Oh, Gosh

It was the start of a long weekend in South Africa when Lucille Blumberg, an infectious disease specialist at the National Institute for Communicable Diseases, received an email from a colleague. A patient on a cruise ship had pneumonia-like symptoms. A Dutch man had died. His wife had collapsed at a Johannesburg airport while in transit. Common tests for influenza and Legionnaires' disease came back negative.[1]

Blumberg asked for a repeat test, with a sample "from low down in the lungs." The result came in at 6 PM on Workers' Day, a public holiday. Still negative for the usual suspects. By this point, Blumberg and a few others suspected hantavirus. Several passengers had travelled to Argentina and Chile, where the virus is endemic. She ordered a hantavirus test first thing Saturday morning.

The result came back that afternoon. "The person doing it was like: oh, goodness," Blumberg told AFP. It was positive. They reran the test several times to be sure. Then they informed the hospitals, the WHO, and contact tracing began.[2]

The Luxembourg connection

Luxembourg Air Rescue has begun repatriating two hantavirus cases from the Dutch cruise ship MV Hondius. The initial reports were confusing. A disease that most people have never heard of, on a ship most people will never board, and suddenly it is an international health scare with patients being flown home by air ambulance from a small country in the middle of Europe.[3]

Hantavirus is not new. It has been known since the Korean War, when thousands of UN troops fell ill with what was then called Korean haemorrhagic fever. The virus is carried by rodents. Humans contract it by inhaling aerosolised particles from rodent excreta. It is rare, it is serious, and it is almost never seen on cruise ships. That last part is what makes this outbreak unusual enough to have required the kind of detective work Blumberg described.

What makes this different

Most cruise ship outbreaks are norovirus. The protocol is well established: isolate, clean, wait. Hantavirus does not spread from person to person. It requires exposure to contaminated environments. For it to appear on a ship, passengers must have encountered infected rodent habitats, most likely during shore excursions, and then boarded while incubating.

The South Atlantic route, Ascension Island, the connections through Johannesburg, the patients scattered across multiple countries: this is the kind of epidemiological puzzle that looks simple in retrospect but is extremely difficult in real time. The doctor who died in Johannesburg was initially classified as a pneumonia case. It was Blumberg's insistence on retesting, and her knowledge of the patients' travel history to hantavirus-endemic regions, that broke the case open.

Then there is the question of what happens next. Hantavirus has a fatality rate that varies by strain, from around 1% for the milder European form to over 30% for some New World strains. The strain involved here has not been publicly identified yet. That detail matters a lot for the patients being flown home and for the contacts being traced.

Luxembourg Air Rescue does this kind of work routinely. Medical repatriation is one of their core missions. But "routinely" usually means heart attacks, strokes, trauma. A rare hemorrhagic fever from a cruise ship in the South Atlantic is not routine. The precautions involved in transporting a hantavirus patient by air are considerable. The crew and the receiving hospital both need to know exactly what they are dealing with.

Blumberg's two words, "oh, goodness," are the sound of someone realising that a problem they thought was contained is actually much larger. The test confirmed what she suspected. The repatriations confirm that the problem has reached Europe. What has not yet been confirmed is how many more samples from how many more ports will come back positive.