One of the hallmarks of plague outbreaks is its seeming ability to disappear for a period of time and re-emerge unexpectedly. New findings published in the journal Emerging Infectious Diseases indicates that Yersinia pestis can survive and even thrive and replicate after being ingested by an amoeba, potentially explaining the plague’s ability to re-emerge after a period of latency.
The findings are part of a larger investigation being done by researchers at Colorado State University to study amoeba interactions with various forms of infectious diseases. To determine how amoebae interact with Y. pestis, the researchers analyzed soil samples found near plague outbreaks in prairie dog colonies. Different species of amoeba were isolated from the soil and bacteria was co-cultured with the amoebae to see if it survived ingestion.
They found that the plague bacteria was able to live for up to 48 hours inside the amoeba and possibly survive for longer. By contrast, most bacteria are destroyed within an hour of being ingested by an amoeba. A species of amoeba called Dictyostelium discoideum seemed to make the best home for the plague bacteria.
The scientists plan to further investigate how long plague can survive in amoebae and whether plague-filled amoebae can develop into a resilient, cystic phase that can re-animate years later.
Image: These are fluorescent confocal images of amoebae after experimental co-culture with Yersinia pestis. Image courtesy of David Markman/Colorado State University.