The Centers for Disease Control and Prevention said on Thursday that no Andes virus cases have been identified in the United States as a result of the cruise-ship cluster reported earlier this month, and that 41 people in this country are being monitored through the standard 42-day window for the virus. The cluster, tied to the expedition vessel M/V Hondius, stands at 11 cases (nine confirmed by sequencing or polymerase chain reaction, two suspected) and three deaths, according to the World Health Organization’s May 8 outbreak notice and updated reporting through May 14. The risk to the American public, the CDC and the WHO both say, remains extremely low.
The vessel left Ushuaia, Argentina, on April 1 with 147 people on board (86 passengers and 61 crew from 23 countries) and stopped at Antarctica, South Georgia Island, Tristan da Cunha, Saint Helena, and Ascension Island before the first illnesses were reported. The WHO has identified patients with ties to the Netherlands, South Africa, Switzerland, and Germany. American passengers are being repatriated to Offutt Air Force Base in Nebraska, and from there to the National Quarantine Center at the University of Nebraska Medical Center in Omaha, the CDC’s May 8 release said.
What the evidence does, and does not, tell us
Andes virus is one of several hantaviruses that cause hantavirus pulmonary syndrome, the severe lung disease that follows fever, fatigue, and muscle aches by several days. It is also the only hantavirus for which person-to-person transmission has been documented. That documentation rests primarily on a 2020 New England Journal of Medicine paper led by Valeria Martínez and colleagues at Argentina’s ANLIS Malbrán institute, which described an outbreak in Epuyén, Chubut Province, between November 2018 and February 2019: 34 confirmed infections, 11 deaths, and three symptomatic “super-spreaders” who attended crowded social gatherings during their prodromal phase.
The Epuyén paper is the single strongest piece of evidence for person-to-person Andes virus transmission, and it remains the basis for the 42-day monitoring window the CDC and WHO are using now. The reported case-fatality ratio in this cluster (three deaths in eight reported cases at the time of the WHO notice) is 38 percent against that eight-case denominator, within the broad 21 to 50 percent range cited in the peer-reviewed literature for hantavirus pulmonary syndrome in the Americas. With sample sizes this small, that proportion will move as cases are reclassified, and any final figure should be read against the larger denominator the 42-day window will produce.
What the published evidence does not yet explain is why Andes virus, of all the hantaviruses, transmits between people at all. “We actually currently have zero data on why Andes is special,” Kartik Chandran, a virologist at Albert Einstein College of Medicine, told Science News on May 13. Gustavo Palacios at the Icahn School of Medicine at Mount Sinai told the same publication that the most plausible route remains respiratory secretions during close, prolonged contact. Jonas Klingström, a virologist at Linköping University in Sweden, framed the broader picture plainly: human-to-human transmission of Andes virus, he said, “is still very, very rare.”
We actually currently have zero data on why Andes is special. — Kartik Chandran, virologist, Albert Einstein College of Medicine
The 42-day window and what counts as exposure
The CDC’s Health Alert Network advisory, issued May 2 and updated May 8, asks U.S. clinicians to consider hantavirus pulmonary syndrome in patients with compatible symptoms (fever, muscle aches, gastrointestinal complaints, then progressive shortness of breath) and an epidemiological link to the Hondius or to a confirmed case within the prior 42 days. Suspected cases should be reported to state or local health departments or to the CDC’s Emergency Operations Center at 770-488-7100. Healthcare providers caring for a suspected patient are asked to use airborne infection isolation and N95 or higher-level respiratory protection, the advisory says.
Two clinical points are worth keeping in view, because they shape how the rest of the window will play out. First, the incubation period for Andes virus is wide: symptoms can appear anywhere from four to 42 days after exposure, so a case appearing four weeks after the last shared meal on the ship would still be within scope. Second, transmission, where it has occurred, has been associated with prolonged close contact in the days when an infected person is symptomatic, not with brief casual encounters. The European Centre for Disease Prevention and Control’s rapid scientific advice on this outbreak draws the same line: contacts are people who shared an enclosed space with a symptomatic case, not the general traveling public.
There is, in short, no peer-reviewed basis for treating this as the early phase of a wider epidemic, and the WHO has explicitly set its global risk assessment at low while keeping the cruise-ship-specific risk at moderate. There is also no peer-reviewed basis for declaring the window closed: the next four weeks will determine whether the cluster ends at 11 cases or grows through contacts identified during monitoring. Both statements are true at once.
What to watch over the next four weeks
Three specifics are worth tracking, and they should be read against named sources rather than against secondary summaries. The CDC’s outbreak page and its HAN advisory carry the official U.S. case and monitoring counts. The WHO’s Disease Outbreak News item, last updated May 8 with a corrigendum on May 9, carries the global counts and the country-of-residence breakdown. Sequencing data, when published, will indicate whether the virus circulating among the Hondius patients shares features with the Epuyén lineage or differs in ways that would matter clinically.
Until then, the careful read is the one the agencies themselves are offering: a small, serious cluster of a rare illness, contained to a defined cohort, being watched for a defined interval, with the open scientific question (why this hantavirus transmits at all) unchanged by the past two weeks.