The mayor of Canóvanas, in the northeast part of the island, reported over the weekend that several people in her city had died of leptospirosis, the bacterial disease Mr. Bastardo is believed to have caught from the floodwaters. The Puerto Rico Department of Health said Sunday night that several cases were being evaluated, but that lab tests had not yet come back to confirm the diagnosis. At the same time, the agency urged people to drink only bottled water and to wear protective shoes near bodies of water that could be contaminated with animal urine.

Carmen C. Deseda, the Puerto Rico state epidemiologist, said that six people were being treated for leptospirosis, even though test results to confirm the diagnosis would not be complete for another week or two. Puerto Rico usually sees a few dozen cases a year and perhaps one death, but officials are expecting an increase because of the flooding.

Forty percent of the island still lacks running water because of the blackout, which still affects 85 percent of the island. As a result, many people are bathing in streams and receiving nonpotable water from huge tanks.

Yarelis Rosa, 37, said her husband, Mr. Bastardo, was infected because he had cut his hand a few days before the storm and it had not fully healed when he spent hours in the floodwaters trying to escape his home in Canovanas. A few days later, Mr. Bastardo’s head, feet and knees hurt and his temperature soared to 106 degrees. She took him to the hospital more than a dozen times, she said.

“I.V., injection, go home. I.V., injection, go home. I.V., injection, go home,” Ms. Rosa said, describing the revolving door of medical treatment.