Modeling the prevalence of Schistosoma mansoni infection in an endemic population

TL;DR

This study models the long-term prevalence of Schistosoma mansoni infection using a nonlinear differential equation system, emphasizing that combined treatment and environmental strategies are essential for disease elimination.

Contribution

The paper introduces a mathematical model integrating treatment, infection, and demographic factors to predict schistosomiasis prevalence and highlights the necessity of combined public health interventions.

Findings

Model predicts a 11% prevalence limit with current treatment alone.

Treatment alone is insufficient for disease elimination.

Environmental and sanitation policies are crucial for eradication.

Abstract

We investigate theoretically if treatment alone can reduce the schistosomiasis's prevalence in an infected population, in a long-lasting sustainable way. We use a non-linear system of ordinary differential equations (a SI system combined with a logistic population growth) which describes the time evolution of the non-infected and infected populations, in terms of the recovering, infection, and demographic rates. Our model leads to the conclusion that the only way to eliminate this endemic disease is to implement public health policies aimed at both treatment and environment. We apply our model to the endemic area of Virgem das Gra\c{c}as, in Brazil, where the prevalence of Schistosiamisis in 2001 was greater than 50\%. The epidemiological data are extracted from a longitudinal study carried on the region between 2001 and 2010 and the demographic parameter from official Brazilian population data. When these estimated parameters are entered, our model gives a limit prevalence for Virgem das Gra\c{c}as of 11\%, which is still significantly high even though treatment in accordance to the government regulations is systematically performed. This estimative reinforces once again, that in order to eliminate Schistomiasis, public health policies aimed at treatment, sanitation, including snail control, and health education programs are mandatory.