Enlarge By Michael Conroy, AP Hens poke their heads out of their cages at a research farm in Montmorenci, Ind. Under new standards, only 7.5% of chicken carcasses at a food plant would be allowed to test positive for salmonella, down from 20% allowed since 1996. HEALTH UPDATES ON TWITTER HEALTH UPDATES ON TWITTER As many as 39,000 fewer Americans could get campylobacter and 26,000 fewer could get salmonella poisoning from chicken and turkey under new food safety rules announced Monday by Secretary of Agriculture Tom Vilsack. The bacteria, which can be life-threatening, are two of the most common causes of food-borne illness. "These standards will have probably the greatest public impact for consumers' health since anything USDA has adopted in the last 15 years," says Caroline Smith DeWaal, food safety director at the Center for Science in the Public Interest in Washington, D.C. FOOD POISONING: '09 a mixed year for food-borne illnesses Under the new standards, only 7.5% of chicken carcasses at a plant would be allowed to test positive for salmonella, down from 20% allowed since 1996. Salmonella levels in chickens were tested at 7.1% nationally in 2009, says Richard Lobb of the National Chicken Council. Salmonella can cause diarrhea, abdominal cramps and fever and can be life-threatening, especially for pregnant women, babies and the elderly. The Centers for Disease Control and Prevention estimates there are 1.4 million cases of salmonella and more than 500 deaths annually in the USA. VIDEO: Mom describes 3-year-old's salmonella symptoms The new rules for campylobacter, which had not been regulated before, are that companies fail if they have more than 10% positives for "highly contaminated" carcasses and 46% for "low level" contamination. The USDA estimates that about 50% of poultry plants are now at this level. In 2008, an estimated 40.2% chickens tested positive for campylobacter, which causes diarrhea, cramping, abdominal pain and fever. The CDC estimates campylobacter infects 2.4 million Americans a year and kills 124. The poultry industry will work hard to fulfill customers' expectations "for safe and wholesome chicken," Lobb says. Guidelines: You share in the USA TODAY community, so please keep your comments smart and civil. Don't attack other readers personally, and keep your language decent. Use the "Report Abuse" button to make a difference. You share in the USA TODAY community, so please keep your comments smart and civil. Don't attack other readers personally, and keep your language decent. Use the "Report Abuse" button to make a difference. Read more