Wisconsin epidemiologist Jeffrey Davis identified Milwaukee's Cryptosporidium outbreak

As doctors' offices filled with Milwaukeeans suffering from a mysterious illness in 1993, Mayor John Norquist called a meeting with state and local officials.

Norquist asked state epidemiologist Jeffrey Davis whether he would drink a glass of Milwaukee's water and when Davis said he would not, Norquist issued a massive boil water advisory that affected more than 1 million residents.

With decades of work in public health, Davis was the perfect person to figure out a little-known parasite cryptosporidiosis could be the culprit that sickened more than 400,000 people.

As state epidemiologist for the past four decades, Davis was Wisconsin's doctor.

He was a medical sleuth who figured out the connection between toxic shock syndrome and tampons and helped determine the infectious agent transmitted by ticks that causes Lyme disease. 

Davis, 72, died of pneumonia in Madison Jan. 16.

"Jeff’s knowledge of the literature helped identify the (Cryptosporidium) outbreak earlier. Cryptosporidiosis at that point was a pretty rare pathogen," said State Public Health Veterinarian James Kazmierczak.

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Knowing about a similar waterborne outbreak elsewhere in the U.S., Davis asked to see data on water quality in Milwaukee and noticed a spike in turbidity at the same time that people began to get sick. At the time, city water supplies were not tested for Cryptosporidium.

"Because of Jeff’s knowledge of what happened earlier with cryptosporidiosis, that became the leading suspect," said Kazmierczak.

Davis grew up in Whitefish Bay and earned an undergraduate degree in chemistry in 1967 at University of Wisconsin-Madison and his medical degree in 1971 at the University of Chicago. He did his internship and residency in pediatrics in Florida and from 1973 to 1975 worked for the U.S. Centers for Disease Control and the South Carolina Department of Health.

After a stint at Duke University Medical Center, he returned to Wisconsin in 1978 as state epidemiologist and chief of the division of acute and communicable diseases. In 1991, his job title changed to chief medical officer and state epidemiologist for communicable diseases.

"He loved being a sleuth and medical detective, leading investigations of all sorts, from toxic shock syndrome to Legionnaires' outbreaks, to the Cryptosporidium water supply outbreak, which was huge," said his wife Roseanne Clark.

"He really was passionate about trying to figure out the source to reduce the impact on as many people as possible. He cared about the health of the people of Wisconsin."

In 1980 when Davis heard about several young women in Wisconsin becoming ill with the sudden symptoms of high fever, vomiting, diarrhea, low blood pressure and the beginnings of kidney failure, he remembered hearing of similar cases in other states. Davis figured out the victims became sick while menstruating and it was his research that connected toxic shock syndrome with super absorbent tampons as a risk factor.

He published more than 250 papers on his research in infectious diseases and public health.

Davis' legacy is not just in the lives he saved through his work but as a mentor to other doctors, including many Epidemic Intelligence Service officers at the Centers for Disease Control and Prevention, said Bruce Klein, a professor of pediatrics and medical microbiology and immunology at UW.

"He was really a wonderful and effective mentor and there are many little Jeffs that carry on his intellectual and scientific spirit and those important values he imbued in trainees," including those who are working for the CDC, as state epidemiologists and academics, said Klein.

Davis is survived by his wife and two sons, Eli and Ethan Clark-Davis. A memorial service was held.