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Which flea species are able to carry the plague bacterium?

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More than 100 species of fleas are known to be capable of carrying the plague bacterium (Yersinia pestis). While many species can harbor the pathogen, they vary significantly in their efficiency as vectors for the disease.1

The Oriental rat flea (Xenopsylla cheopis) is recognized as the most efficient carrier of plague. Other flea species identified as capable of transmitting the disease to humans include:1

Nosopsyllus fasciatus1
Xenopsylla brasiliensis1
Pulex irritans (the human flea)1

Additionally, approximately 10 other species are implicated as carriers of the classic urban form of the plague. These insects typically acquire the bacterium by feeding on infected rodents; once the flea's digestive tract becomes blocked by the multiplying bacteria, it regurgitates the bacilli into a new host—such as a human—during subsequent bites.123