Fear of Disease Sweeps Navajo Land : Epidemic: Hundreds swamp health facilities, worried they have mystery illness that has killed 12. Officials report four new cases and press search for the cause.

As hundreds of patients fearing that they have an unexplained flu-like illness swamped health facilities throughout northwestern New Mexico, federal and state researchers stepped up their efforts Tuesday to pinpoint what they believe may be a new virus.

Scientists are scrutinizing tissue and blood samples from victims of the mysterious ailment, dubbed unknown respiratory distress syndrome or URDS. So far, they remain stumped.

“We really are talking about a new agent or an unusual presentation of a known agent,” said Dr. Gary Simpson, head of the infectious diseases division of the New Mexico Department of Health.

Researchers at the University of New Mexico and the state Department of Health are culturing blood samples from victims to try to induce a hidden bacteria or virus to grow, but so far without success. Using genetic probes and specially prepared antibodies that bind to pathogenic organisms, they have eliminated most of the common bacterial, fungal and viral causes of disease, including pneumonic plague, HIV and legionella, the cause of Legionnaires’ disease, which killed 34 people between 1976 and 1977.

Tissue and blood samples have been shipped to the U.S. Centers for Disease Control and Prevention in Atlanta, where the same tests, and others that are more sophisticated, are being performed. Tissue samples and blood also are being injected into laboratory animals in an attempt to determine whether the disease is transmissible.

Physicians have identified only four possible new cases in the last day, authorities said Tuesday. A woman with some symptoms of the disease was flown to University Hospital in Albuquerque on Monday night, but physicians there were not sure whether she has the disease. Even less information is available about the other three potential cases.

Authorities have found another death caused by the disease, that of a 34-year-old man who died in April. The discovery raises the number of URDS deaths to 12 and the number of confirmed cases to 19. Eight of the dead are American Indians, three are Anglos and one is Latino.

There are another 12 cases for which the state does not have enough evidence to make a diagnosis of URDS. All but one of the cases have been linked to the 24,000-square-mile Navajo Reservation that straddles the corners of Arizona, New Mexico, Utah and Colorado.

Health department officials also said they have been notified of two other cases that meet their criteria for URDS, one in Utah, the other in Kansas. The Kansas woman is in critical condition at a major medical center, said New Mexico state epidemiologist Dr. C. Mack Sewell. A third potential case has been reported in North Carolina, but Sewell said that patient does not meet the criteria for URDS.

Dr. Ronald Voorhees, deputy epidemiologist for New Mexico, cautioned that a certain number of cases of respiratory distress syndrome of unknown origin occur each year “and those cases may not be linked to ours.”

Although researchers have ruled out a number of common infectious agents as the cause of the disease, they are still at a loss to explain its origin. But they suspect it is the result of infection by an unusual virus.

The new syndrome begins with fever, muscle aches and either cough, headache or conjunctivitis (reddening of the eyes). As the condition becomes more severe, fluid collects in the lungs, literally suffocating the patients. It is this so-called interstitial edema that is the defining characteristic of URDS now. Victims have ranged in age from 13 to 34.

Treatment consists of forced ventilation of the lungs and the administering of antibiotics, including tetracycline, erythromycin and chloramphenicol. “But there is no evidence that antibiotics have altered the course of the disease,” Simpson said, and the 12 victims who died received similar treatment.

The epidemic of URDS has touched off a mammoth search for the cause. Last week, epidemiologists fanned out to interview victims and their families, asking questions about the victims’ travel, foods, pesticide use, drug use, exposure to animals and a variety of other factors that may indicate a common source for the disease.

No common links have turned up, however, and researchers are revising their questionnaires to add questions that will be asked on return visits later this week. That questioning is being conducted primarily by local health care officials because of a Navajo cultural reluctance to talk about death and serious illness.

“They don’t like to talk about it,” said Ron Wood of the Indian Health Service, “but if the situation is serious enough, they will.”

Because most of the laboratory tests have been unsuccessful so far, researchers are pinning their hopes on an analytical technique called polymerase chain reaction. It can be used to produce large quantities of any DNA--deoxyribonucleic acid, the genetic blueprint of life--left behind in trace quantities by an infectious agent.

The CDC hopes to have some results from the analysis by the end of the week, but researchers caution that identification of a causative agent may take weeks or even months. Isolation of legionella took four months, they said, but that epidemic occurred before the development of polymerase chain reaction and other tools of genetic engineering.

Data from DNA probes and immunological studies is not expected to be available until the beginning of next week, Simpson said, and information from cultures another week to 10 days after that.

On Tuesday, researchers at the Armed Forces Institute of Pathology suggested that the epidemic might be caused by a virus-like bacterium called Mycoplasma fermentans . That agent has been linked to similar sudden deaths in U.S. military personnel around the world, a 1986-87 outbreak in Ottawa and several other cases since then, said molecular biologist Shyh-Ching Lo of the Institute of Pathology.

Simpson said Tuesday that local tests have shown no evidence of mycoplasma infection and that reports from previous Mycoplasma fermentans outbreaks are largely inconsistent with the characteristics of the current disease. Nonetheless, blood and tissue samples have been forwarded from CDC to Lo for testing.

Sewell also said media reports that two health care workers and a pathologist had developed the disease are incorrect. Two workers on the team have developed colds, but they have been closely monitored and are at home or back to work. He noted that the search for URDS patients is complicated by an outbreak of influenza A that is affecting the region.