Econstudentlog

Infectious Disease Surveillance (I)

Concepts and Methods in Infectious Disease Surveillance […] familiarizes the reader with basic surveillance concepts; the legal basis for surveillance in the United States and abroad; and the purposes, structures, and intended uses of surveillance at the local, state, national, and international level. […] A desire for a readily accessible, concise resource that detailed current methods and challenges in disease surveillance inspired the collaborations that resulted in this volume. […] The book covers major topics at an introductory-to-intermediate level and was designed to serve as a resource or class text for instructors. It can be used in graduate level courses in public health, human and veterinary medicine, as well as in undergraduate programs in public health–oriented disciplines. We hope that the book will be a useful primer for frontline public health practitioners, hospital epidemiologists, infection-control practitioners, laboratorians in public health settings, infectious disease researchers, and medical informatics specialists interested in a concise overview of infectious disease surveillance.”

I thought the book was sort of okay, but not really all that great. I assume part of the reason I didn’t like it as much as I might have is that someone like me don’t really need to know all the details about, say, the issues encountered in Florida while they were trying to implement electronic patient records, or whether or not the mandated reporting requirements for brucellosis in, say, Texas are different from those of, say, Florida – but the book has a lot of that kind of information. Useful knowledge if you work with this stuff, but if you don’t and you’re just curious about the topic ‘in a general way’ those kinds of details can subtract a bit from the experience. A lot of chapters cover similar topics and don’t seem all that well coordinated, in the sense that details which could easily have been left out of specific chapters without any significant information loss (because those details were covered elsewhere in the publication) are included anyway; we are probably told at least ten times what is the difference between active and passive surveillance. It probably means that the various chapters can be read more or less independently (you don’t need to read chapter 5 to understand the coverage in chapter 11), but if you’re reading the book from cover to cover the way I was that sort of approach is not ideal. However in terms of the coverage included in the individual chapters and the content in general, I feel reasonably confident that if you’re actually working in public health or related fields and so a lot of this stuff might be ‘work-relevant’ (especially if you’re from the US), it’s probably a very useful book to keep around/know about. I didn’t need to know how many ‘NBS-states’ there are, and whether or not South Carolina is such a state, but some people might.

As I’ve pointed out before, a two star goodreads rating on my part (which is the rating I gave this publication) is not an indication that I think a book is terrible, it’s an indication that the book is ‘okay’.

Below I’ve added some quotes and observations from the book. The book is an academic publication but it is not a ‘classic textbook’ with key items in bold etc.; I decided to use bold to highlight key concepts and observations below, to make the post easier to navigate later on (none of the bolded words below were in bold in the original text), but aside from that I have made no changes to the quotes included in this post. I would note that given that many of the chapters included in the book are not covered by copyright (many chapters include this observation: “Materials appearing in this chapter are prepared by individuals as part of their official duties as United States government employees and are not covered by the copyright of the book, and any views expressed herein do not necessarily represent the views of the United States government.”) I may decide to cover the book in a bit more detail than I otherwise would have.

“The methods used for infectious disease surveillance depend on the type of disease. Part of the rationale for this is that there are fundamental differences in etiology, mode of transmission, and control measures between different types of infections. […] Despite the fact that much of surveillance is practiced on a disease-specific basis, it is worth remembering that surveillance is a general tool used across all types of infectious and, noninfectious conditions, and, as such, all surveillance methods share certain core elements. We advocate the view that surveillance should not be regarded as a public health “specialty,” but rather that all public health practitioners should understand the general principles underlying surveillance.”

“Control of disease spread is achieved through public health actions. Public health actions resulting from information gained during the investigation usually go beyond what an individual physician can provide to his or her patients presenting in a clinical setting. Examples of public health actions include identifying the source of infection […] identifying persons who were in contact with the index case or any infected person who may need vaccines or antiinfectives to prevent them from developing the infection; closure of facilities implicated in disease spread; or isolation of sick individuals or, in rare circumstances, quarantining those exposed to an infected person. […] Monitoring surveillance data enables public health authorities to detect sudden changes in disease occurrence and distribution, identify changes in agents or host factors, and detect changes in healthcare practices […] The primary use of surveillance data at the local and state public health level is to identify cases or outbreaks in order to implement immediate disease control and prevention activities. […] Surveillance data are also used by states and CDC to monitor disease trends, demonstrate the need for public health interventions such as vaccines and vaccine policy, evaluate public health activities, and identify future research priorities. […] The final and most-important link in the surveillance chain is the application of […] data to disease prevention and control. A surveillance system includes a functional capacity for data collection, analysis, and dissemination linked to public health programs [6].

“The majority of reportable disease surveillance is conducted through passive surveillance methods. Passive surveillance means that public health agencies inform healthcare providers and other entities of their reporting requirements, but they do not usually conduct intensive efforts to solicit all cases; instead, the public health agency waits for the healthcare entities to submit case reports. Because passive surveillance is often incomplete, public health agencies may use hospital discharge data, laboratory testing records, mortality data, or other sources of information as checks on completeness of reporting and to identify additional cases. This is called active surveillance. Active surveillance usually includes intensive activities on the part of the public health agency to identify all cases of a specific reportable disease or group of diseases. […] Because it can be very labor intensive, active surveillance is usually conducted for a subset of reportable conditions, in a defined geographic locale and for a defined period of time.”

“Active surveillance may be conducted on a routine basis or in response to an outbreak […]. When an outbreak is suspected or identified, another type of surveillance known as enhanced passive surveillance may also be initiated. In enhanced passive surveillance methods, public health may improve communication with the healthcare community, schools, daycare centers, and other facilities and request that all suspected cases be reported to public health. […] Case-based surveillance is supplemented through laboratory-based surveillance activities. As opposed to case-based surveillance, the focus is on laboratory results themselves, independent of whether or not an individual’s result is associated with a “case” of illness meeting the surveillance case definition. Laboratory-based surveillance is conducted by state public health laboratories as well as the healthcare community (e.g., hospital, private medical office, and commercial laboratories). […] State and local public health entities participate in sentinel surveillance activities. With sentinel methods, surveillance is conducted in a sample of reporting entities, such as healthcare providers or hospitals, or in a specific population known to be an early indicator of disease activity (e.g., pediatric). However, because the goal of sentinel surveillance is not to identify every case, it is not necessarily representative of the underlying population of interest; and results should be interpreted accordingly.”

Syndromic surveillance identifies unexpected changes in prediagnostic information from a variety of sources to detect potential outbreaks [56]. Sources include work- or school-absenteeism records, pharmacy sales for over-the-counter pharmaceuticals, or emergency room admission data [51]. During the 2009 H1N1 pandemic, syndromic surveillance of emergency room visits for influenza-like illness correlated well with laboratory diagnosed cases of influenza [57]. […] According to a 2008 survey of U.S. health departments, 88% of respondents reported that they employ syndromic-based approaches as part of routine surveillance [21].

“Public health operated for many decades (and still does to some extent) using stand-alone, case-based information systems for collection of surveillance data that do not allow information sharing between systems and do not permit the ability to track the occurrences of different diseases in a specific person over time. One of the primary objectives of NEDSS [National Electronic Disease Surveillance System] is to promote person-based surveillance and integrated and interoperable surveillance systems. In an integrated person-based system, information is collected to create a public health record for a given person for different diseases over time. This enables public health to track public health conditions associated with a person over time, allowing analyses of public health events and comorbidities, as well as more robust public health interventions. An interoperable system can exchange information with other systems. For example, data are shared between surveillance systems or between other public health or clinical systems, such as an electronic health record or outbreak management system. Achieving the goal of establishing a public health record for an individual over time does not require one monolithic system that supports all needs; this can, instead, be achieved through integration and/or interoperability of systems.

“For over a decade, public health has focused on automation of reporting of laboratory results to public health from clinical laboratories and healthcare providers. Paper-based submission of laboratory results to public health for reportable conditions results in delays in receipt of information, incomplete ascertainment of possible cases, and missing information on individual reports. All of these aspects are improved through automation of the process [39–43].”

“During the pre-vaccine era, rotavirus infected nearly every unvaccinated child before their fifth birthday. In the absence of vaccine, multiple rotavirus infections may occur during infancy and childhood. Rotavirus causes severe diarrhea and vomiting (acute gastroenteritis [AGE]), which can lead to dehydration, electrolyte depletion, complications of viremia, shock, and death. Nearly one-half million children around the world die of rotavirus infections each year […] [In the US] this virus was responsible for 40–50% of hospitalizations because of acute gastroenteritis during the winter months in the era before vaccines were introduced. […] Because first infections have been shown to induce strong immunity against severe rotavirus reinfections [3] and because vaccination mimics such first infections without causing illness, vaccination was identified as the optimal strategy for decreasing the burden associated with severe and fatal rotavirus diarrhea. Any changes that may be later attributed to vaccination effects require knowledge of the pre-licensure (i.e., baseline) rates and trends in the target disease as a reference […] Efforts to obtain baseline data are necessary before a vaccine is licensed and introduced [13]. […] After the first year of widespread rotavirus vaccination coverage in 2008, very large and consistent decreases in rotavirus hospitalizations were noted around the country. Many of the decreases in childhood hospitalizations resulting from rotavirus were 90% or more, compared with the pre-licensure, baseline period.”

There is no single perfect data source for assessing any VPD [Vaccine-Preventable Disease, US]. Meaningful surveillance is achieved by the much broader approach of employing diverse datasets. The true impact of a vaccine or the accurate assessment of disease trends in a population is more likely the result of evaluating many datasets having different strengths and weaknesses. Only by understanding these strengths and weaknesses can a public health practitioner give the appropriate consideration to the findings derived from these data. […] In a Phase III clinical trial, the vaccine is typically administered to large numbers of people who have met certain inclusionary and exclusionary criteria and are then randomly selected to receive either the vaccine or a placebo. […] Phase III trials represent the “best case scenario” of vaccine protection […] Once the Phase III trials show adequate protection and safety, the vaccine may be licensed by the FDA […] When the vaccine is used in routine clinical practice, Phase IV trials (called post-licensure studies or post-marketing studies) are initiated. These are the evaluations conducted during the course of VPD surveillance that delineate additional performance information in settings where strict controls on who receives the vaccine are not present. […] Often, measuring vaccine performance in the broader population yields slightly lower protective results compared to Phase III clinical trials […] During these post-licensure Phase IV studies, it is not the vaccine’s efficacy but its effectiveness that is assessed. […] Administrative datasets may be created by research institutions, managed-care organizations, or national healthcare utilization repositories. They are not specifically created for VPD surveillance and may contain coded data […] on health events. They often do not provide laboratory confirmation of specific diseases, unlike passive and active VPD surveillance. […] administrative datasets offer huge sample sizes, which allow for powerful inferences within the confines of any data limitations.”

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August 6, 2017 - Posted by | Books, Epidemiology, Infectious disease, Medicine, Pharmacology

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