Tag Archives: spread

Fleas to flu to coronavirus: how ‘death ships’ spread disease through the ages



Cushing/Whitney Medical Library

Joy Damousi, Australian Catholic University

One of the haunting images of this pandemic will be stationary cruise ships – deadly carriers of COVID-19 – at anchor in harbours and unwanted. Docked in ports and feared.

The news of the dramatic spread of the virus on the Diamond Princess from early February made the news real for many Australians who’d enjoyed holidays on the seas. Quarantined in Yokohama, Japan, over 700 of the ship’s crew and passengers became infected. To date, 14 deaths have been recorded.

The Diamond Princess’s sister ship, the Ruby Princess, brought the pandemic to Australian shores. Now under criminal investigation, the events of the Ruby Princess forced a spotlight on the petri dish cruise ships can become. The ship has been linked to 21 deaths.

History shows the devastating role ships can play in transmitting viruses across vast continents and over many centuries.




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Rats in the ranks

Merchant ships carrying rats with infected fleas were transmitters of the Plague of Justinian (541-542 AD) that devastated the Byzantine Empire.

Ships carrying grain from Egypt were home to flea-infested rats that fed off the granaries. Contantinople was especially inflicted, with estimates as high as 5,000 casualties a day. Globally, up to 50 million people are estimated to have been killed – half the world’s population.

The Black Death was also carried by rats on merchant ships through the trade routes of Europe. It struck Europe in 1347, when 12 ships docked at the Sicilian port of Messina.

The people of Tournai bury victims of the Black Death.
Wikimedia Commons

Subsequently called “death ships”, those on board were either dead or sick. Soon, the Black Death spread to ports around the world, such as Marseilles, Rome and Florence, and by 1348 had reached London with devastating impact.

The Italian writer, poet and scholar, Giovanni Boccaccio, wrote how terror swept through Florence with relatives deserting infected family members. Almost inconceivably, he wrote, “fathers and mothers refused to nurse their own children, as though they did not belong to them”.

Ships started being turned away from European ports in 1347. Venice was the first city to close, with those permitted to enter forced into a 40-day quarantine: the word “quarantine” derives from the Italian quarantena, or 40 days.

By January 1349, mass graves proliferated outside of London to bury the increasing numbers of dead.




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Army and naval ships, as well as travellers around the globe, also carried cholera pandemics throughout the 19th century. In the first pandemic in 1817, British army and navy ships are believed to have spread cholera beyond India where the outbreaks originated.

Egyptians boarding boats on the Nile during a cholera epidemic, drawn by CL Auguste (1841-1905.)
Wellcome Collection, CC BY

By the 1820s, cholera had spread throughout Asia, reaching Thailand, Indonesia, China and Japan through shipping. British troops spread it to the Persian Gulf, eventually moving through Turkey and Syria.

Subsequent outbreaks from the 1820s through to the 1860s relied on trade and troops to spread the disease across continents.

At war with the Spanish Flu

The Spanish influenza of 1918-1919 was originally carried by soldiers on overcrowded troop ships during the first world war. The rate of transmission on these ships was rapid, and soldiers died in large numbers.

One New Zealand rifleman wrote in his diary in September 1918:

More deaths and burials total now 42. A crying shame but it is only to be expected when human beings are herded together the way they have been on this boat.

The SS Port Darwin returned from Europe, docked at Portsea, Victoria. Soldiers are waiting to pass through a fumigation chamber to protect Australia against the Spanish Flu.
Australian War Memorial

The flu was transmitted throughout Europe in France, Great Britain, Italy and Spain. Three-quarters of French troops and over half of British troops fell ill in 1918. Hundreds of thousands of US soldiers travelling on troop ships across the Atlantic and back provided the perfect conditions for transmission.

The fate of cruising

A new and lethal carrier in the 21st century has emerged in the pleasure industry of cruise ships. The explosion of cruise holidays in the past 20 years has led to a proliferation of luxury liners plying the seas.

Like historical pandemics, the current crisis shares the characteristic of rapid spread through ships.

The unknown is in what form cruise ships will continue to operate. Unlike the port-to-port trade and armed forces that carried viruses across continents centuries ago, the services cruise lines offer are non-essential.

Whatever happens, the global spread of COVID-19 reminds us “death ships” are an enduring feature of the history of pandemics.The Conversation

Joy Damousi, Director, Institute of Humanities and Social Sciences, Australian Catholic University

This article is republished from The Conversation under a Creative Commons license. Read the original article.


How ancient seafarers and their dogs helped a humble louse conquer the world



Male (left) and female Heterodoxus spiniger from Borneo.
Natural History Museum, London, Author provided

Loukas Koungoulos, University of Sydney

This is the story of how a parasitic, skin-chewing insect came to conquer the world.

For more than a century, scientists have been puzzled as to how an obscure louse native to Australia came to be found on dogs across the world. Heterodoxus spiniger evolved to live in the fur of the agile wallaby.

Despite little evidence to back the idea, many researchers believed it was linked to people from Asia bringing the dingo to Australia in ancient times. Perhaps people later took dingoes infested with this parasite back home, where it spread to local dogs, and onwards from there.




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But when we approached the question again using the most up-to-date information, my colleague Peter Contos and I came up with a completely different explanation – one that better fits what we know of ancient migration and trade in the Asia-Pacific region.

As we report in the journal Environmental Archaeology, this louse probably originated not in Australia but in New Guinea, an island with a long history of intimate connection with seafaring Asian cultures.

Louse on the loose

H. spiniger is a tiny louse that lives on mammals around the world, mostly dogs. Using its clawed legs to hang on, it bites and chews at the skin and hair of its hosts to draw the blood on which it feeds.

As all its closest relatives are specialised parasites of marsupials, mostly other wallabies, logic suggested that H. spiniger must have evolved within Australia. It also seemed logical it would have spread first to the dingo, Australia’s native dog.

Our first task was to figure out just how far away from Australia it had spread; this would inform the likely pathways by which it could have travelled to the wider world.

We looked at museum collections, entomological surveys, and veterinary research reports to generate a map of its worldwide distribution.

Global distribution of H. spiniger.
Lougoulos and Contos, Author provided

The specimens we found, collected from the late 19th century to the present day, showed that this species is found on every continent except Europe and Antarctica.

But in Australia, we couldn’t find a single verifiable instance of the parasite living on dingoes. The only cases were from agile wallabies and domestic dogs.

That meant the prevailing wisdom had been wrong, and we had to look elsewhere for the origins of H. spiniger.

Don’t blame the dingoes.
Blanka Berankova/Shutterstock

Where did it really come from?

Although marsupials are best known from Australia, they are also found in other parts of the surrounding region. The agile wallaby is also native to the island of New Guinea, which was once joined with Australia.

Dogs have also been in New Guinea for at least as long as the dingo has been in Australia. Traditionally, dogs were kept in Papuan villages, and were used to hunt game, including wallabies.

It came as little surprise, then, that we found H. spiniger on both agile wallabies and native dogs in New Guinea – and only a few decades after the first ever identification of the species.

So here was a more likely place in which the first transfer from wallaby to dog took place. But who took them out of New Guinea and into the wider world?

Austronesian voyagers

New Guinea was first colonised by humans around the same time as Australia. But since that time, compared with Australia it has had notably stronger connections with the outside world, reaching back millennia before European colonisation of Australia in 1788.

Around 4,000 years ago, agriculturalists known as Austronesians sailed out of Taiwan to settle several archipelagos in Oceania. With them they brought domestic species of plants and animals, including dogs.

By 3,000 years ago, at the latest, they reached New Guinea. We suggest this was the crucial moment when dogs first picked up H. spiniger.

In the ensuing centuries, Austronesians went on to settle much of Indonesia, the Philippines, Melanesia and Polynesia, and coastal sections of mainland Southeast Asia.

They even settled as far as Madagascar, suggesting their voyages probably took them around the rim of the Indian Ocean, along the margins of India and the Middle East.

Dogs accompanying the migrants probably helped spread the louse, which is found almost everywhere they went.

This spans an enormous distance – from Hawaii to Madagascar – a testament to the ancient Austronesians’ supreme seafaring skills.

New directions

Our research suggests how the parasite first got around the world, but not precisely when. Its journey probably progressed at different times in different places.

The Austronesian diaspora established trade routes between the places they settled, some of which spanned impressive distances across several island groups.




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Later, foreign traders connected these communities with greater Asia and Africa. And in modern times, dogs continue to be transported as desirable goods themselves.

Trade and contact has probably led to further, possibly ongoing, dispersal of H. spiniger.

Unfortunately there are no archaeological examples that could demonstrate the louse’s early presence outside New Guinea, because this species prefers hot, humid environments.

A genetic approach is a better way forward. A start would be testing specimens from different parts of the world, to see when different regional populations – if they exist – branched off from one another.

This is particularly important in tracking its spread to the Americas, which likely occurred in recent centuries alongside European colonisation.

This research will help us further understand how migration, contact and trade unfolded in the prehistoric Asia-Pacific region, and how it affected the animal species – including the humblest of parasites – we see there today.


This paper would not have been possible without the contributions of Peter Contos, the work of volunteers on the Natural History Museum’s Boopidae of Australasia digitisation project, and the contributions of the public to Wikipedia Creative Commons, for which we are grateful.The Conversation

Loukas Koungoulos, PhD Candidate, University of Sydney

This article is republished from The Conversation under a Creative Commons license. Read the original article.


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