A deadly virus outbreak in Zaire apparently has spread to a second city, according to international relief workers in the central African country.

The identity of the virus has not been announced. Officially, scientists at the Centers for Disease Control and Prevention in Atlanta say they have not yet identified it.

But government officials in Sweden reported last night that they had been informed by U.S. officials that the epidemic of hemorrhagic fever was caused by a strain of the Ebola virus, which can be 90 percent fatal. At the World Health Organization headquarters in Geneva, officials who asked that they not be identified also confirmed that the CDC had identified an "Ebola-type virus" in samples sent to them.

The independent medical relief organization Doctors Without Borders announced yesterday that a team of their physicians -- all European volunteers -- had identified a second Ebola-like outbreak in the town of Musango, located between Zaire's capital, Kinshasa, and Kikwit, where the initial cases were reported.

The Ebola virus is highly communicable; it apparently spreads by direct human contact, especially through blood contact. It attacks the linings of blood vessels and capillaries, leading to severe bleeding from all orifices, and eventually death due to shock or heart attack. A classic symptom -- which the Doctors Without Borders team observed in Musango -- is uncontrolled bleeding from punctures from injections.

The organization said its team reported from Kinshasa, 250 miles west of Kikwit, that there were 30 confirmed deaths of hemorrhagic fever in the Zairean outbreak, out of a total toll of 170. The cause or causes of the other 140 deaths had not been verified, the group said.

According to WHO, the Kikwit outbreak began sometime in early February but wasn't recognized by local doctors until April 10 because the city already was plagued by a separate epidemic of bloody diarrhea.

The outbreak appears to have grown significantly after April 10, when substandard sterile techniques in the operating room of Kikwit's Catholic hospital allowed the deadly virus to spread from an infected surgical patient to medical personnel.

WHO officials reported that among those who have died of the suspected Ebola virus in Kikwit are 10 health care workers. Two of the dead were nursing nuns from the Poverelle order, based in Bergamo, Italy. Two other nuns were also reportedly infected, one of whom was transferred to Musango.

And there, according to Doctors Without Borders, at least 10 more people have contracted the disease in the hospital that received the ailing nun. The team is expected to return to the organization's headquarters in Brussels tomorrow, bringing patient blood samples from Musango for analysis.

Authorities in Zaire have had the city of Kikwit, population 600,000, under quarantine since Tuesday, and three teams of scientists from WHO and the CDC have either arrived in the country or are scheduled to leave the United States shortly. The agencies were not notified of the epidemic until Sunday.

Ebola veteran Dr. Joseph McCormick is the only scientist to have witnessed all three previous known Ebola epidemics, all in Africa. Now chief of infectious diseases at the Aga Khan University in Karachi, Pakistan, McCormick said it is impossible to know when or where Ebola will strike, because it's not known what animal or insect carries the virus. "Without knowing in what species of African animal or insect the virus lurks, it's anybody's guess when or where it will surface," he said.

"One thing I'm sure of," McCormick said, "is that sporadic isolated cases of Ebola hemorrhagic fever are occurring all the time in that part of Africa. And what is clear is that unsound hospital practices are essential to this thing developing into a full-scale epidemic."

All three previous Ebola outbreaks were associated with poor hospital hygiene, particularly reuse of syringes.

"Those dammed needles, I'm telling you, we're seeing epidemics all over the place because of them," McCormick said. He said a 1992 Nigeria outbreak of Lassa fever, a similar hemorrhagic disease, was spread by needles, and in Pakistan "we're experiencing a horrendous hepatitis C epidemic that can be traced directly to reused medical needles." According to McCormick's latest research, 30 percent of all Pakistani adults living in the Punjab region of the country are infected with once-rare Hepatitis C, a virus that causes liver failure or cancer.

"We're seeing rehearsals for something here," Dr. Jonathan Mann of the Harvard School of Public Health said in an interview. "And the rehearsal is for a really big one that won't be limited to Zaire."