DALLAS — Relatives of the first person to die of Ebola in the United States, joined by the Rev. Jesse L. Jackson Sr., continued on Saturday to denounce the treatment he and his family had received from a hospital here and from Texas officials, claiming that he had been cremated without their knowledge or permission and given substandard care because he was African.

Josephus Weeks, a nephew of the Ebola victim — Thomas Eric Duncan, 42, a Liberian who died Wednesday at the Dallas hospital where he had been found to have Ebola on Sept. 30 — said his uncle had been “handled poorly, unfairly, and an injustice was done.”

Mr. Weeks spoke to reporters on Saturday in Chicago with Mr. Jackson and Mr. Duncan’s mother, Nowai Gartay. They asked why Mr. Duncan had not been taken to Nebraska Medical Center, where two Americans who contracted the disease in West Africa have been treated. And they said the Dallas hospital, Texas Health Presbyterian, had not immediately informed them that Mr. Duncan had died and had led them to believe that he was still alive.

“I feel bad about my son,” Ms. Gartay said inside a chapel at the Chicago headquarters of Mr. Jackson’s Rainbow/PUSH Coalition. “We call the hospital — they know that my son died, and they didn’t tell me. They only told me, ‘You can’t talk to your son.’ ”