A suspected hantavirus outbreak on the polar cruise ship MV Hondius has resulted in the deaths of three passengers, with one patient in intensive care in a South African hospital. The World Health Organization (WHO) reported that the outbreak occurred while the ship was traveling between Argentina and Cape Verde. Among the deceased were a Dutch couple, and at least one case of hantavirus has been laboratory confirmed, with five additional suspected cases.

Cape Verdean officials have denied the MV Hondius permission to dock in their ports to protect national public health, with the ship now considering sailing to Spain's Canary Islands for further medical screening. Oceanwide Expeditions, the ship's operator, confirmed the first passenger, a Dutch national, died on April 11, with his wife later becoming unwell and dying after disembarking. A British national fell seriously ill on April 27, was medically evacuated to South Africa, and a variant of hantavirus was identified in this patient. A German national died on May 2, with the cause not yet established. Two crew members also experienced acute respiratory symptoms, though hantavirus has not been confirmed in them, nor has a connection been established to all three deaths.

Hantaviruses are a group of orthohantaviruses primarily found in rodents like mice, rats, and voles, which serve as natural reservoirs. According to Professor Adam Taylor of Lancaster University, there are at least 38 recognized species globally, with 24 capable of causing disease in humans. Dr. Yomani Sarathkumara from the University of Queensland notes that human infections are rare and often misdiagnosed. Transmission typically occurs through the inhalation of or contact with infected rodent faeces, urine, and saliva, or, less commonly, through bites and scratches from contaminated animals. Agricultural communities face higher risks due to increased exposure to infected rodents.

Associate Professor Vinod Balasubramaniam of Monash University Malaysia explained that hantaviruses are generally linked to environmental exposure to rodents and do not usually spread easily from person to person like influenza or COVID-19. There are two main lineages: Old World hantaviruses, found in Europe and Asia, cause Haemorrhagic Fever with Renal Syndrome (HFRS), affecting the kidneys with symptoms like intense headaches, back and abdominal pain, fever, and potential kidney damage. New World hantaviruses, prevalent in the Americas, cause Hantavirus Pulmonary Syndrome (HPS), leading to rapidly progressive pulmonary syndrome and respiratory failure. The Andes virus, common in South America, is primarily spread by the long-tailed pygmy rice rat. Early HPS symptoms are flu-like, making diagnosis difficult.

The incubation period for hantaviruses can range from one to eight weeks. While a small number of studies have documented human-to-human spread of the Andes strain in South America, a systematic review found insufficient evidence for widespread human-to-human transmission. The WHO is investigating the outbreak on MV Hondius. Biologically plausible possibilities for the outbreak include rodent contamination within the vessel (storage areas, cabins) or passengers/crew members being exposed during land-based activities due to the long incubation periods. Person-to-person transmission is considered theoretically plausible but highly unlikely, with the main risk stemming from disturbing contaminated rodent materials in enclosed or poorly ventilated spaces.

The mortality rates vary by hantavirus type: HFRS has a fatality rate of 1% to 15%, while New World hantaviruses causing HPS have a much higher fatality rate of about 40% in the Americas. There is no definitive antiviral drug that works effectively, so infections are typically managed with supportive care, which includes oxygen, fluid management, blood pressure support, and ventilation for HPS. Early diagnosis is crucial for effective supportive care, and broad-spectrum antivirals are currently being researched as potential early treatments.

In March 2025, Betsy Arakawa, wife of actor Gene Hackman, was reportedly found to have died in her Santa Fe home from hantavirus pulmonary syndrome. Historically, a hantavirus outbreak in southern Argentina in 2019 also resulted in at least nine deaths, prompting officials to impose quarantines.