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CDC Telebriefing Transcript

Prevention of Hepatitis in Correctional Settings
and Norwalk Virus, U.S., 2002

January 23, 2003

AT&T MODERATOR: Good morning and good afternoon. Welcome to today's CDC MMWR telebriefing. Now at this point all phone lines are muted or in a listen-only mode. However, we'll be covering a number of subjects today, periodically breaking for questions, and the instructions will be given at that time. Just as a note, should you require any assistance, you may reach an AT&T operator by pressing zero, then star on your phone keypad.

Here to lead our telebriefing is senior press officer, Ms. Karen Hunter. Please go ahead, ma'am.

CDC MODERATOR: Hi, everyone. Thanks for joining us today. Today's MMWR telebriefing will feature two topics. The first will be a CDC report and recommendation on the prevention and control of infections with hepatitis viruses in correctional settings. Our experts will make brief comments, as always, and then we will open it up to reporter questions. Then we'll move on to our second article which is Norwalk virus activity in the United States 2002.

So let's begin with our first topic. Our spokepersons today will be the lead author of the recommendations, Dr. Cindy Weinbaum. She is an MD and her last name is spelled W-e-i-n-b-a-u-m.

Her co-author is Rob Lyerla, PhD. His last name is spelled is L-y-e-r-l-a.

And then Dr. Hal Margolis, who's the director of the Division of Viral Hepatitis at CDC will also be available during the question-and-answer segment. His last name is spelled M-a-r-g-o-l-i-s.

So let's begin now with Dr. Weinbaum.

DR. WEINBAUM: Hi. I hope everyone can hear me. I'm going to give you just a brief overview of CDC recommendations for prevention and control of infections with hepatitis virus especially in correctional settings.

People who spend time in jails, prisons, and juvenile institutions have an increased risk of infectious diseases, including rates of infections with hepatitis B and hepatitis C viruses.

People in prisons, jails, and juvenile institutions are also members of our community. About 98 percent of all incarcerated persons will be released into the community. Jails have a very high turnover rate, over a 1000 percent annual turnover. Prisons have about 40 percent annual turnover.

Of all Americans with hepatitis C virus infections, about 12 to 15 percent have been incarcerated, and of all Americans with chronic hepatitis C virus infection, about 39 percent have been incarcerated.

These recommendations look at the incarceration period as a time for potential interventions basically as an extension of the public health system. Medical prevention measures can be delivered effectively in prisons and things that are covered in this report are hepatitis A vaccination for children in states that have high rates of hepatitis A, in other words, those children who should be vaccinated according to existing CDC recommendations.

Hepatitis C vaccination for children who are unvaccinated. Again children for whom vaccination is already recommended by CDC recommendations should be vaccinated, if they're not, when they're seen in a juvenile institution.

Unvaccinated adults, or adults who haven't previously been infected with hepatitis C should be vaccinated when they come through a correctional setting, because these are people who are at potential high risk for hepatitis C infection.

This again is a recommendation that CDC has already made in the past since 1982. We also recommend hepatitis C testing and counseling for people who are at risk for hepatitis C infection. That would be mostly people who have histories of injecting, drug use, or who are currently injecting drugs.

Prison is a great place for preventing these infections from getting transmitted because it's a venue where we can vaccinate. Other systems that have not vaccinated in prisons have found that in recidivists, that is, in people who were incarcerated, that go out to the community and come back, they've seen high rates of new hepatitis C virus infections.

It's also a good place where education for hepatitis prevention can be incorporated. Most prison systems at least already have health education programs in place, and hepatitis prevention messages should be a part of those messages for HIV and STD prevention that are already being given.

Then, finally, after-care linkages with the community need to be established in order to provide the necessary continuity of care, including counseling and prevention of transmission to others after discharge, prevention of further liver damage, and referrals for chronic hepatitis care and for continuation of a vaccination series that might have been started should also be made.

Finally, the recommendation is for public health systems and correctional systems to work as partners to ensure that these recommendations can happen.

It's essential that these two systems coordinate and communicate in order for public health to extend itself into the correctional setting.

CDC MODERATOR: Okay, thank you, Dr. Weinbaum, and now I think we're ready to open it up for reporter questions.

AT&T MODERATOR: Indeed. Thank you. Ladies and gentlemen, as you just heard, if you do have any questions or comments, we invite you to queue up. Just press the one on your phone keypad. I'll let you know that you'll hear a tone indicating that you've been placed in queue and you may remove yourself from the queue by pressing the pound key.

So, once again, to ask a question at any time during the briefing today, just press the one on your touchtone phone.

Representing Reuters Health, our first question comes from the line of Meagan Brooks. Please go ahead.

QUESTION: Yes. Hi. What are the new recommendations here? I know you went over the ones that are--previously--but according to the synopsis, this new report consolidates previous recommendations and adds new ones.

DR. WEINBAUM: Yeah. The really newest thing about this is that it brings together kind of in one reference a lot of recommendations that have previously been made. We clarified some previous recommendations such as a recommendation for hepatitis C testing. We clarified that that should be, in most settings, based on reported risk behaviors by inmates.

Counseling, testing and education are also things that haven't specifically been recommended for the correctional setting.

QUESTION: Okay, and is this document available? Where is this, that physicians can get this?

DR. WEINBAUM: It's an MMWR, so it's available on the CDC Web site.

QUESTION: Okay; thank you.

AT&T MODERATOR: And thank you, ma'am. Next we go to Mark Fazlollah with the Philadelphia Inquirer. Please go ahead.

QUESTION: Hi. It's Mark Fazlollah and there is in your report 83 percent of the state inmates are former drug users, making them at risk for hepatitis C. Should they all be tested, and if not, why?

DR. WEINBAUM: People who have histories of injecting drug use should be tested for hepatitis C. That 83 percent is not only injection drug use. That's all sorts of drugs. Those statistics are from the Bureau of Justice statistics, and aren't really broken out by injection versus noninjection drug use. So those individuals who report injection drug use, yes, they should be counseled and tested for hepatitis C.

QUESTION: Do you have any estimates on how many that would be?

DR. WEINBAUM: No, we kind a really don't. The only data that I would have is from hepatitis C-related research projects that have been done in a variety of states where they've asked questions about risk factors of incarcerated inmates in prison systems, where they've found that about 15 percent of their standing inmate population have histories of injection drug use.

Again, these are very small samples and they were not done for the reasons of estimating injection drug use prevalence among the general correctional population.

QUESTION: And there is a typo on page 25 where you talk about testing specifically for hepatitis C. Can you clarify what that means.

DR. WEINBAUM: My page numbers might be different from yours. Oh, okay.

QUESTION: You see right under Testing, you see that that's the key issue of testing, that looks like you've dropped a sentence there in explaining who should be tested.

DR. WEINBAUM: I think that you must have a penultimate version of--

QUESTION: No. I think I--that's the one that the press office just sent me moments ago.

DR. WEINBAUM: Okay. We'll have to figure out why you have a different report than they have. If you want to call the press office after the telebriefing, the number if [404] 639-3286, and we can certainly make sure that you're getting the report.

QUESTION: Can you just clarify--

DR. WEINBAUM: I'm sorry. In the meanwhile, let me tell you what that recommendation should say.


DR. WEINBAUM: Which is it should say, "All inmates should be asked questions regarding risk factors for HCV infection during their entry medical evaluations, and all inmates reporting risk factor for HCV infection should be tested for anti-HCV.

QUESTION: And do you have any estimates of the numbers that that would be?


CDC MODERATOR: Okay; next question, please.

AT&T MODERATOR: Okay; very good. Thank you, sir, and United Press International, Steve Mitchell. Please go ahead.

QUESTION: I assume the way these diseases are being transmitted in prisons is primary due to consensual sex or rape. If that's true, what's being done to address that?

DR. WEINBAUM: Potential sex would be a risk for hepatitis B transmission in prison, which we know has occurred in small outbreaks. We don't have any data indicating the presence or absence of hepatitis C transmission in prison, so I can't address that, and hepatitis C is not transmitted effectively by sex, and no, I can't speak to the issue of prison rape at all.

CDC MODERATOR: Next question.

AT&T MODERATOR: Thank you, Mr. Mitchell. Let's go to the line, now, of Jennifer Lin with the Philadelphia Inquirer. Please go ahead.

QUESTION: Hi. With another infectious disease that's prevalent in prisons, HIV, the CDC came out with a recommendation of universal screening. With HCV, you know, a disease that's arguably many times more prevalent in prisons, why did you not advocate universal screening?

DR. WEINBAUM: At the consultant's meeting that was convened when these recommendations were put together, we were presented with data from a couple of different correctional systems where they had looked at risk factors among their inmates who had been tested for hepatitis C, and what they found was that, quite reliable, self-reported risk factors were very predictive of hepatitis C virus positivity.

So kind of based on those data which was what we tried to base all of our recommendations on, was data either published or presented. We recommended targeted testing.

QUESTION: Within the CDC of targeted versus the universal testing?

DR. WEINBAUM: I'm sorry; could you repeat the question.

QUESTION: Was there any debate within the CDC regarding targeted versus universal screening?

DR. WEINBAUM: Well, there was that discussion prior to the presentation of these data, which made it pretty clear that targeted testing was pretty efficient and effective.

QUESTION: And did budget issues influence your recommendation on the testing issue?


CDC MODERATOR: Next question.

AT&T MODERATOR: Thank you, Ms. Lin. We next go to the line of Mike MaGraw with the Kansas City Star. Please go ahead.

QUESTION: Yeah. I'd like to know: Does this report now mean that authorities can identify at least 39 percent of all the persons in the country with Hep C?

DR. WEINBAUM: Yeah. That's an estimate. But yes, I think that this report does mean that a large proportion of people with hepatitis C in the country might be identified through testing in

correctional settings.

AT&T MODERATOR: I see. And our follow-up. There was an earlier question about cost pressures. Have any of the CDC officials involved with this MMWR been lobbied, told, or asked by prison officials, or have prison officials suggested in any way that universal testing would lead to a level of treatment that would be unaffordable for them?

DR. WEINBAUM: We have heard that; however, studies looking at testing.

Well, okay a couple of things. One is that we are not recommending universal testing. The second is that studies looking at HCV testing for a large portion of inmates coming into a correctional facility have looked to see, according to specific criteria needed to start treating, have looked to see how many people would actually be treated based on that large number of people who are tested. And the couple of studies that have tried to determine how many people would actually be treated from hepatitis C if so many people were being tested have found that only about 5 to 7 percent of people who get tested would end up even entering a treatment protocol.

AT&T MODERATOR: I see. Should treatment protocols in prisons in any way differ from suggestions in the last consensus conference?

DR. WEINBAUM: No. No. You know, according to Estelle versus Gamble, it's established that denying treatment in a correctional setting that would be standard of care in the outside is not acceptable.

AT&T MODERATOR: But many prisons today say that they won't treat people if they're x-number of days away from release. That probably then should change, should it not?

DR. WEINBAUM: Well, that actually probably makes sense. Because treatment should not be discontinuous and if you can't assure that people will be able to continue their treatment on the outside, it probably does make sense to defer the initiation of treatment until that person's in a stable setting.

CDC MODERATOR: Okay, let's move on to the next question, please.

AT&T MODERATOR: Okay, and next we'll go to the line of Denise Grady with the New York Times. Please go ahead.

QUESTION: Thank you. I wanted to go back to something you said before about a study showing that the self-reported risk factors were a reliable way to find out who was infected. When that was done, were these people who were known to be infected and then asked about their risk factors, or were the risk factors asked about first and then they were tested?

DR. WEINBAUM: I think it was both. Yes, I think that there was one study that did each different way.

QUESTION: And both showed it to be reliable? I'm asking because these are behaviors that classically people don't want to admit to. Even people in prison. And I would think it would make a difference. If you're already infected, then maybe you'll say so. If you know you're infected. But if might be a different story if you don't know and you're asked these questions.

DR. WEINBAUM: Right. Since the main issue with hepatitis C infection is injection drug use, it seemed that people would be willing to admit to their injection drug use, which they might not be willing to admit to, say sex in a prison. And of course there was potential bias in these studies in that the studies are done by people who are not in the employment of the correctional facility. So reporting might have been different to those individuals than they would to say a corrections officer.

But in one of the studies, we ended up being quite confident that in the current procedures for intake into a correctional facility, these things would be reported and they would be reliable.

QUESTION: Okay. Thank you. One more question if you would, please. Do you know what hepatitis C test costs?

DR. MARGOLIS: This is Dr. Margolis. It's quite variable, and the actual reagent costs are somewhere in the $6 to $10 range. What then is charged, you know, really depends on each locale. So it's kind of hard to come up with a national average.

QUESTION: Okay. Thanks.

CDC MODERATOR: Next question, please?

AT&T MODERATOR: Thank you, and with two participants in queue, we'll go back to Steve Mitchell for a follow-up. Please go ahead.

QUESTION: Hi. Can you address the recommendations that are geared towards prison guards?

DR. WEINBAUM: Anything specific?

QUESTION: Just what are they?

DR. WEINBAUM: Oh. Okay. Yes, basically our recommendations for correctional staff is that individuals who come in to frequent contact with blood should be vaccinated against hepatitis B; that anybody who has an exposure that's potentially infectious should be tested, the source should be tested, if possible, and post-exposure prophylaxis should be given for hepatitis B. And for the most part we defer to OSHA in terms of what their standards are for employment.

CDC MODERATOR: Next question, please?

ATT MODERATOR: Okay, and next we'll go to the line of Mark Foslola. Please go ahead.

QUESTION: Thank you. If my math is correct, when we talk about 39 percent of the infected people being released from corrections, we're talking about more than a million people a year being released with hepatitis C from prisons. The question is: Should testing for hepatitis C be mandatory in prison and if not, why not?

DR. WEINBAUM: Well, I'm sorry, the question is: Should everybody in prison be tested?

QUESTION: No. Should testing for hepatitis C be mandatory among those that are risk for the disease? That are identifiably at risk. Should that be mandatory?

DR. WEINBAUM: CBC makes recommendations. We don't make mandates. So we are recommending that people who have risks for the disease be tested because it's the best standard of public health care. But we're not making a mandate.

QUESTION: Right. But the question is there's a choice between asking inmates whether they would be tested, or having a policy of saying they will be tested. And knowing that more than a million prisoners a year are being released into the public, with a potentially deadly virus, should there be a requirement by prisons? Do you recommend that prisons have a mandatory testing policy?

DR. WEINBAUM: The actual implementation of these recommendations should really be done on a state-by-state and a system-by-system basis. CDC has already recommended in 1998 in our hepatitis C recommendations that testing be done in prisons. We didn't make it mandatory at that time, because we can't. We recommended that it be implemented, you know, as feasible in each jurisdiction.

QUESTION: And are we talking about since 1988? Roughly a million people being turned loose every year with this disease?

DR. WEINBAUM: I'm sorry, that was 1998 that I--

QUESTION: Since 1998, if we're looking at that a million people each year being released? Some of them rotating through the system more than once. But, roughly a million people coming out with this disease.

DR. WEINBAUM: Well, these are probably the same people who went in with the disease. So, I think the main point is that these are individuals who are coming from the community into prisons and released back into the community. It's not that people are going into prisons, getting infected, and then being released on the community.

DR. WEINBAUM: The same people.

QUESTION: Yes. But do they know they have the disease when they're being released? Do you have any estimate of how many of them are aware that they have the disease, have been tested, and are told that they have the disease?

DR. WEINBAUM: Right. We don't have an estimate of how many have been tested and have been told that they have the disease.

CDC MODERATOR: Next question please?

ATT MODERATOR: And there are no other participants in queue, Miss Hunter.

CDC MODERATOR: Okay, thank you, everyone. And we'll now move along to our next topic, which is the MMWR article on Norwalk Virus activity, United States 2002. Our spokespersons are Dr. Marc-Alain Widdowson, and I will spell his full name for you. The first name is spelled M-A-R-C hyphen A-L-A-I-N. The last name is spelled
W-I-D-D-O-W-S-O-N. Dr. Widdowson is a veterinarian, and he will be joined by Steve Monroe, who's a Ph.D., and Steve spells his name, common spelling M-O-N-R-O-E. So let's begin with Dr. Widdowson.

DR. WIDDOWSON: Hi. Good afternoon. Unfortunately I'd like to start with a typo in our report which comes under the title of CDC Laboratory Surveillance, where near the end, the sentence starting "Six of the eleven outbreaks associated with Farmington Hill Strain." Then in parentheses it lists five states and it begins with Arkansas, and actually that should be Alaska. I apologize for that.

Moving onto a quick summary of the report, we present data from Clark County, in Washington State, the State of New Hampshire, New York City, and CDC on recent activity of Norovirus, which formerly was known as Norwalk-Like Virus. And the objective was to illustrate the characteristics of the high levels of Norwalk Virus disease that have been noted by many local health departments throughout the United States. So in Clark County, Washington during November and December 2002, the county received a course of ten outbreaks of acute gastroenteritis, including six from long-term care facilities. Four of those six long-term care facilities accounted for over 90 percent of the cases of acute gastroenteritis reported.

Characteristics of the illness were consistent with Norovirus infection, and stool specimens from each of those four outbreaks tested possible for Norovirus at the Washington State Public Health Laboratory. In the State of New Hampshire in the whole of year 2002, the State of New Hampshire received reports of 35 outbreaks of acute gastroenteritis, again consistent with Norovirus infection, affecting a total of 2,312 persons.

Twenty-eight of those 35 outbreaks, that's 80 percent, were reported from long-term care facilities in November and December 2002. Out of 28 outbreaks, ten tested possible for Norovirus at the New Hampshire Department of Health and Human Services. In addition to these outbreaks, the New Hampshire Emergency Department Syndromic Surveillance System detected an increase in emergency department visits for acute gastroenteritis during December 2002.

In New York City during the period starting November 6, 2002 to January 13, 2003, 66 outbreaks of acute gastroenteritis, again epidemiologically consistent with Norovirus infection were reported to the New York City Department of Health and Mental Hygiene. Fifty-one of these outbreaks were in long-term care facilities, nursing homes, or rehabilitation facilities, and affected 1700 persons. Specimens from six of these outbreaks tested positive for Norovirus at the New York State Department of Health Wadsworth Center.

Additionally, Emergency Department Syndromic Surveillance of the New York City Department of Health and Mental Hygiene detected an increase in emergency department visits of patients with acute gastroenteritis. Control measures in all the above-reported outbreaks included a degree of quarantining of ill persons, increased hand washing among staff and residents, cleaning and disinfection of contaminated areas, and exclusion of sick staff in the workplace until at least 48 hours after recovery from illness.

In regards to the CDC paragraph, from May to December 2002, CDC tested specimens from 37 outbreaks occurring in a wide variety of settings. Specimens from 27 of those 37 outbreaks were positive for Norovirus. Eleven of those 27 positive outbreaks were attributed to a common strain which has been provisionally called Farmington Hill Strain. Five of these outbreaks of this common strain were in cruise ships, and six of these outbreaks were in five states: Georgia, Utah, Kentucky, North Carolina, Kentucky, and Alaska.

Ongoing investigations have as yet not uncovered any of the existing links between any of these eleven outbreaks on land and cruise ships. In addition, this strain was identified in one of the outbreaks reported from New York City, reported in the New York City Paragraph, and two of the positive single specimens collected from emergency departments in New York City.

The data of these outbreaks, in these states suggest a recent increase in Norovirus activity on land, presenting as outbreaks or increased sporadic disease. We also report evidence of an increased prevalence of a common strain of Norovirus. Norovirus is the most common cause of acute gastroenteritis, causing 23 million illnesses annually in the United States.

Though Norovirus is also the most common cause of food-borne illness, reports suggest that the high activity recently noted is especially in closed settings, where person-to-person spread is the most likely mode of propagation. Increased Norovirus illness in closed settings in winter has previously been noted and may reflect the increased incidence of sporadic disease in the community.

No surveillance of non-food-borne outbreaks exist in the United States. And although local state departments are noting a clearly increased activity of Norovirus, no national comparisons can be made with previous years to assess the degree of that increase.

Temporary predominance of a common strain of Norovirus has been seen before. And it possible that characteristics of this predominant strain, found here, may make it particularly transmissible in certain settings such as nursing homes. As noted before, though, investigations are ongoing, no link has been found between the outbreaks caused by this common strain.

Control of outbreaks of Norovirus in closed settings can be difficult due to the low infectious dose of the agent, multiple modes of transmission, and environmental persistence. Efforts are underway to develop a surveillance system for non-food-borne outbreaks of gastroenteritis, which would gather data on epidemiological aspects and laboratory aspects of outbreaks. And CDC is encouraging states to collect specimens from outbreaks and have them tested in sequence for Norovirus strains.

Thank you.

CDC MODERATOR: Now we'll open it up to reporter questions.

ATT MODERATOR: Very good. Thank you. And ladies and gentleman, once again, just press the '1' on your touchtone phone.

We'll go to the Richmond Times, and the line of Tammy Smith. Please go ahead.

QUESTION: Hi. Thank you for taking my question. In reading the report, it says that is there a new strain, and are you saying that this new strain maybe more susceptible to being passed from person to person, and can you explain that?

DR. WIDDOWSON: I'll pass you over to Dr. Steve Monroe, who is the Head of our Viral Gastroenteritis Lab.

DR. MONROE: Thanks for your question. This is Dr. Monroe. We have identified what we are provisionally calling a new strain, the Farmington Hill strain, but it clearly is related to other strains that we've characterized genetically over the past year. So, while it's a type that we've identified, our molecular fingerprinting method is direct sequencing of PCR products. So, by the fingerprinting method, this is a unique strain, but it's not radically different from strains that we've seen in previous years.

Speculation that this strain might be perhaps more transmissible person to person is reflected by a number of points. One, the current predominance of outbreaks in institutional settings and on cruise ships where we assume that person-to-person spread is the most predominant form. The second is that in studies we've done and in studies that have been done in the UK, looking at different strains, the genetic cluster that this strain falls into has been statistically associated with outbreaks in nursing home settings, again suggesting that there's something about strains in this cluster that are more likely to cause them to be transmitted person-to-person.

CDC MODERATOR: Next question?

ATT MODERATOR: And at this point we don't have any further questions. Ms. Smith, did you have a follow-up?

QUESTION: Well, let me see. I guess if this is a new strain, when people get this infection, do they become immune to being infected again? In Virginia we're currently having a lot of outbreaks, so I was wondering, next year people who have had it, will they not get it again, or is this something that you can keep getting over and over?
DR. MONROE: That's a good question. This is Dr. Monroe again. And one peculiarity about infection with Norovirus is in general, from limited studies that have been done in adult human volunteers, is that there does not appear to be long-term protection following infection with this virus. So in studies with volunteers, if they were experimentally infected and became ill, if they were re-challenged, that is experimentally infected again two years later, there was no protection. The same people who were ill the first time became ill the second time.

So, while there may be short-term protection over a matter of say, six months, there does not appear to be long-term protection. And in fact, the cluster that this strain falls into, we saw an increased activity and a predominance of strains from that same cluster, both in the U.S. and globally wherever people were doing characterization, between '95 and '97. So it appears there maybe a cyclical introduction of this strain to this cluster into the community.

QUESTION: Thank you.

ATT MODERATOR: And thank you, Ms. Smith. Next we'll go to the line of Theresa Black with Medell News Service. Please go ahead.

QUESTION: I was wondering if you could define for me the definition you're using for an outbreak? I'm wondering about individual cases of Norwalk Virus that may have occurred person-to-person, that might not get reported to doctors, that might not get reported to public health departments.

DR. WIDDOWSON: Hi, this is Dr. Widdowson here. The definition of an outbreak depends very

much on--it's relatively subjective I guess. States have different objectives, different definitions of what an outbreak is. Theoretically, you're absolutely right, that any two cases of an illness which seem to be connected in any way, that is an outbreak. So outbreaks in effect are occurring all the time, but, quite naturally, people have to set a certain threshold and that threshold differs according to different states.

So when you have clearly a more than expected increase in a close setting, that then is classified as an outbreak. But you're right, in the sense that a lot of people presenting to the physician will be a part of an undetected outbreak, undetected either because it's small and only a few people have been affected, or undetected because it's not associated with any particular testing.

So if there's a communitywide outbreak, it's very difficult to know what the common source is, whereas if everyone's sick in one particular locale, then it's more obvious.

CDC MODERATOR: Next question.

AT&T MODERATOR: Thank you. We'll go to the line of Mandy Gardner with the HealthScout News. Please go ahead.

QUESTION: Hi. I have more of a clarification I think than a question. Are you essentially saying that we're seeing more cases but you don't know precisely how many because you don't have the data to compare from previous years?

DR. WIDDOWSON: That's exactly what we're saying. Whenever assessing this type of data, there are a number of pitfalls. For instance, reporting virus, clearly there's been a lot of increased interest in Norwalk viruses because of the cruise ships, so it could be attributed--this increased activity could be attributed to increased reporting because of the increased awareness.

However, when we speak to experienced local health officials, it's clear that what they're seeing is beyond that, and what they're seeing is a very noted increase in activity in their experience.

You're absolutely correct because there is no formal way of comparing with previous years. We can't say how much of an increase this is.

QUESTION: Just a quick follow-up question. This increase has been noticed by health officials. Is that an increase that's happening specifically on land? I guess the cruise ships was a fairly new development, or a more intense development. So is it the land and the cruise ships that we're seeing increases?

DR. WIDDOWSON: Yeah. I mean, Norwalk virus outbreaks have always occurred on cruise ship but cruise ships are only a very small portion of Norwalk virus activity. The vast majority of Norwalk virus activity is on land. So the cruise ship activity reflects what's going on on land, and in two ways it reflects it.

Firstly, there's increased activity on cruise ships, is a reflection of increased activity on land, if we start looking at the land-based data, which is the objective of this MMWR, and secondly, the actual molecular sequencing shows us that the strains on cruise ships also reflect what's going on on land.

So the cruise ships I guess are a reflection of the main problem which is on land, rather than the other way around.

QUESTION: Okay; thank you.

CDC MODERATOR: Next question.

AT&T MODERATOR: And we'll go to the line of Denise Grady with the New York Times. Please go ahead.

QUESTION: My questions were answered. Thank you.

AT&T MODERATOR: And thank you. Next we'll go to the line of Ted Vigodski with Public Broadcasting. Please go ahead.

QUESTION: Thank you. Either doctor will do for this. It seems as if, as you say, the cruise ship industry is sort of the "canary in the mine" as far as letting us know what might be going on in the rest of the country.

So my question is if you had your druthers, and the states, and the state and territorial epidemiologists go along, what would be a good model to set up a registry to track this type of virus? Would you use sentinel positions, the way you do with influenza? What would be a good way to try to capture this number? Thank you.

DR. WIDDOWSON: Efforts are underway at the moment to do two things. One is to encourage the collection of specimens from outbreaks. So one of the previous problems that we've always had is because of the technical difficulties in diagnosing Norwalk virus, is that many outbreaks were not attributed to Norwalk virus.

So one of the ways of being able to detect Norwalk virus activity is actually to be able to take specimens and test them, and now that technology is widespread throughout the U.S., in addition to the CDC facility here.

In addition to that, we have the reporting of the outbreaks. So even though, if you have it diagnosed, you have a nursing home outbreak that you know is Norwalk virus cause you've tested for it, as yet, there is no system to report that to any national database so comparisons could be made with previous years.

So the second arm of being able to dissect what's going on is to develop a reporting system where people would, epidemiologists, in particular, would log in the outbreaks that they've confirmed to be Norwalk virus, and a combination of those two factors, collecting and testing stool specimens and then reporting nonfood-born outbreaks of Norwalk virus, would help us enormously in assessing the impact, public health burden of Norwalk virus in a community.

CDC MODERATOR: Next question.

AT&T MODERATOR: And next we'll go to the line of Teresa Black with, again, the Medel [?] News Service. Please go ahead.

QUESTION: My question is from what I understand with the CDC, the Norwalk virus is not a nationally notifiable disease. Are you considering adding Norwalk virus to that list, because I know for a fact in the Chicago Department of Public Health, they do not collect data on this at this time; it's not required by the states. So I don't have any numbers, locally, about the incidence of it here in Chicago.

DR. WIDDOWSON: The reporting system in the U.S., having states decide what is officially notifiable in their own states, and reporting at the national level is based on an agreement.

There is a very reliable and complete reporting system for foodborne outbreaks of Norwalk virus, so we do capture some of Norwalk virus activity nationally through foodborne outbreaks.

So when an outbreak is clearly associated with food, then we'll hear about it. Up until the present, the only way we know about the nonfoodborne ones has been anecdotal or when we receive specimens.

At this stage there's no thought of actually making it, the Norwalk virus pathogen per se notifiable, though I think in different states you will find that outbreaks of acute gastroenteritis in nursing homes as well as in foodborne settings, are notifiable at the state level.

CDC MODERATOR: Next question, please.

AT&T MODERATOR: And next we'll go to the line of Denise Grady. Please go ahead.

QUESTION: Thank you. If you assume that this apparent increase is real, I realize the report says the reasons for it are unclear, but I wonder if either of you could even speculate about why a virus like this could be increasing in the population?

DR. MONROE: This is Dr. Monroe again. We don't know what the reason is but I think, as I mentioned, we have seen a similar pattern in data both from the U.S. and from Europe and elsewhere in '95-'96. So I suspect that what we're seeing is a natural cyclical variation in the level of activity and what's happened is that this time, because there are many more states, state health department labs that have the capacity to actually make a confirmed diagnosis, we're able to actually detect the increase and get some quantitative feel for what's going on, but I suspect that this same pattern has occurred in the past and it's perhaps a challenge to us to try to figure out what it is about either the virus of the control measures that allows for an increase in activity like we're seeing at the present time.

CDC MODERATOR: Next question.

AT&T MODERATOR: Did you have a follow-up, Ms. Grady?

QUESTION: No; thank you.

AT&T MODERATOR: Okay. There aren't any other participants in queue, Ms. Hunter.

CDC MODERATOR: Great. Well, that's going to wrap up this week's MMWR telebriefing. Thank you all for joining us.

Anyone wishing additional information on any of this week's MMWR articles should please call our main press office.

That number, again, is [404] 639-3286. Thanks a lot.

AT&T MODERATOR: And ladies and gentlemen, that does conclude your press conference for today.

Thank you very much for your participation as well as for using AT&T's executive teleconference service. You may now disconnect.

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