7,497 research outputs found
Exploring the Time to Intervene with a Reactive Mass Vaccination Campaign in Measles Epidemics.
The current WHO policy during measles outbreaks focuses on case management rather than reactive vaccination campaigns in urban areas of resource-poor countries having low vaccine coverage. Vaccination campaigns may be costly, or not timely enough to impact significantly on morbidity and mortality. We explored the time available for intervention during two recent epidemics. Our analysis suggests that the spread of measles in African urban settings may not be as fast as expected. Examining measles epidemic spread in Kinshasa (DRC), and Niamey (Niger) reveals a progression of smaller epidemics. Intervening with a mass campaign or in areas where cases have not yet been reported could slow the epidemic spread. The results of this preliminary analysis illustrate the importance of revisiting outbreak response plans
Shift of percolation thresholds for epidemic spread between static and dynamic small-world networks
The aim of the study was to compare the epidemic spread on static and dynamic
small-world networks. The network was constructed as a 2-dimensional
Watts-Strogatz model (500x500 square lattice with additional shortcuts), and
the dynamics involved rewiring shortcuts in every time step of the epidemic
spread. The model of the epidemic is SIR with latency time of 3 time steps. The
behaviour of the epidemic was checked over the range of shortcut probability
per underlying bond 0-0.5. The quantity of interest was percolation threshold
for the epidemic spread, for which numerical results were checked against an
approximate analytical model. We find a significant lowering of percolation
thresholds for the dynamic network in the parameter range given. The result
shows that the behaviour of the epidemic on dynamic network is that of a static
small world with the number of shortcuts increased by 20.7 +/- 1.4%, while the
overall qualitative behaviour stays the same. We derive corrections to the
analytical model which account for the effect. For both dynamic and static
small-world we observe suppression of the average epidemic size dependence on
network size in comparison with finite-size scaling known for regular lattice.
We also study the effect of dynamics for several rewiring rates relative to
latency time of the disease.Comment: 13 pages, 6 figure
The front of the epidemic spread and first passage percolation
In this paper we establish a connection between epidemic models on random
networks with general infection times considered in Barbour and Reinert 2013
and first passage percolation. Using techniques developed in Bhamidi, van der
Hofstad, Hooghiemstra 2012, when each vertex has infinite contagious periods,
we extend results on the epidemic curve in Barbour Reinert 2013 from bounded
degree graphs to general sparse random graphs with degrees having finite third
moments as the number of vertices tends to infinity. We also study the epidemic
trail between the source and typical vertices in the graph. This connection to
first passage percolation can be also be used to study epidemic models with
general contagious periods as in Barbour Reinert 2013 without bounded degree
assumptions.Comment: 14 page
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