Lessons from a “plague boat”.

In 1685, a Dutch ship transporting enslaved people to sugar plantations in Recife, in Pernambuco, introduced yellow fever to northeastern Brazil. This was followed, in 1899, by the introduction of plague to Uruguay, most likely by another Dutch vessel, this time carrying rice from Rotterdam.

These were not the only diseases that Europeans brought with them to the Americas – in 1518, Christopher Columbus inadvertently introduced measles and smallpox to the Yucatan, decimating the local Aztec population. Thanks to the Spanish conquistadors, other Old World diseases soon followed.

However, with the exception of syphilis, which some scientists believe was brought to Europe by Spanish explorers returning from the Caribbean, the Andean hantavirus is, to my knowledge, the first significant pathogen to have crossed the Atlantic in the opposite direction (I’m exempting the 2007 swine flu and the bird flu virus which, like other influenza viruses, continually circulate between the Southern and Northern hemispheres).

At time of writing, the outbreak on the Hondius, a luxury Dutch cruise ship, has sickened eight of the 150 passengers who boarded the vessel on March 20 at Tierra del Fuego, in Argentina, and killed three. The boat is now en route to Tenerife, in the Canary Islands, where it is expected to dock on Sunday, at which point anyone confirmed to be infected will be transported directly to the airport for repatriation to their home countries. However, that is unlikely to be the end of the story as it is thought that several other passengers who disembarked this modern-day “plague ship” earlier in its voyage from South America may have been infected with the virus without realising it. Given that hantavirus can incubate for up to ten weeks before the appearance of symptoms that means it may be June before we can all breath easily again.

It is important to say from the outset that though the outbreak on the Hondius resembles the outbreak of Covid-19 on the Diamond Princess cruise ship in February 2020, hantavirus is nothing like as catchy as the coronavirus, SARS-CoV-2, and is unlikely to trigger a global pandemic, much less a regional epidemic comparable to the outbreak of Ebola that devastated West Africa in 2013-2016.

But, as Dr David Berger, an expert on aerosol infections, points out, while the risk of a hantavirus pandemic is low, it is not zero. Nor should we rely on the World Health Organization’s assurances that hand hygiene measures should be sufficient to contain the onboard outbreak. Cruise ships are floating petri dishes and, as with SARS-CoV-2, there is a theoretical risk of aerosol spread in the confined spaces below deck. Berger also notes that the official in charge of the WHO’s response to the Hondius outbreak is Dr Maria van Kerkhove – the same WHO official responsible for the notorious “Covid is not airborne” tweet from March 22, 2020.

I am a supporter of the WHO and believe that, despite Trump’s disengagement from the organisation, it remains essential for our ability to monitor and respond to international disease outbreaks in a timely fashion. However, I also wonder how wise it is to allow suspected cases to be repatriated to their home countries without knowing the full risk of aerosol spread (a KLM flight attendant, who briefly shared cabin space with the 69-year-old Dutch woman, was initially hospitalised with suspected hantavirus in Amsterdam only to be cleared this morning; however, by all accounts, the KLM flight from Johannesburg was packed and several other crew members and passengers might have been infected).

Given this uncertainty, the obvious solution in the interim would be some form of port quarantine. Cape Verde, where the Hondius sought permission to dock on May 4, does not possess this capacity – hence the authorities’ insistence that it anchor off the port of Praia before sailing for Tenerife.

However, Spain, and other European countries such as Italy and France, have a long history of maritime quarantines. Indeed, in the eighteenth century, lazarettos were a standard feature of European entrepots from Venice to Marseille and in 1817 the Bourbons opened a huge quarantine station on an island opposite the Menorcan capital Mahón,

For the next 100 years, some 40,000 souls passed through the Llatzeret de Maó’s imposing Lions Gate. Passengers and crew “suspected” of infection, or who had briefly “touched” an infected plague port, were typically detained for between twenty to thirty days. However, those with confirmed plague, cholera or yellow fever were not so lucky. These unfortunates were carried or carted (depending on their condition) directly onto ramps leading from the dock to a separate area of the compound where they spent forty days contemplating the sky and scudding clouds – hence the term quarantena, Italian for forty days.

Three years ago, I had the opportunity to visit the Llatzeret de Maó with a group of medical historians and explore its grounds. The compound occupies an astonishing 470,000 square metres and boasts 7.5 metre-high double-walls along its perimeter. In addition to a “fumigation” dock where boats suspected of harbouring infectious diseases were submerged in sea-water for 24 hours before being re-floated, the lazaretto has 141 rooms, seven warehouses and an astonishing 49 kitchens, some of which, as we discovered during our sojourn, are still capable of turning out a delicious paella. In bygone days, those who could afford it paid to stay in the “French Quarters”, whose rooms came with maid service, laundry facilities and the Bourbon-equivalent of a mini-bar.

You can read about my visit to the Llatzeret de Maó – and our subsequent discussions on quarantines and the parallels with the Covid lockdowns – here.  

The lazaretto was decommissioned in 1917 and it would be impractical to reopen it today. But I cannot help feeling that a stripped-down version equipped with state-of-the-art healthcare facilities and diagnostics for typing hantaviruses and other poorly understood pathogens would be a better solution to the ongoing risks presented by the Hondius and other plague ships on the high seas.

Board a cruise boat, take your chances.