Pregnant women dying, some along with their unborn babies, and mothers losing their newborn infants — that was the devastating profile of the 1985 outbreak of listeriosis in Los Angeles County.
For more than a quarter of a century, it was this country’s most deadly known foodborne illness outbreak. Three years after it was over, the New England Journal of Medicine (NEJM) reported that between Jan. 1 and Aug. 15, 1985, LA County had confirmed 142 cases of human listeriosis linked to eating soft, Mexican-style cheese.
The NEJM report, published Sept. 29, 1988, said 93 of those infections — 65.5 percent — struck pregnant women or their offspring. The other 49 cases, or 34.5 percent, were non-pregnant adults.
NEJM said 28 died, including 10 newborns and 18 adults. There were also 20 miscarriages.
This week, the 28-state outbreak caused by Listeria-contaminated cantaloupes has now claimed 29 lives, and resulted in one miscarriage. It has the dubious distinction of killing more people than the 1985 outbreak, and now is the deadliest on record in modern U.S. history.
The June 21, 1985 issue of Morbidity and Mortality Weekly Report (MMWR) said the Los Angeles County-University of South California Medical Center first noticed that pregnant Hispanic women were ill with listeriosis.
Between Jan. 1 and June 14, MMWR said there were 58 mother-infant pairs sickened. It said the mothers ranged in age from 15 to 43; the mean age was 28. There was one white woman and one Asian woman among the mothers. All the rest — 96 percent — were Hispanic.
The investigation quickly focused on Mexican-style fresh cheeses, and cheese made by Jalisco Mexican Projects Inc. was eventually implicated in the outbreak. In addition to the food safety investigations, the outbreak involved criminal investigations and about 150 civil cases.
At issue was Jalisco’s use of unpasteurized (raw) milk. The Los Angeles District Attorney alleged that the company could not pasteurize all the milk it purchased, and accused the cheese maker of using both raw and pasteurized milk in its product.
The outbreak investigation brought Jalisco Products into focus fairly quickly. The first case-control study with Hispanic hospital patients revealed they had consumed Mexican-style fresh cheeses in general and “significantly associated with risk of disease” for Jalisco.
Cheese samples were then collected from LA markets and in lab tests four packages of Jalisco cheese grew L. monocytogenes serotype 4b. “The four positive cheese samples were of two varieties, queso fresco and cotija,” according to the outbreak report.
All the samples had different expiration dates, suggesting to the federal Centers for Disease Control and Prevention (DCD) that there was “a continuing problem with this manufacturer’s cheese products.”
It was not until June 13, 1985 that Jalisco recalled the suspect cheese products, which were distributed only within California to Los Angeles and Orange counties. The company’s other products were distributed in as many as 16 states, including all of California.
By 1985, Gary S. and Susan McPherson — a former accountant and his wife from Pasadena — had owned Jalisco Mexican Products Inc. for about four years. In denying knowledge of the contamination until government officials showed up at his door, McPherson said. “You know, Listeria, that was a new word for me, as I think it was for most people in California.”
A year later, McPherson and his cheese-maker, Jose Luis Medina, pleaded “no contest” to misdemeanor criminal charges. McPherson served a 30-day jail sentence and Medina did 60 days in the LA County jail. Together they paid fines totaling $48,000.
At the time, the chief of consumer affairs for the LA District attorney said the lesson for the business community was that food protection laws “are not mere technicalities.”
Jalisco sued the Alta-Dena Certified Dairy, trying to persuade a jury that its milk supplier was the source of the contamination. However, the dairy was cleared of any responsibility for the 1985 listeriosis cases.
Alta-Dena was then the largest dairy in California, and Listeria was never found in its milk or herds. It was found in abundance at the Jalisco plant, where unlicensed employees were being allowed to pasteurize milk.
That jury verdict, however, was a disappointment for families of the victims, including some with children who were born with birth defects because their mothers were listeriosis victims.
Neither Jalisco, which permanently shut down, nor its insurance coverage had enough money — an estimated $100 million — to properly compensate all the victims, according to a plaintiff’s attorney. Jalisco carried about $10 million in insurance, McPherson said at the time the trial ended.
In the end, the exact cause of the contamination remained unknown. The pasteurization methods were faulty, the Jalisco plant was unsanitary and, contrary to the jury verdict, the raw milk from Alta-Dena remained the primary suspect.
“We still felt it was raw milk,” said the LA health official who helped authored the NEJM report. “There was nothing else that was common or made biological sense.”
Several reforms came out of the 1985 outbreak. The extensive studies of herds, physical plant, and cheese manufacturing led the California State Department of Agriculture to use undercover operatives. Federal regulations for fresh cheese were strengthened and more attention was paid to other dairy products.