Dorothy Horstmann, Epidemiologist & Polio Researcher
Dr. Dorothy Horstmann wore many hats, including epidemiologist, virologist, pediatrician, and educator. Her research on the spread of poliovirus through the human bloodstream helped lay the foundation for the development of the polio vaccine. Since 1988, more than an estimated 1.5 million childhood deaths and 18 million paralyzations have been averted because of the polio vaccine.
Dorothy Millicent Horstmann was born on July 2, 1911, in Spokane, Washington but spent much of her youth in San Francisco, California. In 1936, she graduated the University of California, Berkeley with her Bachelor’s degree then went on to graduate from UCSF with her medical degree four years later. Horstmann then did her residency at Vanderbilt University Hospital.
In 1942, she was hired as a Commonwealth Fellow in Internal Medicine at Yale School of Medicine under the aegis of Dr. John Rodman Paul, pioneer of clinical epidemiology and one of the founders of the Yale Poliomyelitis Study Unit created to respond to the increase in polio epidemics. From 1943 to 1944, Horstmann and the rest of the unit were tasked with investigating five polio outbreaks across the United States: in New Haven, Connecticut, Chicago, Illinois, and Bakersfield, California in 1943, and in Hickory, North Carolina and New York City in 1944. They experimented with which samples the virus could be recovered from, such as throat and nose swabs, blood, and feces. They took a novel approach, taking samples from multiple sites over multiple days from one patient, providing insight into how long the virus stayed in certain systems and important sites of infection. Their results underscored the importance of the gastrointestinal (GI) tract (and not nasal passage) in polio pathogenesis. The question of how the virus got from the GI tract to the brain if the virus was ingested, not inhaled, remained.
During the 1943 New Haven outbreak, Horstmann collected blood from the 111 suspected polio patients admitted to the Yale-New Haven Hospital. One sample was different: testing positive for poliovirus, unlike the other 110. The positive result came from a 9-year-old girl, whose blood was drawn within six hours of developing a mild case of the disease and who never developed paralysis. The anomaly prompted Horstmann to look closer at the period of time in between infection and onset of symptoms. She turned to the bloodstream.
Horstmann fed poliovirus orally to monkeys and chimpanzees, in line with previous theories about the route of infection involving the GI tract. Blood samples were taken every day for 7 days after infection to see if and when poliovirus could be identified in the blood. Poliovirus was found in the blood within 4 to 6 days after infection and before onset of paralysis. Her findings were independently confirmed by David Bodian at Johns Hopkins University.
This explained why the virus was rarely detected in the bloodstream–the timing. Common practice was that blood samples were taken after the onset of severe symptoms like paralysis. By then, polio-specific antibodies would be circulating in the bloodstream, and the virus would not be detected in the blood. She continued her research and showed that the virus could be recovered from the blood of people who contact with polio patients and later went on to develop the disease or remained asymptomatic. Her discoveries turned the scientific consensus at the time–-that poliovirus only infects nervous tissue–on its head.
Horstmann’s research highlighted two avenues to stop poliovirus: the gastrointestinal tract and blood. She became a proponent of an oral polio vaccine.
Through her work on polio, Horstmann spent a lot of time with children, sparking an interest in pediatrics. She studied childhood and congenital diseases and the clinical epidemiology of Rubella, Coxsackie, and Echo viruses. Horstmann provided a foundation for another vaccine: the Rubella vaccine for children in the U.S. in 1969.
With a joint appointment in Epidemiology and Pediatrics, Horstmann was the first woman to be appointed a tenured professor in the Yale School of Medicine and the first woman at Yale to receive an endowed chair. Her work did not stop at Yale–serving as President of the Infectious Disease Society of America and being elected to the National Academy of Sciences in 1975. Horstmann retired in 1982 as an emeritus professor and senior research analyst and passed away in 2001.
