University of Washington Department of Health Services Surveillance

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INDEX Surveillance cycle Treaty basis of surveillance Provider vs. Lab reporting Kinds of surveillance PAHO surveillance "Relationships-based" surveillance Sentinel events Research and prevalence studies Surveillance of the unknown Old issues - new infections Limited capacity = limited incentive Access New challenges New Technologies Syndromic surveillance Molecular epidemiology Cultural issues Travel Water and sanitation Poverty Readings Surveillance cycle This is the classic surveillance cycle. This is from a domestic text. Internationally in a system that is working, for example in Cuba, the data would go down to the city or town health officers, and then to the provincial level, and then to the national level. Cuba has an excellent recording system, which is one reason why they were able to eradicate polio late in the 1960's. Treaty basis of surveillance The treaty basis of international surveillance is very thin. There are only three diseases, yellow fever, cholera and plague, that are reportable under the International Health Regulations, the sole treaty-based agreement for international disease reporting. Experts recommended that WHO expand the list by 2 or 3 other diseases and there is informal agreement to do so, but it’s not been through the World Health Assembly. The Assembly is now considering modifying the International Health Regulations. It’s been a very interesting process. There’s no formal way to "force" countries to report. What do you do if a country doesn’t report? WHO can publish that country's name and what they didn’t report in the World Health Epidemiologic Record but other than this minor embarassment there are really no sanctions. Now consider what happens if they do report under international health regulations. There is usually a major overreaction against that country in terms of trade and in terms of travel. So most countries don’t want to report. Yellow fever, being a vector-borne disease, is probably much less an issue than plague. When India reported their plague, they lost $1.2 billion in the Indian economy. They had major out-migration from Surat; hundreds of thousands of people were running away from where the epidemic was allegedly occurring. In fact, if we had had an epidemic of bubonic and highly infectious plague, we would have had it all over India within a week. International airlines cancelled flights, tours cancelled visits, products were quarantined, products were refused, and it was total chaos. That’s where we are with the actual, formal treaty-basis for international reporting, and you can appreciate how that falls a little short of what we need. Provider vs. Lab reporting There are two basic kinds of disease reporting: Provider reporting and Lab-based reporting. In provider reporting the patient comes to the office, is evaluated and tested. The provider waits for the samples to come back to be sure that the diagnosis correct and if it is a reportable disease, reports it. That may be a week of delay. It’s a slow, unreliable system. Many people have advocated, and to some extent (for syphilis and a few other diseases) we have, a lab-based system where the specimens go to the designated lab and that lab then reports. The state or county then notifies the provider who sent in the specimens that they have a report of a positive and for verification. There is a lot of resistance to lab-based reporting, often on the part of the laboratories. They really don’t want the inconvenience. They log things in by specimen, not by person. This also requires them to ship a lot of information to the state, and this takes extra time that they’re not paid for. Reporting is variable by State and county. For example, California has lab-based reporting for all the STD’s. Reporters try not to use names. Some people use aliases, but even without this problem you’re always going to have some duplication in the name set. When we get the data, it usually has a name on it. When we keep the data, we usually take the name off of it. We code it so that we can retrieve the name if we have to. That unique identifier usually helps us to make sure that the case is not duplicated. Obviously privacy is a key concern in surveillance. Kinds of surveillance Systems of international disease reporting: mortal/morbid events, or laboratory-based. Central collection and feedback Informal, adhoc - based on relationships Sentinel event reporting, i.e., new syndromes, "outbreaks" can be seen as sentinel events Ongoing research, prevalence studies What kinds of surveillance are present in the world? There is a central collection and feedback system of international disease reporting. Historically, special initiatives such as EPI (the Expanded Program of Immunizations of WHO) would set up a vertical system just for measles, polio and diphtheria. They would create that vertical system in a country's ministry of health. However there was no surveillance or anything else even though most countries had a list of reportable diseases based on WHO recommendations. There usually was not a systematic information cycle and the list was often longer than it needed to be. For example, we evaluated the surveillance system in Bahrain for like surveillance for Gonorrhea. No one had looked at their reporting—it was all passive reporting from providers. When we actually calculated the rates of Gonorrhea in Bahrain, they were higher than the rates in the United States. This was very surprising to the Bahrain government. It was completely at odds with their self-image. We tried to confirm our findings by looking at the history of neonatal opthalmic disease in nurseries. Here we found that there had been only 3 infants in the previous year where swabs had been taken. All the swabs were positive but the results had never gotten back to the provider. That’s the kind of breakdown that occurs in countries. You have a serious situation, and even if the information is being reported, it isn’t being looked at. It’s not being regularly reported or used. If you begin to compare international rates, you really don’t get much from the information except such and such a disease exists. PAHO surveillance In Latin America, we looked very closely at disease surveillance through PAHO. For many years PAHO had a biweekly reporting system throughout the hemisphere. Every one of the 41 countries in PAHO was asked to report a group of 21 diseases to PAHO every 2 weeks. This worked very well in the Caribbean where they have small populations, excellent surveillance and better organized ministries. It didn’t work very well at all for Brazil. Brazil is huge and diverse. Each of their states decides what’s reportable. Somebody somewhere in Brasilia would fill out a form and send it out to PAHO. PAHO asked us for an analysis of the completeness of reporting through the system, country by country, over a period of five years. We documented that this system was not complete in any sense. PAHO then moved to spending all their surveillance dollars on mortality surveillance reinforcement and vital registration and trying to get ICD9 coding used throughout the countries. The system wasn’t working. When looking at WHO data when in the Weekly Epidemiologic Record, you have to understand the huge gaps in the information that you’re seeing. After this analysis in the early 1980’s, I returned in 1998. We wanted to look at STD’s in the region. Even though PAHO had decided to discontinue the reporting system, the countries had not been informed. We found a number of countries which had never gotten the word that PAHO wasn’t using this information anymore; they continued to report and continued to send in data over a period of eight intervening years. We located some large boxes filled with unfiled reports and screened these boxes to find all the STD reports. The data was as good as it ever was and was as bad as it ever was and we used it to estimate what the rates were. From these records you could appreciate the magnitude of difference in incidence between some of the sub-regions of the region in STD’s. Think about the ability of such information systems for picking up new syndromes and new infections. "Relationships-based" surveillance Surveillance through an informal ad hoc system that’s based on relationships is very important.. This is a system of people who have gotten to know one another internationally. In our context, the relationship will often develop when people come to the University to study and get to know people at CDC or in the health department. People who work in international health tend to network. Those relationships pay off when you actually have an outbreak. When somebody doesn’t really know what’s going on and needs help, they’ll call or fax somebody. In the face of uncertainty one finds the most sympathetic person who knows something about what you need to know, and you ask that person. A relationship of trust is important to assure that information would be treated with confidentiality and sensitivity. That’s a key piece, because the greatest asset—Garrett calls it "transparency"— is the ability to be frank. Sentinel events New syndromes and outbreaks can be sometimes seen as what we call "sentinel events." Those of you in occupational health know what the sentinel event concept is. If you see one case of lower limb paralysis, for example, that means polio is present, and you may not have to see any more than that to know that there is polio in the place you are working. The same thing holds true if you see one case of congenital syphilis. There are certain events that tell you that there is a problem. If you know what that syndrome looks like, you don’t need more information than a single event to warrant an investigation. Research and prevalence studies I included ongoing research and prevalence studies because there are many longstanding research zones in the world. For example, the Medical Research Council of the UK supports the entire Gambian research effort, 300,000 people. At one point they immunized them all with Hepatitis vaccine. They used Gambia, in collaboration with the Gambian researchers, as a research zone. This zone has been there for a decade and will continue to be there for decades. The French have a number of zones where their organization, ORSTOM (Organization of Research and Science and Technologies Overseas), works. One example, is in Nianar in the north of Senegal. Here they have a zone of a number of villages where they demographically monitor the population, count epidemics as they come through, treat and intervene and call the Ministry of Health. There are a number of American studies that have been in place for a long period of time with a number of long-standing collaborations. For example Cite Soleil in Haiti, is a Johns Hopkins collaboration, and the University of Washington has a collaboration in Kenya. Oftentimes researchers forget that there is a public health information loop and a response to an epidemic situation, or they forget to report prevalence incidence figures to the Ministry of Health. There may be a real disconnection between what sophisticated researchers or research teams may be doing in a country and public health aspects of what needs to happen in that zone. It’s an area that really should be looked at. Internationally, can we get better information from zones of systematic research. Surveillance of the unknown How do you do surveillance to something you don’t know how to diagnose? Consider HIV. Long before we had serologic tests for HIV we knew something was going on clinically. In the late 70’s, people in central Africa had been noticing this new syndrome. The first clinical cases of immune compromise were diagnosed in San Francisco in 1982. Serologic tests weren’t available until 1985. So people knew something big was going on long before they had a diagnostic test. CDC has a study right now across a number of states, which is being headed up by Dr. Bob Pinner and colleagues. This is a study of unexpected mortality. It uses ICD9 codes which suggest infectious etiology of disease. Unexpected mortality related to these ICD9 codes is systematically sought in a defined an age group, 15 to 45, in a number of hospitals across a number of states. Prospectively these hospitals are saving certain kinds of biological samples from these individual cases and sending them to CDC to see what might be there. This is one way to look at new emerging infections. This project grew out of the Hanta virus epidemic in the Four Corners region, where there was a cluster of mortality in young adults. Internationally, this would have a very limited application. It could only work in countries where you had good hospital access, where people went to the hospital if they were dying and where you had ICD9 coding system in place. Ruling out known infectious agents: Dr. Berkelman makes the point that you have to be able to rule out the known when you are dealing with the unknown. This is a key point. A great example of this was the Leptospirosis outbreak in Nicaragua. Nicaragua began to have some dramatic morbidity and mortality. For about a week there was a lot of concern in Nicaragua and elsewhere that this was some unknown, new, serious illness in the country. The outbreak was due to a known agent rather than an unknown agent. Old issues - new infections Limited Response Capacity = Limited incentive for monitoring infections Access issues compromise diagnostics Technology can help but not assure success New insight, strategies are needed Limited capacity = limited incentive Some old issues in surveillance are pertinent to new infections. First of all, if you have a limited response capacity to something, you’re going to have a limited incentive to count it. An excellent example is meningitis that occurs regularly as major epidemics in sub-Sahara Africa. This is the "Meningitis belt," and people in the region tell you it’s because of the dry, dusty "Hamartan" winds that come off the desert:. Meningitis kills hundreds if not thousands of people in each country. If you look in the international literature, several people published a report that showed the cyclical, absolutely predictable periodicity and the level of the epidemic. Last year was an epidemic year. The access to vaccine, which is effective, is very limited. One year CDC vaccinated before the anticipated epidemic. This successfully prevented the problem. The next year we didn’t have access vaccines and we had a huge epidemic. The point..here is a preventable problem that the countries don't have the resources to prevent. If you don’t have anything that you can do about something, your incentive for going out and counting really goes down. Even though it was predictable, there was no response. There are other examples where because there is no capacity to respond there is no incentive to count. Reemergence of Tuberculosis—there’s no adequate treatment many places. They have active TB cases and know they’re not being treated. In Indonesia, for example, they know with the number of doses that they’ve given out for Tuberculosis cases that they’ve treated about half of them that they know of, even through their surveillance system. An absolute lack of ability to cope with a problem mitigates against an accurate counting situation. HIV transmission in blood: we know that less than 50% of blood is screened in many countries, about half the countries in the world right now. Dengue and hemorrhagic fever, vector control; Hanta virus, rodent control, Cholera, sanitation and water. Basically the message isn’t too complicated. Here is a patient in the Central African Republic who has tuberculosis in his hip. He has already been to the central hospital in Bangui and is on his way back home. He probably has HIV, but during the time he was in the hospital, nobody ever checked if he had HIV. But this is an example of where it may have been as much a question of learning to look or choosing to look. Why compound this fellow’s difficulties by giving him a stigmatized diagnosis of HIV, since it’s not going to change what’s going to happen to him? So the surveillance cycle can really only apply when you can disseminate use the information effectively in treatment and control, and otherwise there is no reason to count it. Access Access issues certainly compromise diagnostics. The biggest delay in international reporting is laboratory delay. Most people will not report a disease internationally until they have confirmed the diagnosis. That can be problematic. If you’re dealing with something unknown, you’re never going to confirm the diagnosis for it. Especially if the unknown is virulent. Also since diagnostics take a long time, you’re 2 or 3 weeks out from the index case of something that’s perhaps highly infectious before you can react. The World Bank has published this data on access to diagnosis. Although it would be ideal if you had access to laboratory diagnoses, the "surrogate," if you will, is access to the diagnoses of health professionals (nurses, midwives, physicians). These data are highly variable for a number of reasons which include training of the health professionals and patient access to them. Note the number of physicians per thousand population in sub-Saharan Africa (about 0.1 physician per thousand) compared to the established market economies and former socialist economies. There is dramatic difference in access to diagnosis around the globe. This should cause one to pause when you look at reported information on disease. We know that only 30% of deaths are actually medically diagnosed. Even most deaths don’t come to the attention of physicians. Case definition differs. Characteristics of Internationally Used Case Definitions of AIDS Bangui Definition 1986 Caracas Definition 1990 CDC Definition 1993 Kaposi's or Cryptococcal Meningitis 2 major signs plus 1 minor sign Major signs Wt. loss +/- 10% BW Chronic diarrhea > 1 mo. Prolonged fever > 1 mo. Minor signs Persistent cough Pruritic dermatitis Recurrent herpes zoster Oropharyngeal candida Generalized lymphadenopathy Point system for Sixteen Conditions Kaposi's sarcoma Disseminated extrapulmonary TB Oral candida TB Herpes zoster CNS dysfunction Diarrhea Fever Cachexia Asthenia Dermatitis Anemia CXR infiltrates Cough Cough/pneumonia Lymphadenopathy 1. One or more opportunistic diseases (approximately 20 conditions) or CD4 > 200 or TB, pneumonia, cervical cancer 2. Absence of other known immunodeficiency This is an AIDS-specific example of case definition issues, but true for any disease. A case of HUS here may not match clinically with what you think of as a case of HUS in Japan. You run into that oftentimes when you look at the fine points of what clinical diagnoses are. Access is variable, timeliness is variable. New challenges What’s new about the IOM report? There is a global involvement in factors of emergence. These factors create risk situations which could be quantifiably described. The descriptions of new syndromes and new agents are outstripping our diagnostics. For this reason the International Health Regulation group are discussing syndromic diagnosis. Scientifically we don’t know how to quantify risk in this situation. We have no experience with it. In addition, we’re working against the decrease and not an increase in public sector investment. So whatever we want to do in surveillance has probably got to be cost neutral. This means no new dollars for surveillance. There are no information budgets. If you’re working in a country which is struggling to do some of the preventative measures like immunizations, computer systems will not be a priority. This slide shows you emergence in the Asia Pacific to reinforce some of the issues of diagnosis and matching case definitions. Cyclospora, for example, is a newly diagnosed, newly described parasitic illness that causes long-term diarrhea. It was a laboratory breakthrough that allowed us to diagnose and define this disease. Syndromic versus lab-based reporting is a big variable in surveillance of emerging infections. New Technologies What is the Role for New Technologies? Expand scope of reportable conditions i.e., syndromic reporting Push for earlier diagnosis, i.e., "molecular triage" approach Use telecommunications technology for information transfer, collaborative analysis What are the new technologies? We can consider syndromic reporting a new technology. The molecular triage approach is another. This is something they used in New York during the Tuberculosis epidemic. They found that resistance tends to be clone-specific. A given genetic strain of TB is more or less likely to be resistant to XYZ drugs in an epidemic situation. In the New York situation, they could triage specimens early into potentially resistant and non-resistant groups through molecular fingerprinting. They could get the information back to the clinician within 48 hours. The physicians could then treat the infection as resistant or non-resistant. That was a key part in resolving that very dangerous situation. So molecular triage can be very useful in cases of antibiotic resistance. The relationship between genetics and resistance may or may not allow "molecular triage." New geographic information systems are proving to be helpful in the area of disease surveillance because now we can actually place cases spatially exactly on maps. The maps are pretty well formed for the entire world. These data sets from NASA and other places are becoming available now for scientists and health teams to begin to plot and to understand where diseases come from within countries that are far away. This will eventually, be a useful technology in looking at patterns of disease. The final point is communications technology. The Internet solves everything and makes information transfer faster but it doesn’t change the quality of the information. Syndromic surveillance: Syndromes Example Diseases - Acute neurological syndromes Rabies - Acute respiratory syndromes Pneumonic plague, Hantavirus - Epidemic diarrheas and dysentaries Shigella, Cholera - Hemorrhagic fevers Ebola hemorrhagic fever, yellow fever - Diseases targeted for eradication Poliomyelitis - Drug resistant diseases Malaria, tuberculosis This is a summary of the syndromes under discussion. Obviously, if you had large numbers of such syndromes in a confined area you would be concerned. This is going to be clouded by definitional issues. For example, what is a hemorrhagic fever? The minority of people with hemmorhagic fever bleed. Many may be bleeding, but you may not see it. Internationally we have very limited experience with clinical case reporting.. A whole teaching and learning effort is required to make the reports more reliable. Smallpox is a classic example of syndromic reporting used successfully. Smallpox has a classic, clinical presentation. This allowed focused effort and smallpox was eradicated through a successful use of syndromic surveillance. You can work internationally. Bangui Definition 1986 Kaposi's or Cryptococcal Meningitis 2 major signs plus 1 minor sign Major signs Wt. loss +/- 10% BW Chronic diarrhea > 1 mo. Prolonged fever > 1 mo. Minor signs Persistent cough Pruritic dermatitis Recurrent herpes zoster Oropharyngeal candida Generalized lymphadenopathy A group of WHO experts came together in Bangui to provide a syndromic definition for AIDS in Africa. This didn’t rely on HIV testing but on clinical parameters such as diarrhea, weight loss, and night sweats--things that were clinically ascertainable. The definition proved to be very specific but not very sensitive when tested in Uganda by Dr. Seth Berkley. Dispite its shortcomings, the definition was a success. In fact it did let us know approximately how many cases of AIDS were extant in Africa at the time. Since there was no prospect for access to diagnostic testing in any way, it was the best we could do. Otherwise, syndromic case definitions have not been used in a broad way in international reporting. Putting up this kind of a concept is very valuable but operations research questions are major and probably require a prospective effort. Molecular epidemiology There is a great hope for molecular epidemiology. It’s a new field, and it’s very exciting. Unfortunately the techniques are very sensitive to laboratory conditions and contamination. PCR testing and other techniques require training. Obstacles to Molecular Surveillance Techniques are not standardized Risk of contamination high with some (i.e. PCR) For genetically diverse microbes analysis of results is complex Cannot overcome basic access issues Expense prohibitive in resource poor environments Research centers not always timely in results. This map is a good example of a molecular description of the spread of HIV types. It was put together in Southeast Asia where scientists shared HIV types. There is an impetus to collaborate. They are hoping to make a vaccine and obviously you have to know all of the strains that are out there. When there is a vaccine on the horizon, it’s really in the country’s self-interest to go ahead and share biological material with other scientists. This data was also useful to help understand the importance of air travel. We must consider antimicrobial resistance. There has been very little done to genetically specify which strains of these organisms is primarily responsible for resistance. Molecular data is not routinely used in the laboratories. Instead, the Kirby Bauer kind of technique where you put the antibiotic in the plate and see if anything grows is used to screen for resistance and surveillance for resistance. It would be nice to be able to get this data without that additional week of time that it takes to see if you have growth in the presence of antibiotic XYZ. We don’t have any community systems domestically for picking up resistance. Internationally that’s even more the case. In fact, globally we don’t even have hospital systems that record resistance systematically. WHO's very involved here. There is a new "WHONET" system for antimicrobial resistance, which has been put in place in some countries but it hasn’t started working yet. Any of these international surveillance systems will take a long time before they actually get operational, and they will have to be continually evaluated. Although, molecular biology may allow us to be more accurate for the agents and more accurate for resistance, it is a vision for international surveillance that is not a reality at this time. Ideally, you don’t want t surveillance to count what already happened. You want surveillance to alert you to what’s going to happen. The reason for doing surveillance is to detect outbreaks before they occur, to nip them in the bud, to be proactive about decreasing morbidity and mortality. To approach the problem where risk factors are operating rather than where you already have cases occurring and widespread transmission. Timeliness - Predictive Value1 Risk of transmission (vectors, behaviors, "factors")2 Introduction, emergence of new agent3 Widespread transmission If you look at point 1, point 2, point 3 in time, it would be ideal if you could somehow define point 1 and do surveillance on that basis. We really aren’t doing that now, but it’s interesting to think about that in terms of surveillance. Cultural issues Travel  Click image to enlarge We talked about travel, and this is Dr. Gubler's slide showing you the millions of people traveling to all destinations and tropical areas by year, going up systematically between ’83 and ’94. With a lot more people traveling, what does this do to your surveillance? Would you enhance your surveillance in certain high-risk zones where you have a lot of human traffic? Or maybe you would enhance your surveillance for specific pathogens in specific zones. Can WHO develop a great master plan for working around the world to try to figure out where that would be the most strategically important place for you to reinforce public health surveillance? Right now we are counting what’s shown here, because what we have are industry figures, and industry is interested in the number of people getting on an airplane. What would you be interested in as a public health person if you were trying to gauge the amount of mixing that this was causing in populations, and what would be the number you would be looking for? It would probably be both the ins and the outs, maybe the returns. You have to figure that the risk factors information is poorly defined. So we need to think as scientists, what would be the numbers we would notice. This is the spread of influenza H3N2 virus between November 1989 when it was isolated in China down to 1992 where you have epidemic level activity in the US, Canada, Europe. This is from the European Journal of Epi in ’94. How would you begin to look at the susceptibility if you have an epidemic of H3N2 going on in China and Hong Kong? Where is your next port of call for that virus, and how would you define it, and how would you go there to enforce flu vaccinations if you still had time? This example occurred over a period of 3 or 4 years, so theoretically you could have stopped this at some point during its transmission. Water and sanitation. These are some figures that we have to keep in mind when we think about the risk of disease and the risk of emergence. This is a basic infrastructure. There are millions of people without services. How many people are there on the planet? About 6 billion. As of 1993, over 2 billion people didn’t have adequate sanitation and almost 1.5 billion didn’t have water. I would imagine that these figures haven’t gotten a lot better. Almost half of the people in the world live without adequate sanitary services. The emergence of new infections and the perpetuation of old infections in this environment is easy. Perhaps we need a map to guide increased surveillance for diseases with a combination of travel, commercial activity, migration of population, sanitary water services, and where that sanitary water infrastructure is particularly weak.  Click on image to enlarge This community in Venezuela is a place where lots of people have come for the fishing industry. This is a promising economy, but they don’t have adequate water and sanitation. When cholera eventually spread, it came into that kind of village situation. It came into Lima first, but then spread to this kind of village situation up and down the coast. Lima at the time had a uniquely bad sanitary and water infrastructure for the population it was carrying. There had recently been a huge immigration into Lima because of the unrest in the hills. So you had a combination of factors that made Lima the natural entry point for cholera in Latin America. Perhaps in retrospect, if you had had a map that mapped these risk factors systematically, e,g. population vs. adequacy of sanitation and water services, you could have reinforced the public health response there. Poverty Finally, of course, poverty is a risk for new disease as well as old disease. As new diseases emerge, those people who are most at risk are going to get them first. These are usually the people that are undernourished and otherwise disadvantaged and marginalized. If we had a new surveillance system, it would be culturally attuned, including marginalized populations and diverse populations all around the world. Readings: Leduc, James, Tikhomirov, Eugene, "Global Surveillance for Recognition and Response to Emerging Diseases." Annals of the New York Academy of Sciences, Vol. 40, 1994, pp.341-345. Return to Title Page HOME  |  List of Lectures