Chicago, cruise ships are convenient floating hotels through which to see far-flung parts of the world—but as an epidemiologist, I know they are also everything an infectious pathogen could want: thousands of strangers crammed into enclosed spaces for days or weeks, sharing restaurants and high-touch surfaces like elevator buttons and handrails, breathing recycled air.
Each new port of call, which passengers can explore for several days, is an opportunity for bacteria to board the ship—and once they’re aboard, they encounter an efficient environment in which to jump from host to host.
This well-known fact was confirmed by the MV Hondius in April 2026, when an outbreak of the Andean hantavirus began on the Dutch-flagged expedition ship, which was carrying 147 passengers and crew from 23 countries.
Andes virus is one of several types of hantavirus. It is the only virus known to spread from person to person, although it does not spread very efficiently. It is far less contagious than COVID-19 or measles.
As of May 14, a total of 11 cases have been reported in the Hondius epidemic, including 3 deaths.
Maritime outbreaks are one of the oldest problems in public health. From medieval plague quarantines to modern times, they have repeatedly tested the ability to control infectious diseases and played a key role in shaping today’s international public health framework.
However, this interconnected public health system relies on the cooperation of countries around the world.
From port quarantine to global disease control
The word “quarantine” first appears in English in 1663 in the Oxford English Dictionary, which defines it as a period of 40 days during which a person who may be spreading a contagious disease is isolated from the rest of the community.
However, the first official quarantine occurred much earlier, in 1377, when the Republic of Ragusa (today’s Dubrovnik, Croatia) ordered ships coming from plague-affected ports to anchor offshore for 30 days before anyone could come ashore.
A quarter of a century later, Venice extended this period to 40 days, and the term “quarantine” is still used today. In 1423, Venice officially opened Lazzaretto Vecchio, the world’s first permanent isolation island, specifically to deal with the plague introduced by sea.
This system worked during the medieval period as most ports were usually controlled by a single authority. Ships wait because they recognize the state’s right to seize them.
For centuries, quarantine at sea has been conducted according to this principle. Port officials have broad public health powers over incoming ships.
The practice continued in the United States during the 19th century. Cholera ships — the nickname given to the transatlantic ships that carried immigrants and troops and were breeding grounds for cholera and other diseases — arrived from Europe and the Mediterranean and stayed offshore New York for weeks.
At quarantine stations at Ellis Island and Atlantic Coast ports, public health officials inspected ships, quarantined passengers, and captains’ decisions were overridden by public health officials, who have the legal authority to quarantine passengers for long periods of time.
The system was crude and often cruel.
Medieval ships were floating wards in poor conditions: barrels contained putrid water, bread was infested with worms, passengers were crammed into asphalt-sealed berths, bedding was infested with lice, and the bilges reeked of sewage.
Many people died on board. But the system was based on recognized, enforceable authority over the ship and everyone on board, with the goal of protecting the city from disease.
international cooperation
However, as maritime trade and travel become increasingly globalized, no port or government can respond to the outbreak alone. Additionally, advances in vaccines, antibiotics, and sanitation have led many countries to downsize the maritime quarantine systems that once defined disease control at sea.
This has forced the quarantine system to evolve from local port controls to an internationally coordinated framework.
The World Health Organization was founded in 1948 and the International Health Regulations were established in 1969 to manage disease across borders.
Countries agreed to share information, notify each other of the outbreak and coordinate response measures at ports and borders.
Responsibility no longer falls on a single harbormaster, but the system is designed to perform similar coordination functions in an increasingly connected world.
However, even within this system, cruise ships remain an exceptionally vulnerable epidemic environment.
A high-profile example is the COVID-19 outbreak on the Diamond Princess in 2020.
The cruise ship, anchored off the coast of Yokohama, Japan, has caused weeks of chaos among Japanese authorities, British cruise operators and more than a dozen foreign governments as they struggle to coordinate responsibility and containment measures for the 3,700 passengers on board.
Some later analyzes suggested that shipboard quarantine may have amplified the spread. At the time, most observers viewed it as a crisis over the chaos of the pandemic’s early days.
But Hondius’s outburst showed that the problem was more serious.
Ships cross borders – and so do pathogens
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Cruise ships’ combination of intensive social integration, international mobility, and diffuse legal authority continues to challenge modern disease control systems—even decades after the creation of international public health frameworks designed to coordinate these systems, and even for diseases as highly unlikely to cause a pandemic as the Andean hantavirus.
As the cruise industry has grown, it has expanded into more remote and epidemiologically unpredictable environments—exploration cruises in Antarctica, the Amazon, Alaska.
As the industry’s ambitions grow, so do the risks of disease. These trips typically expose large groups of passengers to wildlife, pathogens and ecosystems they have little previous contact with, then seal travelers together for weeks.
Still, the United States in January 2026 opted out of the World Health Organization, the lead agency for the regulatory framework designed to coordinate responses when the disease crosses borders that cruise ships routinely cross.
The Trump administration views withdrawing from international organizations as a means to protect U.S. sovereignty. In practice, this meant that when the Hondius needed to respond, the United States would be involved from outside the systems it had spent decades helping to build.
Cracks appear in the system
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At the time of the Hondius outbreak, the international system was still functioning.
The World Health Organization still issues risk assessments and guidance. The European Center for Disease Prevention and Control is still coordinating the response across Europe. In the United States, the Centers for Disease Control and Prevention belatedly issued a health alert to doctors.
What has changed is that the United States has moved from being a central player in the international public health system to operating more from the margins.
Who can say whether the next big outbreak will come from a disease spread on a cruise ship, or whether the pathogen involved will spread from person to person more efficiently than the Andean strain of hantavirus.
Regardless of its origin, responding to the outbreak depends on cooperation among major governments, rapid information sharing and coordinated logistics.
When a country as globally connected as the United States exits these systems, managing international health emergencies becomes slower, more fragmented, and more reliant on ad hoc negotiations. Ultimately, this could make the world a less safe place. GRS
GRS
This article was generated from automated news agency feeds without modifications to the text.
