In the past, when people traveled by ship, diseases often died out before reaching land, a recent study reveals. Researchers found that the chances of viruses spreading across the sea were very low due to the limited contact on ships. However, on rare occasions, like the arrival of the H.M.S. Dido in Fiji in 1874, diseases could devastate populations with no immunity.
The study, published in The Proceedings of the National Academy of Sciences, delves into how viruses had to overcome significant obstacles to be transmitted across oceans. While in today’s world, global spread of diseases is much more common and rapid, historical data shows that diseases often failed to survive long sea voyages.
Elizabeth Blackmore and James O. Lloyd-Smith embarked on a quest to pinpoint when viral transmission dynamics began to shift. By employing advanced mathematical models, they were able to quantify the likelihood of transmission, a feat praised by experts in the field. Their focus on historical shipping routes shed light on the delayed spread of diseases like smallpox in various regions.
The idea to investigate the role of ships in disease transmission stemmed from Ms. Blackmore’s earlier research during her master’s degree. The study uncovered that smallpox outbreaks in California were not reported until much later in the 19th century, indicating a gradual transformation in viral dissemination patterns.
This groundbreaking research not only sheds light on the historical context of disease spread but also provides valuable insights into the evolution of infectious diseases on a global scale. By understanding how viruses navigated the waves of the past, we can better prepare for future pandemics and mitigate their impact on human populations worldwide.