The Authors 
Dr. Jettison is the parasitologist at the Rocky Mountain Laboratory 
(Hamilton, Mont..), National Microbiological Institute , Public Health 
Service. He has had nearly 25 years’ experience in the study of 
diseases of nature communicable to man in the western United States. 
His overseas assignments during World War II included malaria 
control in the China-Burma-India Theater and scrub typhus research 
in Burma. 
Mr. Kohls is a medical entomologist at the Rocky Mountain 
Laboratory . His research in medical entomology has included 
taxonomic and biological studies of ticks and of arthropod-borne 
diseases, including tularemia. He is the author or coauthor of papers 
on tularemia in beavers and muskrats and on contamination of 
natural waters with Pasteurella tularensis in the northwestern 
United States. 
Public Health Service Publication No. 421 
(Issued concurrently with the July 1955 issue of Public Health Reports, vol. 70, No. 7) 
(Received for publication November 1954) 
Library of Congress Catalog Card No. 55-60031 
UNITED STATES GOVERNMENT PRINTING OFFICE, WASHINGTON : 1955 
For sale by the Superintendent of Documents, U. S. Government Printing Office, Washington 25, D. C. — Price 20 cents 
