Cabo verde: A rare but potentially deadly virus has come into focus after a cluster of infections aboard a cruise ship off the coast of Cabo Verde left three people dead and several others ill. The outbreak, involving a vessel that had traveled across remote parts of the South Atlantic after departing Argentina, has triggered an international response and renewed attention on hantavirus, a disease that typically circulates quietly in nature but can have severe consequences when it infects humans.

According to Anadolu Agency, seven people among 147 passengers and crew have been affected so far, including two confirmed and five suspected cases. While one patient remains in intensive care in South Africa, others are under observation as investigations continue. Despite the severity of some cases, WHO says the overall risk to the general public remains low.

Hantavirus refers to a group of viruses carried by rodents that can occasionally be transmitted to humans. Infection usually occurs through contact with infected rodents or their contaminated urine, droppings, or saliva, or by inhaling airborne particles from dried rodent waste, particularly in enclosed or poorly ventilated environments. Less commonly, transmission can occur through rodent bites. Hantaviruses belong to the Hantaviridae family and are typically carried by specific rodent species, where they can persist without causing illness. While many types exist worldwide, only a limited number are known to infect humans. The virus does not typically spread easily between people. However, one strain known as Andes virus, found in South America, has shown the ability to spread in rare cases involving close and prolonged contact. WHO says the most likely explanation of the current outbreak is that the initial infections occurred before passengers boarded, given travel history and the incubation period. At th e same time, limited human-to-human transmission among close contacts cannot be ruled out.

The ship departed Ushuaia, Argentina, in early April and followed a route across remote regions, including Antarctica and isolated Atlantic islands. According to WHO, the first known case involved a male passenger who developed symptoms, including fever and mild gastrointestinal illness, on April 6 while on board. His condition worsened rapidly, and he developed respiratory distress before dying on April 11. A close contact, his wife, later developed symptoms and disembarked at Saint Helena on April 24. Her condition deteriorated during travel to South Africa, where she died shortly after arrival. Laboratory testing later confirmed hantavirus infection in her case. Both had traveled in South America before boarding, leading WHO to assess that the initial exposure likely occurred off the ship. A third patient, an adult male, developed symptoms later in April and was medically evacuated to South Africa, where he remains in intensive care with confirmed infection. Another passenger, a woman, died on May 2 after developing pneumonia, although confirmation is still pending. Three other suspected cases reported milder symptoms and remain under observation and on board. The ship made multiple stops in remote locations, where passengers may have come into contact with wildlife or rodent habitats. Investigations are ongoing to determine whether such exposures contributed to the outbreak.

Maria Van Kerkhove, WHO director for epidemic and pandemic preparedness and prevention, said Tuesday that no rodents have been reported on board. Laboratory investigations, including sequencing, are ongoing to determine the exact strain. The current working assumption is that the cases may be linked to Andes virus, although this has not yet been confirmed. Passengers have been asked to remain in their cabins while disinfection and monitoring continue.

Hantavirus infections are relatively rare but can be severe. In the Americas, the virus can cause hantavirus cardiopulmonary syndrome, a rapidly progressing illness affecting the lungs and heart, with fatality rates that can reach up to 50%. In Europe and Asia, infections more commonly cause hemorrhagic fever with renal syndrome, which affects the kidneys and blood vessels and generally has lower mortality. Globally, WHO estimates that between 10,000 and more than 100,000 infections occur each year, with the largest burden in Asia and Europe. Symptoms typically appear between one and eight weeks after exposure and often begin with fever, headache, muscle aches, and gastrointestinal symptoms such as abdominal pain, nausea, or vomiting. In severe cases, the disease can progress rapidly to breathing difficulties, fluid buildup in the lungs, and shock. Early diagnosis of hantavirus, according to WHO, can be challenging because early symptoms are common with other febrile or respiratory illnesses, such as influenz a, COVID-19, viral pneumonia, leptospirosis, dengue, or sepsis.

Hantavirus infections are considered relatively uncommon globally, but they are reported across multiple regions and can have serious consequences. In the Americas, eight countries reported 229 cases and 59 deaths in 2025, reflecting a case fatality rate of more than 25%, according to WHO data. In Europe, 1,885 cases were recorded in 2023, while in East Asia, particularly China and the Republic of Korea, thousands of cases of hemorrhagic fever with renal syndrome continue to be reported each year, although overall incidence has declined in recent decades. Fatality rates vary widely depending on the region and strain, ranging from less than 1% to 15% in Europe and Asia and reaching up to 50% in the Americas. The virus is closely linked to environmental and ecological factors, as it is carried by wild rodents. Changes in rodent populations, seasonal patterns, and human activity, particularly in rural or outdoor settings, can influence transmission risk.

There is no specific antiviral treatment or widely available vaccine for hantavirus infections, according to WHO. Treatment focuses on supportive care, which becomes critical as the disease can worsen rapidly, particularly in severe cases affecting the lungs and heart. Patients are closely monitored and may require oxygen therapy, mechanical ventilation, or medications to stabilize blood pressure and support organ function. In the most serious cases, patients may need intensive care, including advanced life-support measures such as extracorporeal membrane oxygenation or dialysis if kidney failure develops. WHO says early recognition and prompt transfer to facilities equipped with intensive care units can significantly improve survival, especially for patients with hantavirus cardiopulmonary syndrome. Because there is no targeted treatment, prevention, particularly avoiding exposure to rodents and contaminated environments, remains the most effective way to reduce risk. Prevention also includes maintaining cle an living and working spaces, sealing openings that allow rodents to enter buildings, storing food securely, and using safe cleaning practices in areas where contamination may be present. Health authorities also advise avoiding dry sweeping or vacuuming rodent droppings, instead dampening contaminated areas before cleaning, and maintaining good hand hygiene. During outbreaks or when cases are suspected, early identification and isolation of infected individuals, monitoring of close contacts, and the application of standard infection prevention measures are considered essential to limit further spread.

Health authorities are now focused on containing the outbreak and completing investigations into how the infections occurred. WHO says efforts are ongoing to medically evacuate the remaining patients on board so they can receive specialized care. Once that process is completed, the ship is expected to continue to the Canary Islands, where Spanish authorities have agreed to receive the vessel and carry out a full epidemiological investigation and disinfection. Further laboratory testing and contact tracing continue for those who may have been exposed during the voyage or after disembarking. WHO is coordinating with multiple countries linked to the ship's route, including Cabo Verde, Spain, South Africa, the Netherlands, and the United Kingdom, to ensure a consistent response. While the situation remains under close monitoring, WHO continues to assess the overall risk to the global population as low, noting that current evidence does not suggest widespread transmission beyond the identified cases.