It's hard to imagine a more common stressor for new parents than the recurring riddle: Why is the baby crying? Did she just rub her eyes—tired? Is he licking his lips—hungry? The list of possible culprits and vague signs, made hazier by brutal sleep deprivation, can sometimes feel endless. But for one family in New England, the list seemed to be swiftly coming to an end as their baby continued to slip away from them.

According to a detailed case report published today in the New England Journal of Medicine, it all started when the parents of an otherwise healthy 8-week-old boy noticed that he started crying more and was more irritable. This was about a week before he would end up in the pediatric intensive care unit (PICU) of the Massachusetts General Hospital.

His grandmother, who primarily cared for him, noticed that he seemed to cry more vigorously when the right side of his abdomen was touched. The family took him to his pediatrician, who could find nothing wrong upon examination. Perhaps it was just gas, the pediatrician concluded—a common conclusion.

Rapid decline

But when the baby got home from the doctor's office, he had another crying session that lasted hours, which only stopped when he fell asleep. When he woke, he cried for eight hours straight. He became weaker; he had trouble nursing. That night, he was inconsolable. He had frantic arm and leg movements and could not sleep. He could no longer nurse, and his mother expressed milk directly into his mouth. They called the pediatrician back, who directed them to take him to the emergency room

There, he continued to cry, weakly and inconsolably. Doctors ordered a series of tests—and most were normal. His blood tests looked good. He tested negative for common respiratory infections. His urinalysis looked fine, and he passed his kidney function test. X-rays of his chest and abdomen looked normal, ultrasound of his abdomen also found nothing. Doctors noted he had high blood pressure, a fast heart rate, and that he hadn't pooped in two days. Throughout all of the testing, he didn't "attain a calm awake state," the doctors noted. They admitted him to the hospital.

Four hours after he first arrived at the emergency department, he began to show signs of lethargy. Meanwhile, magnetic resonance imaging of his head found nothing. A lumbar puncture showed possible signs of meningitis—high red-cell count and protein levels—and doctors began courses of antibiotics in case that was the cause.

Six hours after his arrival, he began losing the ability to breathe. His oxygen saturation had fallen from an initial 97 percent to an alarming 85 percent. He was put on oxygen and transferred to the PICU. There, doctors noted he was difficult to arouse, his head bobbed, his eyelids drooped, and he struggled to take in air. His cry was weak, and he made gurgling and grunting noises. He barely moved his limbs and couldn't lift them against gravity. His muscles went floppy. Doctors decided to intubate him and start mechanical ventilation.