1927
Dr. Tonn is born in Watertown, Wisconsin to Harry James and Elise Tonn.
1949
Dr. Tonn receives a Bachelor of Science from Colorado State University.
1950
Dr. Tonn receives a Master of Science from Colorado State University.
1959
Dr. Tonn receives a Doctor of Philosophy from Oklahoma State University.
1961
Dr. Tonn becomes a research associate at Louisiana State University, through which he also works in Costa Rica.
1963
Dr. Tonn becomes the director of Taunton Field Station in Massachusetts.
1963
Dr. Tonn receives a Master of Public Health from Oklahoma Medical School.
1965
Dr. Tonn is appointed chief of the planning management and operations unit with the World Health Organization in various locations.
1987
Dr. Tonn retires from the World Health Organization.
1984
Dr. Tonn is appointed president of the Society for Vector Ecology.
1988
Dr. Tonn becomes an adjunct professor of parasitology at the University of Texas at El Paso.