90-Second Read: How South African scientists identified Hantavirus on a cruise ship thousands of miles away

South African infectious disease expert Lucille Blumberg was part of a team that identified a Hantavirus outbreak on a Dutch cruise ship. That pushed the South African disease experts toward another theory: the rare, rodent-borne Hantavirus infection, which is found in parts of South America. Those positive tests, which also identified the Andes strain of Hantavirus, allowed the WHO to inform the cruise ship what it was dealing with and announce an outbreak on board. A U.K.-based colleague had written about a passenger from a cruise ship sailing thousands of miles away in the Atlantic Ocean who had been evacuated and admitted to a Johannesburg hospital with suspected pneumonia.

Blumberg and other experts at South Africa's National Institute for Communicable Diseases were suddenly thrown into the race to identify the cause of an outbreak aboard the Dutch cruise ship MV Hondius. The team then began looking more closely at where the ship came from, Argentina, and the fact that passengers on board were avid bird watchers and had reportedly been to parts of South America where there were birds, but also rodents. Blumberg called the head of the only laboratory in South Africa that can test for Hantavirus. The elderly British man had arrived at a private hospital in Johannesburg days earlier and was seriously ill, but health workers weren't sure of the underlying cause.

People in protective gear remove waste from the MV Hondius cruise ship after its arrival at the Port of Rotterdam, Netherlands, Monday, May 18, 2026. By the time he was evacuated from the ship, two elderly Dutch passengers who had been on board the MV Hondius cruise liner had already died, but there had been little alarm. Legionella is well described in outbreaks in hotels and on cruise ships, and influenza certainly is. While Hantavirus is not easily spread from person to person, the WHO says the Andes virus can be transmitted between people.

At first, Blumberg and her colleagues thought it might be Legionella, a bacterium that causes a serious form of pneumonia, Legionnaires' disease. The experts also ran an extensive panel of tests for other respiratory diseases. The team did a second set of tests to be sure, Blumberg said.