Global Risk of Madagascar's Pneumonic Plague Epidemic is Limited

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Mathematical models have proven the risk of the on-going pneumonic plague epidemic in Madagascar spreading elsewhere in the world is limited, with the estimated number of exported cases staying below 0.1 person in each country between August 1 and October 17.

Mathematical models have proven the risk of the on-going pneumonic plague epidemic in Madagascar spreading elsewhere in the world is limited, with the estimated number of exported cases staying below 0.1 person in each country between August 1 and October 17.

The study also estimated the epidemic’s basic reproduction number, or the average number of secondary cases generated by a single primary case, at 1.73. The case fatality risk was 5.5 percent. This was the world’s first real-time study into the epidemiological dynamics of the largest ever pneumonic plague epidemic in the African nation. The study employed several mathematical models.

Madagascar has seen a surge in pneumonic plague cases since August 2017; reportedly 2,217 people were diagnosed positive and there were 113 fatal cases by November 14. The epidemic prompted United Nations bodies, including the World Health Organization and UNICEF, and major nongovernmental organizations such as Doctors Without Borders to send relief to the nation. It is one of the largest epidemics in Madagascar since the late 19th century, when pneumonic plague was imported from abroad.

Pneumonic plague, which is the most severe form of plague caused by the bacterium Yersinia pestis, can be transmitted between people through breathing airborne droplets or through contact with the patient’s bloody sputum. The severe lung infection has a high mortality rate, but it can be cured if treated with antibacterial drugs at an early stage.

Read more at Hokkaido University

Image: This is the expected number of pneumonic plague cases travelling from Madagascar between Aug. 1 and Oct. 17. (Credit: Tsuzuki S., et al., Eurosurveillance, Nov. 16, 2017)