A Model for Chagas Disease with Oral and Congenital Transmission

Daniel J Coffield,Meir Shillor,Ensela Mema,Alexandra Zetye,Amanda Pruzinsky,Bruce Pell,Anna Maria Spagnuolo,Herbert B Tanowitz

doi:10.1371/journal.pone.0067267

Abstract

This work presents a new mathematical model for the domestic transmission of Chagas disease, a parasitic disease affecting humans and other mammals throughout Central and South America. The model takes into account congenital transmission in both humans and domestic mammals as well as oral transmission in domestic mammals. The model has time-dependent coefficients to account for seasonality and consists of four nonlinear differential equations, one of which has a delay, for the populations of vectors, infected vectors, infected humans, and infected mammals in the domestic setting. Computer simulations show that congenital transmission has a modest effect on infection while oral transmission in domestic mammals substantially contributes to the spread of the disease. In particular, oral transmission provides an alternative to vector biting as an infection route for the domestic mammals, who are key to the infection cycle. This may lead to high infection rates in domestic mammals even when the vectors have a low preference for biting them, and ultimately results in high infection levels in humans.

Highlights

Chagas disease is caused by infection with the parasite Trypanosoma cruzi and is a major source of suffering throughout Latin America
The Southern Cone Initiative was implemented in the 1990s with the goal of interrupting the transmission of Chagas disease in South American countries through insecticide spraying and blood screening [10,11,12]. This program has led to a dramatic decrease in transmission in several countries in South America, with some regions reporting a considerable drop in infections from Triatoma infestans, the primary vector, and transmission virtually at zero [13,14]
This work presents a new model with seasonally dependent coefficients for the domestic transmission of Chagas disease, building upon the work in [21]

Summary

Introduction

The Southern Cone Initiative was implemented in the 1990s with the goal of interrupting the transmission of Chagas disease in South American countries through insecticide spraying and blood screening [10,11,12]. This program has led to a dramatic decrease in transmission in several countries in South America, with some regions reporting a considerable drop in infections from Triatoma infestans, the primary vector, and transmission virtually at zero [13,14]. Additional control measures are treatment for acute Chagas disease and for congenital transmission cases [15]

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