A study shows how climate may control the intensity of human plague, a disease that has killed approximately 200 million people during three recorded pandemics. Lei Xu and colleagues explored the association between climate and human plague severity in China, where the most recent pandemic originated.
The researchers analyzed China's human plague data, including 1.6 million confirmed cases of infection, along with a dryness/wetness index of precipitation amounts over a 500-year period for 120 locations across China.
In the northern part of the country, which tends to have an arid climate, increased rainfall generally elevated plague intensity.
The wet conditions likely promoted seed production and vegetation growth, leading to greater food sources for flea-harboring rodents, according to the authors.
The fleas, in turn, may carry Yersinia pestis, the pathogen that causes plague.
In southern China, which has a more humid climate, heightened precipitation generally decreased plague severity, which the authors suggest may be due to inhibited flea population growth and increased mortality of rodents due to flooding and other causes.
According to the authors, the findings demonstrate that precipitation can affect plague severity, but that the impact of rainfall in China may depend upon a particular region's overall aridity or humidity.
Source: Proceedings of the National Academy of Sciences via EurekAlert! [June 07, 2011]
The researchers analyzed China's human plague data, including 1.6 million confirmed cases of infection, along with a dryness/wetness index of precipitation amounts over a 500-year period for 120 locations across China.
In the northern part of the country, which tends to have an arid climate, increased rainfall generally elevated plague intensity.
The wet conditions likely promoted seed production and vegetation growth, leading to greater food sources for flea-harboring rodents, according to the authors.
The fleas, in turn, may carry Yersinia pestis, the pathogen that causes plague.
In southern China, which has a more humid climate, heightened precipitation generally decreased plague severity, which the authors suggest may be due to inhibited flea population growth and increased mortality of rodents due to flooding and other causes.
According to the authors, the findings demonstrate that precipitation can affect plague severity, but that the impact of rainfall in China may depend upon a particular region's overall aridity or humidity.
Source: Proceedings of the National Academy of Sciences via EurekAlert! [June 07, 2011]