MV Hondius Andes Hantavirus Outbreak - Initial Assessment

19 May 2026 - The only hantavirus capable of human-to-human transmission has claimed three lives and left one patient on life support; PSYOPOLY tracks the full MV Hondius cluster.

By Filip Skierski

Epidemiology Overview

Andes virus is an enveloped, tri-segmented, negative-sense RNA virus belonging to the genus Orthohantavirus, family Hantaviridae, within the order Bunyavirales [1]. The Andes strain is one of approximately 38 recognised or suspected hantavirus strains. Transmission to humans primarily occurs through inhalation of aerosolised particles contaminated with infected rodent urine, faeces, or saliva, linking infection risk closely to environmental and ecological exposure patterns [2].

The Andes strain remains particularly significant because it is currently the only documented hantavirus variant with evidence of human-to-human transmission [3]. This distinction substantially alters outbreak containment and biosecurity considerations compared with conventional zoonotic spillover pathogens. According to the World Health Organization and Pan American Health Organization epidemiological alert published in 2025, eight countries within the Southern Cone of South America reported a combined total of 229 cases and 58 deaths from hantavirus cardiopulmonary syndrome (HCPS), with Bolivia and Paraguay demonstrating increased incidence compared with previous surveillance data [4].

Historical outbreaks further demonstrate the outbreak potential of Andes virus. Most notably, the Epuyén outbreak in Argentina resulted in 34 confirmed cases and 11 deaths, providing some of the strongest evidence supporting person-to-person transmission [5]. Additional cluster investigations in southern Argentina suggested incubation periods ranging from 8–45 days and indicated that infected individuals may be most infectious during the prodromal phase, with limited evidence of healthcare worker transmission [6].

Symptoms and Clinical Significance

Early hantavirus infection is largely non-specific in nature and clinically overlaps with many common viral syndromes, creating substantial diagnostic uncertainty. The Centers for Disease Control and Prevention suggests that infected individuals are likely most infectious during the early symptomatic (prodromal) phase [3].

Common early symptoms include:

  • Fever
  • Myalgia (predominantly affecting larger muscle groups)
  • Headache
  • Fatigue
  • Dizziness

The principal clinical concern associated with the Andes strain is progression to Hantavirus Cardiopulmonary Syndrome, a severe disease characterised by rapidly progressive respiratory compromise and cardiopulmonary failure. Mortality rates have been reported as high as 50% in some outbreaks [7]. This is broadly supported by CDC estimates suggesting that nearly 40% of patients who develop respiratory manifestations of HCPS will die [8].

Treatment and Management

Currently, there is no approved vaccine or specific antiviral treatment for hantavirus infection [8]. Management therefore remains primarily supportive.

Patients progressing to severe HCPS may require:

  • Intensive care admission
  • Mechanical ventilation
  • Vasopressor support
  • Extracorporeal membrane oxygenation (ECMO) in severe cases

It is important to note that not all infections progress to HCPS, although the potential for rapid deterioration contributes significantly to the public health and biosecurity concern surrounding the virus.

Ultimately, the risk to the general public is considered very low as it requires extensive human to human contact as reported by health care professionals worldwide including those working on current isolation measure for the passengers of MV Hondius. It is important to note that not all infections progress to HCPS, although the potential for rapid deterioration contributes significantly to the public health and biosecurity concern surrounding the virus.

italic text This briefing is intended for informational and analytical purposes only and does not constitute medical advice, clinical guidance, or public health instruction. Individuals concerned about possible illness or exposure should seek advice from a qualified healthcare professional or relevant public health authority.

References

  • (1) Velavan TP, Schmidt-Chanasit J. When Rare Zoonoses Travel: Andes virus, Hantavirus Cardiopulmonary Syndrome, and the Preparedness Gap. International Journal of Infectious Diseases. 2026. DOI: https://doi.org/10.1016/j.ijid.2026.108778
  • (2) HANTAAER2023.pdf
  • (3) CDC – About Andes Virus
  • (4) Pan American Health Organization / World Health Organization. Epidemiological Alert: Hantavirus in the Americas Region. 19 December 2025. Washington, D.C.: PAHO/WHO.
  • (5) Health Service Navigator – Andes Strain of Hantavirus
  • (6) Lázaro ME, Cantoni GE, Calanni LM, et al. Clusters of Hantavirus Infection, Southern Argentina. Emerging Infectious Diseases. 2007;13(1):104. DOI: https://doi.org/10.3201/eid1301.060404
  • (7) Coelho RM, Kehl S, Periolo N, et al. Virological Characterization of a New Isolated Strain of Andes Virus Involved in the Recent Person-to-Person Transmission Outbreak Reported in Argentina. medRxiv. 2024. DOI: https://doi.org/10.1101/2024.10.08.24312738
  • (8) CDC – Clinician Brief: Hantavirus Pulmonary Syndrome

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