Hantavirus is a rare but extremely dangerous rodent-borne virus that can be deadly. Upon infection, the fatality rate ranges from 38% to 50%, meaning that if you have been infected, you likely have a 50-50 chance of survival, with each day potentially marking the onset of increasingly severe symptoms. The virus spreads through aerosolized rodent urine, droppings, or saliva. However In a recently reported case, albeit limited, the Andes strain (a type of Hantavirus) has shown potential for human-to-human transmission which has never been seen before in cases of these virues. The recent outbreak in May 2026 on the Dutch-flagged MV Hondius cruise ship, which originated from Argentina, is the first-ever recorded instance of multi-country spread. As of May, there are a total of 11 confirmed cases, of which 3 patients have unfortunately passed away, according to WHO reports.
The ship departed on the 1st of April, 2026, carrying a total of 175 people, comprising 114 passengers and 61 crew members. In early April, 28 individuals displayed signs of illness, prompting notification to the WHO on the 2nd of May, 2026. By May, the crew managed to test the passengers showing symptoms of the sickness via PCR sequencing, confirming a total of eight cases (six positive, two probable). Following these findings, three of the infected passengers passed away, and the cruise staff quarantined on Cape Verde with the remaining sick individuals. The other ~108 passengers, representing 23 different nationalities, were reportedly cleared and repatriated to the US, Europe, or Asia according to WHO. All infected passengers were also returned to their home countries and are now being monitored and receiving treatment.
Why Is the Hanta Virus soo dangerous?
Hantaviruses belong to the Hantaviridae family and are enveloped, negative-sense RNA viruses. The first systematic studies emerged during the Korean War in 1951, when over three thousand UN troops developed hemorrhagic fever with renal syndrome (HFRS). It was not until 1978 that South Korean virologist Dr. Ho Wang Lee managed to isolate the virus from a field mouse collected near the Hanta River. This location also gave rise to the name Hantaan Virus (HTNV) as its prototype. However, the “New World” hantaviruses causing HPS were actually identified in 1933 during the Four Corners outbreak in the US Southwest (Sin Nombre virus), although no comprehensive studies could be conducted at that time.
The virus is a type of zoonosis, meaning that rodents are its natural reservoir, causing lifelong asymptomatic infections in their hosts. The infection persists in these animals without harming them much and the virus is shed in urine, feces, and saliva. Humans are dead-end hosts, meaning we cannot carry the virus; instead, we suffer from its increasingly deadly symptoms and, in normal cases, do not spread it. Outbreaks, like the recent one, usually occur when the rodent population in a territory persistently blooms and humans disturb these infested areas. Deforestation, agriculture, and climate-driven habitat changes could also lead to infection; however, the likelihood of infection without physical contact with the shedding of rodents is very low. Virus particles aerosolize easily when dried droppings are disturbed, but exposure through contaminated food and water is rare. Most strains, as mentioned before, do not spread person-to-person, except for limited transmission of the New World type of Andes Virus (ANDV), named after its country of origin in South America.
The symptoms are what make this virus truly dangerous. Incubation occurs in the first 1-8 weeks, during this early phase, fever-like symptoms, chills, muscle aches, fatigue, dizziness, nausea, and abdominal pain are commonly observed. The later stages of the various strains of the virus present a more diverse array of symptoms. In the case of the “New World” type (HPS/HCPS), the following symptoms can occur: low blood pressure, heart strain, heavy cough, and shortness of breath, stemming from rapid pulmonary edema that fills the host’s lungs with fluid. For the HFRS (Old World type), internal bleeding, kidney failure, and low blood pressure typically manifest. Diagnosing the virus in the early stages is extremely challenging, as symptoms mimic those of the flu, and only blood tests can confirm it. The best-case scenario offers mild symptoms or, with early supportive care, a chance of full recovery with mild to no lasting effects; however, even that is not guaranteed, and survival without prompt ICU intervention is technically impossible. The virus can progress so rapidly that within 24-48 hours of reaching the cardiopulmonary phase, it can lead to respiratory failure, cardiac collapse, and death. This is why the fatality rate can be as high as 50% according to recent data, and no specific antiviral treatment exists yet.
CNN has recently reported that in the early stages, the cruise was denied boarding from the islands due to the severity of the virus; however, after resolving diplomatic issues, the virus was ultimately delivered to nine countries, as far as we know.
It only adds to the concern that the Andes strain (responsible for the current outbreak) has shown person-to-person spread, displaying potential for further transmission once it reaches outside of close quarters. Human infections are incredibly hard to diagnose on time due to nonspecific and mild symptoms, triggering a massive immune overreaction that damages blood vessels, lungs, and kidneys. Within that cruise, there were approximately 160 other people who could have been infected but have not shown signs yet. Some individuals with stronger immune systems, could experience fever-like symptoms without even noticing it, making it possible for the team to have missed diagnosing them. Given the nature of this type of strain, it could spread further through human contact.
The virus can survive in cold conditions for weeks, making even a deceased host infectious for a long period of time, and there is no broad eradication program because it is not a high-volume disease, or at least it was not. Currently, there is no specific antiviral or licensed vaccine for most strains, especially for the New World Hantavirus Pulmonary Syndrome (HPS), and the available treatment is purely supportive, including oxygen, mechanical ventilation, and fluid and blood pressure support. At this stage, the treatment focuses solely on buying time for the immune system to clear the virus, with survival depending on outliving the symptoms. Some inactivated vaccines are used in Asia (e.g., for Hantaan virus in China/Korea), but they are not broadly available or effective against all strains.
Present efforts in the US to create an antidote include DNA vaccines developed by the Army’s Hooper lab, which have shown strong neutralizing antibodies, however, these have only passed phase 1 trials. The mRNA and protein subunit candidates being developed at the University of Saskatchewan and the University of Bath are also in the pre-clinical phases so without a major “Warp Speed“-style push like that seen during the COVID-19 pandemic, full approval of these could take up to 10 years, although researchers note that recent events may accelerate interest.
Even though the Virus is known to be dangerous, its extremely rare cases of infection make a lockdown unlikely. Nevertheless, it is always important to stay informed. To keep up with the recent outbreak of the Hantavirus, subscribe to our newsletter, or head straight to WHO’s official Disease Outbreak News Page, where you can find the latest reports.
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