Press Briefing Transcript

Update on Multistate Outbreak of Listeria Associated with Cantaloupes

Wednesday, September 28, 2011 – 2:00pm ET

• Audio recording (MP3, 8.58MB)

Operator: Please stand by. Today's call will begin momentarily. Thank you. 

Operator: welcome and thank you for standing by. At this time all participants are in a listen-only mode.  During the question-and-answer session today you may press star-one to ask a question. Today's conference is being recorded. And at this time I′ll turn the call over to Mr. Tom skinner, you may begin, sir. 

Tom Skinner: Thank you, Shirley, and thank you all for joining us on this telebriefing on a multistate outbreak of listeriosis. Joining us is the director of the CDC, Dr. Thomas Frieden, as well as the Commissioner of the Food and Drug Administration, Dr. Margaret Hamburg.  Both will provide some opening remarks regarding the outbreak, and then also joining us is Dr. Barbara Mahon from the CDC and Miss Sherri McGarry from the Food and Drug Administration who will be on hand to help answer questions if necessary.  So I′m going to turn it over to Dr. Frieden at this point. 

Tom Frieden: Good afternoon, and thank you very much for joining us.  Listeria is a rare but deadly disease, and we have at this point definitively confirmed 72 cases and 13 deaths with laboratory confirmed listeria including two pregnant women who so far, as far as we know, are doing okay both in term of their own outcomes and their fetus or newborn child.  The individuals most at risk from listeria are the elderly, pregnant women in term of the risk to the fetus and newborn, and people with weakened immune systems - people who have undergone a transplant or are on treatment for cancer or who otherwise have a weakened immune system. However, even people without a weak immune system can develop fever and diarrhea with listeria, and listeria is an illness which in those with underlying conditions can be quite serious or deadly.  In fact, as has been accurately reported in the media, this is the deadliest outbreak of a foodborne disease that we've identified in more than a decade.  This is a reflection of the fact that listeria has a high lethality for people who are highly susceptible. 

The vehicle was rapidly identified through a collaborative effort of the Colorado Health Department along with ourselves and FDA to be a single producer of cantaloupe, Jensen Farms, and that recall has now been in place for more than two weeks. So for the public it's important to know that if you know the cantaloupe that you have is not Jensen Farms, then it's okay to eat.  But if you're in doubt, then throw it out.  Jensen Farms cantaloupe may be present in people's refrigerators and has been used, although now recalled in some cut fruit salads.  So if you have a doubt as a member of the public, you can ask the supplier or supermarket what the source was.  Many of the cantaloupes themselves may not have a label on them. The case that they came in would, but they have been recalled, and the supermarket would know.  So consumers should know to check the label or ask a supermarket and if they can't confirm that it's not Jensen Farms, then it's best to throw it out. 

I will highlight that this is an example of a very rapid response from the state of Colorado.  They identified in the first week a large number of listeria cases.  They immediately began an epidemiologic investigation of those cases and informed ourselves and the FDA.  They worked with doctors in the community to identify this so that when CDC was first notified of the suspected outbreak the Friday before Labor Day weekend on September 2, we were able to work through the weekend with the state.  We worked 24/7/365 to protect people and identify threats.  The result was that within days we were able to identify the source, then get the shipments stopped and inform the public and get the recall done. 

Listeria is an unusual bacteria in a couple of ways.  One is that the -- what's called the incubation time, the time between which -- between when you consume it and when you get sick is longer than it is for many other bacteria.  It can be one to three weeks.  It can even be two months or more in some cases.  So people who consumed the cantaloupe some time ago may continue to develop illness in the coming days and weeks.  So we do anticipate that there will be a rising number of cases in the days and weeks to come. Also, it's unusual in that it flourishes even in the cold.  So unlike most other bacteria, if you′ve got a contaminated cantaloupe in your refrigerator, that -- the listeria in the cantaloupe will continue to grow in your refrigerator.  That's unusual.  That's not what we see with salmonella or other bacterial infections, and it's one of the reasons that we unfortunately may see a continued number of cases from cantaloupe that are already in people's refrigerators now over the coming days and weeks.  But we can reduce the number of additional cases by encouraging people to check the label.  If it's not Jensen Farms, it's okay to eat. But if you can't confirm that it's not Jensen Farms, then it's best to throw it out.  I′ll turn it over now FDA commissioner Hamburg. 

Margaret Hamburg: Thank you very much, Dr. Frieden.  I think he's given a very comprehensive overview of the current situation.  I do want to reiterate what Dr. Frieden said. This has been a very important collaboration to address a serious foodborne outbreak.  We at FDA have been collaborating closely with CDC in this investigation along with our local and state partners in Colorado since the initial laboratory testing by the Colorado Department of Public Health and Environment identified the listeria monocytogenesbacteria that with linked with cantaloupes in mid-September. 

FDA working with our partners conducted a product trace back in laboratory testing, efforts identified the matching outbreak strains in samples collected at Jensen Farms, which is located in Granada, Colorado.  Since then FDA has worked closely with CDC and Jensen Farms and public health authorities as well as retailers in states in which the products were shipped to make sure that the product is no longer in commerce.  I think everyone has really pulled together in this multistate outbreak to protect consumers from contaminated product and to provide important safe food handling information that consumers will find helpful every day, and especially information for those at high risk for listeriosis who need to pay special attention to this concern. 

This outbreak has been a tough one for all involved.  It's the first time we've seen listeriosis in -- listeria contamination in whole cantaloupes, and we're working very hard to determine how this happened.  Sherri McGarry from our coordinated outbreak and evaluation network or CORE as we call it, is available on this phone call to talk more about the ongoing investigation.  And as Dr. Frieden pointed out, we are seeing more illnesses, that's the nature of listeriosis. And we will see more cases as was just said, likely through October because patients can develop this disease up to two months after eating contaminated food. It's important for consumers to know that we at FDA, working with our partners are ensuring that recalled cantaloupes have been removed from grocery store shelves. It's important to know that the shelf life of cantaloupes is relatively short, about two weeks.  However, to reiterate what we've already said, if by any chance you may have Jensen Farms Rocky Ford cantaloupes still in your refrigerators, please do not eat it and throw it out.  And as was just said, consumers can inquire of their retailers where cantaloupe came from, and retailers are prepared to provide that information if they are not already providing it to you in their stores. 

We at FDA are continuing to work on the root cause analysis to determine how this happened and to find ways to prevent this from happening in the future.  I should probably mention, though, that Jensen Farms has ended their harvest for this season so that there are not additional cantaloupes being harvested.  And I also want to just say that these kinds of outbreaks are a powerful reminder that despite the fact that we have one of the safest food supplies in the world, it does remain vulnerable to contamination, and the American people remain vulnerable to foodborne illness.  That is why the Congress passed the Food Safety Modernization Act which the President signed into law this year.  And the FDA is very serious about implementing this important and historic law, but it is crucial that we have the resources to be able to fully implement this law that has as its goal the effort to put in place the kind of preventive controls so that these kinds of outbreaks will not occur in the future. I′ll turn it back to questions and answers. 

Tom Skinner: Shirley, I believe we're ready to begin questions, please. 

Operator: Thank you, we will now begin the question-and-answer session.  If you would like to ask a question, press star-one and record your name clearly.  To withdraw your question, you may press star-two.  One moment for our first question.  Our first question comes from Elizabeth Weise with USA Today, you may ask your question. 

Elizabeth Weise: Hi, thank you very much for taking my call.  I have two questions.  First, just a quick housekeeping question.  I′m seeing both Holly, Colorado, and Granada, Colorado.  CDC is using Holly, FDA is using Granada.  What's the actual - where are you saying that Jensen Farms is based? 

Margaret Hamburg: As I understand it, the farm is actually in Granada, and the corporate offices are in Holly, Colorado. 

Elizabeth Weise: Okay, good.  Now the question I had is -- so if the Food Safety Modernization Act were to be fully in place, if FDA had already been able to write all the rules that you guys are in the midst of writing and those were in place and had been in place a year ago, how would that have potentially stopped this outbreak? 

Margaret Hamburg: Well, first I think we have to be clear that we do not know the source this outbreak at the present time.  We know the organism that has contaminated the cantaloupes, but we don't know how that occurred.  And there are a number of ways in which it could have occurred.  So, you know, it's a little bit hard to speak with absolute specificity to answer your question.  But I think as you probably know, the Food Safety Modernization Act is asking us to put in place systems of preventive controls working with the food industry that identify the likely sources of contamination, the points of vulnerability in the life cycle of a food product, and then strategies to reduce those vulnerability.  And with respect to fresh fruit and produce, there are a number of sort of typical points of potential contamination.  And we are, as you recognize, putting together regulations to address issues about fruit and produce safety. 

Tom Frieden: This is Dr. Frieden at CDC.  In addition to the lead work FDA does on food safety and production, CDC does the monitoring or surveillance in humans.  Colorado happens to be only one of ten states that is funded by CDC for FoodNet approach to rapidly identifying and intervening with potential foodborne illness.  And part of the Food Safety Modernization Act is the continued enhancement of our ability to identify and track foodborne infections.  As the food supply has gotten more complex over recent years, it′s gotten both more challenging and more important to do rapid, quick identification of contaminated food.  The number of multistate outbreaks of foodborne illness has increased substantially in recent years.  In this year alone, this is the 12th large, multistate outbreak of a foodborne illness that the CDC and out state and local partners has identified.  This is a reflection at least of better quality monitoring and perhaps also of the increasing complexity and centralization of the food supply. 

Tom Skinner: Next question, Shirley. 

Operator: Thank you.  Next question comes from MaryClare Jalonick from the Associated Press. You may ask your question. 

MaryClare Jalonick: Hi, I have two quick questions.  I know that you guys are still having ongoing investigation.  But if there's any more that you can tell us about what was found on the farm -- you released a few details saying that the strains were found in cantaloupe and on the equipment.  But if there's any other details you can give us about maybe where this was on the farm or, you know, any clues to what the contamination might be.  Also secondly, wondering if you guys are going to be releasing a list of retailers to which the cantaloupe was shipped.  I know it must be a lot.  But it seems like that's a lot of work for consumers to go to their grocery stores and ask what the source was.  Just sometimes you guys do release information like that.  I′m wondering if you're going to be releasing information.  Thanks. 

Margaret Hamburg: Let me speak to the latter because I think it's a lot more accurate for the consumer to actually ask their retailer in terms of the ability to get that information out and, of course, when you put stuff on the web site, not everybody accesses it.  So I think it is an important message that if people are uncertain to ask their retailer.  That's how they'll get the most accurate and most direct information.  Let me turn to Sherri McGarry, on the FDA team, to speak a little bit more about the ongoing investigation.  And of course, we will provide information as we know it.  But we also want to avoid speculating.  But she's -- she is deeply involved and will speak to the facts on the ground. 

Sherri McGarry: Thank you, Dr. Hamburg.  Yes, let me share with you a little more information on what we're doing.  And that is a team of experts, both the state of Colorado expertise combined with FDA were at the farm conducting an environmental assessment.  To really get at the heart of what may have happened to cause this contamination and not just how it may have been contaminated, but was there any opportunity for continued growth or spreading of that contamination.  So what we basically are doing is we will look at various parameters, environmental in particular that may have contributed to that contamination and spread.  And some of those things that we'll be looking at is any potential animal intrusion.  We'll be looking at water quality.  We'll be looking at the growing practices, the harvesting practice. We'll also be looking at the process within the facility for packing and potentially rinsing the cantaloupes themselves and how they were stored and whether there was potential again for amplification of the pathogen in that process.  So we'll be looking at a lot of different factors from the environmental perspective to see how this contamination may have occurred, how it could have been spread.  And then most importantly, we're going to take these lesson learned, share that with our partners and industries, CDC and the states, and what we want to do is we want to really prevent this from happening in the future.  And again, that's quite consistent with the Food Safety Modernization Act.  And that's our goal here is to prevent future outbreak like this particular situation.  

Operator: Thank you.  Our next question comes from William Neuman from the New York Times, you may ask your question. 

Willie Neuman: Hi, thank you.  I′ve been going back and trying to look at past cantaloupe and melon outbreaks, and it looks like there have been quite a few over the last ten years or so both for cantaloupes in particular and melons in general.  Have you guys that, and do you have some numbers you could give us?  And seeing the fact that there have been a number of outbreaks, is there a problem with cantaloupes or melons in general?  Some sort of built-in problem or structural problem, and does something need to be done specifically to fix this particular produce industry? 

Tom Frieden:  I′ll start and maybe Dr. Hamburg wants to say more.  We have identified over about the past decade about ten outbreaks where cantaloupe was the definite vehicle.  There may, certainly, have been other outbreaks, it′s not always possible to identify the definite vehicle.  In seven of those outbreaks, salmonella was the bacteria. In three it was the virus, the norovirus.  I think part of what's happening is that our ability to identify food sources is improving. So it's not that food is getting riskier, but we're getting better at identifying problems that have probably been there for a long, long time.  It's still a good thing to eat fresh fruit and vegetables, and we encourage people to do that.  It's a good thing to wash them before you eat them.  And to wash your hands after handling food.  I don't know, Dr. Hamburg, if you or anyone else at FDA would like to comment. 

Margaret Hamburg: Well, I think to reiterate a point that actually Sherri McGarry made in her last answer, which is that it is very, very important as we take these efforts to investigate the cause of outbreaks, to identify the lessons learned and apply them going forward. This is the first outbreak that we've seen with listeria, as I understand it.  And I think, you know, that is a surprise.  And certainly something that we need to be mindful of going forward.  But, you know, we really do feel strongly that we need to be developing these preventive rules and really taking lessons that inform our prevention policies so that we will be able in a few years' time to be seeing fewer, not more.  That, of course, is the goal. 

Tom Skinner: Next question, Shirley. 

Operator: Thank you.  Next question comes from Miriam Falco with CNN Medical News. You may ask your question. 

Miriam Falco: Thanks for taking the question.  I′ve got two quick questions. Number one, you kind of alluded to it, but when do you expect any of these melons to be no longer edible because they're just rotten?  So that if people haven't checked the label yet and they haven't thrown the cantaloupes out, at what point should illnesses stop just because the vegetables are no good anymore?  And then the second question I have is about the advice that you give on how to handle melons.  And you suggest washing them off and drying them off.  If you're supposed to cook meats that may have listeria so you can kill the bacteria, how is washing it off enough? 

Sherri McGarry:  This is Sherri.  On the first question, cantaloupes, fresh who cantaloupes have a short shelf life as we alluded to.  It's about two weeks.  The recalled cantaloupes were shipped from July 29 through September 10.  And this is the 27th or 28th, somebody can correct me there.  So we really are nearing the end of the shelf life of the product. In addition to its recalled product, so the recall itself should be removing that product from the shelves.  But its short shelf life certainly contributes to it not even being edible for much longer.  And once you actually cut the cantaloupe as well, that shelf life get shortened even more.  So we're really looking at a short shelf life product.  But consumers do have their own practices so we need to be cognizant some folks may hold that a little bit longer than we might expect.  So that's why it's so important that if consumers potentially have this recalled product that they not eat it, that they throw it away.  So this is a really important message. 

 Miriam Falco: Washing. 

Sherri McGarry:  And I think that washing question really goes back to the fact that if you have recalled product, we don't want you trying to wash off the contamination.  We want you to throw that product away.  We don't want anyone else getting sick.  So it's important to have that recalled product thrown away if it's from Jensen Farm recalled product. 

Tom Frieden: This is Tom Frieden at CDC. I′m going to have to drop off the call.  And I understand there are still quite a few questions.  Dr. Mahon will remain on the call for CDC and FDA, as well.  I do want to reiterate that if you have cantaloupe in your refrigerator that you are in doubt about the source of, it's best to throw it out.  Even though the shelf life is coming to an end around now, the incubation period for listeria is on average one to three weeks and can be as much as two months or more.  So unfortunately there is continued risk from product that's already out there and for that reason, check the label.  If there's no label, you can either throw it out or ask the place you bought it from if the label is something other than Jensen Farms, then it's okay to eat.  If it is Jensen Farms, then by all means throw it out and take other steps to make sure that you and others who consume it don't become ill.  Particularly for those who are elderly, for pregnant women, and people with weak and compromised immune systems.  And identification and rapid response of food contamination and other outbreaks like this is one of the reasons why it's so important to have 24/7 coverage as we do at the CDC nationally but also at the state and local health departments around the country.  We have time for more questions, but I have to step off now. 

Tom Skinner: Next question, Shirley.

Operator: Thank you our next question comes from JoNel Aleccia with MSNBC.com. 

JoNel Aleccia: Hi, thanks for taking the call.  One question we've had trouble pinning down is what is the volume of cantaloupes that have been recalled, and another question I understand in New Mexico that these went to Walmart and whole foods stores.  Doesn't sound like you want to provide a list of retailers.  But consumers haven't really been able to tell where these went.  As MaryClare noted, it is kind of inconvenient for them to ask grocers and the grocers sometimes might not know. 

Sherri McGarry:  This is Sherri McGarry.  Just a couple of points.  The volume of product really -- the most accurate information is going to come from the distributor itself and the recalling firm.  So we don't want to speculate, but we want to make sure that you have the most accurate information.  And the source of that really would be Jensen Farms, who's conducting the recall.  We are, of course, working vigilantly to ensure that that product is being removed from the market, we conduct recall effectiveness checks, and we at any time, if we have any indication that that product might still be on shelves at the market, we are working vigilantly to remove that product.  So again, with that short shelf life, we don't think that's a significant factor here.  And with regard to the second part --

 JoNel Aleccia: Volume. 

 Sherri McGarry:  For the volume question, it really goes back to Jensen Farms as the best source of that information.  All of the product is under recall, the entire production.  And again, there is information listed on FDA's web site. There's a recent update, it does list the states and where the product has been distributed.  So that is very useful information.  The states also have more specific information that they can go to the retailers and distributors as well to ensure that product has been removed.  So again, in our FDA web site update there is information on the states and the states distributed involved and those states also have additional information. 

Lola Russell: Shirley, this is Lola, I′m picking up for Tom Skinner.  Next question, please. 

Operator: The next question comes from Susan Schwartz with ABC News.  You may ask your question. Hello? Mrs. Schwartz, your line is open.  Go ahead with your question.  They're not responding.  We'll go ahead to the next question.  That comes from Bill Tomson with Dow Jones.  You may ask your question. 

Bill Tomson: Hi, thank you.  I wanted to -- there's been several numbers out there about how many people have died from this outbreak.  And the number you mentioned today and the number that's in the latest CDC update is 13.  But I′m wondering -- and you've already say that the illnesses will expect to be more.  Can we also expect the death toll to be higher, and are there right now more deaths that are believed by states to be linked to this outbreak but have not been confirmed by the CDC?  I′m trying to figure out why the discrepancy in numbers has -- that's been reported.  Thanks. 

Barbara Mahon: This is Barbara Mahon at CDC. And CDC is reporting the confirmed cases, cases that are confirmed as part of the outbreak based on laboratory testing, to match them to the strains of listeria that have been causing the outbreak.  To date there's 72 cases and 13 deaths, as you heard earlier.  We do expect that the number of cases will increase.  The number of deaths may increase, as well.  There's a number of suspect cases that are under investigation both in states and that are undergoing laboratory confirmation.  So we'll make those data available as they become confirmed. 

Bill Tomson: There's no real suspect cases, we're talking about deaths, right? 

Barbara Mahon: There are suspect cases.  I′m not sure whether there are suspect deaths in states, but there are suspect cases that are under investigations. When we determine the outcome and whether they're associated with the outbreak, we will report them. 

Lola Russell: Bill, do you have another question? 

Bill Tomson: I don't.  Thank you. 

Lola Russell: Thank you.  Shirley, next caller, please. 

Operator: Thank you, the next question comes from Eric Whitney with Colorado Public Radio. You may ask your question. 

Eric Whitney: I have two questions. One, you said this is the second deadliest outbreak.  When was the deadliest outbreak and when did that occur?  And two, Colorado's health department identified the cantaloupes from this part of Colorado as the culprit in the outbreak September 12.  How many days later was a recall action taken, and why wasn't a recall action taken on the 12th when we knew where these cantaloupes were coming from, and they were all coming from a single distributor? 

Sherri McGarry: This is Sherri.  I think the first part of that question is probably for CDC. I′m happy to answer the second part of the question.  So for the second part of the question, it's important to note that there's different parts of an outbreak investigation.  The first, of course, is identifying what food might be involved. And that can just be certain type of cantaloupes such as Rocky Ford.  The next step really is to take it to identifying a common source.  And that takes a little more time. That's what we call a trace back. And trace backs as we've heard in other outbreaks, can be challenging.  This one was rather quick.  And once we were able to identify that single source, we work with a firm immediately to implement a voluntary recall by that firm which was announced on the 14th.  So we need to, in an outbreak situation, go to the epidemiology which very often identifies the general food, and then we get more specific in a trace back, identify the single source as soon as we were able to specify that, the recall happens, and that's announced.  It was announced by Jensen Farms, and they were cooperative in that recall announcement.  And I′ll turn it back to CDC. 

Barbara Mahon: Thanks. This is Barbara Mahon.  So just to clarify, I think that what Dr. Frieden mentioned was that this is the deadliest outbreak in more than a decade.  And the second deadliest outbreak occurred in 2008, linked to contaminated peanut butter with salmonella.  There have also been a number of listeria outbreaks in the more distant past that have had more deaths than this.  But the largest listeria outbreak occurred in 1985, and that was due to contaminated Mexican-style cheese.  I think it's important to note that those -- we haven't seen a lot of very large listeria outbreaks over the last number of years.  And to a large extent, that's due to the improvements in the safety of hot dogs and contaminated deli meats that previously had been the source of many of the largest outbreaks. Industry and FDA [Editor′s Note: FSIS] and CDC, health departments worked together to identify those -- the sources of those outbreaks and then to really improve manufacturing processes so that those outbreaks decreased.  We've also seen concurrent with that, this was a decrease in the overall rate of listeriosis.  So as this is the first outbreak associated with melon, it shows us, I think, where we can be working to make improvements in the future. 

Lola Russell: Next question, please. 

Operator: The next question comes from Jennifer Brown with the Denver Post, you may ask your question.

Jennifer Brown: Yes, Dr. Hamburg, you mentioned earlier that even though we have one of the safest food systems in the world, there is still going to be some contamination.  Could you expand on that a little bit?  Especially when we're talking about produce that has -- is grown obviously outside in dirt, you know, with birds overhead and what kind of danger are always going to be out there that no number of inspectors could prevent from getting contaminated. 

Margaret Hamburg: Well, I think we all recognize that we don't live in a risk-free world.  And we are very fortunate as a nation to have quite an abundant and safe food supply.  But there are a number of things that we can do to make that food supply safer.  We know that every year our citizens suffer from preventable disease, hospitalization, and death due to foodborne outbreaks.  And that is why it is so important that the Food Safety Modernization Act with its fundamental mandate to really transform our food safety system into one that is focused on prevention rather than responding after the fact when outbreaks occur, I think is going to really advance our ability to further ensure the safety of the food supply.  And as Dr. Frieden mentioned, it's very, very important that we support the critical partnership among the components of our food safety system and that everyone has a role to play.  State and local, public health, FDA, and CDC are international partners because just as the food supply has gotten more complex with broad distribution across states domestically, we also have a food supply that is increasingly global in nature with food coming from many, many parts of the world.  Some of which have less sophisticated regulatory systems than our own.  And of course working closely with industry who, you know, has the ultimate responsibility for ensuring the safety and wholesomeness of their products.  We are really very committed to the full implementation of the Food Safety Modernization Act.  And within FDA we've also been putting in place new systems, including our new outbreak response and evaluation teams to enable very rapid and comprehensive response to these kinds of situations.  So we, I think, are situated to really continue to improve the safety and wholesomeness of the American food supply moving forward.  But it remains an important vulnerability and a demonstrated source of preventable disease and, sadly, death. 

Barbara Mahon: This is Barbara Mahon.  If I could add a few other thoughts.  This outbreak illustrates a general trend which is that the complexity in the change in the food supply.  And it shows how effective public health surveillance can lead to the identification of new threats.  Both so that they can be -- so an outbreak can be identified and ended as soon as possible when it's happening, and also so that we can learn from it for the future to make food safer.  Foodborne illness is preventable.  And this sort of surveillance and epidemiologic investigation is really essential for preventing those illnesses and death which can be prevented.

 Operator: The next question comes from Lisa Schnirring with CIDRAP News. You may ask your question. 

Lisa Schnirring: Hi, thanks for taking our calls today.  I′m wondering about the outbreak strains.  The updates mention that there's four of them.  And I′m wondering if you can tell us if they're closely related or if they're pretty different from each other.  The second part of my question is -- just wondering what the infectious dose is for listeria compared to other foodborne pathogens.  Thanks. 

Barbara Mahon: This is Barbara Mahon.  And I can address that first, and colleagues at FDA may also have responses they'd like to give.  It is unusual to see four strains in an outbreak as we are in this one.  These strains are not particularly closely related.  They come from two different serogroups, two different types of serotypes of listeria.  And the reasons for that are under investigation.  In terms of the infectious dose, it is not well understood.  It's an area of active investigation.  And it may well vary for different people with a more vulnerable people being able to be infected with lower doses, and perhaps higher doses needed for -- to make other people ill. 

Lisa Schnirring:  Thank you. 

 Operator: Thank you, next question comes from Maryn McKenna with Wired.com. You may ask your question. 

 Maryn McKenna: Thank you. So something of a followup from Lisa's question.  Since as you said this is the first association between cantaloupe and listeriosis, is there anything you can say to us about the preferred host or sort of natural history of listeria that's pointing you in particular directions as you do the field investigation?  For instance, whether there's a water contamination problem or rodent problem on the farm or anything that might make this different from, for instance, the investigation of the salmonella outbreaks in cantaloupe earlier? 

Sherri McGarry: Hi, Sherri McGarry again.  And as part of our root cause investigation of environmental assessment, we're looking at how the contamination may have occurred.  And certainly as far as hosts goes, animals are certainly a reservoir for listeria, we're looking at potential animal inputs.  Again, it's early on in our investigation from the root cause perspective, and as we have new information in the findings of that, we will certainly share them with you.  And of course the industry and our other state and federal partners. 

Lola Russell: Next question, please. 

Operator: Thank you.  Our next question comes from Kerry Sheridan with AFP. You may ask your question. 

Kerry Sheridan: Hi, thanks.  Just a couple of things.  I wanted to just confirm -- were any of these cantaloupes exported outside the US?  And is there any link to potentially a listeria outbreak in spinach that was reported from Publix market in Florida today? 

 Sherri McGarry: The cantaloupes were exported, and those countries have been notified of those shipments So they've been fully made aware of that information.  [Editor′s Note: There is no evidence that Jensen Farms cantaloupe was ever distributed to foreign countries].  And the second part of your question, if you could just repeat that one more time. 

Kerry Sheridan: Okay.  Could I ask you to follow up on which countries they were exported to. 

Sherri McGarry: I think we'll have to get back to you on that specific question.  Was there another question? 

Kerry Sheridan: The other question was about spinach.  A recall of spinach dip from Publix market in Florida.  I was wondering due to suspected listeria.  I was wondering if there's any link between the two. 

Sherri McGarry:  No, there's no apparent link at all between those two instances. 

Kerry Sheridan: Okay.  Thanks. 

Operator: Thank you.  Our next --

 Lola Russell: We'll be taking our last question. 

Operator: Then our last question comes from Barbara Cotter with Gazette in Colorado Springs. You may ask your question. 

Barbara Cotter: Yes, we asked some of our readers what questions they might have.  Several want to know, making sure that cantaloupes are the only fruit coming from the Rocky Ford area or Jensen Farms that have been infected. They were wondering about watermelons or any other fruits from this area. 

Sherri McGarry: Jensen Farms does produce other products. At this time the production season has pretty much ended for the cantaloupes and also for some of the other products that have been mentioned.  At this point in time we have no concern at this point time for any product -- any other products produced by Jensen Farms.

Barbara Cotter: Okay.  And then there was one other question that somebody else had regarding people who are not in high-risk groups.  You can -- I mean, folks can get sick, but it's not serious, right?  They're wondering how long the effects of an illness might last. 

Sherri McGarry: I defer that to CDC. 

Barbara Mahon: Yes.  Hi, Barbara Mahon.  People who are not in high–risk groups who are exposed to listeria can get an illness with diarrhea and fever. It's very rarely serious, but it's -- it's certainly possible that it's serious. It's also possible that somebody could be in a high-risk group and not know that. So we do recommend that people who are not in high-risk groups who want to reduce their risk of listeriosis also not eat these Jensen Farms cantaloupes. 

Barbara Cotter: Okay. 

Lola Russell: Okay. I wanted to thank you for participating today.  Additional questions can be sent to either the CDC or the FDA press office, and the telebriefing will be available by transcript later on today. Thank you for participating.  Thank you. 

Operator: Thank you, and this does conclude today's conference.  We thank you for your participation. At this time, you may disconnect your lines. 

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U.S. DEPARTMENT OF HEALTH AND HUMAN SERVICES