Fletcher, Stephanie M., Mary-Louise McLaws, and John T. Ellis. “Prevalence of Gastrointestinal Pathogens in Developed and Developing Countries: Systematic Review and Meta-Analysis”. Journal of Public Health Research 2, no. 1 (July 16, 2013): e9. Accessed June 6, 2020. https://jphres.org/index.php/jphres/article/view/jphr.2013.e9.