Invasive Strep A is sneaky, its virulence due in part to antigens on its cell surface that are so similar to human heart, bone and muscle tissues that they serve as a disguise; the bacteria appear familiar and safe, catching the immune system off guard.

Some scientists theorize, too, that certain people have immunological markers that predispose them to bad outcomes. In addition, strep specialists think it's likely that the immune system itself may cause harm by overreacting. One infectious disease specialist says it's like turning on a sprinkler system in an art museum to counteract cigar smoke: a major, destructive offensive against a nonthreat.

The Utah Health Department started tracking invasive Group A Strep only a year ago — too soon to figure out whether public health or private citizens can do anything to avoid it, says Susan Mottice, a state epidemiologist. They have not yet found predictability in what feels too much like brutal random chance. There were 70 reported cases of invasive Strep A last year; officials are certain that's an undercount. It's an unsettling fact, experts say, that the number of invasive cases is increasing.

It's unclear how Lisa's strep began, but impossible not to wonder. Had she tripped on something and discounted the ensuing bruise as nothing? Did she pick it up at work? Did it sneak in through the C-section site? Many local physicians familiar with her case declined to discuss it because of potential litigation. Hospital risk management teams counseled even those doctors not involved with Lisa's care not to discuss strep for this article.

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In the burn unit, surgeons sliced out dead tissue on her mottled limbs, hoping to save as much leg as they could and at least part of her right hand. A day after that they removed her legs below the knees. When the tissue continued to die, they went in again, and then again, each time taking off more, until the legs ended just inches below her hips. Two days after they amputated her legs, they cut off her right arm, leaving a stump midway from elbow to shoulder.

The tally of limbs and organs strep claimed had effectively reduced one-third of her body, and Steve wondered how much more she could take. Unspoken was "Would she want this? How much can someone lose and still want to live?"

As the strep took its toll, LDS emergency room nurses Lorie Hutchison and Anne Marie Bickmore set up a "Lisa Speckman Update" on Bickmore's voicemail. Hutchison would call the hospital each morning, then try to figure out how to phrase the increasingly grim news. "How do you tell people, 'They're cutting off her legs?' " remembers Hutchison, who would write her message, practice it out loud, then rewrite the words to soften the brittle edges, trying to find the right balance of truth and hope.