1. Instituto de Microbiología, Colegio de Ciencias Biológicas y Ambientales, Universidad San Francisco de Quito, Quito, Pichincha, Ecuador
2. Department of Veterinary and Biomedical Sciences, University of Minnesota, Saint Paul, Minnesota, USA
3. Mid Central Research & Outreach Center, Willmar, Minnesota, USA
4. Environmental Health Sciences Division, University of California, Berkeley, California, USA