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Posted in Food Safety on April 8, 2020
A major subject of interest here at Make Food Safe is the theory and practice of testing. Because food safety hinges on microbes that are too small to see, tests of various kinds are crucial if you’re trying to track and respond to outbreaks of foodborne illness. Now, there’s another tiny agent of infectious disease that’s on everyone’s minds: the coronavirus COVID-19, which as of this writing has sickened more than 1,300,000 people and killed more than 70,000 worldwide. An important factor in the outbreak has been the race to develop, manufacture, and deploy tests for the coronavirus in order to identify asymptomatic carriers and verify illness in those who have fallen ill. Food testing has been doing this the whole time! COVID-19 testing for the win!
COVID-19 testing and food safety testing use a lot of the same technology and face some of the same bottlenecks. This article will expound on the tech and look at some of the logistical challenges faced by both.
Polymerase chain reaction tests, also called PCR, are the industry standard for identifying viruses, bacteria, and other pathogens. It works by copying genetic material: tune it to look for a gene that’s unique to the pathogen you’d like to test for, and it’ll make many copies of that snippet so that they’re a simple matter to pick out.
PCR tests require a few things to work. Firstly, you need to know what genetic sequence you’re looking for, so you need some knowledge of the pathogen in question. Secondly, you need to make sure that the sequence you’re testing for is actually unique to what you’re looking for.
Running the test itself is a simple matter, and the ingredients aren’t too complicated: the chemicals and equipment you need to assemble the test aren’t usually in short supply. Processing the test after it’s been administered, however, takes time — at least a couple of hours, sometimes a day or more. In most cases, it also requires a lab. Furthermore, you need technicians in the lab processing the test, and you need people to administer the test in the first place.
PCR is also used widely in food safety. It’s usually a more reliable and complete diagnostic of foodborne pathogens than other, more rapid tests. It’s also a quicker and easier test than WGS, or whole genome sequencing, which maps out the entire genome of an organism (as the name implies).
You don’t have to look directly for viruses in order to find them. You can infer that they’re instead by looking for antibodies. Those are the chemicals produced by the body’s immune system to take down specific germs.
In the body, antibodies tag specific invaders for the immune system to target. The antibodies are tuned to specific viruses or bacteria. If you find the antibody, that means that the pathogen is present as well, or has been there recently.
Antibody tests are much quicker than PCR. They can be conducted in a matter of minutes, rather than hours. They require a lot less equipment, as well.
Like PCR, antibodies are used in both coronavirus and food safety testing. With food safety, however, it’s not always useful to look for antibodies after the fact, and acquired immunity to different foodborne pathogens is not quite so prized as it is in the corona context. (You can, of course, go looking for the relevant antibodies to determine whether someone has fallen ill with a foodborne pathogen).
Instead, antibodies in food testing are used for their unique qualities. Of particular interest is the way that they stick to the outsides of particular pathogens. If you can attach fluorescent particles to antibodies, or make those antibodies light up themselves, then they can be used to pick out where infectious agents are in the body.
The rollout of coronavirus testing in the United States has been slowed by a few factors
Different sorts of equipment that’s necessary for the test has been hard to find in some places. Sometimes, that means the test kits themselves, which in the early days of the outbreak weren’t as widely available.
It’s not just the test kits that have been disrupted. As Ed Yong has written over at the Atlantic, COVID-19 has disrupted delicate global supply chains that provide essential medical equipment. The region of China in which the outbreak started was previously a global center for the manufacture of masks to protect people from the virus. Northern Italy was a regional center for Q-TIPS before it became what it is today.
In order to administer the test, medical workers need personal protective equipment, or PPE. That means masks, but it also means gloves, protective suits, face shields, and other garments. It’s important to get fully suited up before you stick a cotton swab up someone’s nose. That’s because health care workers administering the test have reported that it’s a bit of a messy process — the person administering the test is exposed to a considerable amount of fluids, and thus a considerable amount of risk, so it’s crucial that they have enough PPE to stay safe.
Food safety testing is a different ballgame. The basic supplies that are used in procedures like PCR are generally more available. Because food safety testing is a constant activity, rather than an intensive event, the equipment and personnel necessary are generally not so tied up, and the system is often under less stress.
There are some similarities, however. In the case of food, there’s often items that are moving from suppliers to middlemen to grocery stores to customers — they’re out there in the real world, floating around. If those items are vectors for foodborne disease, then testing becomes a race to find out whether they’re compromised and try and track them down before they get someone sick. Coronavirus presents a similar epidemiological situation: if someone’s infected and out in the community, you want to track them down and isolate them before they have the chance to infect anyone else.
By: Sean McNulty, Contributing Writer (Non-Lawyer)