The Virus Without a Name

A cruise ship in the Atlantic. A rare virus from South America. Three dead, passengers from 23 countries tracked across four continents. And a story that begins not at sea, but in the desert of the American Southwest in 1993.

This morning, the Dutch-flagged cruise ship MV Hondius is sailing toward the Canary Islands carrying more than 140 passengers and crew, one unburied body, and a confirmed outbreak of hantavirus that has killed three people and triggered a coordinated public health response across four continents. The World Health Organization has confirmed eight cases — five confirmed, three suspected — linked to the Andes virus, a strain of hantavirus that circulates in South America and is the only known hantavirus capable of spreading between people. Health authorities in at least 23 countries are tracking former passengers. In the United States, authorities in Arizona, California, Georgia, Virginia, and Texas are monitoring Americans who were aboard the vessel; none have shown symptoms. The CDC has classified the event as a Level 3 emergency response. The WHO says the risk to the wider public remains low. And the story of how scientists know that — how they know what hantavirus is, what it does, and how to contain it — begins not in a South American river valley but in a canyon in New Mexico, 33 years ago.

What the Desert Taught Us

In May 1993, a young Navajo couple died within days of each other in the Four Corners region of the American Southwest — the place where Arizona, Colorado, New Mexico, and Utah meet — from what appeared to be sudden, catastrophic respiratory failure. They were young and healthy. Their deaths were baffling. Medical investigators from the Indian Health Service, the New Mexico Office of Medical Investigations, and the CDC converged on the region and quickly found other cases with identical symptoms: a sudden fever, muscle pain, then a precipitous collapse into acute respiratory distress. Before 1993, hantaviruses were known to science, but only in Asia and Europe, where they caused a different disease — hemorrhagic fever with renal syndrome. What was killing young, healthy people in the American desert was something new. Working with astonishing speed, a collaborative team of federal, state, and local scientists identified the culprit within weeks: a previously unknown hantavirus, carried by the western deer mouse, Peromyscus maniculatus. They named it the Sin Nombre virus — the virus without a name — and the disease it caused hantavirus pulmonary syndrome, or HPS. Of the 48 confirmed cases nationwide that year, 27 people died. The fatality rate was 56 percent.

The scientific detective work that followed the 1993 outbreak is one of the great examples of public health infrastructure working as it should. Researchers identified the deer mouse as the reservoir, established transmission routes — inhalation of contaminated rodent droppings, urine, or saliva — and determined that the Sin Nombre virus, unlike the strain now circulating on the Hondius, did not spread between people. From 1993 to 2023, the CDC detected 890 cases of hantavirus in the United States, of which 35 percent resulted in death. Surveillance systems built after 1993 tracked the virus's spread and mapped its reservoirs. When subsequent research turned up evidence of hantavirus antibodies in indigenous communities in Paraguay and Argentina in 1998, scientists were already looking — because the Four Corners outbreak had taught them to. The Andes strain identified on the MV Hondius is the direct descendant of that research lineage: a virus discovered because a young couple in New Mexico died mysteriously in the spring of 1993, and because the scientists who responded to their deaths built the tools that allowed the world to recognize, name, and respond to what is happening in the Atlantic today.

Medical researchers in protective gear conducting fieldwork in a desert landscape, evoking the 1993 Four Corners hantavirus investigation

In 1993, public health investigators converged on the Four Corners region of the American Southwest after a young Navajo couple died within days of each other from an unknown respiratory illness — and discovered a new virus that science had never seen in the Western Hemisphere.

The MV Hondius is expected to dock in Tenerife this weekend, where its remaining passengers will finally disembark after more than a week at sea under precautionary measures. The investigation into how the outbreak began — most likely tracing back to a four-month birdwatching trip through Argentina and Uruguay taken by the Dutch couple who were among the first to die — will continue for months. Argentina is capturing and testing rodents along the route the couple traveled. Pakistan's foreign ministry is working the phones on a different crisis entirely. Somewhere in five American states, former passengers are checking their temperatures and waiting. And in the background of all of it is the network of surveillance, science, and institutional memory built in the wake of an outbreak that killed 27 Americans in the summer of 1993 — people whose names are not remembered, but whose deaths produced the knowledge that is protecting the world right now. That is what public health looks like when it works: not the crisis, but the long, quiet labor that comes before and after it.