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Updated: May 3, 2026
'Bioluminescent' Reporter Phage for the Detection of Category A Bacterial Pathogens
Published on: July 8, 2011
Comparison of the transmission efficiency and plague progression dynamics associated with two mechanisms by which
Christopher F Bosio1, Clayton O Jarrett1, Dana P Scott2
1Laboratory of Bacteriology, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, Montana, United States of America.
Abstract:
Yersinia pestis can be transmitted by fleas during the first week after an infectious blood meal, termed early-phase or mass transmission, and again after Y. pestis forms a cohesive biofilm in the flea foregut that blocks normal blood feeding. We compared the transmission efficiency and the progression of infection after transmission by Oropsylla montana fleas at both stages. Fleas were allowed to feed on mice three days after an infectious blood meal to evaluate early-phase transmission, or after they had developed complete proventricular blockage. Transmission was variable and rather inefficient by both modes, and the odds of early-phase transmission was positively associated with the number of infected fleas that fed. Disease progression in individual mice bitten by fleas infected with a bioluminescent strain of Y. pestis was tracked. An early prominent focus of infection at the intradermal flea bite site and dissemination to the draining lymph node(s) soon thereafter were common features, but unlike what has been observed in intradermal injection models, this did not invariably lead to further systemic spread and terminal disease. Several of these mice resolved the infection without progression to terminal sepsis and developed an immune response to Y. pestis, particularly those that received an intermediate number of early-phase flea bites. Furthermore, two distinct types of terminal disease were noted: the stereotypical rapid onset terminal disease within four days, or a prolonged onset preceded by an extended, fluctuating infection of the lymph nodes before eventual systemic dissemination. For both modes of transmission, bubonic plague rather than primary septicemic plague was the predominant disease outcome. The results will help to inform mathematical models of flea-borne plague dynamics used to predict the relative contribution of the two transmission modes to epizootic outbreaks that erupt periodically from the normal enzootic background state.
Insights
Yersinia pestis transmission by fleas is inefficient in both early and blocked stages. Some mice resolved infection and developed immunity, with bubonic plague being the primary outcome.
Area of Science:
- Vector-borne diseases
- Infectious disease transmission
- Bacteriology
Background:
- Yersinia pestis, the plague bacterium, can be transmitted by fleas in two main phases: early-phase (mass transmission) and late-phase (after flea gut blockage).
- Understanding the efficiency and outcomes of these transmission modes is crucial for predicting plague dynamics.
Purpose of the Study:
- To compare the transmission efficiency of Yersinia pestis by Oropsylla montana fleas during early-phase and blocked feeding stages.
- To investigate disease progression and outcomes in mice following transmission by infected fleas.
Main Methods:
- Fleas were experimentally infected with Yersinia pestis.
- Mice were exposed to infected fleas during either the early-phase transmission window or after fleas developed proventricular blockage.
- Disease progression was monitored in mice infected with a bioluminescent Y. pestis strain.
Main Results:
- Transmission efficiency was variable and generally inefficient for both early-phase and blocked flea feeding.
- Early infection focused at the flea bite site and draining lymph nodes, but did not always lead to systemic disease.
- Some mice cleared the infection and developed immunity, especially after intermediate early-phase transmission.
- Two distinct patterns of terminal disease were observed: rapid onset and prolonged onset.
- Bubonic plague was the predominant outcome, rather than primary septicemic plague.
Conclusions:
- Both early-phase and blocked flea transmission of Yersinia pestis are relatively inefficient.
- Flea bite transmission can lead to resolution and immunity, challenging models assuming inevitable systemic spread.
- The findings are vital for refining mathematical models of plague epizootics and understanding the roles of different transmission modes.
