Infection Prevalence Bacterial Loads and Transmission Efficiency in Oropsylla montana (Siphonaptera: Ceratophyllidae) One Day After Exposure to Varying Concentrations of Yersinia pestis in Blood

摘要

Unblocked fleas can transmit Yersinia pestis, the bacterium that causes plague, shortly (≤4d) after taking an infectious bloodmeal. Investigators have measured so-called early-phase transmission (EPT) efficiency in various fleas following infection with highly bacteremic blood (≥10⁸cfu/ml). To date, no one has determined the lower limit of bacteremia required for fleas to acquire and transmit infection by EPT, though knowing this threshold is central to determining the length of time a host may be infectious to feeding fleas. Here, we evaluate the ability of Oropsylla montana (Baker) to acquire and transmit Y. pestis after feeding on blood containing 10³ to 10⁹cfu/ ml. We evaluated the resulting infection prevalence, bacterial loads, and transmission efficiency within the early-phase time period at 1d postinfection. Fleas acquired infection from bacteremic blood across a wide range of concentrations, but transmission was observed only when fleas ingested highly bacteremic blood.