Presentation Information
[POS-34]Individual-Based Model of Anthelmintic Distribution against Echinococcosis in Red Foxes
*Kisara Oe1, Satoshi Takahashi2 (1. Graduate School of Humanities and Sciences, Nara Women's University (Japan), 2. Nara Women's University (Japan))
Keywords:
Individual-Based Model,Echinococcosis
Echinococcosis is a severe zoonotic disease caused by the larvae of Echinococcus multilocularis. In Hokkaido, red fox (Vulpes vulpes schrencki) serves as its primary definitive host. Field mice (Craseomys rufocanus bedfordiae) ingest eggs of echinococcus in Infected foxes excrement and act as intermediate hosts. Foxes predation on infected field mice completes infection cycle of Echinococcosis. Humans become infected by ingesting contaminated food or water, leading to severe liver and other organ damage after a prolonged incubation period. In this study, we develop a population dynamics model of foxes and field mice with echinococcosis infection and search efficient strategies for anthelmintic bait distribution.
We construct a lattice-based model on a torus space. The lattice size is 10 by 10 and each grid cell corresponding to square region of 1 square kilometres area. The field mice population is represented by density in each grid cell, while individual foxes are modeled as agents with specific states, such as infection status, territoriality, and survival. The probability of foxes infection is assumed to be proportional to the fraction of infected field mice in their diet. The probability of field mice infection is proportional to the number of infected foxes whose territories contain that mouse. In this study, we examine different anthelmintic bait distribution strategies. The total amount of bait is the same across all strategies.
By computer simulation, we found that the strategy with shorter distribution intervals but fewer number of baits per distribution results in lower final infection rates in foxes. When the probability of finding the bait by fox is higher, reduction of infection rate by shorter distribution intervals become more remarkable. A strategy of distributing baits only in the central cells resulted in a higher infection rate than strategy distributing 20 baits to all the cells. The strategy distributing baits only in high-infection areas nearly eliminates the infection. These results suggest that optimizing deworming strategies should consider distribution intervals, ease of finding bait, and focusing efforts on high-risk areas.
We construct a lattice-based model on a torus space. The lattice size is 10 by 10 and each grid cell corresponding to square region of 1 square kilometres area. The field mice population is represented by density in each grid cell, while individual foxes are modeled as agents with specific states, such as infection status, territoriality, and survival. The probability of foxes infection is assumed to be proportional to the fraction of infected field mice in their diet. The probability of field mice infection is proportional to the number of infected foxes whose territories contain that mouse. In this study, we examine different anthelmintic bait distribution strategies. The total amount of bait is the same across all strategies.
By computer simulation, we found that the strategy with shorter distribution intervals but fewer number of baits per distribution results in lower final infection rates in foxes. When the probability of finding the bait by fox is higher, reduction of infection rate by shorter distribution intervals become more remarkable. A strategy of distributing baits only in the central cells resulted in a higher infection rate than strategy distributing 20 baits to all the cells. The strategy distributing baits only in high-infection areas nearly eliminates the infection. These results suggest that optimizing deworming strategies should consider distribution intervals, ease of finding bait, and focusing efforts on high-risk areas.