Episode 03: The Food-Water-Virus Nexus
“Something I think is so important right now is supporting our food systems. This virus has taken such a tremendous toll on everything from farm to fork…we all can help support these essential workers and businesses; many of which are struggling.”
erin dicaprio
A conversation with Dr. Erin DiCaprio about basic virology, virus transmission in food and water systems, COVID-19 + food safety, and canning/preservation at home. Recorded April 28, 2020.
guests on the show
Dr. Erin Dicaprio
Dr. Erin DiCaprio’s area of expertise is in microbial food safety, with emphasis on foodborne viruses. Her research is focused on determining the mechanisms by which fresh produce is contaminated by foodborne viruses during production and processing and which biological and environmental factors influence viral persistence in these foods. Dr. Dicaprio is involved with the Master Food Preserver Program and interacts with the general public to disseminate knowledge on safe food handling, preparation, and storage. To learn more, check out her website.
Transcript
Mallika Nocco
Welcome to Water Talk from the University of California Division of Agriculture and Natural Resources. I'm Dr. Mallika Nocco, a cooperative extension specialist in soil plant water relations and irrigation management.
Sam Sandoval
Hi, I'm Sam Sandoval. I'm a faculty and extension specialist in water resources.
Faith Kearns
And I'm Faith Kearns, the academic coordinator for the California Institute for Water Resources.
Mallika Nocco
Welcome everyone to today's episode of Water Talk. And today we are talking about the food-water-virus nexus, as well as preservation of food. Our guest is Dr. Erin DiCaprio, who is a cooperative extension specialist in community food safety located at UC Davis, for expertise in microbial food safety with an emphasis on food borne viruses. Hello, Erin, thank you for joining us.
Erin DiCaprio
Hi, everyone. Happy to be here.
Mallika Nocco
So to get started, we just wanted to ask some very basic questions that we're thinking of as virus 101.
Sam Sandoval
Erin, could you tell us a little bit about viruses and what they are and what they are not? Are they alive?
Erin DiCaprio
Great question. I actually start most of my talks addressing this very question. Viruses aren't considered to be living organisms. They're obligate intracellular parasites, meaning they require a very specific type of host cell and a specific organism to be able to replicate or increase their numbers. They also don't have any type of their own energy generating mechanisms so there's no cellular respiration for viruses. That's another one of those distinguishing characteristics that helps us say they're not living organisms. Viruses can have either DNA as their genetic material or RNA. So that's another factor that distinguishes them from other types of living cells. Coronavirus, for example has an RNA genome so it doesn't have any DNA in the viral particle. So these are all things that are unique to viruses and really help us make that distinction between being a living organism or not.
Mallika Nocco
Another question that I have just related to water and surfaces is how do viruses move around? How are they transported? Do they do they move through the water when they're on a surface? Are they sticking to it? Do we know a lot about their actual motility?
Erin DiCaprio
Well, I guess I should probably talk about the different types of viruses because I think this has a really big impact on how they persist in the environment and in foods. So there are two basic structures of viruses. There are what we call non-envelope viruses that are essentially just viral genetic material that's encased in a protein coat. And these are typically what we see the structure of food and waterborne viruses being. These non-envelope viruses, they're really hardy in the environment because of their simplistic structure. The protein is relatively stable against some common sanitizers like alcohol based hand sanitizers, for example.
The other type of virus structure is what we call an envelope virus. So this virus has viral nucleic acid that's encased in viral protein. But then on the surface, it has this lipid bi-layer that we call the envelope that's derived from host cell membranes and the virus, depending on the type of virus, will embed different viral proteins in that envelope. But because that's a lipid bi-layer, it's much less stable in the environment. So envelope viruses typically, we don't find persisting for long periods of time in water or in food or on surfaces. Norovirus is kind of our prototypical food waterborne virus, that's a non-envelope virus. Coronaviruses are envelope viruses, so we don't think they persist for long times outside of the body. There have been several recent studies with varying results, but I think overall a few days of survival in the environment is kind of the maximum for coronavirus and similar other envelope viruses. These viruses, they're host specific, so the source is ultimately going to be us as humans as carriers of the virus that shed it in our feces, maybe in our respiratory secretions, which is the case with coronavirus.
There are some types of viruses that are also zoonotic. So they're in animals as a natural reservoir and they can be passed to humans through direct contact with those animals. Generally, non-envelope viruses that cause waterborne or foodborne disease, those are coming from people. And so the sources are primarily untreated sewage, or they can also be shared in the vomit of people that are exhibiting symptoms. So if that contaminated water, or if there's a contaminated surface, is contacted by human hands and that hand then goes into the mouth that can lead to disease. Or if a food were to contact that contaminated water or surface because these non-envelope viruses are so stable, if we then eat that food we can also become sick.
Sam Sandoval
Okay, pretty much we have two: non-envelope and envelope.
Erin DiCaprio
That's correct. Basically, yes. And in it, they really, those structures play a critical role on the environmental stability of the viruses. Non-envelope viruses are really hardy in the environment, difficult to inactivate. Envelope viruses don't remain infectious for long periods outside of the body and we can generally inactive them with more mild sanitizers or heat treatments.
Sam Sandoval
Great, great to know. So, you know Erin, about a week or two weeks ago, I saw an article that you posted, I think it was in the Sac Bee or one of the Sacramento magazines about how can we ensure food safety with both our groceries and our take out right now. So could you elaborate on that please?
Erin DiCaprio
I've been fielding a lot of questions related to food safety and SARS COV2, so that's the virus that causes COVID-19. Given the state of understanding right now, there's no evidence of food or food packaging being a vehicle for transmitting this particular virus. So SARS COV2 is transmitted by respiratory droplets, meaning that you know, you have to be in close proximity to someone that has an active COVID-19 infection and would be shedding that virus via talking sneezing, coughing, and those droplets from the respiratory secretions would have to contact your mucous membranes for you to get sick. There's also strong evidence that you know, just general close human contact can also transmit the virus.
So you can imagine if someone sneezed on their hand there could be infectious virus there, if you shook their hand and then touch your own membranes, you could also contract the disease. And there's also what we consider high contact surfaces out there. So things like door handles or railings where there's high likelihood that a number of people are going to be touching that same surface. Imagine if there's someone walking around with a COVID infection. If they sneeze on their hands and then they touch the door handle, someone that follows them might touch that same handle and then touch their mucous membranes and get sick.
When it comes to food, generally that's not a high touch surface. There's not a high number of people in the grocery store, picking up a can of soup or even an apple to check out, this is something they want to take home with them. So really, foods are generally going to be a low touch surface, so lower risk inherently there. Also based on what we know, this virus does not seem to persist for long periods of time on surfaces. So even if there was some kind of event where someone's stocking a shelf that has the infections sneezes on a can of soup that can of soup is probably going to sit on the shelf long enough for that virus to become inactivated. We also know based on evidence with the original SARs, one that emerged in the early 2000s and also other envelope viruses, that cooking temperatures are adequate to inactivate these viruses.
People are concerned about food and food packaging potentially carrying these viruses, but overall, I think the risk is really low. You know, of course, if you're getting takeout and delivery person was sick and sneeze directly on that package, potentially it could be there. But really the key and general good food safety practice all along is to wash your hands after you handle packaging, and certainly before you eat any of that food. And that's part of the guidance around controlling for coronavirus is to wash your hands as much as possible because we know that this virus has to get into your respiratory tract to cause infection. And one of the good ways to do that is make sure your hands are free of the virus because we touch our faces a lot. It's something we all do. I try and catch myself now but I do it quite frequently myself.
Mallika Nocco
So speaking of washing your hands, I am a canner and I do preserve so I'm kind of coming from that space. But I do wash my hands very fastidiously when I'm canning and just thinking about the way in which communities are responding and families are responding right now. Many people are starting their own gardens. We're seeing like a resurgence in Victory Gardens. And I think the next step that's going to happen is there's going to be a lot of people who want to preserve their own food, who want to do some canning. And I know that you work a lot with the University of California Agriculture and Natural Resources Master Food Preserver program. Can you tell us a little bit about that program and what types of food safety issues that new preservers and new canners should be aware of right now?
Erin DiCaprio
Great. I have the honor of working as the food safety technical advisor for our statewide Master Food Preserver program. Folks might be familiar with the Master Gardener program. So this is kind of a sister program to the Master Gardeners. So this is a volunteer run and driven program and the mission is really to deliver research based home food preservation techniques to consumers. We teach a wide array of food preservation techniques. But I think probably the thing everyone's mind goes to initially when we talk about home preserving is canning. So in the United States now, we have a very good recent history of safety with canned foods, commercially canned foods, not so much in the early 1900s. We had a lot of issues with botulism and canned foods, fruits and vegetables, in particular meats as well. And because of that, California led the way on developing these regulations of how we produce canned foods to make sure that people don't contract botulism from canned fruits and vegetables produced in the state. After California set these regulations in place, the federal government actually adopted the same regulations.
Now nationally, we have very strict regulation of production of canned foods in this country. And because of that, we don't have really any cases of botulism associated with legally commercially canned products. And one of the key things that we teach through the Master Food Preserver program is how can I safely canned foods in the house? How as a consumer can I be sure that I'm using a recipe and a process that has been validated for safety? So our volunteers go through a really rigorous training program. I give them information related to food safety specifically. But they also have hands on labs where they're learning how to use the equipment to can properly, they get access to all of our research based resources and recipes. And then they go out into the public and put on workshops on how to do these things safely. They also field a lot of questions on their helpline. So they've seen a real uptick recently, and people reaching out with questions related to home food preservation. And so they try to help guide folks to where they can find the appropriate, safe, tested directions for how to preserve different kinds of foods in the home.
Mallika Nocco
I think that that uptick is just going to keep rising just based on the uptick that we're seeing in what is being planted right now. Many of those, you know, items aren't coming up yet.
Erin DiCaprio
Yeah, I think there's going be a major need for the Master Food Preservers to keep doing what they are doing. But now in the virtual environment, right?
Sam Sandoval
Speaking of having this close environment and so on, I've seen that you have done quite a lot of work on norovirus, and I think this is also referred to as cruise ship illness. What is unique to this cruise ship ecosystem that spreads the illness? And are there any other ecosystems that you think that it can be referred to, to this?
Erin DiCaprio
Yeah, so I think with this virus, too, we've seen that cruise ships are kind of a hotbed for spreading infectious disease. And, unfortunately, I think it's because of the high density of people in these locations. The close quarters that they're all staying in. There's a lot of communal food and social events that I think everyone realizes now is kind of this perfect environment for spreading infectious disease. And so norovirus is known as the cruise ship disease. It's caused a lot of those ships to come back early, because nearly everyone on board has had symptoms of nausea, vomiting and diarrhea, which I can't even imagine what that environment is like. And so norovirus is actually a very infectious virus, and it's transmitted by the fecal oral route. So you actually have to ingest this virus to get sick, but we know that for norovirus that you only have to ingest one to ten viral particles to get sick.
So you can imagine if there's one person on this cruise ship that is sick and they don't wash their hands adequately enough and they touch a door handle. We know this virus can be stable for days, weeks, even months on surfaces. So, then you know passerbys that touch that door handle then don't wash their hands before they eat, easily become infected and that goes on and on and on. I think for this particular coronavirus, there's still a lot of unknowns. We don't know quite yet know how many of the virus particles actually have to get into your respiratory tract to cause disease. Unfortunately I think we're going to learn a lot of this after this pandemic has subsided. But I think the outbreaks we've seen on cruise ships with COVID-19 really kind of emphasize the same thing, that when you have a high density of people in a closed space, you can really get rapid transmission of the virus within that population.
Sam Sandoval
Erin, I am literally taking virology 101 here, so let me see if I'm getting my notes right. So, we have envelope and non-envelope viruses. The envelope are not stable. What that means is that it will not last that long in the environment. Now the non-envelope, they are very stable, so careful with them, it will last in the environment. And then we have this kind of contamination, direct and indirect. Surfaces can be an indirect way to get the virus, so someone else is contaminated and you touch it and get your hands in your mouth and your mucus and there you go. And then the direct will be actually talking with other people or being close. Now cooking, you highly recommended to cook because cooking if you're worried about what you are buying that it will not get contaminated. And the other one is washing. So fruits, vegetables, wash them thoroughly. So whatever is there, it will get there. Did I get it right?
Erin DiCaprio
You're a great student!
Faith Kearns
Erin, just as somebody who's been studying kind of these viruses, I'm just curious, from a more big picture perspective, what you see as maybe unaddressed issues right now, things that are not sort of a common part of the dialogue or major issues that you see coming up that will challenge our ability to, quote unquote, get back to normal.
Erin DiCaprio
So I think that the hardest thing for me to see is this promise that we're going to have a vaccine or an antiviral drug anywhere in the near future. This type of work is really hard. And I don't want people to think this is something that's going to be turned around in any type of quick fashion. And I understand anytime there's something new that people are proposing, there's kind of this level of excitement, this might be the magic bullet that frees us. Vaccine development really takes years to get something that that's effective. In reality, getting more testing done is really going to be what helps open things up. But because we don't, we're still collecting information about this virus. We don't even know if you can get it in a second time and kind of how long if there's immunity how long does that last?
Sam Sandoval
So let me let me ask you one last question here. So when what would you like those folks outside of the foot biology work to know about what you do?
Erin DiCaprio
Great question. So my research group, we primarily focus on understanding how these viruses end up in foods to begin with. We know that they can be in water that's contaminated with sewage, but that's not particularly a concern here in the US, but we still have a number of outbreaks associated with these viruses. So we do a lot of work looking at how workers in particular can be a source of virus. We're also interested in understanding norovirus. We also work with hepatitis A virus a bit in my group, how long the virus persists in different foods. So if we do have a leafy green that's contaminated with one of these viruses, how long will that virus remain infectious in that commodity?
And then we're also really interested in looking at how we can mitigate foodborne viral diseases. So what kind of control measures can we implement to help reduce risk? Are there different treatments that we can apply to foods to help eliminate these viruses? So this you know, this is really something that we've been working on for a while, and we're, of course, pivoting a little bit now to just try and start doing some work with corona viruses. So there's a lot of just questions we don't have answers to at this point and USDA has put out some calls as well as other funding agencies to help us understand how long do these this does this coronavirus survive on foods or food packaging. We're kind of pulling from data we have, but we don't have that specific data set to say it only survives on the surface of an apple for two hours. So we're starting to work in that area as well. But something that I think is just so important right now is supporting our food systems. You know, this has taken such a tremendous toll on everything from farm to fork. And so I'm really interested in exploring ways that I might be able to help other folks that are working within the food system to help support these essential workers and support these businesses that, many of which are struggling right now.
Mallika Nocco
Thank you so much, Erin for joining us. I think all of us got some very burning questions answered today. Thanks for listening and join us next time on Water Talk.