By Marilynn Marchione Milwaukee Journal Sentinel (KRT) MILWAUKEE, Wis. _ A new, previously unidentified germ is likely to be what’s causing a growing international outbreak of severe pneumonia, health officials said Monday. If so, it would be the first novel germ since hantavirus in 1993, the Nipah virus that killed pig farmers in Malaysia in 1998 and 1999, and the bacteria that cause Legionnaire’s disease in 1976. Officials think it’s more likely to be a virus than bacteria but have ruled nothing out. It behaves like severe influenza, but experts have not detected any signs of that well-studied virus in samples so far, said Julie Gerberding, director of the Centers for Disease Control and Prevention. If it were a common or known germ, “we would have found it by now,” she said. Gerberding said the pattern doesn’t fit bioterrorism, and that no cases as yet have been confirmed in this country. “It will not be surprising to us if we identify cases in the U.S.,” she added. So far, 167 cases and four deaths have been confirmed in the last few weeks of what officials are calling Severe Acute Respiratory Syndrome, or SARS. Most have been in Hong Kong, Vietnam and Singapore, though Chinese officials said 300 cases starting last November may have been the mystery illness. The World Health Organization has termed it a global health threat and warned against traveling to parts of Asia. Officials said they think the germ is spread by close contact and droplets from respiratory secretions of infected people, but not through casual contact. There were these developments Monday: _The State Department and other high-ranking government officials have been involved in helping control the outbreak, said U.S. Health and Human Services Secretary Tommy G. Thompson. Chinese officials agreed Monday to allow health officials into the country to investigate the situation, and the CDC and WHO hope to have an international team there by the end of this week. _Four potential cases were being investigated in the U.S. but officials said they were unlikely to turn out to be SARS. Ten others have largely been ruled out. New cases were being investigated in Canada, England, France, Israel, Slovenia and Australia. _Officials strengthened recommendations to postpone travel to Hong Kong, parts of China and Vietnam. Travelers returning to the U.S. on direct flights from Hong Kong to airports in Chicago, Los Angeles, New York City, Newark, N.J., and San Francisco were being greeted by quarantine officials and given cards warning that they may have been exposed to the germ and should see a doctor if they develop symptoms. _The CDC activated its emergency response center to manage the outbreak and sent 12 staffers to other countries to investigate. Gerberding said people shouldn’t panic because the illness doesn’t appear to be spread through casual contact, and seems to take very close contact with an infected patient or body fluids. She also said officials are always vigilant for the emergence of a killer flu strain like one that caused the 1918 pandemic that killed more than 20 million people. This germ behaves a lot like flu and started in crowded conditions in Asia where new flu strains invariably originate. But scientists in Hong Kong have long been experts at identifying such novel flu strains. “The fact they haven’t been able to diagnose influenza in a patient (with SARS) is a strong argument against that” as a cause, Gerberding said. Two things make SARS highly unusual, Gerberding said. One is that so many health care workers have become infected from patients, more than what typically happens with infectious diseases. Second is the rapid development of pneumonia and severity of it. The incubation period seems to be two to seven days, and illness starts with a sudden high fever that quickly leads to cough, shortness of breath and pneumonia. Many victims have needed breathing machines and those who have died succumbed to respiratory failure. ___ (Reid J. Epstein Milwaukee contributed to this report.) ___ ‘copy 2003, Milwaukee Journal Sentinel. Visit JSOnline, the Journal Sentinel’s World Wide Web site, at http://www.jsonline.com/ Distributed by Knight Ridder/Tribune Information Services.