BIG PINEY -- Back in the days when every ranch had a milk cow, before pasteurization was common practice at all, undulant fever -- human brucellosis -- was a fact of rural life in Wyoming, like cheat grass and hard winters.

"I had undulant fever, my mother had it, I'm sure my father would have tested positive for it," 79-year-old Dan S. Budd said during a recent interview at his ranch house west of Big Piney. "Most of the people of my generation that lived with livestock had it. They got it from unpasteurized milk."

Indeed, tests done in 1934 backed up Budd's general sense that the disease -- which does not spread from person to person -- was remarkably common.

Robert Wise, writing in the Journal of the American Medical Association, reported that at that time, an estimated 20 percent of the adult population in the United States, and 10 percent of the children, had been exposed to the brucella bacteria.

Today, what controversy remains about the disease is generally focused on Wyoming and the greater Yellowstone area. The question here is how best to control brucellosis in one of its last reservoirs in the United States -- the wild bison and elk.

But, as Dan Budd attests, Wyoming, like other states with agrarian roots, has known the disease on a far more intimate level in the past. Now it is a tiny but persistent problem, a shadow of an endemic disease that played a significant role in shaping U.S. food safety policy.

Medical historians say understanding the history of a disease can help adjust policies for its future control. For people concerned about reducing brucellosis in the United States, the decline of the disease can be traced to the popularization of pasteurization, and to federal efforts to test and slaughter livestock with the disease.

Concern about human brucellosis came to be a driving force behind the push for uniform milk pasteurization in the early '50s and was the inspiration for the still-common practice of ear-tagging cattle.

Brucellosis can cause a cow to abort her first calf, and reduces the milk production of dairy cattle. In people, the disease is marked by rolling, or undulating, fever, as well as varying combinations of fatigue, joint pain, swollen internal or sexual organs, and depression.
Once, it was a household disease, spread by drinking the unpasteurized milk of the family milk cow. Uniform pasteurization took it out of the kitchen and made it a disease more likely to strike on the job. Veterinarians, butchers and meatpackers were especially vulnerable.
As test-and-slaughter efforts made the disease increasingly rare in cattle in the United States, it once again became more likely that people would get the disease by eating unpasteurized dairy products -- not from the family cow, but on travels to Mexico.

'A taste of home'
In 2002, 125 cases of brucellosis were diagnosed in the United States and reported to the Centers for Disease Control. Texas reported 37 cases, the most of any state, followed by California (32), Illinois and Michigan (seven apiece,) and Florida and Utah (six apiece).
"We see 20 to 50 cases a year, thereabouts" in Texas, said Jim Schuermann, a Natrona County High School graduate who is now an epidemiologist with the Zoonosis Control Division of the Texas Public Health Department.

"About 90 percent of our cases are in our Hispanic population, (people) who have either gone to Mexico or had a family member return with unpasteurized ... cheese products," Schuermann said.
California public health officials report the same pattern of brucellosis within that state's Hispanic communities. They say it is a difficult pattern to break.

Unpasteurized cheese is "a taste of home," said Dr. Ben Sun, public health veterinarian for the state of California. "They may be willing to risk getting sick because supposedly it tastes better than a pasteurized product."

Although there is currently in the United States a movement back to consuming raw milk for its purported health benefits, public health officials are quick to point out that diseases that can be carried in the unpasteurized product include rabies, e. coli, tuberculosis and brucellosis.

Both Texas and California sponsor educational efforts aimed at discouraging people from bringing cheese back from Mexico, or eating cheese homemade in the United States.

California food safety officials also work with sheriff's offices to conduct sweeps of swap meets and yard sales where such cheeses are available to those who know where to look and what to ask for.

"We estimate it is a very large underground industry, and a very large problem," said Steve Lyle, a spokesman with the California Department of Food and Ag.

Preference against pasteurization
A five-hour drive south of the Texas border finds the Mexican prairie state of Chihuahua, home of traditional cheese makers -- and consumers -- who curse the notion of pasteurization, even as the federal government is beginning to demand it.

Near the city of Cuauhtemoc, Mexico's sizable Mennonite communities have long specialized in making fresh, raw cheese. The soft, smooth, butter-colored melting cheese is the preferred ingredient for many Mexican dishes.

The medium-sized factories that dot the countryside here make cheeses with names such as Queso Chihuahua and Queso Mennonita. Cheese made one day is sold the next, so the aging process that kills some bacteria is not a part of these kinds of cheese.

Most of that cheese is made from safe, uncontaminated milk, perfectly good to eat. But when a problem of tainted milk does arise, there is no safety net of pasteurization to protect consumers.
The quesarias are popular stops for North American travelers who are in the know. Returning north, cheese makers say some tourists will buy as many as 20 of the 2-kilogram bars, intent on sneaking them past border inspectors.

People from the United States who are even more likely to consume these cheeses are Mexican-Americans. Mexicans living in the United States stream across the border to visit family during the holidays. What homecoming does not feature the finest home cooking, with the best ingredients to be had? In central Mexico, to many, that means unpasteurized cheese.

Henry Weabe, manager of a mid-sized cheese factory near Cuauhtemoc, said that under pressure from the government, his factory will shift to pasteurizing the milk it uses this year. But he's not happy about the change, and neither, he thinks, will his customers be.

"We have problems selling the cheese if we pasteurize it," he said in December. Not only will the new machinery force the cost of cheese up, but, "The people here think pasteurized cheese has no flavor. People don't like pasteurized cheese," Weabe said.

Disease and history
The role a disease plays in the communities it affects changes with time. Brucellosis, still a major factor shaping wildlife and livestock management policy in Wyoming, was once a significant shaper of public health policy nationwide.

Susan Jones, a veterinarian and professor of disease history at the University of Colorado, said understanding the history of a disease can help clarify how existing public policies came to be and whether they have remained effective over time.

"History affects what you see and how you see it," Jones said.

"We need to understand both the biology and the history of a disease in order to understand how we might deal with it in the future," she said. "Both these things change over time. Those changes shape public policy and the environment in which these organisms are trying to succeed, evolutionarily."

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