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Ports and disease


The origin of quarantine

HMS Hazard Sep 20 1841 flying yellow quarantine flag, with notes.
View full size imageHMS Hazard flying yellow quarantine flag, by Sir Oswald Brierly. © NMM

Countries took great efforts to prevent the entry of infectious diseases from abroad. For centuries, the usual method was quarantine.

This was the detention of any ship either known to be carrying disease or coming from a port where an epidemic had broken out. 

Quarantine delayed the disembarkation of passengers and the unloading of cargo until the ship seemed to be free of disease.

View of the New York Quarantine, Staten Island.
View full size imageView of the New York Quarantine, Staten Island, 1833. © NMM

Quarantine was first used to keep out plague after the Black Death hit Europe. The term comes from the Italian word quarante - the 40-day period during which arriving ships were detained.

In time, quarantine was used for many other diseases, and most maritime countries set up a network of quarantine stations.

London's quarantine defences

Quarantine guard ship 'Rhin', Standgate Creek.
View full size imageThe quarantine guard ship Rhin at Standgate Creek. © NMM
To prevent epidemics reaching London from the sea, the first line of defence had to be much further down the Thames.

The first quarantine station was at Stangate Creek, near Sheerness, on the Medway. Ships flying the quarantine flag were placed under guard here until they were declared healthy. 

The shortcomings of quarantine

Quarantine was too crude to be effective for many reasons:

  • as bacteria and viruses were not discovered until the late 19th century, there was little proper understanding of infectious disease and modes of transmission
  • quarantine was not always enforced efficiently
  • for centuries, customs officials rather than doctors carried out checks on vessels and their cargoes, so mistakes were far more likely
  • healthy people on board quarantined vessels were subjected to increased risk of catching disease.

Clearly, a more sophisticated way of stopping the spread of disease was necessary.


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