As contaminated flood waters recede in the Houston area, patients with skin infections are spilling into local hospitals and clinics, the Houston Chronicle reports.

Over the holiday weekend, doctors saw significant—but not overwhelming—upticks in soggy skin wounds and infections, as well as other ailments linked to Hurricane Harvey clean-up and recovery efforts. Those included respiratory problems, such as mold allergies and pneumonia cases, issues with drug withdrawals in those who lost access to medications during the disaster, and other injuries that include those from electrical shocks.

Dr. James McCarthy, chief of emergency medicine at Memorial Hermann Hospital’s Red Duke Trauma Institute, south of Houston’s Midtown, told the Chronicle that the natural disaster altered the very nature of holiday medicine. "Harvey changed the composition of our Labor Day weekend census from the typical overload of trauma cases from traffic accidents to a lot of soft-tissue infections," he said.

Just west of the city, doctors at Memorial Hermann Urgent Care-Tanglewood also reported a surge in cases of skin wounds and infections. In some instances, patients came in simply concerned that wounds such as scrapes, cuts, and bites would become infected after exposure to the flood waters.

They have good reason to think that. Flood waters are undoubtedly contaminated. They’re likely to contain some amount of sewage and human pathogens from flooded plumbing and sewers, as well as pesticides, oils, and potentially toxic chemicals swept up from homes, businesses, refineries, and chemical plants.

The city has begun testing the water to see what exactly is in it, but a city spokesperson told the Chronicle that the test results were not yet available. Last week, a Texas A&M research team reported that Harvey flood waters collected from Cypress, Texas—just northwest of downtown Houston—had 125 times the amount of E. coli considered safe for swimming.

With the uptick in skin infections, McCarthy said that Memorial Hermann had also sent samples to the city health department to determine if there were particularly nasty bugs floating in the flood waters. The results had not come back yet.

Most of the skin infections have been easily treated with antibiotics. But McCarthy and Dr. Beau Briese, an emergency department doctor at Houston Methodist Hospital, reported that they’ve seen a small, yet unusual, number of severe infections, including ones that developed into life-threatening sepsis cases.

Still, some doctors and medical volunteers are pleasantly surprised there have not been more medical disasters. None of the infections have turned fatal, and there have been no deaths from Harvey-caused health problems, injuries, or patient evacuations so far.

Doctors have also seen a thin silver lining to the catastrophe. “We've actually picked up a lot of chronic problems in people not accessing the medical system," Briese told the Chronicle. "It's been a nice, unexpected benefit." That includes the case of a pale woman, who responders initially thought was suffering from anemia after the storm, but instead she had a blood cancer. She’s now receiving chemotherapy.

Not everyone showing up in hospitals and care centers needs care, however. Hurricane Harvey washed up the old myth that exposure to flood waters can increase risk of contracting tetanus, a potentially lethal infection, Stat News reported. That pushed many to worry about whether they were up to date with their booster shots and spurred some to go to clinics to try to get them. But as the Centers for Disease Control and Prevention notes, “exposure to flood waters does not increase the risk of tetanus, and tetanus immunization campaigns are not needed.”