Close, sustained contact.<\/p>\n
That, health officials have repeatedly said, is the only way that the Andes hantavirus, which caused an outbreak on a cruise ship and has gripped the world\u2019s attention, spreads among people.<\/p>\n
\u201cYou have to be in close contact with someone who has a lot of symptoms,\u201d Dr. Jay Bhattacharya, acting director of the Centers for Disease Control and Prevention, said in an interview<\/a> on Fox News.<\/p>\n But scientists who have studied hantaviruses for decades are far less certain about how the virus might behave.<\/p>\n They agree with health officials that the Andes virus is not particularly contagious and is unlikely to spur a bigger outbreak. But they said research has shown that under certain circumstances, the virus can be transmitted without direct contact.<\/p>\n \u201cIt\u2019s important to be honest scientifically and communicate that, because otherwise you lose credibility,\u201d said Steven Bradfute, a viral immunologist and hantavirus expert at the University of New Mexico.<\/p>\n In an interview, Dr. Tedros Ghebreyesus, director general of the World Health Organization, acknowledged that officials have emphasized close contact as the way the virus spreads to avoid panicking people over rarer possibilities.<\/p>\n \u201cIt\u2019s very difficult to explain to people saying, \u2018OK, this is the exception, this is the norm,\u2019\u201d he said. \u201cWhen you say the exception, they might still think that that\u2019s something frequently happening as well.\u201d<\/p>\n The hantavirus outbreak that began on the Dutch cruise ship MV Hondius last month has thus far sickened at least nine people and killed three. Many of the roughly 150 passengers, including 18 in the United States, are being closely monitored in quarantine. The remaining were given a set of instructions<\/a> to avoid spreading the virus to others including: take your temperature daily, don\u2019t fly commercial and try to use your own bathroom.<\/p>\n On CNN\u2019s State of the Union on Sunday, Dr. Bhattacharya could not recall when some passengers who disembarked on April 24 in St. Helena, an island in the Atlantic Ocean, had arrived on American soil. None had symptoms at the time of their travel, he said, so officials had not seen a need to alert the public or trace contacts.<\/p>\n \u201cThe virus doesn\u2019t spread unless somebody has active symptoms,\u201d he said.<\/p>\n That, too, is not certain, although some scientists believe people may be most contagious just as they are developing symptoms.<\/p>\n Some labs have studied hantaviruses for decades, but there is still much that\u2019s not known about them because they grow slowly and are difficult to analyze genetically.<\/p>\n Hantaviruses are naturally found in rodents. The Andes virus, found primarily in Argentina, where the cruise ship began its journey, is the only hantavirus species known to spread among people. But scientists were slow to acknowledge that possibility.<\/p>\n \u201cIt was very difficult to convince people of that, even here in Argentina,\u201d said Valeria Martinez, a virologist at the National Institute of Infectious Diseases in Buenos Aires.<\/p>\n