1982: Two outbreaks of food poisoning with extreme symptoms among customers of McDonald's in Oregon and Michigan alert microbiologists to an emerging pathogen: E. coli O157:H7.
1985: An O157:H7 outbreak in a Canadian nursing home kills 19 of the 55 people affected.
1986: A Minnesota outbreak is traced to raw milk.
1988: The USDA forms the National Advisory Committee for Microbiological Criteria for Foods.
1990: A town's water supply is contaminated in Missouri; four die. The bacteria isolated this time show signs of drug resistance.
1991: 23 people in Massachusetts are sickened by contaminated apple juice.
In Oregon, swimming in a contaminated lake leads to an outbreak.
1992: The USDA declares a "war on pathogens."
1993: An outbreak started by Jack in the Box hamburgers sickens more than 700, kills four.
USDA declares "zero tolerance" for \o7 E. coli \f7 O157:H7 in food.
Parents of children affected by \o7 E. coli \f7 form Safe Tables Our Priority.
USDA requires safe-handling labels on ground beef.
1994: The USDA declares the bacterium an "adulterant" in raw ground beef. Testing begins at grinding plants and stores. Positive tests result in an automatic recall. Testing also marks a change from organoleptic meat inspection--judging by sight and smell--to microbiological, judging by tests for invisible organisms.
1995: The USDA pushes the meat industry to adopt HACCP, a risk-reduction strategy developed by NASA for production of sterile astronaut rations.
1996: Outbreak caused by Odwalla apple juice sickens 60, kills one.
Outbreaks in Scotland, Japan and Germany sicken thousands, kill more than 25.
1997: A recall of 20,000 pounds of ground beef swells to 25 million pounds at Hudson Foods in Nebraska. Hudson is ruined. The episode highlights shortcomings of the USDA testing program, under which meat grinders are the ones held responsible though the contamination occurs at slaughter.
1998: USDA scientists suggest in Science magazine that unnatural \o7 E. coli \f7 O157:H7 colonization begins in the feedlot. A fast-fattening grain diet that adversely affects the cow's digestion is named as a potential cause.
A sensitive new test shows the bacteria to be almost universal among U.S. cattle.
Food and Drug Administration requires a warning label on fresh fruit juices in the wake of the Odwalla incident.
Largest meat plants adopt HACCP.
1999: Medium-sized meat plants adopt HACCP.
2000: Small meat plants adopt HACCP.
The USDA and FDA legalize sale of irradiated ground beef.
Thousands sickened, seven die in waterborne outbreak in Ontario, Canada.
2001: The pathogen is considered so widespread that the Centers for Disease Control and Prevention issues warnings about petting zoos and swimming pools.
The CDC estimates 73,000 cases of \o7 E. coli \f7 poisoning and 60 deaths.
The National Cattlemen's Beef Assn. rejects a suggestion that a switch back to hay is merited. It points to conflicting studies, argues that the move might not work and says the change would be loss-making for the industry.
The USDA's National Advisory Committee for Microbiological Criteria for Foods considers extending the \o7 E. coli \f7 "adulterant" rule to steaks that have been pierced during tenderization.