Twice a day, Brinker or one of his farmhands wanders a barn holding more than 5,000 pigs, looking for sneezing, coughing or panting. It's low-tech surveillance, and Brinker knows the stakes are high.
The U.N.'s Food and Agriculture Organization has urged countries to step up surveillance on hog farms. But in the United States, that task falls to the industry, not public health officials. Meat companies police their own farms to root out disease.
Critics question how effective this system of voluntary self-regulation can be. But Brinker is confident he and other hog farmers could spot the disease quickly.
"If you're a person who does this for a living, it just comes as second nature," he said.
The effort to detect swine flu on U.S. farms gained urgency over the weekend as Canadian officials quarantined pigs infected with swine flu by a worker returning from Mexico. If the virus infects U.S. pigs, it could spread through herds kept in crowded barns and possibly threaten people.
Swine flu is a respiratory illness caused by a virus. The virus routinely causes outbreaks in pigs but doesn't usually kill many of them. Most recover.
As of Monday, there were at least 380 cases in the U.S. spread among 36 states. Globally, the virus had infected more than 1,447 people in 20 countries, according to the World Health Organization and other health bodies.
The CDC confirmed Monday two cases of H1N1 in Southern Nevada, CBS station KLAS-TV in Las Vegas. One case involves an 11-year-old boy who has since recovered. The other case involves a 39-year-old woman who is in the hospital.
Some health experts fear that overworked farmhands could fail to spot a diseased pig.
"There are undoubtedly public health risks" in the current system of self-detection, said Michael Greger, a physician and director of public health and animal agriculture at the Human Society of the United States. "But unfortunately, we don't shore up the levees until there is a disaster."
Smithfield Farms Inc. and Tyson Foods Inc., the nation's two biggest pork producers, say they have stepped up disease-control efforts since the swine flu outbreak, like limiting farm visitors and testing more pigs.
The industry's self-surveillance has managed to catch some disease outbreaks in the past, such as avian flu and mad cow disease in 2004. But reporting has been slow in other cases.
In 2002, California poultry farmers were slow to report an outbreak of avian flu that infected 35 million birds, according to a National Academy of Sciences report. It found that reporting the outbreak was delayed partly because farmers didn't think the flu was dangerous to people.
The report called the infected area of California the "Triangle of Doom."
"But the Triangle of Doom was also kept quiet by corporate decision-makers who feared that consumer demand would plummet if the public knew they were buying infected meat and eggs, safe though they may be to eat," the report said.
Georges Benjamin, executive director of the American Public Health Association, a Washington-based advocacy group representing public health workers, said the meat industry's self-surveillance has improved.
"People are beginning to do better surveillance around the country, but it isn't nearly as substantial as it needs to be," Benjamin said.
Some say voluntary surveillance by farmers could delay an organized response to a flu outbreak.
"Surveillance is critical - it can't just be industry-led," Greger said. "When there are human health implications to these industrial farming practices, one needs some sort of outside regulator to ensure human populations aren't at risk."
Greger favors using inspectors from the Department of Health and Human Services or the Agriculture Department to examine herds. That would avoid conflicts of interest involving farmers who could lose money if a flu outbreak curbed consumer demand or kept hogs out of the food supply.
Smithfield, Tyson and the National Pork Producers Council said that current self-detection methods are adequate.
Smithfield spokeswoman Keira Ullrich said the company limits farm access to essential personnel, bars visitors recently returned from abroad and requires frequent hand-washing. Tyson spokesman Gary Mickelson said the company has restricted who can visit hog farms.
Although experts say pork - even from infected pigs - is safe to handle and eat, the flu already has taken a toll on hog farmers, with lean hog prices falling from about 66 cents per pound earlier this month to 55 cents Thursday on the Chicago Mercantile exchange. The economic damage could grow if countries ban U.S. pork exports, which account for about 25 percent of sales.
Tyson said Monday that none of its plants has been affected by bans by Russia and China on pork exported from some U.S. states.
The pork industry has argued against referring to the disease as "swine" flu, and the U.S. government and the World Health Organization have complied, instead calling it "H1N1." But health experts confirm the virus originates in swine.
The hog industry has a financial incentive to root out sick hogs, because the costs of a major flu outbreak can be so high, said Jennifer Greiner, head of science and technology for the National Pork Producers Council.
An outbreak of foot-and-mouth disease in 2001 cost the British livestock industry an estimated $5 billion after the government slaughtered 6 million sheep, cows and pigs to contain it. Mass slaughters and quarantines would likely have to be taken in the United States if the new swine flu spread through hog herds.
To contain outbreaks, the livestock industry hopes to speed communication once a virus is detected, Greiner said.
Companies identify flu viruses by sending tissue or mucus samples to regional labs. After bioterrorism fears rose in 2002, the Agriculture Department linked those labs in a communications network. The labs alert each other of any outbreaks, through the USDA-administered National Animal Health Laboratory Network.
USDA staffers inspect live pigs and carcasses for disease at slaughterhouses. But they don't visit farms. The department did not return messages seeking comment on the industry's surveillance system for swine flu.
Brinker said it's not hard to spot a sick pig on his farm outside Auxvasse, Mo. The 5,000 pigs are kept in pens of 20 to 22 each. Brinker monitors how much food and water the hogs consume, because they lose their appetite when sick.
He's wary of any calls for outside regulators to inspect hog farms, in part because that would raise costs for a business with already-thin profit margins.
"You create another layer of bureaucracy, and all those costs have to be passed on to the consumer," he said.