The memory is still vivid. On July 4, 1976, the bicentennial of the start of the American Revolution, I went with my wife to San Francisco to see the play 1776. It was presented outdoors in Golden Gate Park with actors in period costumes. Then we went to visit my aunt and uncle in Half Moon Bay. We all went over the hill to see the fireworks in Hayward. On the way back I was suddenly hit with diarrhea. The car stopped, I jumped out in the bushes, and exploded at both ends. I was better by morning, but now I was itching all over. I had jumped out into poison oak!
My training had taught me this was a classic example of food poisoning, most likely from Staphylococcus aureus. But what food was the staph in and how did it get there? We all had eaten the same food and no one else was sick. Then I remembered – I was the only one to buy a cup of coffee at a concession stand at the play. Coffee? Not likely. But I added some cream from a pitcher that had been out in the sun all day. Cream was the perfect media for staph to grow in. How did it get in the cream? I didn’t follow it any further and didn’t report it to anyone who would. I didn’t seek medical attention from anyone who would report it. I didn’t need medical attention, the illness was over.
The Centers for Disease Control and Prevention (CDC) estimates that in the United States food poisoning causes about 48 million illnesses each year. This is just a guestimate because, as in my own case, most are never reported. Even if they were, the overworked county health departments in charge of the initial investigation wouldn’t have the time to investigate. They concentrate on more important hospitalizations and deaths. The CDC reports that 128,000 hospitalizations and 3,000 deaths occur each year from food poisoning. The big three causes are Salmonella, E. coli, and Norivirus. Seventy-five per cent of food poisoning comes from these three.
Only 10 per cent of reported cases are successfully traced to their source. It usually takes a week or more before the incident is reported to the county health department and CDC, and two weeks at the earliest before an investigator starts knocking on doors. CDC has a standard questionnaire asking what foods were eaten and what restaurants were visited. People seldom remember everything they ate yesterday, much less two or three weeks earlier. All the information is fed into a computer that collates the most common foods and restaurants encountered to provide a list of the most likely suspects. Tracing it back to a farm or other source is a matter of luck and good detective work. Rules of thumb are often used, but these have proven to be more distracting than helpful. Salmonella typhimurium comes from mice and rats. Salmonella enteriditis comes from poultry and eggs. E coli H7O141 comes from cows. Norivirus comes from people.
Very often mishandling in food preparation has more bearing than the source itself. Donald Trump once gave a party for 1,000 guests and hundreds came down with food poisoning. The most likely suspect was egg custard. The caterer took a week to make all the custards and never refrigerated them! They never did find the source of the eggs, but egg producers took all the blame.
Undercooked pork can be a source of Trichinosis. My parasitology professor related that whenever he needed a sample of Trichina worm while he was at Berkeley he just asked the janitor for some of his sausage. The janitor had developed immunity. A veterinary student I knew wasn’t so lucky. He licked the knife he was using to cut up the bear he had killed and almost died from trichinosis!
Sometimes an investigation takes unexpected turns. An outbreak of Salmonella enteriditis in Los Angeles was traced to an oriental restaurant. They were making their own mayonnaise and keeping it on the shelf unrefrigerated. The organism was in the mayonnaise. They only had one supplier for the eggs for the mayonnaise, a small commercial egg flock. My department got involved to quarantine them and try to determine how they got infected. The breeder flock they got their birds from regularly tested for SE and all the tests were negative. Fish and Game came out and captured wild sparrows and animals but only found it in one opossum. Then they tested the water in a small stream running by the farm. Bingo! The stream was loaded with it. The stream was coming from a sewage treatment plant – the disease was coming from human sewage! Everyone with the runs dumps it in the toilet, and where does that go? The sewage treatment plant. This plant was 30 years old and handling 10 times the amount of sewage it was designed for. One of the veterinarians then tested water released from eight other sewage treatment plants in the Los Angeles area. Six of the eight were releasing water with Salmonella and/or E coli!
Human sources were finally indicated in a recent big outbreak of a rare kind of E coli in Germany. There are over 1.000 serotypes of E coli, but only seven cause disease in people. It took over two months to finally track it down to a sprout farm. First they blamed it on cucumbers. They found E coli H7O147 on a cucumber, then on lettuce. But the causative organism of the outbreak was E coli H7O104, a different culprit. They finally traced it to a sprout farm and decided the infection came from workers on the farm.
Most people are surprised to learn that the majority of foods involved in food poisoning are raw vegetables. Properly cooking meat and eggs kills the organisms, but nobody cooks cucumbers. How it gets into the vegetables is still poorly understood.
Tremendous efforts have been made to remove food poisoning organisms at the farm. “Farm to fork” security has been a buzzword for over 40 years. E coli O147 incidence has been cut in half, but Salmonella remains a big stumbling block. Salmonella food poisoning has been actually increasing. The big three, Salmonella typhimurium, newport, and enteritidis, have been successfully eradicated from commercial poultry farms. Improvements at the slaughter plant have reduced levels of other Salmonellas by 90 per cent. But people still keep getting sick from Salmonella. Back to the drawing board.
Interest has been rekindled in irradiating meat and produce to kill food poisoning pathogens. The technology was developed in the 1950s but met stiff consumer resistance to anything involving radiation. The process doesn’t make the produce radioactive, but you can’t convince some people of that. Some people are still opposed to pasteurization of milk, developed in the 1920s. When I was in Vietnam in the mid 1960s the U.S. military PX sold unrefrigerated irradiated milk with a shelf life of six months. Irradiation not only kills pathogens, it reduces the need for refrigeration and extends shelf life before spoilage. I tried some and never glowed in the dark. Researchers are also looking at using microwaves to kill pathogens.
Better control at the farm level accompanied with irradiation would greatly reduce the incidence of food poisoning, but it can’t completely eliminate it. Food can still become re-contaminated by infected food handlers, dirty water, and poor sanitation. The bugs have outwitted us so far. The experts still say the one biggest step in avoiding food poisoning is washing your hands in the kitchen.