Iowa State University Veterinarian Records, RS 22/6/0/9, University Archives, Special Collections Department, Iowa State University, http://www.add.lib.iastate.edu/spcl/arch/rgrp/22-6-0-9.html
Canine heartworm infection, caused by Dirofilaria immitis, has made an alarming incursion into Iowa during the past 4 to 5 years. Review of clinical records at Iowa State University for the past 5 years show 46 cases of heartworm infection. Now it has gotten to the stage where veterinarians in some areas of Iowa are regularly encountering the disease and routinely check for its presence.
Greve, J. H.
"Heartworms In Iowa,"
Iowa State University Veterinarian: Vol. 33
, Article 4.
Available at: http://lib.dr.iastate.edu/iowastate_veterinarian/vol33/iss1/4