Link Between Mysterious Illness, Rats Is Confirmed

Federal researchers confirmed Thursday that the mysterious flu-like illness that has killed 12 people in the Southwest is caused by a virus transmitted through rat droppings, but they said the virus is probably a new strain that has not been seen before.

Its detection illustrates the potential for the emergence of deadly new infectious agents, according to a report from the U.S. Centers for Disease Control and Prevention in Atlanta.

Traces of the virus, known as a hantavirus, have been found in six of nine patients tested, as well as in rodents from the affected area.

Officials said they expect more cases of the so-called Four Corners illness, also called unexplained respiratory distress syndrome, or URDS, before the outbreak is contained.

All but one case has been linked to the Four Corners area of Utah, Colorado, Arizona and New Mexico, with most occurring on the Navajo reservation. Two-thirds of the victims have been American Indians.

Eight of the deaths have occurred in New Mexico and four in Arizona. The toll from the illness rose to 12 late Wednesday with the death of a 22-year-old American Indian woman in Gallup, N.M.

She died before physicians could begin treating her with an experimental anti-viral agent called ribavirin, which had killed the virus in a similar outbreak overseas.

The number of people affected by the illness has risen to 24 with the discovery of one case in Utah and one in Colorado, the first reported in each of those states, and another case in New Mexico.

Officials said they expect more cases because the incubation period of the virus--the time between exposure and the development of symptoms--is 42 days, making it likely that other people were exposed to rodents carrying the virus before the cause of the illness was tentatively identified and announced a week ago.

Physicians said they hope to prevent further deaths by treating new victims with ribavirin. However, it is not approved for general use in the United States, and physicians must obtain permission from state health departments to administer it.

The initial symptoms of the illness include high fever, muscle aches and either headache, coughing or a reddening of the eyes. As the disease progresses, sometimes over a period of hours, breathing becomes more difficult as fluids accumulate in the lungs.

Hantaviruses are carried by rodents, which do not themselves become sick. Dust from their dried excretions is inhaled by humans, which causes the disease.

There is no evidence of person-to-person transmission of the virus, so family members and health care workers are believed to be safe.

Outbreaks of hantaviruses have been recognized in Europe and Asia since the 1930s, and thousands of United Nations troops were infected during the Korean War, officials said.

Similar outbreaks also have struck U.S. military personnel training in Korea.