May 21, 2010

Ungraded eggs in Canadian state leads to Salmonella outbreak

A three-year outbreak of salmonella in British Columbia, Canada has been linked to restaurants that serve poor quality, ungraded eggs to their customers.

An investigation by the British Columbia Centre for Disease Control (BCCDC) and local health authorities found that eggs from the chicken meat industry and eggs from unregistered producers were in part behind a 300% increase in the incidence of Salmonella Enteritidis since 2007.

"We have been in an outbreak situation for three years," said physician epidemiologist Eleni Galanis. "Salmonella usually increases in the summer time, but the rates have been much higher than we are used to," she said.

About 500 cases of salmonella have been reported in British Columbia since 2008 and investigators estimate that the real number of cases may be 13-37 times that. One in seven cases led to hospitalisation, but no deaths have been reported.

"Because so many people eat eggs it is difficult to tease out the source," Galanis said. "By following these cases and clusters of cases, health authorities have found in both restaurants and in retail stores in the Lower Mainland ungraded and broiler hatching eggs being sold to customers or being prepared into meals."

Graded eggs are cleaned and inspected before being sold to consumers. Eggs that come from unregistered producers are not inspected and are more likely to be contaminated, Galanis said. "Farmers are allowed to sell their surplus eggs at the farm gate, but they are not allowed to sell them for resale," she said. BCCDC believes that people were buying surplus eggs in large quantities and reselling them to retailers and to restaurants.

British Columbia farmers registered to produce table eggs, or eggs that appear on store shelves as Grade A. Grade A eggs adhere to rigorous standards for cleanliness, and regular inspections are made to reduce the risk of salmonella contamination, said Al Sakalauskas, executive director of the British Columbia Egg Marketing Board.

Ungraded eggs enter the market when people buy from unregistered producers, Sakalauskas said. "We subscribe to a national standard called "Start Clean, Stay Clean", which is an on-farm food safety standard that includes several inspections a year with the objective of finding whether salmonella bacteria is present on the farm," he said. "When it is present, the eggs are held and pasteurised through the breaker industry. They do not enter the table market," he explained.

"Producers who are not part of the programme do not adhere to any of these standards," Sakalauskas said. "I don't know why any restaurant would risk the health of its customers by buying ungraded eggs in some back-door deal."

The bacterium likely entered British Columbia's food system through broiler eggs imported into British Columbia from the US for meat production, said Galanis.

In 2006, Salmonella Enteritidis occurred with a frequency of three cases per 100,000 people, but that rate rose to 10.2 cases in 2009. "In the last years it has been our most common strain, which is not normal. It has been increasing dramatically," Galanis said. The Salmonella Enteritidis bacterium causes diarrhoea, vomiting and stomach cramps. Symptoms often take 12 to 36 hours to appear.