A-Z Index × Submit A-Z Index × Submit A-Z Index Search Dropdown × Submit Facebook Twitter LinkedIn Syndicate Emerging Infectious Disease journal ISSN: 1080-6059 Disclaimer: Early release articles are not considered as final versions. Any changes will be reflected in the online version in the month the article is officially released.
By using historical contact tracing data, we estimated that 23.4% of case-patients caused 80% of Andes virus (ANDV) person-to-person transmission. We demonstrated a low but nonnegligible probability of observing a large-scale ANDV infection outbreak in a rodent-free setting consisting of close contacts, despite the historically self-limited person-to-person transmission of ANDV.
Hantaviruses are rodentborne zoonotic enveloped RNA viruses belonging to the family Hantaviridae ( 1 ). The genus Orthohantavirus , which belongs to the subfamily Mammantavirinae, is the only genus in Hantaviridae that can cause disease in humans ( 1 ). Infections in humans occur mainly through inhalation of aerosolized excreta from infected rodents, which can lead to hantavirus pulmonary syndrome, a severe respiratory disease with a case-fatality rate of up to 50% in the Americas, depending on the infecting hantavirus type ( 2 ). Although uncommon, person-to-person transmission of Andes virus (ANDV), a member of the genus Orthohantavirus , has been documented in South America in recent decades, typically in high-intensity close-contact settings, such as households and social gatherings ( 3 – 9 ).
On May 2, 2026, an ANDV outbreak aboard the MV Hondius cruise ship was reported to the World Health Organization (WHO), with the first case illness onset on April 3 ( 10 ). Subsequent epidemiologic investigations proposed a working hypothesis that person-to-person transmission originated from a seed case in a person who probably acquired infection through environmental exposure during travel in Argentina before boarding the ship on April 1 ( 10 ). By July 2, a total of 13 ANDV cases had been identified, including 12 laboratory-confirmed and 1 probable case; 3 of those cases were fatal ( 10 ). According to the initial WHO notification for the outbreak on May 2, public health and control measures, including contact tracing, case isolation, clinical care, and medical evacuation of symptomatic passengers, had been implemented onboard the ship ( 11 ). By using historical contact tracing data, we aimed to estimate key epidemiologic characteristics of person-to-person transmission of ANDV, including the serial interval (SI) distribution and transmission heterogeneity, given that those traits strongly shape outbreak size.
We conducted a literature review of historical ANDV outbreak investigations and extracted contact tracing data from ANDV case clusters that involved person-to-person transmission events. We only included studies conducted in Argentina, given that the seed case-patient of the 2026 outbreak was most likely infected there, according to the WHO report ( 10 ). We identified 5 eligible studies that provided detailed contact histories and viral genetic evidence strongly supporting person-to-person transmission and linking infections to specific viral lineages or strains ( 3 – 7 ). We extracted symptom onset dates to calculate the SI and compiled case-cluster sizes to estimate the effective reproduction number (R t ) and transmission heterogeneity measured by a dispersion parameter (k) ( 12 ). In case-clusters, we considered terminal…