Harry Figueroa, a teacher who went a week without the oxygen that helped him breathe, died here last week at 58. His body went unrefrigerated for so long that the funeral director could not embalm his badly decomposed corpse.

Miguel Bastardo Beroa’s kidneys are failing. His physicians at the intensive care unit at Doctors Hospital in Carolina are treating him for a bacterial disease that he probably caught in floodwaters contaminated with animal urine.

José L. Cruz wakes up in the middle of the night three times a week to secure a spot in line for dialysis. His treatment hours have been cut back to save fuel for the generators that power the centre.

“Because of the electricity situation, a lot of people died and are still dying,” said Mr. Figueroa’s daughter, Lisandra, 30. “You can’t get sick now.”

Hospitals are running low on medicine and high on patients as they take in the infirm from medical centres where generators failed. A hospital in Humacao had to evacuate 29 patients—including seven in the intensive care unit and a few on the operating table—to an American military medical ship off the coast of Puerto Rico when a generator broke down.

Nearly three weeks after Hurricane Maria tore through Puerto Rico, many sick people across the island remain in mortal peril. The government’s announcements each morning about the recovery effort are often upbeat, but beyond them are hidden emergencies. Seriously ill dialysis patients across Puerto Rico have seen their treatment hours reduced by 25 percent because the centres still lack a steady supply of diesel to run their generators. Less than half of Puerto Rico’s medical employees have reported to work in the weeks since the storm, federal health officials said.

There are urgent attempts to help. The federal government has sent 10 Disaster Medical Assistance Teams of civilian doctors, nurses, paramedics, and others to the island. Four mobile hospitals have been set up in hospital parking lots, and the Comfort, a medical treatment ship, is on the scene. A 44-bed hospital will soon open in badly wrecked Humacao, in the southeast.