The Liberian man battling the Ebola virus is on a ventilator and receiving kidney dialysis, while also getting an experimental antiviral drug that doctors hope will help him recover, health officials said Tuesday.

A little more than a week after being tested positive for the virus, the patient, Thomas Eric Duncan, 42, remained in critical condition Tuesday. The hospital said that Duncan would continue to receive the experimental drug brincidofovir, which is being developed by the biotechnology company Chimerix and is being tested against various viruses in clinical trials. Chimerix has announced that the Food and Drug Administration agreed to make the drug available to treat Ebola on an emergency basis.

The drug had never been tried before in people infected with Ebola, but test-tube experiments in government labs suggested the drug might be effective, the company said.

Dr. David Lakey, Texas' health commissioner, said Tuesday that the next few days could be decisive in determining whether any of the 48 people who have had contact with Duncan develop the virus. So far officials said none of the 48 have become ill. They are getting their temperatures taken twice a day.

The Rev. Jesse Jackson arrived in Dallas on Tuesday and met with pastors and other community leaders in Oak Cliff, the neighborhood where Duncan had been staying before he was hospitalized. Residents of the neighborhood say they have been stigmatized because of Duncan's illness, and have even been denied entry into stores at times.

Under quarantine in Spain

At a Madrid hospital, three more people were under quarantine Tuesday for possible Ebola after a Spanish nursing assistant became infected there, authorities said. More than 50 others were being monitored as experts pressed to figure out why Spain's anti-infection practices failed. The nursing assistant, part of a special team that cared for a Spanish priest who died of Ebola last month, was the first case contracted outside of West Africa.

The government came under heavy criticism and health care workers, who have been sparring with the government over cutbacks, said they had not received proper training or equipment to handle an Ebola case. And some opposition politicians called for the health minister, Ana Mato, to resign.

The nursing assistant's husband has shown no signs of having the disease but was hospitalized as a precaution, said Dr. Francisco Arnalich, of the Carlos III hospital.

Madrid's regional government even got a court order to euthanize and incinerate the couple's mixed-breed dog, Excalibur, against their objections, without even testing the animal. A government statement said "available scientific information" doesn't guarantee that infected dogs can't transmit the virus to humans. Some reports in medical journals suggest that dogs can be infected with Ebola without showing symptoms, but whether they can spread the disease to people is unclear.

Ebola's source in nature hasn't been pinpointed. The leading suspect is a certain type of fruit bat, but the World Health Organization lists chimpanzees, gorillas, monkeys, forest antelope and porcupines as possibly playing a role in spread of the disease. Even pigs may amplify infection because of bats on farms in Africa.

U.N. OKs $49M in fight

At the United Nations, a budget committee has approved $49 million in funding for the global body's unprecedented emergency mission to combat Ebola.

The General Assembly budget committee on Tuesday adopted a resolution supporting the U.N. secretary-general's funding request, which is expected to cover operations through the end of December.

This is the first mission the U.N. has created in response to a public health crisis.

The New York Times and Associated Press contributed to this report.