An agent-based model of exposure to human toxocariasis: a multi-country validation

Authored by K. Kanobana, B. Devleesschauwer, K. Polman, N. Speybroeck

Date Published: 2013-07

DOI: 10.1017/s0031182013000310

Sponsors: Institute of Tropical Medicine Antwerp Directorate General of the Belgian Development Cooperation Ghent University

Platforms: R

Model Documentation: ODD

Model Code URLs: Model code not found

Abstract

Seroprevalence data illustrate that human exposure to Toxocara is frequent. Environmental contamination with Toxocara spp. eggs is assumed to be the best indicator of human exposure, but increased risk of exposure has also been associated with many other factors. Reported associations are inconsistent, however, and there is still ambiguity regarding the factors driving the onset of Toxocara antibody positivity. The objective of this work was to assess the validity of our current conceptual understanding of the key processes driving human exposure to Toxocara. We constructed an agent-based model predicting Toxocara antibody positivity (as a measure of exposure) in children. Exposure was assumed to depend on the joint probability of 3 parameters: (1) environmental contamination with Toxocara spp. eggs, (2) larvation of these eggs and (3) the age-related contact with these eggs. This joint probability was linked to processes of acquired humoral immunity, influencing the rate of antibody seroreversion. The results of the simulation were validated against published data from 5 different geographical settings. Using simple rules and a stochastic approach with parameter estimates derived from the respective contexts, plausible serological patterns emerged from the model in nearly all settings. Our approach leads to novel insights in the transmission dynamics of Toxocara.

Tags

Agent-based modelling Rule-Based Modelling exposure Toxocara human toxocariasis multi-country