Three people have died and nine others are critically ill in an Andes hantavirus outbreak linked to the cruise ship MV Hondius, prompting quarantine measures for more than 150 individuals worldwide. The U.S. Centers for Disease Control and Prevention has required 18 Americans exposed to the virus to remain in quarantine facilities in Omaha, Nebraska, at least until May 31.

Crew and passengers of the MV Hondius, as well as individuals who had contact with an infected passenger on subsequent airline flights, are being monitored for six weeks following their last potential exposure. Andes hantavirus is the only known hantavirus capable of spreading from person to person, unlike other strains typically transmitted through rodent droppings or urine.

The illness caused by Andes virus leads to severe respiratory distress as the virus infects cells lining blood vessels throughout the body, causing them to become leaky. This allows plasma to seep into tissues and the lungs, disrupting breathing, lowering blood pressure, and potentially causing shock. Most fatalities occur either upon hospital admission or within the first 24 hours.

"I’ve been talking to patients at noon and at two in the afternoon, they’re already connected to mechanical ventilation, and at three, they are already on ECMO. So this is very, very fast development," said Pablo Vial, a clinical virologist. Extracorporeal membrane oxygenation (ECMO) is used when standard ventilators are insufficient.

There are currently no approved vaccines or specific antiviral treatments for hantaviruses. An antiviral drug effective in lab cultures failed in clinical use, and steroid treatments like methylprednisolone showed no benefit. However, plasma from recovered patients has proven helpful when administered early, possibly because antibodies prevent the virus from entering blood vessel cells.

"Antibodies in recovered people’s blood may keep the virus from entering blood vessel cells," Vial said. Immunologist Mattias Forsell added, "Antibodies that linger for decades in people who have recovered from infections of Puumala virus could also fight Andes virus." According to unpublished data reviewing 100 cases across eight Chilean hospitals over roughly eight years, 21 patients died.

Unlike severe influenza or COVID-19, survivors of Andes hantavirus typically experience no lasting lung damage. The biological effects of vascular leakage usually reverse within 48 to 72 hours, an unusually rapid recovery for a severe respiratory illness.