Andes virus on cruise ships: An evidence-stratified review of transmission risks and biosecurity strategies

Highlights

• •Andes virus(ANDV) transmission evidence requires structured interpretation beyond binary conclusions.
• •We proposed a three-tier framework for assessing ANDV transmission risks in cruise settings.
• •Rodent exposure and close-contact transmission were distinguished from unproven airborne hypotheses.
• •Cruise-specific vulnerabilities might increase consequences despite limited transmission evidence.
• •A journey-wide biosecurity framework enables balanced preparedness and response.

Abstract

The 2026 Andes virus (ANDV) cluster associated with the merchant vessel (MV) Hondius cruise ship highlights the limitations of hantavirus control strategies that have traditionally focused on rodent-source exposure alone. No evidence supports heating, ventilation, and air conditioning (HVAC)-mediated long-distance ANDV spread. Such strategies are insufficient for ecologically sensitive cruise routes, enclosed ocean-going environments, international passenger movement, and limited onboard medical capacity. Current evidence indicates that ANDV has limited but documented potential for person-to-person transmission. Transmission is most plausibly associated with acute-phase viremia, exposure to body fluids or short-range droplets, prolonged close contact, caregiving, and specific contextual conditions; it should not be equated with sustained community transmission by highly efficient respiratory viruses. On the basis of epidemiologic investigations, clinical shedding studies, animal models, viral genetic evidence, and environmental stability data, this review analyzes how high-consequence pathogens may have their public health impact amplified in cruise-ship settings. It further proposes prevention and control measures covering pre-voyage ecological exposure assessment, embarkation screening, early onboard recognition, tiered isolation, rapid shipboard testing, medical evacuation, and cross-border coordination. The central lesson from the MV Hondius event is that cruise ships operating on ecologically sensitive routes should move beyond conventional sanitation-centered management toward a whole-of-journey biosecurity model based on evidence stratification and graded response.

1. The MV Hondius event as a signal of high-consequence pathogen risk

Drawing on open-source surveillance reports, peer-reviewed literature, and institutional risk assessments, this review evaluates Andes virus (ANDV) exposure pathways and corresponding biosecurity measures in the cruise-ship setting, with explicit recognition of the evidence gaps that necessarily shape our interpretation.

On the basis of publicly available evidence, the merchant vessel (MV) Hondius event, which involved 13 confirmed hantavirus cases including 3 deaths among approximately 150 passengers and crew, represents a warning signal of high-consequence pathogen risk amplification in an enclosed ocean-going setting from an international public health perspective, rather than as definitive proof of efficient ANDV person-to-person transmission or long-distance aerosol transmission (Table 1).

Table 1.

Evidence chain and limitations related to ANDV person-to-person transmission.

Evidence type	Representative studies or sources	Main contribution	Key limitation	Implication for cruise-ship control
Epidemiologic clusters	Martinez et al. [13]; earlier clusters in Argentina and Chile	Suggested that ANDV can be transmitted between humans, often in household, caregiving, or close-contact contexts.	Early studies did not fully control for shared environmental exposure.	Strengthen case isolation, caregiving protection, and contact registration.
Whole-genome transmission chains	Alonso et al. [16]; EID 2020	Clarified multi-generation transmission chains and superspreading during the Epuyen outbreak.	Highly setting-specific; limited case numbers.	Collect and preserve samples early for genomic tracing after clustered cases occur.
Clinical shedding studies	Ferres et al. [25], 2024	Detected viral RNA in blood, gingival crevicular fluid, saliva, nasopharyngeal samples, and urine during acute illness; some samples showed infectivity evidence.	Infectious titers, shedding duration, and the relative contribution of each fluid require further quantification.	Strengthen body-fluid contamination control, eye and face protection, and hand hygiene.
Animal models	Riesle-Sbarbaro et al. [6], 2023; Coelho et al. [8], 2025	Supported horizontal transmission and direct-contact transmission in Syrian hamster models.	Specific routes, strain differences, and extrapolation to humans remain limited.	Support close-contact precautions, but do not justify assuming long-distance airborne transmission.
Genetic evidence	Bellomo et al. [7], 2023; Warner et al. [22], 2025	Linked candidate variants, strain background, and genomic stability to studies of transmission phenotype.	Causality of candidate sites still requires reverse-genetics validation.	Avoid explaining clusters simply as transmission-enhancing viral mutation.

Abbreviations: ANDV, Andes virus; RNA, ribonucleic acid.

Available public information suggests that the initial risk may have been related to pre-embarkation or itinerary-associated ecological exposure in endemic areas of South America, including outdoor activities, contact with rodent-infested environments, or inhalation of aerosols contaminated with rodent excreta. Whether sustained onboard rodent-source exposure occurred, whether a clear person-to-person transmission chain developed, and how the transmission chain was structured remain to be clarified through complete environmental sampling, exposure-history assessment, contact investigation, and viral genomic tracing. This review therefore does not attribute the event to a single route of transmission. Instead, it frames the event as a composite public health scenario involving ecological exposure introduction, risk amplification in an enclosed ocean-going environment, and increased complexity of cross-border emergency response [1], [2], [3], [4], [5].

For ANDV, the foundational risk remains environmental exposure related to infected rodents. Person-to-person transmission has been supported by previous studies, but it is usually conditional and associated with acute-phase viremia, exposure to body fluids or short-range droplets, prolonged close contact, caregiving, and the convergence of particular settings. Passengers and crew may be exposed to rodent-contaminated environments in the Andean region of South America, subantarctic islands, field landing sites, port-supply areas, or transfer settings. After a suspected case appears onboard, limited secondary transmission may occur through close contact, shared cabins, caregiving, or exposure to body fluids or droplets [6], [7], [8], [9].

This event also reinforces the risk difference between ecologically sensitive routes and ordinary recreational cruise itineraries [1], [2], [3], [4], [5]. In this review, ecologically sensitive routes are defined as cruise-ship itineraries traversing regions with known hantavirus-endemic rodent reservoirs, where passengers may encounter rodent excreta or infected rodents during port calls or shore excursions. The Andean region of South America, subantarctic islands, polar landing sites, and some remote ports may have complex zoonotic pathogen ecologies. Passengers and crew may encounter rodent activity or other potentially contaminated environments before embarkation, during shore excursions, at field landing sites, at supply stops, or during return transfers. Once a suspected case enters the relatively closed communal living environment of a cruise ship, subsequent risk is no longer determined solely by the intrinsic transmissibility of the pathogen. It is also shaped by cabin layout, frequency of shared activities, medical recognition capacity, isolation conditions, sample-transfer pathways, and the efficiency of coordination with port states.

For ecologically sensitive routes, cruise-ship biosecurity must therefore incorporate multidimensional risk assessment and response measures addressing ecological exposure, limited secondary transmission, restricted onboard medical capacity, delayed cross-border medical evacuation, and imperfect interfaces among international rules. ANDV should not be treated as equivalent to highly efficient respiratory pathogens such as severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). At the same time, continued reliance on the traditional framework of “rodent control-routine cleaning-passive medical consultation” is insufficient [10], [11], [12].

This review uses the MV Hondius event as a case study to ask a focused question: how should cruise-ship biosecurity systems interpret and respond to a high-consequence zoonotic pathogen with documented but limited person-to-person transmission potential? We therefore synthesize the evidence for ANDV transmission routes, define their evidence boundaries, and translate these findings into graded biosecurity strategies for ecologically sensitive cruise routes. Accordingly, the principal lesson of the MV Hondius event is not that ANDV has become an efficiently transmitted respiratory virus. Rather, it is that current cruise-ship prevention and control systems remain poorly adapted to high-consequence pathogens associated with ecologically sensitive routes. A traditional strategy centered on rodent control, routine cleaning, and passive care seeking does not adequately cover pre-voyage ecological exposure assessment, embarkation risk screening, early recognition during navigation, tiered isolation of suspected cases, contact management, rapid shipboard testing, medical evacuation, and cross-border coordination (Fig. 1).

Fig. 1.

Evidence-stratified framework of ANDV transmission risk and cruise-ship amplification pathways. A) Transmission chain and viral shedding from rodent-

Source exposure through acute-phase viremia, multi-fluid shedding, close-range contact, to conditional secondary transmission. B) Epidemiological scene and potential amplification pathways in enclosed cruise-ship settings, categorized by evidence level (strongly-supported, intermediate-evidence, and limited-evidence engineering hypothesis) [6], [13], [22]. Illustrated using Photopea (PS-based image editor). Abbreviations: HVAC, heating, ventilation, and air conditioning; ANDV, Andes virus.

2. Evidence boundaries for ANDV person-to-person transmission

2.1. Conditional person-to-person transmission and its implications for cruise-ship control strategies

Within the hantavirus family, ANDV is one of the few subtypes for which multiple studies have documented limited person-to-person transmission. Human-to-human spread of ANDV is supported by convergent lines of evidence: epidemiologic cluster tracing in Argentina and Chile [13], [14], [15], complete transmission-chain reconstruction from the Epuyen outbreak through whole-genome sequencing [16], characterization of superspreading dynamics [17], and controlled animal-model studies [6], all pointing to transmission under delimited conditions [6], [7], [13], [16], [17], [18].

This evidence does not support classifying ANDV as a generally efficient respiratory pathogen. A more rigorous interpretation is that ANDV has limited but documented person-to-person transmission potential. When close contact, body-fluid or droplet exposure, particular viral genetic backgrounds [7], [8], [9], and enclosed congregate settings coincide, clustered transmission may occur. The host distribution and genetic diversity of ANDV have been characterized in surveillance studies from endemic regions of South America [19], [20].

Clarifying these evidence boundaries has direct implications for prevention and control on cruise ships. If ANDV is treated only as a traditional rodent-borne hantavirus, prevention may overemphasize rodent control and environmental sanitation while neglecting contact management, body-fluid contamination control, personal protective equipment escalation, and medical transfer. Conversely, if it is misclassified as a highly efficient respiratory pathogen similar to SARS-CoV-2 or influenza viruses, risk communication may become exaggerated, resources may be misallocated, and unnecessary public alarm may result. We propose reframing the prevention model on three tiers: environmental contact with infected rodents as the primary hazard, prolonged proximity to symptomatic individuals as the key secondary mechanism, and the confined vessel setting as a factor that multiplies operational difficulty [6], [7], [8], [9], [21].

Bellomo and colleagues proposed that some genomic variants may be associated with attenuation in animal models and lineages linked to person-to-person transmission. Whether these sites directly determine transmission capacity, however, remains to be verified through reverse-genetics experiments, standardized animal-transmission studies, and comparative analyses across multiple strains [7], [18]. Warner and colleagues further reported high genomic stability after successive in vivo passage, indicating that short-term increases in transmission should not be simply attributed to rapid adaptive viral mutation [22]. Genomic surveillance during outbreaks may further clarify the relationship between viral evolution and transmission dynamics.

2.2. Clinical recognition, pre-symptomatic transmission caution, and case management

ANDV infection can cause hantavirus pulmonary syndrome (HPS), also referred to as hantavirus cardiopulmonary syndrome (HCPS). Early manifestations are nonspecific. Patients may present with fever, myalgia, fatigue, headache, gastrointestinal symptoms, or mild respiratory symptoms, which can be misdiagnosed as influenza-like illness, travel fatigue, seasickness, acute gastroenteritis, or other travel-associated conditions [23]. In cruise-ship settings, diverse passenger origins, limited medical resources, and limited crew experience with rare high-consequence pathogens may delay early recognition.

Compared with common travel-associated illnesses, the critical risk of ANDV infection is that some patients can progress within hours to days to pulmonary edema, hypoxemia, shock, and multiorgan injury. Severe disease is associated with disruption of endothelial barrier function, increased vascular permeability, and dysregulated host inflammatory responses following viral infection [24]. Cruise-ship medical systems generally lack intensive care unit (ICU)-level continuous monitoring, mechanical ventilation, extracorporeal membrane oxygenation, and the capacity to independently confirm high-consequence pathogens or manage complex infectious cases. Therefore, the central problem in the cruise-ship setting is not that severe disease is impossible to detect, but that systems often lack the capacity for low-threshold early warning, dynamic monitoring, rapid screening, risk stratification, and timely medical evacuation [8], [25].

Conclusions about “pre-symptomatic transmission” should be drawn with methodological rigor to avoid unsupported amplification of risk. Current studies indicate that ANDV infection can involve acute-phase viremia, and viral RNA has been detected in gingival crevicular fluid, saliva, nasopharyngeal secretions, urine, and other body-fluid samples. Some reverse transcription quantitative polymerase chain reaction (RT-qPCR)-positive body-fluid samples have shown evidence of infectivity [8], [25]. These findings suggest that individuals in the prodromal or early symptomatic phase, before they are recognized as suspected cases, may cause secondary infection through close contact, caregiving, body-fluid contamination, or droplet exposure. However, in the absence of complete time-series data, viral-culture evidence, and clearly resolved transmission chains, statements such as “high-titer infectious virus 48 h before respiratory failure” or “multiple rounds of hidden onboard transmission” should not be treated as generalizable rules for control planning [8], [25].

Thus, clinical prevention and control for ANDV on cruise ships should be shifted upstream to exposure-history assessment, recognition of symptom clusters, early isolation of suspected cases, dynamic vital-sign monitoring, and medical-evacuation planning, rather than waiting until typical respiratory failure appears before initiating emergency response [8], [19].

3. Risk amplification in cruise ship settings

Cruise ships do not alter the basic biology of ANDV, but their operational environment can amplify the difficulty of recognizing, isolating, treating, and coordinating responses to high-consequence pathogen events. For ecologically sensitive routes, risk does not arise only from enclosed onboard space. It emerges from a continuous chain: pre-voyage or shore-based ecological exposure, communal living and close contact onboard, limited medical resources, and complex cross-border coordination (Fig. 1). Therefore, ANDV control in cruise-ship settings should not simply apply airborne-transmission models used for ordinary respiratory infections, nor should it remain confined to traditional rodent control and routine cleaning. Instead, it should integrate evidence-based transmission-pathway assessment, environmental engineering conditions, onboard medical capacity, and international governance interfaces [1], [2], [3], [4], [5]. We classified evidence into four levels. Level I indicates direct or convergent evidence from outbreak investigations, genomic linkage, clinical data, or experimental studies supporting a route. Level II indicates biologically plausible and indirectly supported evidence, but with incomplete route-specific confirmation. Level III indicates limited evidence derived from environmental stability, analogical transmission data, or operational observations without direct ANDV cruise-ship confirmation. Level IV indicates precautionary or engineering hypotheses without direct evidence for ANDV transmission in the relevant setting (Table 2).

Table 2.

ANDV-related risk factors, evidence level, and control priorities in cruise-ship settings.

Risk factor or route	Evidence level	Main risk in cruise-ship settings	Control priorities
Rodent-contaminated environmental exposure	Level I (Strong)	Field landings, enclosed huts, port storage areas, supply zones, and areas with rodent activity.	Pre-voyage ecological risk assessment; exposure-history screening; shore-activity management; rodent surveillance.
Close contact / body-fluid exposure	Level I (Strong)	Shared cabin residence, caregiving, handling vomitus, blood, or excreta.	Single-room isolation; core close-contact registration; caregiving personal protective equipment (PPE); immediate management of body-fluid contamination.
Short-range exposure to oral or nasopharyngeal secretions	Level II (Moderate–strong)	Close conversation, communal meals, medical examination, coughing, or vomiting.	Medical masks or respiratory protection; eye and face protection; reduction of nonessential close gatherings.
Contaminated surfaces / contaminated textiles	Level III (Moderate)	Bathrooms, bedding, towels, medical areas, and high-touch surfaces.	High-frequency surface cleaning; sealed transfer of contaminated linens; hand hygiene.
Local contaminated aerosol exposure	Level III (Limited)	Suspected-case cabins, medical points, poorly ventilated small spaces, cleaning disturbances.	Local ventilation optimization; mobile high-efficiency particulate air (HEPA) filtration; appropriate respiratory protection.
Exposure during sampling, waste management, and transfer	Level III (Moderate)	Medical-point sampling, waste packaging, transfer routes, shore-side handover.	Standardized sampling procedures; triple packaging; infectious-waste management; personnel training.
Long-distance aerosol / HVAC cross-cabin transmission	Level IV (Insufficient)	Shared ventilation units, return-air crossover, inadequate isolation-zone setup.	Temporary negative-pressure isolation; independent exhaust; pressure monitoring; engineering contingency plans.

Abbreviations: HVAC, heating, ventilation, and air conditioning; PPE, personal protective equipment; HEPA, high-efficiency particulate air.

3.1. Transmission-route evidence and reasonable boundaries for engineering controls

Current evidence supports three route categories with differing confidence levels: (i) rodent-to-human environmental exposure (well-documented); (ii) close-contact person-to-person transmission via body fluids or droplets (supported by multiple outbreak investigations); and (iii) long-distance aerosol transmission (hypothetical, not demonstrated for ANDV).

Engineering controls such as HVAC upgrades should be prioritized for known routes (i-ii) while remaining optional for speculative routes (iii).

Enclosed cabins, inadequate local ventilation, and prolonged co-presence may indeed increase exposure to short-range droplets, contaminated aerosols, and high-touch surfaces. However, this does not mean that the virus has been shown to cause shipwide long-distance spread through central air-conditioning systems. Ventilation design on cruise ships should prioritize measurable objectives—reducing localized exposure intensity, enabling physical separation of isolation zones, and minimizing shared-air pathways between case areas and communal spaces [19], [26], [27]. That HVAC-mediated long-distance spread remains unproven for ANDV does not negate the value of engineering controls, but it does argue against presenting ventilation upgrades as a primary countermeasure in the absence of direct evidence.

Cruise ships are characterized by high population density, frequent shared activities, relatively small cabins, shared dining and entertainment facilities, and limited access to external medical support. These factors complicate transmission control and exposure tracing. For ANDV, the strongest evidence remains for rodent-contaminated environmental exposure and close-contact/body-fluid exposure. Short-range exposure to oral and nasopharyngeal secretions has a moderate evidence base. Risks related to contaminated surfaces and textiles should be assessed in relation to the degree of body-fluid contamination, viral environmental stability, material characteristics, and contact behavior [19], [26].

Likewise, carpets, upholstered materials, curtains, bedding, decorative seams, and other porous or complex surfaces inside cruise ships may increase the difficulty of cleaning and disinfection and may create short-term residual risk after body-fluid contamination or frequent contact. In the absence of direct evidence on virus survival on these materials, infectious-virus recovery, and real-world contact transmission, however, they should not be described as long-term viral reservoirs. These materials complicate terminal cleaning and contamination management and should therefore be incorporated into zoning-based cleaning, contaminated-linen handling, and return-to-service assessment [27].

3.2. Environmental disinfection and fit-for-purpose risk control

ANDV is an enveloped virus and is generally susceptible to appropriate hand-hygiene measures and surface-disinfection procedures [28]. Recent environmental-stability work showed that ANDV can remain infectious for a short period on some dry environmental surfaces at room temperature, while World Health Organization-recommended hand-rub formulations and common surface disinfectants can effectively inactivate the virus [28]. Cruise ship environmental control should therefore avoid two extremes: ignoring the contact-transmission risk associated with body-fluid contamination and high-touch surfaces, or portraying cruise ship interiors as long-term viral reservoirs that are difficult to decontaminate.

A more practical environmental-control strategy includes zoning-based cleaning and disinfection of suspected-case cabins, bathrooms, medical points, and transfer routes; immediate containment and disinfection of areas contaminated by body fluids, vomitus, blood, or excreta; categorization, sealed transfer, and high-temperature laundering of contaminated textiles; appropriate protection for cleaning staff, including gloves, gowns, eye and face protection, and respiratory protection consistent with the risk level; and management of medical waste from shipboard medical points and temporary isolation areas as infectious waste [18], [28].

For cruise ships operating on ecologically sensitive routes, cleaning and disinfection protocols should be incorporated into pre-voyage drills and crew training rather than improvised after an outbreak has occurred, ensuring that response procedures are standardized and executable [18], [28].

3.3. Cross-border governance challenges

Cruise-ship outbreak response involves flag states, port states, countries of passenger origin, operating companies, insurers, shore-based hospitals, laboratories, and international organizations. Medical-system capacity and emergency-response capability differ substantially among these actors [29], [30]. During a crisis, port states must balance humanitarian rescue, domestic public health security, and medical-system capacity. Ship operators must provide complete case information, exposure lists, cabin distribution, medical records, cleaning and disinfection logs, and transfer needs. If collaborative plans have not been established in advance, responsibility allocation, resource mobilization, and legal boundaries may become unclear and delay optimal response, amplifying the public health risk.

The International Health Regulations (IHR) provide a general framework for notification and cooperation in cross-border public health events [31], but more detailed operational guidance is needed for ocean-going cruise ships, expedition routes, and high-consequence pathogens. Key issues include criteria for medical evacuation of severe cases, pre-designated receiving ports, shore-based ICU and extracorporeal membrane oxygenation (ECMO) capacity, triple packaging and cross-border transfer of biosafety-relevant samples, transport of asymptomatic high-risk contacts, assessment of ship disinfection before return to service, and related operational standards. These matters should be clarified in advance through regional memoranda of understanding and industry guidelines. If negotiated only after an event occurs, they are likely to produce delayed decisions and unclear responsibilities [31], [32], [33].

A pragmatic approach is to begin with regional cooperation memoranda and standard operating checklists for ecologically sensitive expedition routes, particularly those involving South America, Antarctica, the South Atlantic, and comparable regions. Such checklists should identify pre-designated receiving ports, hospitals capable of ICU or ECMO care, reference laboratories and sample-transfer contacts, aeromedical evacuation providers, accommodation pathways for asymptomatic high-risk contacts, procedures for infectious waste and contaminated textiles, standards for terminal disinfection and return-to-service assessment, and multilingual risk-communication templates. The purpose is not to weaken the public health autonomy of port states, but to specify port assessment, case transfer, sample testing, allocation of isolation resources, and information-sharing processes before a crisis occurs.

4. Operational recommendations for ANDV preparedness and response on cruise ships

Based on the above analysis of transmission evidence and risk characteristics, cruise-ship control of ANDV should move from a traditional passive post-event response to active risk management that is whole-of-journey, graded, and operationally feasible (Table 3). The prevention chain can be divided into four core stages or levels: pre-voyage ecological exposure alert, embarkation and onboard suspected case response, cluster-event response, and severe or fatal event response. Each stage should specify trigger conditions, core actions, and principles for de-escalation or termination, creating a closed-loop management system (Fig. 2).

Table 3.

Suggested graded response for suspected ANDV events on cruise ships.

Stage/level	Trigger condition	Core measures	Principles for de-escalation or termination
Level I: Ecological exposure alert	The route includes ANDV-endemic areas, high-risk field landing sites, or environments with potential rodent exposure.	Pre-voyage education; rodent-source exposure questionnaire; crew training in PPE, sampling, and cleaning/disinfection; stockpiling of point-of-care testing (POCT) reagents and transfer materials.	After completion of pre-voyage risk assessment and material verification, enhanced routine monitoring continues during the voyage and is lifted automatically after voyage completion.
Level II: Embarkation/ onboard suspected-case response	Fever, myalgia, gastrointestinal symptoms, or respiratory symptoms plus field exposure in an endemic area, rodent-contaminated exposure, or contact with a suspected case.	Single-cabin isolation; medical mask use; contact, droplet, and eye/face protection; sampling and testing; close-contact registration; limitation of nonessential gatherings.	Adjust according to symptoms, exposure level, repeated test results, and public health assessment; do not use a single negative nucleic acid test as the only release criterion.
Level III: Cluster-event response	Two or more epidemiologically linked symptomatic cases onboard, positive POCT or shore-based testing, or a clearly identified high-risk contact chain.	Establish isolation zones; escalate PPE; stratify management of cabinmates, caregivers, and key shared-activity contacts; notify flag state, port state, and IHR focal points; initiate remote consultation.	De-escalate after 14 consecutive days without new cases, completion of contact observation, terminal environmental disinfection, and risk assessment by competent authorities.
Level IV: Severe/fatal event response	Respiratory failure, shock, death, or need for shore-based advanced life support.	Activate medical evacuation plan; coordinate with pre-designated receiving port and hospital; implement triple-packaged sample transfer; conduct protected transfer of asymptomatic high-risk contacts; activate crisis communication.	Lift measures after joint assessment of medical management, quarantine management, and return-to-service conditions by the port state, flag state, operator, and public health agencies.

Abbreviations: ANDV, Andes virus; PPE, personal protective equipment; POCT, point-of-care testing; IHR, International Health Regulations.

Fig. 2.

Whole-of-journey biosecurity framework for ANDV control on ecologically sensitive cruise routes [26]. Illustrated using Photopea (PS-based image editor). Abbreviations: ANDV, Andes virus; HVAC, heating, ventilation, and air conditioning; PCR, polymerase chain reaction; PPE, personal protective equipment.

4.1. Physical infrastructure and diagnostic capacity

New expedition cruise ships and vessels that regularly operate on ecologically sensitive routes should be equipped with modular convertible negative-pressure isolation cabins or isolation zones. When a high-consequence pathogen alert is triggered, they should be rapidly convertible into temporary isolation units with independent exhaust and pressure monitoring.

Existing cruise ships can adopt combined solutions using mobile high-efficiency particulate air (HEPA) filtration units, portable negative-pressure devices, temporary isolation zones, and cabins with independent bathrooms. Smaller vessels with fewer passengers should prioritize early recognition, personal protective equipment (PPE) stockpiles, remote consultation, and transfer agreements. They should not mechanically apply large-ship engineering standards that may waste resources.

Shipboard testing should rely on closed nucleic acid testing platforms where available and should primarily support rapid screening and transfer decisions. Virus isolation, culture, and processing of high-titer samples from suspected ANDV cases should be restricted to appropriately qualified high-level biosafety laboratories. Cruise-ship medical points should not conduct viral culture, in order to reduce laboratory exposure risk. The purpose of shipboard point-of-care testing (POCT) is to shorten time to suspected-case identification, guide isolation stratification, and prioritize medical transfer; it is not a substitute for confirmatory testing and genomic tracing by shore-based public health laboratories. Results must be interpreted together with clinical symptoms and epidemiologic history.

At present, ANDV-specific rapid diagnostic capacity is not routinely available on most cruise ships. Shipboard testing, where feasible, should be regarded as a triage-support tool rather than definitive diagnosis. Test performance will depend on specimen type, timing relative to symptom onset, viral load, assay validation, and operator training. A negative early test should therefore not override compatible exposure history and clinical deterioration. Confirmatory RT-qPCR, serology, and genomic sequencing should remain the responsibility of qualified shore-based reference laboratories.

4.2. Case definition, exposure-risk assessment, and contact stratification

For routes originating from or calling at ANDV-endemic areas, a concise and operational exposure-risk assessment should be performed before the voyage and at embarkation. The assessment should ask whether travelers entered areas with rodent activity, contacted environments contaminated with rodent feces or urine, participated in outdoor camping or stayed in enclosed huts, cared for a suspected case, or had close contact with persons with fever or respiratory symptoms.

Response triggers should combine symptoms, exposure history, and clustering signals rather than relying on a single temperature threshold.

Close contacts should be managed by risk strata rather than by indiscriminate expansion of control measures. Core close contacts include cabinmates, caregivers, persons with body-fluid contact, persons with prolonged close face-to-face contact, and participants in shared high-risk activities. Other persons in the same ventilation unit may be classified as general or potential exposure groups according to activity traces, cabin distance, ventilation structure, and duration of exposure. In the absence of clear exposure evidence, they should receive symptom monitoring and risk communication rather than being managed in the same way as core close contacts, minimizing disruption to normal ship operations.

4.3. Cross-border governance and coordination mechanisms

Cruise-ship biosecurity is a typical cross-border public health governance issue. The most practical path forward is not an immediate mandatory global agreement covering all cruise ships, but regional memoranda of understanding and operational checklists for ecologically sensitive expedition routes, especially those involving South America, Antarctica, and the South Atlantic.

Such checklists should specify pre-designated receiving ports, hospitals with ICU or ECMO capacity, reference laboratories, aeromedical evacuation providers, sample-transfer contacts, procedures for transporting asymptomatic contacts, and standards for terminal disinfection assessment. These elements should be directly callable during emergencies.

Within the IHR framework, a dedicated guidance document for cruise-ship events involving high-consequence pathogens could further clarify the responsibilities and minimum obligations of flag states, port states, operating companies, and countries of passenger origin. The goal is not to weaken the public health autonomy of port states, but to clarify in advance the processes for port-entry assessment, medical evacuation, allocation of isolation resources, information sharing, and risk communication, thereby avoiding the loss of critical treatment windows while cases remain at sea or at offshore anchorage.

Multisource information monitoring and early-warning networks can further improve the efficiency of cross-border public health responses [32], [33].

4.4. Genomic surveillance and data-sharing infrastructure

Establishing pre-approved data-sharing pathways before an event occurs, including agreements on sample custody, sequencing turnaround times, and public communication protocols, will reduce delays and improve the evidence base for real-time decision-making.

These recommendations are based on publicly available evidence and expert judgment; feasibility will vary by vessel type, route, and regulatory context. Prospective validation through simulation exercises and pilot implementation on selected ecologically sensitive routes is recommended.

This review is qualitative in nature; quantitative risk modeling was beyond its scope. Cost-effectiveness analyses and formal health-economic evaluations should complement these recommendations in future work.

During an ongoing outbreak, real-time or near-real-time genomic sequencing of clinical specimens can clarify transmission chains, identify potential viral evolution, and inform risk-assessment updates. Shipboard or port-based rapid sequencing platforms, coupled with standardized data-sharing agreements with national reference laboratories and international databases (e.g., GISAID, GenBank), should be incorporated into cruise-ship biosecurity protocols for ecologically sensitive routes.

5. Summary and outlook

The central lesson of the 2026 ANDV cluster associated with the MV Hondius is not that cruise-ship settings have proven efficient aerosol transmission of ANDV. Rather, enclosed ocean-going environments may amplify the response difficulty posed by pathogens that originate from animal-source exposure, have limited person-to-person transmission potential, and can cause severe disease with high case fatality. The key methodological takeaway from the MV Hondius event is the need for graded evidence interpretation: confirmed hazards (rodent-source exposure, close-contact spread) deserve full operational weight, whereas unverified mechanisms (long-range aerosol transmission, shipboard environmental persistence at scale) should be flagged as hypotheses pending direct evidence [6], [7], [8], [9], [21], [28], [29].

Future cruise-ship preparedness will require moving beyond conventional sanitation toward an integrated, voyage-long defense architecture. Under this model, ecological risk assessment at the route-planning stage connects forward to clinical surveillance during embarkation, which in turn links to tiered containment, environmental control, diagnostic testing, evacuation, and post-voyage data sharing under pre-established international agreements [31], [32], [33]. Sustaining safe cruise operations on ecologically sensitive routes will ultimately depend on aligning three pillars that are currently managed in isolation: evidence-based clinical protocols, vessel-level engineering preparedness, and cross-border governance frameworks [31].

Conflict of interest statement

The authors declare that there are no conflicts of interest.

Author contributions

Peng Xie: Writing – review & editing, Writing – original draft. Jintao Li: Conceptualization, Supervision.