Three deaths, a vessel turned away, and what a strange outbreak in the South Atlantic tells us about a much older story.
By Robert W. Malone, MD, MS · Chief Medical Officer, Curativa Bay
This week, I want to start where the news started.
A Dutch-flagged expedition cruise ship called the MV Hondius left Ushuaia, Argentina, more than a month ago, made its planned stops in Antarctica, returned briefly to Ushuaia, sailed north past Saint Helena, and on Sunday anchored off Praia, the capital of Cape Verde, an archipelago off the west coast of Africa. By the time it dropped anchor, three of its passengers were dead. Six more were symptomatic. One British national had been airlifted off and was in critical condition in a Johannesburg ICU. Two crew members were in urgent need of evacuation.
Cape Verde refused permission for the ship to dock.
The official reason — and Cape Verde’s reason was the right one — was the protection of public health. The country’s health authorities sent a medical team aboard to assess the symptomatic crew. They are now monitoring the situation from offshore, and the ship may be redirected to Las Palmas or Tenerife in the Canary Islands, where the docking question will be asked again.
The suspected pathogen is hantavirus. One laboratory-confirmed case so far. Five additional suspected cases. The World Health Organization has been clear that the broader risk to the public is low — hantavirus is rare in humans and, for the strains we usually encounter, is not transmitted easily from person to person. It is most often acquired through contact with rodent excreta.
So why am I, as Chief Medical Officer of a hypochlorous acid company, choosing this story to introduce you to the Curativa Bay Substack?
Because of what the story is actually about — which is not hantavirus.
What the Cruise Ship Is
A cruise ship is a fascinating epidemiological object. It is, in essence, a small floating city — a few hundred or a few thousand people living in close quarters for weeks at a time, eating from shared kitchens, breathing recirculated air, sharing surfaces in narrow corridors, sleeping behind thin walls. When something biological boards that ship, whether it walked on two legs through a customs checkpoint or scurried in on four through a cargo hold, the entire vessel becomes the host environment.
This is why cruise ships have been the location, over the years, of some of the most instructive outbreaks in modern public health. Norovirus on the Diamond Princess. Legionella outbreaks in onboard water systems. Influenza, repeatedly. SARS-CoV-2 famously, on multiple vessels, including the same Diamond Princess that has by now contributed more to our understanding of respiratory pathogen transmission than most universities. The ship turns the population into an unblinded study cohort whether the operators intend it or not.
I want to be careful here. The hantavirus suspected on the Hondius is not, in the ordinary sense, the kind of pathogen we worry about in cruise-ship transmission models. The strains that infect humans most often are acquired through environmental exposure to rodent waste, not by inhaling someone else’s cough. So if you are imagining the Hondius as another Diamond Princess — passengers infecting each other in dining rooms — the analogy is wrong, and Cape Verde’s quarantine decision was about caution and burden of proof rather than about a clear human-to-human chain.
But the Hondius matters for the same reason the Diamond Princess mattered. The ship is the laboratory the world keeps building for itself.
And the fact that we keep building it should make us think hard about what is on board, and what could be on board the next time.
The Pathogens We Actually Worry About
Here is what your epidemiologist friends spend their lunches arguing about. Not the hantavirus on this particular ship. The next outbreak. The one that does spread efficiently, person to person, in close quarters. The one that gets onto a vessel because someone touched a doorknob, or a serving spoon, or a bathroom faucet, and then someone else touched it twenty seconds later.
Norovirus is the classic example. The infectious dose for norovirus is somewhere between ten and a hundred viral particles. Ten. That is a number so small that essentially any contaminated surface in a high-traffic area becomes a transmission vector. Norovirus survives on surfaces for days. It resists most household disinfectants at the concentrations commonly used. It fells cruise ships routinely — every winter, you will read another headline.
Influenza, on a ship, can move through a closed population in days. Respiratory syncytial virus the same. Methicillin-resistant Staphylococcus aureus — MRSA — colonizes surfaces and hands, and on a cruise ship full of older passengers (the demographic skews older for expedition cruises like the Hondius), MRSA infections in wounds or surgical sites can become serious quickly.
And then there is the broader category of communicable disease the public health community calls emerging — the pathogens we do not yet know about, or the ones we know about but have not seen at scale. The next coronavirus. The next H5N1 spillover. The next thing that boards a ship in a port and gets discovered three thousand nautical miles later, when there is no port that will take you.
When a cruise ship ties up at the dock and a passenger steps off, that passenger walks into an airport, into a city, onto a connecting flight to somewhere on the other side of the world. The ship is a node in a much larger network. What gets onboard becomes what gets ashore, and from there, becomes what arrives in your city six weeks later.
This is not catastrophizing. This is just what infectious disease specialists call routine.
Four Conditions, Three Centuries of Unbroken Logic
In every introductory epidemiology course, students learn that for a communicable disease to transmit from one person to another, four things must be true. There must be a pathogen present. The pathogen must be present in sufficient quantity to cause infection — what we call the infectious dose. There must be a route of entry into the new host. And the new host must be susceptible, meaning they do not already have immunity.
If any one of these four conditions fails, transmission fails.
The four-condition model is more than a hundred years old. It has not been overturned. It has not been replaced. It has been refined and quantified, but the underlying logic is the same logic John Snow used in 1854 to take the handle off the Broad Street pump and stop a cholera outbreak in central London. Break one of the four conditions, and the chain collapses.
Disinfection — environmental disinfection, the kind done on doorknobs and dining surfaces and bathroom fixtures and HVAC ductwork — is the most direct intervention against the first two conditions. Reduce the pathogen present. Reduce the quantity below the infectious dose. Break the chain on the surfaces and in the air, before the chain ever reaches a human host.
This is where the rest of the conversation gets interesting. Because for most of the last century, the disinfectants we have used to break that chain have come with their own costs.
The Trouble With Most Disinfectants
Bleach kills almost everything. It also damages tissue, off-gasses chlorine fumes, requires PPE for safe use at concentrations high enough to kill resistant pathogens like norovirus (which requires bleach concentrations as high as 5,000 parts per million to inactivate), and is dangerous to use in occupied spaces.
Quaternary ammonium compounds — the active ingredients in most institutional disinfectant sprays — are positively charged molecules that struggle to penetrate the negatively charged matrix of bacterial biofilms. They are ineffective against non-enveloped viruses like norovirus and parvovirus. They have been associated with occupational asthma in cleaning staff. They leave persistent residue on surfaces. And resistant strains of bacteria have been documented.
Hydrogen peroxide vapor works, but it is a respiratory irritant and requires evacuation of the space being treated.
Alcohol kills most enveloped viruses but evaporates quickly, is flammable, and is largely ineffective against spores and non-enveloped viruses.
Each of these chemistries is useful. None of them is good enough alone. And none of them — none of them — can be safely deployed in occupied spaces while passengers and crew continue going about their business.
This is the gap I want to close.
The Molecule the Body Has Been Using for Six Hundred Million Years
The Curativa Bay Substack is the editorial home of a company built around a single biochemical insight. The molecule the human immune system itself produces to destroy pathogens — hypochlorous acid, or HOCl — is also one of the most powerful broad-spectrum antimicrobial agents we have ever identified. It is produced by your white blood cells, every minute of every day, when those cells encounter a bacterium or a virus or a fungus. The reaction is catalyzed by an enzyme called myeloperoxidase, and the resulting HOCl molecule attacks pathogens through four simultaneous oxidative mechanisms — membrane disruption, enzyme inactivation, nucleic acid oxidation, and biofilm degradation. There is no documented resistance to HOCl in over a century of clinical and industrial study, because there is no single target for evolution to find.
What makes the molecule operationally interesting — and the reason a company exists around it — is that it can now be stabilized outside the body, in solution, at controlled concentrations. It can be sprayed on a wound. It can be fogged into a room. It can be applied to food-contact surfaces, to children’s toys, to door handles in a passenger corridor, to the air handling system of a vessel — all without evacuating the space, without PPE, without leaving toxic residue. After it reacts, it degrades into water and a trace of saline. That is its full byproduct profile.
Norovirus, which requires 5,000 ppm of bleach to kill, is killed by HOCl at concentrations between 160 and 200 ppm. That is a 25- to 31-fold concentration advantage, achieved with a molecule the human body itself produces. The applications across cruise ships, schools, hospitals, food processing, and public-health stockpiles are, in my professional opinion, substantial — and they are precisely the kind of applications where conventional chemistry has fallen short.
Why I’m Writing Here
I came on as Chief Medical Officer of Curativa Bay because, after a long career thinking about countermeasures, I have not encountered another antimicrobial platform that combines this kind of broad-spectrum lethality with this kind of human-tissue safety. The combination is rare in chemistry and common in biology — for good reason. The body has been engineering it for hundreds of millions of years.
The Curativa Bay Substack will be the place where I, and the team here, write regularly about what this molecule means for medicine, public health, biodefense, and the everyday questions of how we protect ourselves and our families from communicable disease. We will cover the science. We will cover the history of antimicrobial chemistry and the failures that brought us to where we are. We will write about wound care, about chronic non-healing infections, about hospital-acquired infections, about pandemic preparedness, about federal stockpiles, about humanitarian deployments. We will write about the institutional and political conversations that shape what countermeasures are available to whom, and at what cost.
We will not catastrophize. The hantavirus outbreak on the Hondius is, in all likelihood, a contained tragedy with a small number of victims and a manageable public-health response. WHO is correct that the broader risk is low. Cape Verde made the right call. The cruise will be redirected. The investigation will continue.
But the Hondius is also, in a smaller way, a flare in the sky. A reminder that ships can carry things across oceans. That ports have the right to say no. That public-health infrastructure depends on the ability to break the chain of transmission before it reaches the next person. And that the chemistry we use to break that chain matters enormously — to the safety of the workers wielding it, to the patients sleeping near it, to the children playing on the surfaces it has touched.
There is a better chemistry for this. Your body has been using it since long before any of us learned to build ships.
I am glad you are here. Subscribe, and stay with us. The next pieces will go deeper — into the four mechanisms HOCl uses to destroy pathogens, into the unsolved problem of biofilm-driven chronic wounds, and into what a serious national biodefense posture would actually look like in 2026.
Thank you for reading.
— Robert W. Malone, MD, MS
Dr. Robert W. Malone is the Chief Medical Officer of Curativa Bay (CuraClean Technologies). He is a physician, scientist, and the inventor of foundational mRNA vaccine technology. He has served on multiple biotechnology and biodefense advisory bodies and writes regularly on pandemic preparedness, medical countermeasures, and public-health policy.
