Just 15% of Puerto Rico currently has electricity three weeks after Hurricane Maria struck.

48 people have died, but officials expect that number to rise.

The US territory is struggling to keep its vulnerable populations alive as hospitals deal with the lack of power and low supplies of medications.

Hospitals workers told Business Insider that they are running rescue missions to bring services and medication to people trapped in their homes.

Nearly a month after Hurricane Maria barreled across Puerto Rico, 85% of the US territory remains without power.

The death toll has climbed to 48, though officials expect that number to rise once more accurate counts can be made. Some 117 people are missing.

Residents on the ground told Business Insider that in some ways, people are worse off now than they were just days after the storm hit. A lack of electricity underlies many of the island's most pressing problems, but the most dire issue is how to keep people alive.

Although 98% of the island's hospitals are reportedly open, very few of them have steady electricity. Patients at hospitals that lack generators are being referred to facilities that do have them, and doctors at those hospitals are struggling to cope with the influx.

Emergency health services are paralyzed. Many sick people are trapped in their homes with no one to call and no phone line — cellular or otherwise — to call from. Those with lifelong medical conditions are helpless to get the medications they need.

"We can't even text our neighbors to have dinner — of course we can't call 911," Maritza Stanchich, a professor of Caribbean studies at the University of Puerto Rico, told Business Insider

A doctor gives a general check-up to a child living in a shelter set up for residents left homeless by Hurricane Maria on Friday, Oct. 13. AP/Ramon Espinosa

'You can't get sick now'

In some cases, instead of seeing patients at the hospital, health workers are going door to door on what are essentially rescue missions to help people trapped in their homes.

"Yesterday alone, we saw 130 patients, sometimes climbing over fences to reach patients unable to move who are essentially trapped in their homes and are being kept alive and fed by neighbors," said a hospital worker who declined to give her name since she was not authorized to speak publicly.

Supplies of life-saving medications like oxygen and insulin are running out. Some of them have spoiled. In other cases, there simply isn't enough to go around.

Lisandra Figueroa told the New York Times that her father passed away a few days ago at age 58 after going a week without the oxygen he needed to breathe.

“A lot of people died, and are still dying. You can’t get sick now," she said.

One woman living outside San Juan, who also requested to remain anonymous, said her grandfather lives in the center of the territory and relies on dialysis to clean his blood. Powerless to get to a hospital, he hasn't had the procedure in three weeks.

"He's stuck in his house in the middle of the island because there are no roads," the woman said. "We really need a helicopter at this point."

People with diabetes and other life-threatening diseases who rely on refrigeration to keep their medications stable remain some of the most vulnerable on the island. Six days after the storm hit, Stanchich told Business Insider that during a visit to see a neighbor in the hospital, she came across a woman crying in the hallway.

"She was pleading for ice because her husband's insulin was out," Stanchich said.

Insulin, the hormone that regulates blood-sugar levels and can be taken intravenously, must be refrigerated and can be only kept at room temperature (up to 77 degrees Fahrenheit) for 28 days, according to the Independent Diabetes Trust. Even evening temperatures in Puerto Rico have exceeded that level most days since the storm.

Puerto Rico has one of the highest rates of diabetes in the US. The latest estimates suggest that roughly 16% of Puerto Ricans have diabetes, compared with about 10% of the rest of the US population.

"The problems are compounded by the fact the heat and humidity are overwhelming, even by Puerto Rican standards," Diego Ramirez-Bigott, a longtime resident of the Ocean Park neighborhood of San Juan, told Business Insider shortly after the storm hit.

Antibiotics to treat bacterial diseases, which were previously rarely used, are also suddenly in demand since contact with flood water puts people at risk of exposure to dangerous microbes like Leptospira, which can lead to kidney and liver damage and even death if left untreated.

Where is the aid?

Arden Dragoni, his wife Sindy, their children and dog sit inside what remains of their home destroyed by Hurricane Maria. AP/Ramon Espinosa

President Donald Trump has expressed frustration at the obligation to provide aid to the US territory's 3.4 million American citizens, writing on Twitter last week that “we cannot keep FEMA, the Military & the First Responders, who have been amazing (under the most difficult circumstances) in P.R. forever!”

The same day Trump issued that tweet, Energy Secretary Rick Perry referred to the island as a "country" (rather than part of the US) while answering questions about attempts to revive Puerto Rico's electrical grid.

Shortly after those statements, however, Congress passed a disaster relief package to help several states as well as the US Virgin Islands and Puerto Rico.

But many residents on the ground told Business Insider that it is seems as if no aid has arrived.

"We went somewhere today where they still hadn't seen any help," the hospital worker said. "There is a huge problem because the lack of communication has made it so that people have no idea what help is available or when FEMA is coming."

Many of the island's roads remain impassible — of 5,073 total miles of roadways, just 392 miles' worth are open, the New York Times reported. And even in areas that have received emergency supplies, many have yet to be distributed. Diana Isabel Sotomayor, who is from Puerto Rico but is currently studying at the University of Copenhagen, has been following the situation closely on social media since her family is there. About a week after the storm hit, Sotomayor told Business Insider that she had seen reports of food and water at the ports, but that it was "a matter of distribution — the roads are destroyed."

The fate of Puerto Rico's grid

A teenager left homeless by Hurricane Maria looks out the window of the shelter where he is living on Thursday, Oct. 12. It has no electricity. AP/Ramon Espinosa

At a news conference last week, Puerto Rico's governor, Ricardo Rosselló, said they aimed to restore 25% of the electrical system “within the next month.”

That still leaves thousands of people without the electricity they need to keep themselves cool in the heat, run life-preserving hospital equipment, and charge phones and other battery-powered devices. In this vacuum, Tesla has started shipping its massive Powerpack batteries to the island.

While many have been quick to point to Puerto Rico's bankrupt economy as the source of its woes, Puerto Rico isn't the only part of the US with infrastructure that's vulnerable to natural disasters.

After Hurricane Irma lashed Florida and caused power outages throughout the state, eight people trapped in a nursing home died after the facility's backup generator failed to come online to power the air conditioning. That was a failure on the part of the nursing home and the larger region to plan for a natural disaster, Vivek Shandas, an urban-planning professor at Portland State University, told Business Insider.

Still, it wasn't shocking, since most parts of the US badly need to update levees, buildings, transit hubs, and power lines, he said.

"Generally speaking, the US gets about a D+ for things like this," Shandas said. "Much of our infrastructure was built in the late 1800s, and it's beginning to fall apart."