1 Department of Epidemiology, School of Public Health, Shahroud University of Medical Sciences, Shahroud, Iran.
2 Department of Microbiology, Institute Aggeu Magalhaes-Fiocruz PE, Recife, PE, Brazil.
3 Department of Epidemiology and Biostatistics, Research Centre for Emerging and Reemerging infectious diseases, Pasteur Institute of Iran, Tehran, Iran.