Keeping Food Bugs At Bay
Interviewed by Rasa Fournier
Wednesday - December 14, 2011
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Dr. Willis Chang
Infectious diseases specialist at Pali Momi
Where did you receive your schooling and training?
I attended the UH John A. Burns School of Medicine. Then I went to the UCLA-based hospital system in California for my infectious diseases fellowship. I have been in practice since 1992.
What causes food poisoning?
There are a lot of different organisms and other mechanisms that cause food poisoning. There are bacteria, but sometimes the poisoning might come from a ceramic pitcher. The glaze could have heavy metal toxins, and if you put acidic juices in it the toxins can leach out.
One way we look at it is how quickly the toxins act. Immediate toxicity usually comes from toxins that bacteria produce. When you eat it, it’s like ingesting poison and causes nausea, vomiting and/or diarrhea, sometimes within a few hours. The major organisms that cause this are staphylococcus aureus. It’s a common bacteria, but certain strains produce toxins as they munch on food. The other bacteria in this category is bacillus cereus. It’s usually found in grains, typically rice. The bacteria forms spores that don’t get killed when you cook the rice. If you eat the rice right away it’s fine, it’ll pass right through you. But if it sits out, the bacteria germinates and secretes a toxin. There’s also clostridium perfringens that is associated with pork intestines, and that can be lethal.
There are other types of food poisoning where you eat the contaminated food and you don’t get sick for several days. That’s because this type of bacteria have to start growing in you. That’s where we see salmonella or campylobacter, and those are both associated with chickens. Salmonella is especially associated with eggs. The chicken may be infected in its intestines and it transfers to the egg because the shell is porous. Crack eggs only if you’re going to use them immediately. Don’t let it sit for hours. With campylobacter, the problem is cross contamination
using the same knife to cut a cooked chicken that you used when it was raw, or the same cutting board, especially if it hasn’t been cleaned.
Then there are the really bad ones that cause dysentery, like certain strains of E. coli. Some salmonella can cause typhoid fever. Cholera is caused by food poisoning from bacteria in fish.
People get anxious when they hear the word E. coli, but it’s an extremely common bacteria that you find in just about everybody’s intestines. It’s only certain strains of E. coli that produce the toxins that can kill people.
There are also viruses that can be food borne, like norovirus.
How can you tell if food poisoning is what made you sick?
The only way is to test the food, but sometimes that’s impossible like when there’s a big outbreak. If it’s a big enough problem the Department of Health and the Centers for Disease Control will do a food history on everybody who’s sick. Based on the symptoms and what they ate, they’ll look for the most likely culprit.
At what point should someone call a doctor?
If it goes on for more than 24 hours or if they can’t hold anything down, have a high fever, or see blood in their stool, call a doctor.
Is there anything particular to Hawaii?
Salmonella is not uncommon in Hawaii. Island-style parties it’s potluck and everybody brings a dish or two that sits out on for hours. In that kind of setting food poisoning can easily occur, especially in more perishable dishes like mayonnaise-based foods.
Food poisoning from fish also is common in Hawaii. The biggest one is scombroid fish poisoning. It can happen in any kind of seafood. If seafood is not stored properly, it can start to deteriorate more quickly than other foods, which can trigger an allergic reaction like hives.
Then there’s ciguatera. It’s a toxin that is accumulated in certain reef fish, especially the top carnivore-type fish. The ones we see here are ulua and kahala. Little fish eat algae that contain toxic microorganisms. It doesn’t affect the fish, but it concentrates in their intestines and flesh, and when the bigger reef fish eat them it keeps accumulating. Higher and higher concentrations of the toxin build up in their flesh. Then you catch it, eat it and get poisoned by it. You can eat small quantities and not get sick, but if you eat something that has a high level in it, it can cause pretty severe illness diarrhea and neurologic problems. It can affect your heart.
What are some tips to prevent food poisoning?
There’s a danger zone of temperature: between 40 degrees and 140 degrees Fahrenheit. Food in that temperature zone can harbor the growth of bacteria. Below 40 is refrigerator temperature so it slows or halts bacterial growth. Over 140 is when you’re cooking. Keep the foods hot or keep them cold and you’ll be OK. You don’t want to leave it out at room temperature.
One exception is listeria. Recently there was an outbreak with cantaloupe, which is pretty unusual because fruit is sterile. But if there’s bacteria on the outside and you cut into it, you can contaminate the fruit. Listeria can withstand and actually grow at colder temperatures, including in the refrigerator. Listeria is dangerous to the very young, very old and pregnant women. It can cause miscarriages.
Seems like all the dangers could make people paranoid.
We live with bacteria all over the place, it’s in our homes, our workplaces. It’s on your face, your mouth, your skin. Generally the body knows how to handle it, but we have to take precautions. Our big advancements in life expectancy come from public health practices, sanitary sewers, refrigeration. Proper handling of food is important.
It’s a good time to talk about this because it’s holiday time, and people should be aware of proper handling and storage of food. You don’t want Grandma to get sick because she ate something bad.
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