Public health conditions are rapidly deteriorating across Puerto Rico as government agencies struggle to restore basic services such as power and clean drinking water and deliver emergency supplies two weeks after Hurricane Maria ravaged the U.S. territory. The situation is dire across much of the island but even more so for its most vulnerable, low-income minority communities.

Only about half the territory's residents had access to potable drinking water, and electricity had been restored to just 5 percent of Puerto Rico as of Tuesday, when President Donald Trump visited the capital, San Juan, according to the Federal Emergency Management Agency.

"The sense of desperation is only growing with every passing day," said Chris Skopec, executive vice president for global health and emergency response with Project HOPE, a Millwood, Virginia-based nonprofit now working in Puerto Rico. "In these kinds of conditions, the ability for an epidemic to spread is really ripe."

In Caño Martín Peña, a densely populated community of mostly wooden homes originally built by impoverished squatters in a flood zone in the heart of San Juan, existing public health issues were exacerbated by the storm.

The community is plagued by untreated sewage that flows into the adjacent Martín Peña Channel. Before Hurricanes Irma and Maria, even moderate rainstorms would cause the debris-clogged channel to overflow, sending raw sewage into basements and causing skin rashes and asthma. Outbreaks of mosquito-borne diseases dengue and Zika are common in the community of 23,000, where 25 percent of adults are unemployed and the median household income is $13,500, according to 2010 U.S. Census data.

"People are drinking whatever comes from the faucet, and it's turbid," said Lyvia Rodríguez del Valle, executive director of the Caño Martín Peña Land Trust Project Corporation, a public-private partnership working with the community. "People lost their roofs. They cannot close their doors, so we are having issues with mosquito bites and other insects, we are having plagues like rats and everything else."

In La Perla, a historically impoverished neighborhood of San Juan, the hurricane damaged homes and power lines and scattered debris in the streets. Credit: Alex Wroblewski/Getty Images

Volunteers from outside aid organizations have helped clear trees and other debris from the streets, but the government response is just starting, Rodríguez del Valle said. Government officials provided an initial delivery of 60 blue tarps on Sunday to the community where 800 families lost their roofs. City garbage trucks began removing debris piles the same day.

"We have barely seen the government here," Rodríguez del Valle said.

More than 12,300 federal staff representing 36 departments and agencies are now on the ground in Puerto Rico and the U.S. Virgin Islands engaged in response and recovery operations, according to FEMA.

'We Could See Significant Epidemics'

Rodríguez del Valle said the mosquito bites that have been reported in Caño Martín Peña in recent days suggest diseases like dengue, Zika or chikungunya, which take several days or longer to surface after the initial bites, are on their way.

Health experts say mosquito- and water-borne diseases present a serious concern for all of Puerto Rico.

"Unless there is massive intervention to implement some type of health infrastructure, we could see significant epidemics in the coming weeks," said Peter Hotez, dean of the National School of Tropical Medicine at Baylor College of Medicine in Houston.

"I'm concerned about typhoid, paratyphoid and shigella [bacterial diseases that can spread through non-potable water] on the diarrheal side and the vector-borne diseases, especially dengue, because we have dengue in Puerto Rico every year anyway," Hotez said.

Jose Acevedo crosses a river on foot after the bridge near Morovis, Puerto Rico, was washed away after Hurricane Maria made landfall on September 27. Credit: Joe Raedle/Getty Images

Twenty miles east of San Juan in Loiza, a coastal community where 65 percent of residents are black and and nearly half of residents live below the poverty level, there are already reports of diarrheal diseases.

"We are seeing increasing rates of gastrointestinal disease as there are increasing reports of people drinking river water, and otherwise unable to access clean water," Skopec, of Project HOPE, said. "It's a very bad situation and the outlook is that it's going to continue to get worse before it gets better."

Skopec, whose organization is operating a mobile clinic and conducting home visits in the town, said the exact cause of the disease is not known.

On Radio, Hospitals Beg for Fuel for Generators

South of San Juan in Salinas, a low-income community largely of African descent on the Caribbean Coast, community leaders say they have received little outside assistance.

"The hospitals are on the radio asking for diesel and fuel to run their generators," said Ruth Santiago, an environmental lawyer for Comité Diálogo Ambiental, Inc. (Environmental Dialogue) in Salinas. "Elder centers, they are asking families to pick up their relatives."

A doctor from a First Medical Relief team conducts health check-ups in an assisted-living center. The team said residents needed water, and many were hungry and needed medication, which has been difficult to get. Credit: Joe Raedle/Getty Images

In an address in Puerto Rico on Tuesday, President Trump praised his administration's response to the storm and compared Hurricane Maria, where the early reported death toll from the hurricane was 16 people, to what he called a "real catastrophe like Katrina" where thousands died.

The governor of Puerto Rico raised the official death count to 34 after Trump left, but that, too, is likely low. Puerto Rico's Center for Investigative Journalism reported that morgues are at capacity, the official system for registering deaths is barely functioning, and the number could rise into the hundreds due to the territory's damaged health care infrastructure.

Leaving Home Behind: 'You Try to Be Strong'

Santiago has driven back and forth to San Juan four times in the past two weeks since Maria made landfall, but she said she is only starting to see military and other supply vehicles on the roads in recent days.

"I don't know why were are not getting the kinds of things that are basic necessities 13 days out from Hurricane Maria," Santiago said. "I know many people who are getting airline tickets and they are just leaving."

Irma Maldanado stands in what remains of her home. Her father has emphysema and uses an oxygen machine, but they had no way of getting medical supplies after Hurricane Maria struck. Credit: Joe Raedle/Getty Images

Airlines are now offering reduced airfares for those seeking to leave the island, though commercial flights remain limited after Maria severely damaged radar equipment at the main airport, in San Juan.

Cruise ship company Royal Caribbean International offered free passage to thousands of evacuees from Puerto Rico and the U.S. Virgin Islands aboard a ship that arrived in Fort Lauderdale on Tuesday.

For those who evacuate the region and those who remain, many will have to cope with mental health issues related to the storm.

People waited in long lines at San Juan's main airport for seats aboard the limited number of flights off the island. Credit: Hector Retamal/AFP/Getty Images

Marcella Chiapperino lost her home and business in Frederiksted, St. Croix, in the U.S. Virgin Islands, to Hurricane Maria after both had been battered by Hurricane Irma two weeks before. Chiapperino said she had her first real night of sleep after boarding the Royal Caribbean ship last Thursday but was still haunted by nightmares. "I was woken up by a dream of this wave coming and wind and pulling me outside the window," she said. "It just sucked me out."

"You try to be strong," she said, "but I think a lot of people will have some kind of post traumatic experience from this."