TITLE:
The Effect of Patchy Host Distribution on the Dynamics and Persistence of Directly-Transmitted Pathogens: A Cellular Automata Study
AUTHORS:
Anthony E. Kiszewski, Tamara Awerbuch-Friedlander
KEYWORDS:
Spatial Stochastic; Cellular Automata; Infectious Diseases; Simulation; Habitat Fragmentation; Dynamical Systems
JOURNAL NAME:
Applied Mathematics,
Vol.4 No.10B,
October
4,
2013
ABSTRACT:
The effect of fragmented host
distributions on the transmission dynamics of directly-transmitted pathogens
was explored via stochastic automata simulation. Sixteen diverse population
distributions varying in shape and density were used as a substrate for
simulated outbreaks. Extended neighborhoods (80 cells), with probability of
infection weighted by proximity to an infective source were used to define the
overall probability of transitions from susceptible to infected. A static
probability defined transitions from infected to recovered. The duration of
active transmission as well as the proportion of each population infected per
outbreak was averaged over a series of 30 simulations per parameter set. The
level of aggregation for each population, measured in terms of the Moran
Coefficient (MC) of spatial autocorrelation, was found to
affect both the intensity of an outbreak and its length of persistence. Denser
populations produced the most cases and lasted longer than those that were
sparser. Elongated distributions, measured as the ratio between perimeter and
area (PA) reversed some of the trends of increasing density. Long, narrow
distributions produced fewer cases and were less persistent than populations
composed of more compact clusters but with similar MC. Thus, both the shape and
density of host distribution patterns affected the incidence rate, duration of
epidemics and the percent of the population infected. Certain patterns of
habitat fragmentation, thus, may put more hosts at risk of becoming infected
than others.