A Dallas nurse who caught Ebola while treating a Liberian patient who died of the disease has received a plasma transfusion donated by a doctor who beat the virus.

Ebola has killed more than 4,000 people nearly all of them in West Africa in an outbreak the World Health Organisation has called “the most severe, acute health emergency seen in modern times.” US health officials say they are ramping up training for medical workers who deal with the infected.

Nurse Nina Pham was among about 70 staff members at Texas Health Presbyterian hospital who cared for Thomas Eric Duncan, according to medical records. They drew his blood, put tubes down his throat and wiped up his diarrhoea. They analysed his urine and wiped saliva from his lips, even after he had lost consciousness.

The 26-year-old nurse was in his room often, from the day he was placed in intensive care until the day before he died.

Nina Pham, 26, became the first person to contract the disease within the United States Photograph: AP

Pham and other health care workers wore protective gear, including gowns, gloves, masks and face shields and sometimes full-body suits when caring for Duncan, but Pham became the first person to contract the disease within the United States. Duncan died on Wednesday.

On Monday night, members of the church that Pham’s family attends held a special Mass for her in Fort Worth. The Rev Jim Khoi, of Our Lady of Fatima Church, said Pham’s mother told him the nurse had received a transfusion that could save her life.

“Her mom says that she got the blood from the gentleman, a very good guy. I don’t know his name but he’s very devoted and a very good guy from somewhere,” Khoi said.

Jeremy Blume, a spokesman for the nonprofit medical mission group Samaritan’s Purse, confirmed that the plasma donation came from Dr Kent Brantly, the first American to return to the US from Liberia to be treated for Ebola. Brantly received an experimental treatment and fought off the virus, and has donated blood for transfusions for three others, including Pham.

“He’s a doctor. That’s what he’s there to do. That’s his heart,” Blume said.

Brantly said in a recent speech that he also offered his blood for Duncan, but that their blood types didn’t match.

Khoi said Pham’s mother assured him the nurse was comfortable and “doing well”, and that the two women had been able to talk via Skype.

Pham had been monitoring her own temperature and went to the hospital on Friday night with a low fever. She was in isolation and in stable condition, health officials said.

Since she tested positive for the disease, public-health authorities have intensified their monitoring of other hospital workers who cared for Duncan.

US Centers for Disease Control and Prevention director, Dr Tom Frieden, said he would not be surprised if more fall ill because Ebola patients become more contagious as the disease progresses.

Pham’s name appears frequently throughout the hundreds of pages of medical records provided to the Associated Press by Duncan’s family. They show she was in his room on 7 October, the day before he died.

Her notes describe nurses going in and out of Duncan’s room wearing protective gear to treat him and to mop the floor with bleach.

Church members sing during evening mass at Our Lady of Fatima Catholic Church in Fort Worth, Texas. Ebola patient Nina Pham is a member at the church. Photograph: Mark Rogers/AP

She also notes how she and other nurses ensured Duncan’s “privacy and comfort”, and provided “emotional support”.

Frieden has said a breach of protocol led to the nurse’s infection, but officials are not sure what went wrong. Pham has not been able to point to any specific breach.

The CDC is monitoring all hospital workers who treated Duncan and planned to “double down” on training and outreach on how to safely treat Ebola patients, Frieden said. He could not provide a number of healthcare workers under surveillance.

Health officials have relied on a “self-monitoring” system when it comes to US healthcare workers who care for isolated Ebola patients. They expect workers to report any potential exposures to the virus and watch themselves for symptoms.

Besides the workers, health officials continue to track 48 people who were in contact with Duncan before he was admitted to the hospital and placed in isolation. They are monitoring one person the nurse was in contact with while she was in an infectious state.

None has exhibited symptoms, Frieden said.

Among the things the CDC will investigate is how the workers took off protective gear, because removing it incorrectly can lead to contamination. Investigators will also look at dialysis and intubation – the insertion of a breathing tube in a patient’s airway. Both procedures have the potential to spread the virus.

Duncan, who arrived in the US from Liberia on 20 September, first sought medical care for fever and abdominal pain on 25 September. He told a nurse he had traveled from Africa, but he was sent home. He returned on 28 September and was placed in isolation because of suspected Ebola.

Officials said there was a dog in the nurse’s apartment that has been removed to an undisclosed location for monitoring and care. They do not believe the pet shows any signs of Ebola. A dog belonging to an infected Spanish nurse was euthanised, drawing thousands of complaints.

The Ebola outbreak has hit hardest in the west African countries of Liberia, Sierra Leone and Guinea.