Andes virus: MV Hondius outbreak

Andes virus (ANDV)

• is a type of hantavirus, within the order Bunyavirales
  
  
• ANDVinfection in humans was first described in 1995 in Argentina, and was identified in Chile later in the same year
  • is a cause of hantavirus cardiopulmonary syndrome (HCP) in South America, which is a potentially fatal, acute medical complication of specific hantavirus infections
    
• wild rodents of the family Cricetidae are the natural animal reservoir of ANDV, particularly the long-tailed pygmy rice rat (Oligoryzomys longicaudatus). Humans can acquire ANDV infection by contact with infected rodents or their excreta in South America, principally in Argentina and Chile, and rarely through contact with an infected person
  
• are several ANDV hantavirus strains associated with HCPS (1)
  • officially classified strains include Castelo dos Sonhos virus, Lechiguanas virus and Orán virus, whilst Araucária virus, Araraquara virus, Bermejo virus, Buenos Aires virus, Juquitiba virus, Paranoa virus and Plata virus are unclassified strains

Andes virus: MV Hondius outbreak

MV Hondius cruise ship outbreak (April–June 2026) demonstrated the behavior of Andes virus (ANDV) in confined, close-contact environments outside traditional rural, endemic zones.

Key Clinical Features

Sustained Human-to-Human Transmission:

• confirmed as the only orthohantavirus capable of direct person-to-person spread
• index case:
  • soonotic acquisition via contact with the long-tailed pygmy rice rat (Oligoryzomys longicaudatus) or its excreta in southern South America, prior to departure from Ushuaia, Argentina
• secondary spread:
  • confined quarters facilitated subsequent transmission among passengers and crew. Genomic sequencing revealed near-identical viral strains (maximum one nucleotide variance), confirming a single introduction followed by secondary human-to-human propagation.

Mortality and Demographics:

• total cluster: 13 cases (12 laboratory-confirmed, 1 probable).
• deaths: 3.
• case Fatality Ratio (CFR): 23%, highlighting the severe and aggressive progression of Hantavirus Cardiopulmonary Syndrome (HCPS).
• median age: 65 years (reflecting the travel cohort).

Risk Mapping & Exposure Criteria

High-risk contact vectors in shared or confined spatial environments include:

• sharing tight physical infrastructure (e.g., stateroom cabins, shared bathroom facilities)
• close proximity during dining (sharing tables/meals)
• close proximity threshold:
  • being within 2 metres (6 feet) of a symptomatic case for greater than 15 minutes without appropriate personal protective equipment (PPE).

Public Health & Isolation Protocols

Due to the prolonged incubation period of ANDV, international bodies (WHO, ECDC, UKHSA) mandated a coordinated global contact-tracing strategy spanning 33 nations. Standardized protocols include:

• Quarantine duration:
  • mandatory 42 to 45 days of active isolation from the date of last known exposure
• Surveillance:
  • weekly PCR testing throughout the quarantine window to detect pre-symptomatic viral loads early.

Notes:

• while ANDV is traditionally limited to rural South American habitats, the MV Hondius event highlights that international travel and close-quarter environments present a real risk for secondary clusters
  • clinicians should maintain a high index of suspicion and take a thorough travel history in patients presenting with unexplained acute respiratory distress or suspected HCPS

Reference:

1. Public Health England (May 2021). Andes hantavirus: epidemiology, outbreaks and guidance
2. Harris GH et al. Andes Virus — A Clinical Review. NEJM July 15, 2026.