In the past, when people traveled on ships, illnesses often died out before reaching land, a recent study reveals. The arrival of Christopher Columbus’s fleet in the Americas is an example. Researchers calculated that if one person had the flu on the Santa Maria in 1492, there was less than a 0.1 percent chance of spreading it to the New World.
On December 22, 1874, the H.M.S. Dido arrived in Fiji from Sydney, Australia, carrying about 200 people, including a king of Fiji and his son who had measles. This led to an epidemic that claimed the lives of 20,000 people in Fiji, a quarter of the population, who had no immunity to the disease. However, during the time of sail and steam travel, such occurrences were rare.
A recent report published in The Proceedings of the National Academy of Sciences uses mathematical models to demonstrate the challenges viruses face in crossing the sea. The study showed that most infectious diseases were contained on board ships and did not spread to the shore.
In today’s world, new diseases, like Covid-19, can spread rapidly across the globe. Elizabeth Blackmore, a doctoral student at Yale, and James O. Lloyd-Smith, an ecologist at the University of California, Los Angeles, sought to determine when viral transmission patterns changed. Their use of mathematical modeling has allowed them to quantify the likelihood of transmission, a feat that historians have not accomplished before.
The researchers focused on the history of smallpox outbreaks in California, which were not reported until 1806 and 1838. This delay in reporting suggests that viral transmission patterns may have shifted over time. The study has been praised by experts in the field for breaking new ground and providing valuable insights into the spread of infectious diseases through maritime travel.
By studying historical data and using advanced mathematical models, researchers are gaining a better understanding of how epidemics spread across oceans. This research can help inform public health policies and strategies to prevent the spread of infectious diseases in the future.
