San Diego sees surge in salmonella cases this year
Through mid-December, San Diego County recorded 730 salmonella cases, the highest total observed in at least 25 years.
That number comes amid a large number of salmonella-related recalls this year that have ranged from Cap’n Crunch cereal and Duncan Hines cake mix to goldfish crackers and hamburger meat.
According to county reports, salmonella rates in San Diego County have run higher than they are in the state or the nation in recent years. While more frequent outbreaks have contributed to the increase, better testing has contributed to the overall rise nationwide, said Dr. Eric McDonald, medical director of the county’s epidemiology and immunization services branch.
According to estimates from the U.S. Centers for Disease Control and Prevention, only about one in 20 salmonella cases ever gets diagnosed. The severe gastrointestinal distress caused by the bacteria usually passes without hospitalization, so a formal diagnosis usually isn’t made. However, recent advances in testing make it easier and quicker to prove that salmonella is present.
“People who wouldn’t have even gotten tested 10 years ago are getting tested more often today, and that clearly has something to do with the in- crease,” McDonald said.
As to why exactly San Diego’s numbers are higher than they are in other parts of the state and nation, that’s a bit of a mystery.
This year, though, there have been food-related cases related to nationwide outbreaks alongside a local salmonella cluster that has been linked to unpasteurized queso fresco cheeses purchased in Tijuana, McDonald said.
“We have three confirmed salmonella cases and another dozen that are probable and awaiting confirmation. Seven of them reported consuming Mexican cheeses purchased in Tijuana,” McDonald said last week.
The rest, he said, have secondary links to someone who consumed queso fresco, an iconic style of cheese made from fresh milk and usually consumed shortly after it’s made. When this cheese is made from unpasteurized milk, the odds are greater that it may carry the bacteria that cause listeria, brucella and tuberculosis.
Health consequences for the recent queso fresco cluster were often relatively severe, McDonald added.
“In the cheese-related outbreak, two of the three confirmed cases, plus five of the 12 unconfirmed cases, were sick enough that they had to be hospitalized,” McDonald said.
Though it is technically illegal for a company to make and sell cheese from unpasteurized milk and sell it to the public unless it has been aged for at least 60 days, queso fresco is often made in small batches at the household level in Mexico. And those who cross into San Diego from Tijuana are allowed to bring some cheese along for personal use.
“We’ve seen people bring tens of pounds back, suitcases full,” said Dr. Steve Waterman of the CDC. “There is no doubt that some of it gets sold or shared once it arrives in the United States.”
These days, Waterman is chief of the CDC’s Dengue Branch in San Juan, but before moving to that post, he was stationed in San Diego and was a central figure in the crossborder education efforts around queso fresco.
He was co-author of a 2009 study that surveyed border crossers about their knowledge of the dangers of unpasteurized queso fresco. Results showed that 58 percent were aware that the cheese could make them sick and 56 percent said they thought that the cheese could be unsafe for pregnant women. However, nearly 20 percent of respondents said they had eaten the cheese while pregnant.
Those results, Waterman said, galvanized a public health campaign that continues today focused on those at highest risk of getting sick.
“You know, this is culturally sort of a loved food in Mexico, and I don’t think we’re going to stop Mexican Americans or immigrants from eating this cheese, but we’re trying to educate the pub- lic that pregnant women, people with compromised immune systems like those with cancer, older people and infants should not be consuming it,” Waterman said.
There are many queso fresco varieties available that are made from pasteurized milk, but those made with raw milk continue to have an appeal for many, especially those born and raised south of the border.
Such is definitely the case for chef Claudette Zepeda-Wilkins, owner of El JardÍn in Liberty Station. Some of her earliest memories, she said, are of queso fresco made with fresh milk on her aunt’s ranch in El Salto outside Guadalajara. That fresh taste, with its grassy notes, she said, is simply lost through the heating process of pasteurization. For her, she said, it’s the pasteurized stuff that her body just can’t take. But she’s spent a lifetime eating unpasteurized queso fresco without a problem.
“I eat what you can get in the United States, and it just makes me a little sad,” she said.
She stresses, though, that any food needs to be prepared in a sanitary manner.