes out of the wall, and I can take my Q-tip and swab up in there," Kwait said.
Kwait will send the water sample she collects to a lab see if it contains MAC bacteria.
"If it does then we look at the DNA of that MAC and see if it matches the DNA of the actual patients specimen," Kwait said.
If there is a match, Kwait will know where in her house Betty acquired the infection.
So far, Kwait has taken samples from air conditioners, heaters, sinks, showers, and hot water heaters in 37 houses, concentrated in the Main Line.
"I'm thinking of going back to be a plumber," she jokes.
Results are back for 28 homes. MAC bacteria were found in 20 of them, and 12 of those samples were DNA matches for the strain in the patient.
The infection is very rarely fatal, but it does significantly impact quality of life.
"Just yesterday I had a patient in the office who specifically said to me, you know I get up, I make dinner, and then I just want to lie right back down on the couch again, just the process of making dinner exhausts me," Lande said.
What's more, recurrence rates are high, even after the typical 18-month course of three antibiotics.
"These are people that are doing everything right," Lande said. "They're generally very healthy women that are trying their best to have a healthy lifestyle, and are sort of mysteriously coming down with this infection with an increasing incidence, so we feel it's important to try to get to the bottom of this."
Lande is quick to stress that even women who perfectly fit the MAC profile still have a low risk of infection. Her hospital still diagnoses only about 80 patients a year with the disease.