The spatial spread and final size of models for the deterministic host-vector epidemic

Radcliffe, J.; Rass, Linda

doi:10.1016/0025-5564(84)90094-4

Cited by 10 publications

(2 citation statements)

References 11 publications

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“…We calculate IAR using the classical final size approach which is exact for directly transmitted SIR-type diseases 19 but only an approximation for vector-borne diseases. 20 Nonetheless, this approximation is excellent over realistic parameter ranges because only a very small proportion of mosquitoes are infected with YF virus even during epidemics (necessitating pooled testing). 21 See appendix for the mathematical details.…”

Section: Infection Attack Ratementioning

confidence: 99%

Fractional dosing of yellow fever vaccine to extend supply: a modelling study

Peak

Lipsitch

2016

The Lancet

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Background The ongoing yellow fever (YF) epidemic in Angola strains the global vaccine supply, prompting WHO to adopt dose sparing for its vaccination campaign in Kinshasa in July–August 2016. Although a 5-fold fractional-dose vaccine is similar to standard-dose vaccine in safety and immunogenicity, efficacy is untested. There is an urgent need to ensure the robustness of fractional-dose vaccination by elucidating the conditions under which dose fractionation would reduce transmission. Methods We estimate the effective reproductive number for YF in Angola using disease natural history and case report data. With simple mathematical models of YF transmission, we calculate the infection attack rate (IAR, the proportion of population infected over the course of an epidemic) under varying levels of transmissibility and five-fold fractional-dose vaccine efficacy for two vaccination scenarios: (i) random vaccination in a hypothetical population that is completely susceptible; (ii) the Kinshasa vaccination campaign in July–August 2016 with different age cutoff for fractional-dose vaccines. Findings We estimate the effective reproductive number early in the Angola outbreak was between 5·2 and 7·1. If vaccine action is all-or-nothing (i.e. a proportion VE of vaccinees receives complete and the remainder receive no protection), n-fold fractionation can dramatically reduce IAR as long as efficacy VE exceeds 1/n. This benefit threshold becomes more stringent if vaccine action is leaky (i.e. the susceptibility of each vaccinee is reduced by a factor that is equal to the vaccine efficacy VE). The age cutoff for fractional-dose vaccines chosen by the WHO for the Kinshasa vaccination campaign (namely, 2 years) provides the largest reduction in IAR if the efficacy of five-fold fractional-dose vaccines exceeds 20%. Interpretation Dose fractionation is a very effective strategy for reducing infection attack rate that would be robust with a large margin for error in case fractional-dose VE is lower than expected.

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Section: Infection Attack Ratementioning

confidence: 99%

Fractional dosing of yellow fever vaccine to extend supply: a modelling study

Peak

Lipsitch

2016

The Lancet

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“…Differential equation-based, age-structured difference and matrixbased models have provided insight into the population dynamics of ticks and the dynamics of tick-borne disease (Gaff, Gross, & Schaefer, 2009;Haile & Mount, 1987;Mount, Haile, & Daniels, 1997;Ros & Pugliese, 2007;Sandberg, Awerbuch, & Spielman, 1992). Spatially explicit components have been added using remote sensing, GIS and partial differential equation models (Bunnell, Campbell, & Squires, 2004;Diuk-Wasser et al, 2010;Radcliffe & Rass, 1984). While helpful, most of these models focus primarily on proportional interactions between ticks and hosts that inform our understanding of tick populations and pathogens, but not individual movement.…”

Section: Introductionmentioning

confidence: 99%

Modelling the Effects of Habitat and Hosts on Tick Invasions

Nadolny

Gaff

2018

LiB

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Many tick species are invading new areas because of anthropogenic changes in the landscape, shifting climatic variables and increasing populations of suitable host species and tick habitat. However, the relative influences of habitat and hosts in tick dispersal and tick population establishment remain in question. A spatially explicit agent-based model was developed to explore the spatio-temporal dynamics of a generic tick population in the years immediately following the introduction of ticks into a novel environment. The general model was then adapted to investigate a case study of two recent tick species invasions into the Mid-Atlantic United States. The recent simultaneous range expansions of two ixodid tick species, Ixodes affinis and Amblyomma maculatum, provided an opportunity to determine if invasion patterns observed in the field could be replicated in silico on a small scale. The models presented here indicated that for generalist parasites, habitat connectivity is a better indicator than host mobility for spatial and genetic patterns of parasite range expansion. In addition, our results demonstrate the utility of including genetic variables into agent-based models: gene flow functions as a proxy for measuring dispersal, and models can be validated using results from the field.

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The asymptotic speed of propagation of the deterministic non-reducible n-type epidemic

Radcliffe

Rass

1986

J. Math. Biology

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A model has been formulated in to describe the spatial spread of an epidemic involving n types of individuals, when triggered by the introduction of infectives from outside. Wave solutions for such a model have been investigated in and have been shown only to exist at certain speeds. This paper establishes that the asymptotic speed of propagation, as defined in Aronson and Weinberger, of such an epidemic is in fact c0, the minimum speed at which wave solutions exist. This extends the known result for the one-type and host-vector epidemics.

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The spatial spread and final size of models for the deterministic host-vector epidemic

Cited by 10 publications

References 11 publications

Fractional dosing of yellow fever vaccine to extend supply: a modelling study

Fractional dosing of yellow fever vaccine to extend supply: a modelling study

Modelling the Effects of Habitat and Hosts on Tick Invasions

The asymptotic speed of propagation of the deterministic non-reducible n-type epidemic

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