[1][2] Treffert first attended Bethany Lutheran College where he focused on pre-medical courses and earned an associate in arts degree in 1953.
[1] In 1976, he held positions in the private practice of psychiatry, was executive director of the Fond du Lac County Health Care Center and the medical director of the Alcoholism Rehabilitation Unit of St. Agnes Hospital in Fond du Lac.
From 1979 to 1980, Treffert was president of the State Medical Society of Wisconsin and from 1981 to 1987 was chair of its board of directors.
[1] Treffert maintained a website on autism, savant syndrome, and related conditions hosted by the Wisconsin Medical Society.
[4][5] He held a research director position at the Treffert Center, Agnesian HealthCare in Fond du Lac, Wisconsin.