Return of the Plague

There is a new outbreak of the plague.  Yes, I’m talking about *that* plague.

Over the past three months, Madagascar has confirmed more than 2,000 cases of bubonic plague and pneumonic plague.  The outbreak has resulted in 171 deaths, a fatality rate of 8 percent.  It is the country’s worst outbreak in half a century, for the first time striking densely populated cities.  (WSJ)

While the plague appears to be peaking in Madagascar, it is now in danger of spreading to nine neighboring countries and territories.  Comoros, Ethiopia, Kenya, Mauritius, Mozambique, La Réunion (France), Seychelles, South Africa and Tanzania are currently on alert for possible outbreaks.

Fortunately, at this point “the overall global risk is considered to be low.” (WHO)

Bubonic plague is caused by the bacterium Yersinia pestis.  It can spread to humans from the bite of infected fleas.  The fleas in turn are carried by rats.  Pneumonic plague is a more virulent form of the disease, and can be transmitted through the air from simply coughing and sneezing.

One of the most infamous plague outbreaks was “The Black Death,” which originated in Asia and spread throughout Europe from 1346-1353.  It is estimated to have killed up to 50 million people, a whopping 60 percent of Europe’s entire population.  (History Today)

U.S. researchers studied the cellular and molecular mechanisms underlying Y. pestis’ effect on the lungs, and discovered two distinct phases.  In the first 24-36 hours, the infection begins in an anti-inflammatory state.  By 48 hours it progresses to a highly pro-inflammatory state, resulting in death after three days.  The researchers used an Agilent Bioanalyzer System and GeneSpring software in their analysis.

Chinese researchers studied the body’s transcriptomic (cellular RNA) responses to pneumonic plague.  They found that within 12 hours of infection, 600 genes in the lungs are differentially expressed.  Within 48 hours, this number grows to 2,000 genes.  Overall, the results suggest that fully virulent Y. pestis inhibits both innate and adaptive immune responses.  The researchers used an Agilent Bioanalyzer System and RNA 6000 Nano kit in their analysis.


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