Hot zone. Researchers are seeking DNA data on hantavirus in El Bolsón, Argentina.

Human-to-Human Spread of Argentine Hantavirus?

Researchers in Argentina may have found the first known cases of person-to-person transmission of hantavirus, an often lethal infectious agent normally transmitted only by rodents. The cases are part of an outbreak since September in and near the Andes mountain town of El Bolsón, where a score of people have been infected with hantavirus, of which half have died. The lung failure triggered by the virus was identified as a major health threat in 1992 after it caused a spate of deaths in the U.S. Southwest.

Argentine authorities have tracked "several cases that are incredibly hard to explain except by person-to-person spread," says hantavirus expert Brian Hjelle of the University of New Mexico, who recently visited the outbreak area. The most striking involves a 13-year-old girl who had not been near the disease area but may have picked up the virus after joining her parents, both of whom had been infected in El Bolsón. Researchers at the Carlos G. Malbran Institute in Buenos Aires, the country's major center for infectious-disease research, have published in Medicina, an Argentine journal, additional data suggesting that the virus may have been passed from person to person.

As disturbing as the reports are, researchers have no biological evidence of human-to-human spread. To get a better handle on this, Hjelle and C. J. Peters--chief of the special pathogens branch at the U.S. Centers for Disease Control and Prevention (CDC), who visited Argentina last month--each hope to obtain DNA "fingerprints" of local strains of the virus and track the route of infection. Neither Hjelle nor Peters has received DNA samples so far, however.

One U.S. researcher suggests that the Argentines have been distracted by a government reorganization in December that led to sharp budget cuts and layoffs at Malbran. Elsa Segura, Malbran's director, confirms that the government reorganization has taken an emotional toll. But she says the collaboration with CDC is moving forward and that hantavirus research has not been slowed.