When Illness Goes Offshore: Defence Strategies for Rare Pathogen Claims at Sea

The situation aboard m/v Hondius is a reminder, that serious medical incidents on cruises can quickly escalate from a public health event into a complex, high-value, multi-jurisdictional claims scenario. Oceanwide has confirmed that there were 149 people on board from 23 nationalities. Five cases of Hantavirus have been confirmed with three fatalities.

For operators, insurers and their defence teams, the issue is not whether a shipboard medical emergency can occur despite proper systems but whether the operator can demonstrate that it had appropriate systems in place and that they were implemented promptly and effectively. The relevant standard is not perfection but auditable competence. The International Health Regulations serve as the standard, along with the WHO Guide to Ship Sanitation, the WHO Handbook for the Management of Public Health Events on Board Ships, and, in this case, Dutch ship sanitation certification requirements.

That framework outlines the operational expectations which will be scrutinised in detail in any later claim. Things such as illness surveillance, medical logging, prompt isolation of symptomatic individuals, high standards of environmental hygiene, safe food and clean water controls, vector and rodent control, medical escalation procedures, and timely engagement with health authorities will all be considered. The question for defendants is a practical one:  what was done, when, by who, and what contemporaneous records support it.

Causation is always the most difficult position for defendants as rare infectious diseases seldom follow neat factual narratives. Exposure may have occurred before embarkation, during an excursion, through an environmental source on board, or, in some cases, by person-to-person transmission. Public health material recognises that identifying the causative agent and establishing attribution may take time and, in some cases, remain inconclusive. In the current reporting on Hondius, public commentary has already pointed to competing possibilities, including exposure in South America before boarding, exposure during the voyage, or an onboard environmental source. This uncertainty increases reserving volatility and makes aggressive claimant pleading more likely.

A defence can live or die on data. Having the right records in place is crucial, such as timestamped medical records, symptom-onset records, cleaning and isolation records, food and water checks, vector control documentation, cabin movements, and any laboratory sequencing or epidemiological analysis. It is not sufficient to prove that a protocol existed in the manual. A strong defence needs an evidence-led chronology capable of testing alternative exposure routes and challenging the simplistic assertion that the infection was acquired on board. 

Operators may review this incident to inform future pre-boarding checks, ensuring guest safety and minimising the risk of a repeat incident. Given that Hantavirus is present and endemic in Argentina, and the growth of expedition cruises departing from the region, enhanced procedures may both reduce risk and strengthen evidential tracing if issues arise.

There is then the separate issue of the legal framework. Claims arising from international carriage by sea may fall within the scope of the Athens Convention. Athens was designed to provide a structured regime for passenger death and personal injury claims arising “in the course of carriage”, including jurisdictional rules and, in some circumstances, liability limits and compulsory insurance architecture. It distinguishes between “shipping incidents” and other incidents. For non-shipping incidents, the claimant ordinarily bears the burden of proving fault or neglect. An infectious outbreak will not obviously fit within the category of a classic shipping incident, and the debate will therefore turn to whether fault can be established by reference to the operator’s systems and response. 

This defence position is consistent with established disease litigation at sea. The fact of illness does not in itself establish negligence. The claimant must still prove that the carrier's failings caused or materially contributed to the loss. Norovirus cases have previously turned on whether the carrier could show that appropriate outbreak measures were taken, and whether the outbreak was introduced by a boarding passenger rather than caused by any defect in the ship or failure in the operator’s systems¹. The lesson is straightforward. A strong documentary trail is essential, clearly showing a functioning outbreak plan, active surveillance, isolation, cleaning, and coherent decision-making. A defence can deteriorate quickly when the records are poor. 

Cross-border complexity increases the exposure. In a case such as this, the ship’s flag, the nationality of passengers and crew, the ticket contract, the ports involved, and the place of treatment or death may all point in different directions. The publicly available facts already indicate a voyage beginning in Argentina, a ship positioned off Cape Verde, one medically evacuated patient in South Africa, others to Germany and the Netherlands and onward consideration of disembarkation in the Canary Islands. The passengers have now all been disembarked and repatriated to their home countries.

In catastrophic injury and fatal cases, the varying nationalities and locations of incidents can significantly affect the trajectory of a potential claim. Those facts can affect which court may hear the case, which law applies, and therefore how liability and damages are assessed, as well as which authorities hold the relevant evidence. 

It also needs to be considered that the passenger and crew claims may proceed on different legal tracks, as the latter may engage employment obligations and the Maritime Labour Convention, 2006 (MLC). 

None of the above means that serious outbreak claims are not indefensible. 

The immediate priorities to ensure a defensible position are: 

• Identify a defence strategy early;
• preserve all onboard records; 
• secure the medical chronology; 
• obtain the itinerary and excursion data; 
• identify all points of possible exposure; 
• confirm what notifications were made to health authorities and when; and 
• retain the right experts, usually in epidemiology, infectious disease and maritime operations, before the narrative hardens around a claimant-friendly version of events. 

In parallel, insurers need to assess jurisdictional exposure, the likely application of the Athens framework, potential aggregation issues, and whether a coordinated approach is needed for multiple claimants in different jurisdictions. 

The substantial media interest can conflate regulatory response, tragedy and legal liability. Measures such as public health escalations, port refusals, and quarantines reflect state precautions, not carrier negligence. Illness alone does not shift the burden of proof, dilute causation, or convert uncertainty into liability. Sympathy for affected passengers cannot substitute for evidence. In international carriage cases, courts have consistently rejected hindsight reasoning and simplistic causal narratives. Where alternative exposure pathways remain scientifically plausible, liability cannot be inferred solely from the outcome. To argue otherwise is to confuse public health management with legal responsibility and to ascribe rights beyond those conferred by the applicable conventions.

The current situation regarding Hondius is still developing, and it would be wrong to jump to conclusions on liability. What it does show, however, is why rare pathogen claims at sea are so difficult. They sit at the intersection of public health, maritime regulation, contract law, insurance law, and private international law. They are heavily fact-sensitive. They are vulnerable to hindsight. And they are won or lost on the quality of the operator’s systems and the quality of the records showing those systems in action. For insurers, cruise lines and their defence teams, that is where the real contest lies. 

1. Nolan -v- TUI [2016] Lloyd’s rep 211