Fast transport and slow deaths

The factors that influence the spread and/or limitations of disease can often be quite unexpected, and in some cases, the causes remain unknown.

The delivery of tea to England by fast ship may have kept the English drinking tea, which constrained them to boil their water to make the tea, which killed the bacteria that caused cholera and other diseases. On the other hand, fast transport also caused some curious outbreaks of disease.

Airport malaria is a known phenomenon today, where people close to airports may very occasionally catch malaria when an infected mosquito emerges from an aircraft and draws blood from somebody before it dies. That sort of thing was far less likely in the days of steamships, but not impossible, even with a sailing ship like the barque Hecla, which once carried yellow fever to Wales.

Hecla reached Swansea with a cargo of copper ore from Cuba on 8 September 1865, and did not raise the quarantine flag. The ship had left one crewman, dead of yellow fever in Cuba, and she was under-crewed due to three deaths at sea that were put down to yellow fever.

Another sailor, James Saunders, died just after landing, and doctors judged this to be yellow fever, so his body was immediately buried in a tar sheet, his house was cleared and disinfected with lime wash and chloride of lime, and his clothing and bedding were destroyed.

Nobody had any idea that the disease was spread by mosquito bites, so the ship’s water supply, almost certainly complete with mosquitoes in all stages of life, was left unexamined. The ship’s owners resisted moving the ship, and while it was disinfected, though it later moved after locals intimated that it might mysteriously catch fire. This removal would have had no effect on the mosquitoes, though the fire would have curtailed the outbreak.

Before the outbreak ran its course, at least 27 people fell ill with yellow fever and 15 of them died, while there were a few other “possibles”, but how did a tropical disease reach Wales? Yellow fever and its mosquitoes had travelled from Africa to the Caribbean with African slave ships and been established there, but non-tropical Wales was safe from any permanent threat from yellow fever, back then.

The ship travelled in warm weather that let the mosquitoes survive, and it arrived in warm weather, which allowed the mosquitoes to spread, briefly into parts of Swansea. Still, in these days of global warming and climate change, who can say what the future might hold?

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In China in the late 19th century, political unrest was common, but new technology brought hope to some of China’s urban poor. They could take steam trains into rural areas to shoot, kill and skin ground rodents, and take the skins back to the city for sale. In an age before plastics, skins were always saleable, and if the local people had silly traditions, like not shooting a sick-looking animal, the city slickers saw those animals as fair and easy game.

Bubonic plague is a disease that harms rodents, fleas and humans. A flea bites an infected mammal, gets an infection that blocks its bloodsucking apparatus, so the next time it tries to feed, some of the plague bacteria “blow back” into the new food source, and so the disease spreads. When a host dies, fleas move to any other warm body—like the person skinning the old rodent host.

The hunters caught fast steam trains back to the city before they fell ill, and from there, bubonic plague infected rats in the city, either from the hunters or from fleas that were still in the fur of the skins. Over time, some of the rats found their way onto fast steam ships that went around the world from Chinese ports.

In earlier times, plague usually killed the rats before sailing ships reached port, but steamships bustled from port to port, and sooner or later, some of the rats made it to the other end, found their way ashore to die, and shared their fleas and their ills. Indian ports were hit, along with those in Sydney, San Francisco, Madagascar, Paraguay, South Africa and more. In every port, people died because of fast ships.

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There is fairly wide agreement that the spread of HIV was brought about by long-haul truck drivers in Africa making use of prostitutes along the way, followed by an entry into the more general population of the western world, thanks to jet aircraft. The world got lucky with SARS, as my next two posts will explain.