Climate change may worsen plague

By Katharine Gammon, LiveScience Contributor
14 Jun 2011 When the climate gets wetter, plagues can get worse, according to a new study that reveals why the plague was much worse in China’s north than in the south. The results also suggest that climate change could mean more virulent plagues in northern China and North America, as parts of the globe get wetter. A bacterium called Yersinia pestis, which is carried by rodents, is responsible for three types of plague: bubonic (also called Black Death), septicemic, and pneumonic plague. Together, these illnesses have been responsible for the deaths of millions of people the world over, including an estimated third of Europe’s population during the Middle Ages. While modern antibiotics can effectively treat plague, thousands of cases are still reported each year to the World Health Organization, and the bacterium has been identified as a possible biological warfare agent. Chinese and Norwegian researchers examined the association between climate and the severity of human plague in China during the most recent outbreaks between 1850 and 1964, when 1.6 million people became ill. They analyzed the plague data along with an index of precipitation over a 500-year period for 120 locations across China. [Read: 7 Devastating Infectious Diseases] “We have found [a] very clear relationship between the amount of precipitation and the occurrence of human plague: the more precipitation, the more plague in the north of China whereas the less in the south,” study author Nils Stenseth, of the Centre for Ecological and Evolutionary Synthesis at the University of Oslo in Norway, told LiveScience. The study results were published last week in the Proceedings of the National Academy of Sciences. More precipitation is expected in certain parts of the globe with a warming climate, according to the researchers, which might mean more cases of plague in the future.  They found that in the northern regions of China, which generally has a dry climate, increased rainfall was linked to more cases of plague; the researchers suspect the wetter conditions gave rise to more vegetation, so flea-bearing rodents had more food.  More fleas that can carry the Y. pestis pathogen would mean more plague cases. …

Climate Change May Worsen Plague