A Role for Early-Phase Transmission in the Enzootic Maintenance of Plague

Mitchell, C. Madeline; Schwarzer, Ashley R.; Miarinjara, Adélaïde; Jarrett, Clayton O.; Luis, Angela D.; Hinnebusch, B. Joseph

doi:10.1371/journal.ppat.1010996

Cited by 8 publications

(4 citation statements)

References 70 publications

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“…Mathematical model helps explore the propagation mechanism and provide theoretical support for the public authorities to make prevention and control measures. Lots of differential equation models have been formulated to character the dynamics of different diseases such as Ebola, COVID-19 and Plague, and to evaluate the availability of the prevention measures, see [3] - [12] for examples. And many scholars had modified the early compartment epidemic models, such as SIR and SEIR et al to simulate the evolution process of diseases and to analyze their epidemiological characteristics, see [13] - [21].…”

Section: Introductionmentioning

confidence: 99%

Method and Application of Estimating Epidemiological Parameters Based on Data-Driven Approach

Sun,

Zhang,

Zhao

2024

IEEE Access

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Determining initial variables and key parameters, such as case fatality ratio (CFR), dynamic case fatality ratio (DCFR), reproduction number (R 0 ), and so on, helps shed more light on the transmission and control of emerging and re-emerging infectious diseases. Here, we established a SAIUHR model, which describes the dynamic changes of susceptible, asymptomatic infectious, under-reported symptomatic infectious, hospitalized and recovered individuals. And we proposed a novel approach based on our model to calculate the report rate, starting time, basic reproduction number, the initial conditions for the compartments, CFR and DCFR. Finally, we apply our method to epidemiological datasets from China, Italy, Germany, and France. The results show that the goodness of fit for the cumulative confirmed cases is greater than 97.45% in each of the countries, DCFR is more effective than CFR in predicting the future tend of infectious disease, and improving the report rate, raising the control strength and shortening the wait time are the effective strategies against infectious diseases. This study highlights the implications of taking proper restrictions and strong policies to deal with emerging and re-emerging infectious diseases from their spread in the early stage.INDEX TERMS Basic reproduction number, data-driven, epidemic model, parameter estimation.

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Section: Introductionmentioning

confidence: 99%

Method and Application of Estimating Epidemiological Parameters Based on Data-Driven Approach

Sun,

Zhang,

Zhao

2024

IEEE Access

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“…At this stage, however, the bacterial aggregates are not firmly entrenched in the proventriculus and after initially impeding blood feeding, potentiating some transmission, they are dislodged and swept back into the midgut, allowing normal blood feeding to resume ( 1 , 2 ). Early-phase transmission occurs primarily during the first blood meal after the infectious blood meal and is inefficient, with few bacteria transmitted, and requires several newly infected fleas feeding simultaneously for successful transmission ( 4 – 6 ).…”

Section: Introductionmentioning

confidence: 99%

“…This more cohesive, mature biofilm infection develops within one to a few weeks after infection, and in some fleas consolidates to fill the proventriculus and prevent blood flow into the midgut during feeding attempts, again leading to regurgitation of blood mixed with bacteria into the bite site ( 9 , 12 ). These completely blocked fleas are the most efficient transmitters, as they can transmit large numbers of bacteria during continuous, persistent feeding attempts before they succumb to starvation within a few days ( 6 ). Thus, the two transmission modes essentially correspond to different stages of Y. pestis biofilm development in the flea, characterized by aggregated bacteria within a matrix of extracellular polymeric substances (EPS).…”

Section: Introductionmentioning

confidence: 99%

Role of the Yersinia pestis phospholipase D (Ymt) in the initial aggregation step of biofilm formation in the flea

Jarrett,

Leung,

Motoshi

et al. 2024

mBio

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Transmission of Yersinia pestis by fleas depends on the formation of condensed bacterial aggregates embedded within a gel-like matrix that localizes to the proventricular valve in the flea foregut and interferes with normal blood feeding. This is essentially a bacterial biofilm phenomenon, which at its end stage requires the production of a Y. pestis exopolysaccharide that bridges the bacteria together in a cohesive, dense biofilm that completely blocks the proventriculus. However, bacterial aggregates are evident within an hour after a flea ingests Y. pestis , and the bacterial exopolysaccharide is not required for this process. In this study, we characterized the biochemical composition of the initial aggregates and demonstrated that the yersinia murine toxin (Ymt), a Y. pestis phospholipase D, greatly enhances rapid aggregation following infected mouse blood meals. The matrix of the bacterial aggregates is complex, containing large amounts of protein and lipid (particularly cholesterol) derived from the flea’s blood meal. A similar incidence of proventricular aggregation occurred after fleas ingested whole blood or serum containing Y. pestis , and intact, viable bacteria were not required. The initial aggregation of Y. pestis in the flea gut is likely due to a spontaneous physical process termed depletion aggregation that occurs commonly in environments with high concentrations of polymers or other macromolecules and particles such as bacteria. The initial aggregation sets up subsequent binding aggregation mediated by the bacterially produced exopolysaccharide and mature biofilm that results in proventricular blockage and efficient flea-borne transmission. IMPORTANCE Yersinia pestis , the bacterial agent of plague, is maintained in nature in mammal-flea-mammal transmission cycles. After a flea feeds on a mammal with septicemic plague, the bacteria rapidly coalesce in the flea’s digestive tract to form dense aggregates enveloped in a viscous matrix that often localizes to the foregut. This represents the initial stage of biofilm development that potentiates transmission of Y. pestis when the flea later bites a new host. The rapid aggregation likely occurs via a depletion-aggregation mechanism, a non-canonical first step of bacterial biofilm development. We found that the biofilm matrix is largely composed of host blood proteins and lipids, particularly cholesterol, and that the enzymatic activity of a Y. pestis phospholipase D (Ymt) enhances the initial aggregation. Y. pestis transmitted by flea bite is likely associated with this host-derived matrix, which may initially shield the bacteria from recognition by the host's intradermal innate immune response.

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“…In addition to bio lm-mediated proventricular blockage, Y. pestis can be transmitted through a regurgitative mechanism shortly after the ea becomes infected 23 . This mechanism appears to be independent of blood meal source, but can also result in non-productive transmission suggesting it may slow epizootic spread of disease 24 . Although these two methods of transmission are believed to require distinct proteins from the bacteria and eas, both occur from the midgut.…”

Section: Introductionmentioning

confidence: 99%

Transovarial transmission of Yersinia pestis in its flea vector, Xenopsylla cheopis

Pauling,

Beerntsen,

Song

et al. 2023

Preprint

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Yersinia pestis is the causative agent of bubonic plague, a deadly flea-borne disease responsible for three historic pandemics. Today annual cases of human disease occur worldwide following exposure to Y. pestis infected fleas that can be found within the rodent population where plague activity cycles between epizootic outbreaks and extended periods of apparent quiescence. Flea transmission of Y. pestis is most efficient in “blocked” fleas that are unable to feed, whereas mammalian transmission to fleas requires a susceptible host with end-stage high titer bacteremia. These facts suggest alternative mechanisms of transmission must exist to support the persistence of Y. pestis between epizootic outbreaks. In this work, we addressed whether vertical transmission could be a mechanism for persistent low-infection across generations of fleas. We demonstrate that Y. pestis infection of the Oriental rat flea, Xenopyslla cheopis, spreads to the reproductive tissues and is found in eggs produced by infected adult fleas. We further show that vertical transmission of Y. pestis from eggs to adults results in midgut colonization indicating a strong probability that it can reenter the sylvatic plague cycle.

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A Role for Early-Phase Transmission in the Enzootic Maintenance of Plague

Cited by 8 publications

References 70 publications

Method and Application of Estimating Epidemiological Parameters Based on Data-Driven Approach

Method and Application of Estimating Epidemiological Parameters Based on Data-Driven Approach

Role of the Yersinia pestis phospholipase D (Ymt) in the initial aggregation step of biofilm formation in the flea

Transovarial transmission of Yersinia pestis in its flea vector, Xenopsylla cheopis

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