Deep in the Atlantic Ocean, the MV Hondius, a Dutch-flagged cruise ship, carried one of the deadliest diseases on the planet, a hantavirus strain known as the Andes virus. As of May 14, the Centers for Disease Control and Prevention (CDC) affirmed a 38% mortality rate, and the European Centre for Disease Prevention and Control (ECDC) reported 11 total cases connected to the ship: eight confirmed, two probable, one inconclusive, and three deaths. No new cases or deaths had been reported since the previous update, and ECDC said the risk to the general EU/EEA population remained very low.
The Andes virus, also called ANDV, belongs to the hantavirus family. What makes it stand out is that the Andes virus causes hantavirus pulmonary syndrome, a life-threatening illness that attacks the lungs, and is the only hantavirus with documented person-to-person transmission.
However, that does not make it as transmissible as COVID-19 or the flu. ECDC says Andes hantavirus transmission between people is “rare and typically requires prolonged close contact in enclosed settings.” The current working hypothesis is that at least one passenger was exposed before boarding, likely through land exposure somewhere in South America, with further transmission possibly occurring onboard.
Andes virus is primarily a South American disease. WHO places its endemic range (natural habitat) in Argentina and Chile, with related strains and cases documented in Uruguay, southern Brazil, and Paraguay.
What makes the MV Hondius outbreak distinct is how it crossed borders. Passengers connected to the outbreak disembarked in Saint Helena on April 24, Praia in Cabo Verde on May 6, and Tenerife on May 10 and 11. After the ship reached the Canary Islands, passengers and most crew were repatriated to their home countries or transit points on specially arranged non-commercial flights. The ship carried passengers and crew from 23 countries, including nine EU/EEA countries: Belgium, France, Germany, Greece, Ireland, the Netherlands, Poland, Portugal, and Spain.
To understand what the virus actually does inside the body, The Tower spoke with Dr. Sanjay Mehta, an infectious disease physician and father of Kai Mehta (‘28).
“The virus is inhaled and then triggers an inflammatory response in the lungs,” Dr. Mehta said. “This leads to leakage of fluids into the lung from the blood vessels. The fluid in the lungs limits the ability of the person to get oxygen into their blood, and then a cascade of organ failure follows.”
In the most critical cases, patients require ECMO, extracorporeal membrane oxygenation, a machine that takes over both pumping and oxygenating the blood when the heart and lungs can no longer function independently.
Dr. Mehta also noted a key difference from COVID-19. Unlike SARS-CoV-2, which spreads before symptoms appear, Andes virus transmission appears tied to symptomatic individuals. “If we can isolate persons with symptoms, we can stop the chain of transmission,” he said, which explains why public health officials moved quickly to quarantine ship passengers.
He flagged one detail relevant to San Diego readers specifically: hantavirus is present in the county. A mouse recently tested positive at the Rancho Penasquitos farmhouse. “If cleaning up an area with rodent droppings, I would recommend wearing a mask,” Dr. Mehta said.
Despite Dr. Mehta’s warning Ronik Gupta (‘27) said he had no prior awareness of hantavirus before being asked about the outbreak, and had not known the virus had already turned up in San Diego County.
Early symptoms of the Andes virus are fairly ordinary — fever, fatigue, muscle aches, headache, dizziness, chills, nausea, vomiting, diarrhea, and abdominal pain. According to the WHO, symptoms can appear as early as one week and as late as eight weeks after exposure. After this initial wave of symptoms, patients can develop sudden breathing distress and a dangerous drop in blood pressure — fast enough that earlier, milder symptoms get dismissed as a passing flu.
CDC has confirmed no Andes virus cases in the United States connected to this outbreak, and the risk of broader spread to the American public remains extremely low. Still, the CDC repatriated affected American passengers to high-containment facilities, including the Nebraska Biocontainment Unit and Emory University Hospital in Atlanta. Officials are monitoring exposed individuals closely because the incubation period can stretch for weeks.
There is no vaccine or specific antiviral treatment for hantavirus. Treatment is entirely supportive: doctors manage breathing, circulation, fluid levels, and complications while the patient’s immune system works through the infection. WHO notes that early supportive care and transfer to a facility with full intensive-care capacity can meaningfully improve survival odds.
As of now, the Andes virus outbreak remains a travel-linked event involving passengers, crew members, and close contacts tied to a single ship. What officials are watching is the incubation window. Because the Andes virus can take up to eight weeks to show symptoms, some exposed passengers may not yet know they are infected. Until that window closes, this outbreak is not over.
