90-Second Read: Origins of Cruise-Ship Hantavirus Outbreak Under Scrutiny

For one thing, long-tailed pygmy rice rats, the species that carries highly contagious Andes Hantavirus, were not trapped at the landfill. Across the border in Chile, a PhD student at the University of Development, Lissette Ulloa-Zepeda, and her fellow researchers published surveillance results in May from genetic sequencing of Andes Hantavirus samples from 2013. The quarantine period for Andes Hantavirus, based on how long it takes for symptoms of illness to appear, is currently about 42 days.

The likely location of April's Hondius infections points to the Argentina-Chile border region where the Dutch couple who first became ill aboard the cruise ship had traveled in early February. Andes Hantavirus is transmitted by the pygmy rice rats, much as North America's sin nombres Hantavirus is generally from deer mice. In the case of North America's Hantavirus, people become ill if they stir up mouse poop and breathe the airborne virus.

Among the more than 180 individuals aboard the Hondius, three people died of the severe respiratory disease caused by Hantavirus pulmonary syndrome. California's public health department reported that the five passengers known to be from the state are symptom free. What has turned up could lengthen quarantine periods for those exposed, the journal Science reported on June 11.