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Hantavirus symptoms are drawing renewed public attention as health authorities investigate severe respiratory illness cases linked to a reported outbreak aboard a cruise ship. Experts say the virus, commonly associated with rodent exposure, can rapidly develop into serious respiratory complications in infected individuals.

On May 2, 2026, a group of passengers suffering from severe respiratory illness aboard a cruise ship was reported to the World Health Organization (WHO). The vessel is carrying a total of 147 passengers and crew members. As of May 4, 2026, seven cases have been identified, which include two laboratory-confirmed cases of hantavirus and five suspected cases. This situation has resulted in three fatalities, one patient in critical condition, and three individuals exhibiting mild symptoms.

The onset of illness occurred between April 6 and April 28, 2026, and was marked by symptoms such as fever, gastrointestinal issues, rapid progression to pneumonia, acute respiratory distress syndrome, and shock. Ongoing investigations are being conducted. The outbreak is being addressed through a coordinated international response, which encompasses thorough investigations, isolation and care of cases, medical evacuations, and laboratory analyses.

In its website, the United Nations health agency provides some information about hantavirus:

Hantaviruses are zoonotic viruses that naturally infect rodents and are occasionally transmitted to humans. Infection in people can result in severe illness and often death, although the diseases vary by type of virus and geographical location.

In the Americas, infection has been known to lead to hantavirus cardiopulmonary syndrome (HCPS), a rapidly progressive condition affecting the lungs and heart, while in Europe and Asia hantaviruses has been known to hemorrhagic fever with renal syndrome (HFRS), which primarily affects the kidneys and blood vessels.

While there is no specific treatment that cures hantavirus diseases, early supportive medical care is key to improve survival and focuses on close clinical monitoring and management of respiratory, cardiac and kidney complications. Prevention depends largely on reducing contacts between people and infected rodents.

Viral family and classification

Hantaviruses belong to the family Hantaviridae, within the order Bunyavirales. Each hantavirus is typically associated with a specific rodent reservoir species, in which the virus causes long‑term infection without apparent illness.

Although many hantavirus species have been identified worldwide, only a limited number are known to cause human disease.

·       Hantaviruses present in North, Central and South America are known to cause HCPS. The Andes virus is part of this family and is known to cause limited human-to-human transmission among close and prolonged contacts, primarily in Argentina and Chile.

·       Hantaviruses found in Europe and Asia are known to cause hemorrhagic fever with HFRS. Human-to-human transmission has not been documented in this part of the world.

Burden of disease

Hantavirus infections are relatively uncommon globally but are associated with a case fatality rate of <1–15% in Asia and Europe and up to 50% in the Americas. Worldwide, it is estimated that from 10 000 to over 100 000 infections occur each year, with the largest burden in Asia and Europe.

·       In East Asia, particularly China and the Republic of Korea, HFRS continues to account for many thousands of cases annually, although incidence has declined in recent decades.

·       In Europe, several thousand cases are reported each year, mainly from northern and central regions where Puumala virus circulates. In the Americas, HCPS is much rarer, with hundreds of cases reported each year across the continent.

·       The United States of America has reported fewer than 1000 cases, while South American countries such as Argentina, Brazil Chile, and Paraguay report small numbers of cases annually. Despite the lower incidence, HCPS has a high case fatality rate, commonly between 20% and 40%, making it a disease of major public health concern.

Transmission

Transmission of hantaviruses to humans occurs from contact with contaminated urine, droppings or saliva of infected rodents. Infection may also occur, although less commonly, through rodent bites. Activities that involve contact with rodents such as cleaning enclosed or poorly ventilated spaces, farming, forestry work and sleeping in rodent-infested dwellings increase exposure risk.

To date, human-to-human transmission has been documented only for Andes virus in the Americas and remains uncommon. When it occurs, transmission between people has been associated with close and prolonged contact, particularly among household members or intimate partners, and appears most likely during the early phase of illness, when the virus is more transmissible.

Symptoms and clinical presentation

In humans, symptoms usually begin between one and eight weeks after exposure, and typically include fever, headache, muscle aches and gastrointestinal symptoms such as abdominal pain, nausea or vomiting.

·       In HCPS, the disease may progress rapidly to cough, shortness of breath, accumulation of fluid in the lungs and shock.

·       In HFRS, later stages may include low blood pressure, bleeding disorders and kidney failure.

Diagnosis

Early diagnosis of hantavirus infection can be challenging because early symptoms are common with other febrile or respiratory illnesses, such as influenza, COVID-19, viral pneumonia, leptospirosis, dengue or sepsis.

A careful patient history is therefore essential, with particular attention to possible rodent exposure, occupational and environmental risks, travel history, and contact with known cases in areas where hantaviruses are present.

Laboratory confirmation relies on serological testing to detect hantavirus-specific IgM antibodies or rising IgG titres, as well as molecular methods such as reverse transcription polymerase chain reaction (RT-PCR) during the acute phase of illness, when viral RNA may be detectable in blood.

Samples collected from patients are a biohazard risk; laboratory testing on non-inactivated samples should be conducted under maximum biological containment conditions. All non-inactivated biological specimens should be packaged using the triple packaging system when transported nationally and internationally.

Treatment

There is no licensed specific antiviral treatment or vaccine for hantavirus infection. Care is supportive and focuses on close clinical monitoring and management of respiratory, cardiac and kidney complications. Early access to intensive care, when clinically indicated, improves outcomes, particularly for patients with hantavirus cardiopulmonary syndrome.

Prevention and control

Preventing hantavirus infection depends primarily on reducing contacts between people and rodents. Effective measures include:

·       keeping homes and workplaces clean

·       sealing openings that allow rodents to enter buildings

·       storing food securely

·       using safe cleaning practices in areas contaminated by rodents

·       avoiding dry sweeping or vacuuming rodent droppings

·       dampening of contaminated areas before cleaning

·       strengthening hand hygiene practices.

During outbreaks or when cases are suspected, early identification and isolation of cases, monitoring of close contacts, and application of standard infection prevention measures are important to limit further spread.