South African infectious disease expert Lucille Blumberg was part of a team that identified a hantavirus outbreak on a Dutch cruise ship thousands of miles away. On the morning of May 1, while South Africa celebrated Labour Day, Blumberg received an urgent email from a UK-based colleague. The message concerned a passenger from a cruise ship sailing in the Atlantic Ocean who had been evacuated and admitted to a Johannesburg hospital with suspected pneumonia. Others aboard the vessel were also ill. The colleague, who monitors diseases in remote British overseas territories in the South Atlantic, asked Blumberg to follow up on the passenger, who had been evacuated from the ship in Ascension Island.
Rapid Response to a Mysterious Outbreak
Blumberg and other experts at South Africa’s National Institute for Communicable Diseases were suddenly thrust into the race to identify the cause of an outbreak aboard the Dutch cruise ship MV Hondius. “Even though it was a public holiday, we moved, we moved really fast,” Blumberg told The Associated Press. “It was busy. There were many conversations. There were online discussions, and there was laboratory testing happening at the time.” Within 24 hours, they determined that the man’s illness was caused by hantavirus, a rare rodent-borne virus.
Process of Elimination
The elderly British man had arrived at a private hospital in Johannesburg days earlier and was seriously ill, but health workers were unsure of the underlying cause. By the time he was evacuated, two elderly Dutch passengers who had been on board the MV Hondius had already died, but there had been little alarm. Ascension Island health authorities reported a cluster of illnesses on the ship that appeared to be pneumonia to the World Health Organization. Initially, Blumberg and her colleagues suspected Legionella, the bacterium causing Legionnaires’ disease, or bird flu. “I called my infectious disease colleagues, and we had a caucus, and we discussed the usual ones,” Blumberg said. “Legionella is well described in outbreaks in hotels and on cruise ships, and influenza certainly is. These people had visited islands where avian influenza is well documented.” Tests for all those were negative. The experts also ran an extensive panel of tests for other respiratory diseases, all of which were negative.
Collaboration with International Experts
The team then began looking more closely at where the ship came from—Argentina—and the fact that passengers were avid bird watchers who had reportedly been to parts of South America with birds and rodents. This pushed them toward another theory: the rare, rodent-borne hantavirus infection, found in parts of South America. “It’s a well-described, not common, but it’s a well-described virus in Chile and Argentina,” Blumberg said. Their work was aided by collaboration with hantavirus experts from South America and the United States, facilitated by the WHO. “You can get onto a Zoom online and ask your questions and get advice. This is not something every day. So that was quite extraordinary,” Blumberg said.
Positive Tests and a ‘Wow Moment’
By Saturday morning, Blumberg called the head of the only laboratory in South Africa that can test for hantavirus. “I said, we want to do hanta, and she said, ‘yeah, I’m coming.’” Tests on the sick man's blood samples came back positive for hantavirus that afternoon. The team did a second set of tests to be sure, Blumberg said. The positive tests, which also identified the Andes strain of hantavirus, allowed the WHO to inform the cruise ship and announce an outbreak. While hantavirus is not easily spread person-to-person, the WHO says the Andes virus can be transmitted between people. The test results also led Blumberg to rush to collect blood samples from a Dutch woman—one of the first two cruise passengers to die—who had disembarked from the ship on St. Helena and flown to South Africa, where she died. A posthumous hantavirus test on her was also positive. “It was a bit of a wow moment,” Blumberg said. “And at least once you know what you’re dealing with, it’s much easier to respond.”
The British man who was the first confirmed case of hantavirus infection from the cruise ship is improving in hospital, South Africa’s health ministry said. Meanwhile, the ship arrived at the Dutch port of Rotterdam, where it was disinfected, and the remaining crew members disembarked. “I’ve been doing outbreaks for 25 years. That’s what we do. We do them every day,” Blumberg said. “I think the important thing was to respond immediately to a question that clearly was urgent and then to take it from there.”
