r/Outbreak

I definitely didn’t have a hantavirus outbreak on a cruise ship on my 2026 infectious disease bingo board, but at least I get to turn a previous paper from grad school into something possibly useful for the public . The MV Hondius is a Dutch-flagged polar exploration vessel currently floating in Cabo Verde, an archipelago sitting off the coast of Senegal and Gambia. The ship had started in Ushuaia, Argentina on March 20^(th), but as of today we have lab-confirmation of hantavirus in at least one individual. Three passengers are dead with a 69-year-old British man in intensive care in Johannesburg. The thing is, hantavirus on a cruise ship is genuinely unusual, so let’s go over what the underlying epidemiology says might be going on aboard that ship.

The first fatality on the Hondius was a 70-year-old man who died of hemorrhagic fever aboard the ship (EDIT: this may not have been true hemorrhagic fever but a hemorrhagic pulmonary syndrome and the two often get conflated and then parroted by people like me trying to also report on the topic, more information is needed); his wife was evacuated to Johannesburg where she passed as well. The third death happened on the vessel itself, but details are still a bit murky. Two additional symptomatic individuals have been identified as crew (we’ll get to what that might mean). We’ve got at least 6 people affected, three of whom are dead. While we’re still in the “denominator problem” stage of this outbreak, not knowing how many people have been infected just not as severely or completely asymptomatically, that corresponds to a 50% fatality rate among those who have experienced symptoms so far. I assume that number will shift toward the lower end as things get investigated and milder cases are identified.

The main question the outbreak is how the rodent-borne virus got on the cruise ship. Rats on ships is not a new problem with regards to infectious disease outbreaks with countless examples from history (The Black Death and The Justinian Plague coming to mind).

Hantaviruses are a group of viruses with members across the world within the Hantaviridae family found in rodent hosts. The viruses co-exist with their rodent populations without causing major health problems in their hosts. It is when spillover occurs into humans that they can lead to severe and often fatal diseases. People typically catch it through the inhalation of aerosolized particles from rodent urine, feces, or saliva, something not uncommon when cleaning a shed, sweeping a barn, or working in fields. So while a cruise ship isn’t exactly the exposure pattern one would first think of, it’s not that abnormal either. The ship left Patagonia, well within the range of the ANDV hanta-variant carrying long-tailed pygmy rice rat and other possible carrier species in the area. It wouldn’t be weird for a couple of rodents to scurry their way into the bottom levels of a cruise ship while supplies for the planned journey are being loaded. Once aboard, the enclosed, climate controlled environment becomes a nice place for spreading aerosolized viral particles that would then be found in storage areas, supply closets, ventilation ducks, and the service compartments below deck where rodents could go unnoticed. The additional symptomatic individuals being crew makes me think this could be the case, but I’d need to see more skew toward crew being infected vs passengers, which I don’t think is the case yet. However it got on board, people have been infected and viral sequencing is underway in the labs which should help clarify which specific hantavirus strain we’re dealing with here.

Here’s the part that really worries infectious disease researchers and medical professionals working in the realm of ANDV. Most hantaviruses can’t spread from person-to-person. The major exception seems to be ANDV, which can go from person-to-person through contact with infected bodily fluids, with transmission being most likely during the prodromal phase or shortly after that has ended. Mortality rates are estimated at between 40-50% and there’s no specific anti-viral treatment or vaccine for it, care being supportive in nature with oxygen, fluids, and ventilation for severe cases that advance to Hanta Pulmonary Syndrome.

So, if sequencing confirms ANDV the containment methods needed change pretty drastically with the need for respiratory isolation of cases, rigorous contact tracing of all 170 passengers and 70 crew, monitoring for secondary transmission chains, and the hopeful removal of future sources of aerosolized rodent excreta. If we find out it’s a different variant like the Seoul virus that brown rats carry, the risk of person-to-person contact is much more negligible. We’ll see what happens in the coming weeks.

What to watch out for

Over the coming days and weeks I’ll update as new information comes out. Some things to look out for will be the sequencing results to determine ANDV vs a less problematic strain. I’ll be curious to see if we see more cases among the crew popping up as well, given they work in the areas where rodent excrement would be found more often. I’m also wondering what the temporal distribution of cases looks like. I haven’t been able to find anything on that yet, but were they clustered closely in time or spread out across days to weeks (the 1-5 week incubation period makes this question much more difficult to answer as well). We’ll also see if the ship’s own investigation finds any evidence of the rodents themselves, either bodies, nests, or droppings; I assume this has to be a major focus.

This is pretty much the second play-through of plague inc, covid was the first.

There playing on casual mode now, we are still weak from covid, and wars happening, we are as close as possible to die, I say as soon as it gets to your country,

live and let die ask out your crush, buy a yacht, smoke drink steal we are fucking screwed