The Only Hantavirus Known for Human-to-Human Transmission: Andes Virus

Posted on 2026-05-28

The Andes Virus (ANDV) occupies unique position in emerging infectious disease research due to one defining characteristic: it is the only hantavirus with documented human-to-human transmission.

ANDV is the strain responsible for the recent outbreak of hantavirus linked to the Dutch expedition cruise ship MV Hondius, which has renewed attention to this unusual member of the hantavirus family. The first case was reported on the 2nd of May 2026 and as of the 27th of May 2026, the outbreak has resulted in 13 cases and 3 deaths [1]. This is far from the first outbreak associated with ANDV. Since its identification in southern Argentina in 1995, multiple outbreaks have been reported across South America, several of which drew international attention due to evidence suggesting interpersonal transmission [2]. 

One of the most extensively studied outbreaks occurred in Epuyén, Argentina, between 2018 and 2019, resulting in 34 confirmed cases and 11 deaths [3]. Combined epidemiological investigations and viral genomic sequencing provided some of the strongest evidence for person-to-person transmission of ANDV [3]. Supporting this, molecular analyses from a separate 2014 outbreak in Argentina identified near-identical full-length viral genome sequences among patients, further reinforcing evidence of direct interpersonal transmission [4]. 

Like other New World hantaviruses, ANDV is associated with hantavirus pulmonary syndrome (HPS), a severe respiratory disease characterised by endothelial dysfunction, increased vascular permeability, hypoxemia and progression to cardiopulmonary failure [5]. Following a non-specific prodromal phase, patient deterioration can occur abruptly, often requiring intensive respiratory and haemodynamic support. Once HPS has developed, the disease carries a case fatality rate as high as 50% [6].

Figure 1. Pathophysiology of hantavirus pulmonary syndrome (HPS) caused by ANDV. Infection of pulmonary endothelial cells by ANDV leads to endothelial dysfunction, increased vascular permeability, pulmonary edema, hypoxemia and ultimately cardiopulmonary collapse. 

The primary reservoir host of ANDV is the long-tailed pygmy rice rat (Oligoryzomys longicaudatus). In these rodents, the infection is established in a chronic and asymptomatic state, with transmission between rodents primarily occurring through bites during aggressive encounters. However, human infection most commonly occurs through the inhalation of aerosolised virus. This occurs when infected dried rodent excreta, such as urine and faeces, are disturbed during activities such as cleaning [7]. 

Several studies have also provided insight into the potential mechanisms underlying the spread between humans. One investigation analysing transmission clusters concluded that human-to-human transmission of ANDV likely occurs during the prodromal phase of infection, before the onset of severe cardiopulmonary symptoms [8]. This has important public health implications, as individuals experiencing mild symptoms may continue engaging in prolonged close-contact interactions, thereby increasing the risk of transmission. Furthermore, the incubation period of ANDV can extend to as long as 40 days, creating additional opportunities for secondary exposure before diagnosis or isolation measures are implemented [9]. 

Although prolonged contact has long been identified as a contributing factor, the precise routes of interpersonal transmission are not yet completely understood. One key study published by Pizarro et al. in 2020 used immunohistochemical analysis of infected rodent tissue and human tissue samples from fatal HPS to investigate the localisation of ANDV. Viral antigens were identified in the salivary glands, pulmonary epithelium and macrophages of both the rodents and humans. These findings support the hypothesis that both saliva and respiratory droplets may contribute to this transmission [10].  

Figure 2: The theorised transmission route of ANDV. ANDV is maintained through rodent-to-rodent transmission and spreads to humans via inhalation of infected rodent excreta. ANDV is hypothesised to spread between humans through respiratory droplets. 

The repeated emergence of ANDV outbreaks has highlighted gaps in preparedness for high-consequence zoonotic pathogens. Despite decades of research, no licensed vaccine or approved antiviral therapy for hantavirus currently exists in Europe or the United States [11]. Although ribavirin has shown promising experimental benefits in some hantavirus infections [12], it remains unlicensed for hantavirus treatment [13]. Research into hantavirus has been limited by the sporadic nature of outbreaks, small patient populations and the challenges associated with high-containment research. These factors have hindered the development of effective vaccines and therapeutics. 

These outbreaks have reinforced the importance of improved surveillance and rapid diagnostic capacity. Methods such as ELISA and RT-PCR remain central to laboratory diagnosis [14]. The development of reliable, rapid immunological assays may improve early case identification in remote outbreak settings where laboratory infrastructure is limited. Molecular surveillance and genomic sequencing have become increasingly important for tracing transmission chains, monitoring viral evolution and distinguishing zoonotic exposure from interpersonal spread. 

In summary, ANDV remains one of the most significant hantaviruses from both a clinical and public health perspective due to its unique capacity for human-to-human transmission. Recent outbreaks have highlighted the importance of rapid diagnostics and molecular surveillance. As emerging zoonotic threats become increasingly important to global health preparedness, reliable research tools are essential for advancing hantavirus research and supporting the development of therapeutics and vaccines. 

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References: 

[1] European Centre for Disease Prevention and Control. (2026). Andes hantavirus outbreak in cruise ship. [online] Available at: https://www.ecdc.europa.eu/en/infectious-disease-topics/hantavirus-infection/surveillance-and-updates/andes-hantavirus-outbreak [Accessed 27 May 2026]. 

‌[2] UK (2021). Andes hantavirus: epidemiology, outbreaks and guidance. [online] GOV.UK. Available at: https://www.gov.uk/guidance/andes-hantavirus-epidemiology-outbreaks-and-guidance [Accessed 27 May 2026]. 

[3] Martínez, V.P., Di Paola, N., Alonso, D.O., Pérez-Sautu, U., Bellomo, C.M., Iglesias, A.A., Coelho, R.M., López, B., Periolo, N., Larson, P.A. and Nagle, E.R., 2020. “Super-spreaders” and person-to-person transmission of Andes virus in Argentina. New England Journal of Medicine, 383(23), pp.2230-2241. 

[4] Alonso, D.O., Pérez-Sautu, U., Bellomo, C.M., Prieto, K., Iglesias, A., Coelho, R., Periolo, N., Domenech, I., Talmon, G., Hansen, R., Palacios, G. and Martinez, V.P. (2020). Person-to-Person Transmission of Andes Virus in Hantavirus Pulmonary Syndrome, Argentina, 2014. Emerging Infectious Diseases, [online] 26(4), pp.756–759. doi:10.3201/eid2604.190799. 

‌[5] MacNeil, A., Nichol, S.T. and Spiropoulou, C.F. (2011). Hantavirus pulmonary syndrome. Virus Research, [online] 162(1–2), pp.138–147. doi:10.1016/j.virusres.2011.09.017. 

‌[6] World Health Organisation (2026). Hantavirus. [online] Who.int. Available at: https://www.who.int/news-room/fact-sheets/detail/hantavirus [Accessed 27 May 2026]. 

[7] Velavan, T.P. and Schmidt-Chanasit, J. (2026). When Rare Zoonoses Travel: Andes virus, Hantavirus Cardiopulmonary Syndrome, and the Preparedness Gap. International Journal of Infectious Diseases, [online] p.108778. doi:10.1016/j.ijid.2026.108778. 

‌[8] Martinez, V.P., Bellomo, C., San Juan, J., Pinna, D., Forlenza, R., Elder, M. and Padula, P.J. (2005). Person-to-Person Transmission of Andes Virus. Emerging Infectious Diseases, [online] 11(12), pp.1848–1853. doi:10.3201/eid1112.050501. 

[9] Vial, P.A., Valdivieso, F., Mertz, G., Castillo, C., Belmar, E., Delgado, I., Tapia, M. and Ferrés, M. (2006). Incubation Period of Hantavirus Cardiopulmonary Syndrome. Emerging Infectious Diseases, [online] 12(8), pp.1271–1273. doi:10.3201/eid1208.051127. 

[10] Pizarro, E., Navarrete, M., Mendez, C., Zaror, L., Mansilla, C., Tapia, M., Carrasco, C., Salazar, P., Murua, R., Padula, P., Otth, C. and Rodríguez, E.M. (2020). Immunocytochemical and Ultrastructural Evidence Supporting That Andes Hantavirus (ANDV) Is Transmitted Person-to-Person Through the Respiratory and/or Salivary Pathways. Frontiers in Microbiology, [online] 10. doi:10.3389/fmicb.2019.02992. 

‌[11] Paulsen, G.C., Frenck, R., Tomashek, K.M., Alarcon, R.M., Hensel, E., Lowe, A., Brocato, R.L., Kwilas, S.A., Josleyn, M. D and Hooper, J.W. (2023). Safety and Immunogenicity of an Andes Virus DNA Vaccine by Needle-Free Injection: A Randomized, Controlled Phase 1 Study. The Journal of Infectious Diseases, [online] 229(1), pp.30–38. doi:10.1093/infdis/jiad235. 

[12] Safronetz, D., Haddock, E., Feldmann, F., Ebihara, H. and Feldmann, H. (2011). In Vitro and In Vivo Activity of Ribavirin against Andes Virus Infection. PLoS ONE, [online] 6(8), p.e23560. doi:10.1371/journal.pone.0023560. 

[13] Who.int. (2024). Hantavirus cluster linked to cruise ship travel, Multi-country. [online] Available at: https://www.who.int/emergencies/disease-outbreak-news/item/2026-DON600 [Accessed 27 May 2026]. 

[14] Vial, C., Martinez-Valdebenito, C., Rios, S., Martinez, J., Vial, P.A., Ferres, M., Rivera, J.C., Perez, R. and Valdivieso, F. (2016). Molecular method for the detection of Andes hantavirus infection: validation for clinical diagnostics. Diagnostic Microbiology and Infectious Disease, [online] 84(1), pp.36–39. doi:10.1016/j.diagmicrobio.2015.07.019. 

‌Written by Eleanor Crawley