ASP, MOCR, CAR, CLNS and LAC designed the study. CAR developed the mathematical algorithm for analyzing the epidemiological curve. PCN and MGRC conducted data collection. ASP performed the statistical analysis, CAR and ASP critically reviewed the mathematical data. CLNS, ASP, LAC and EGSJ have critically reviewed the relationship between epidemiological data and socioeconomic variables. ASP wrote the article. All authors read and approved the manuscript.