Public health surveillance (also epidemiological surveillance, clinical surveillance or syndromic surveillance) is, according to the World Health Organization (WHO), "the continuous, systematic collection, analysis and interpretation of health-related data needed for the planning, implementation, and evaluation of public health practice."Public health surveillance may be used to track emerging health-related issues at an early stage and find active solutions in a timely manner.
The World Health Organization (WHO) is a specialized agency of the United Nations that is concerned with international public health. It was established on 7 April 1948, and is headquartered in Geneva, Switzerland. The WHO is a member of the United Nations Development Group. Its predecessor, the Health Organization, was an agency of the League of Nations.
Public health has been defined as "the science and art of preventing disease, prolonging life and promoting human health through organized efforts and informed choices of society, organizations, public and private, communities and individuals". Analyzing the health of a population and the threats it faces is the basis for public health. The public can be as small as a handful of people or as large as a village or an entire city; in the case of a pandemic it may encompass several continents. The concept of health takes into account physical, psychological and social well-being. As such, according to the World Health Organization, it is not merely the absence of disease or infirmity.
Public Health surveillance systems can be passive or active. A passive surveillance system consists of the regular, ongoing reporting of diseases and conditions by all health facilities in a given territory. An active surveillance system is one where health facilities are visited and health care providers and medical records are reviewed in order to identify a specific disease or condition.Passive surveillance systems are less time-consuming and less expensive to run but risk under-reporting of some diseases. Active surveillance systems are most appropriate for epidemics or where a disease has been targeted for elimination.
Techniques of public health surveillance have been used in particular to study infectious diseases. Many large institutions, such as the WHO and the CDC, have created databases and modern computer systems (public health informatics) that can track and monitor emerging outbreaks of illnesses such as influenza, SARS, HIV, and even bioterrorism, such as the 2001 anthrax attacks in the United States.
The Centers for Disease Control and Prevention (CDC) is the leading national public health institute of the United States. The CDC is a United States federal agency under the Department of Health and Human Services and is headquartered in Atlanta, Georgia.
Public health informatics has been defined as the systematic application of information and computer science and technology to public health practice, research, and learning. It is one of the subdomains of health informatics.
Influenza, commonly known as the flu, is an infectious disease caused by an influenza virus. Symptoms can be mild to severe. The most common symptoms include: high fever, runny nose, sore throat, muscle pains, headache, coughing, and feeling tired. These symptoms typically begin two days after exposure to the virus and most last less than a week. The cough, however, may last for more than two weeks. In children, there may be diarrhea and vomiting, but these are not common in adults. Diarrhea and vomiting occur more commonly in gastroenteritis, which is an unrelated disease and sometimes inaccurately referred to as "stomach flu" or the "24-hour flu". Complications of influenza may include viral pneumonia, secondary bacterial pneumonia, sinus infections, and worsening of previous health problems such as asthma or heart failure.
Many regions and countries have their own cancer registry, one function of which is to monitor the incidence of cancers to determine the prevalence and possible causes of these illnesses.
A cancer registry is a systematic collection of data about cancer and tumor diseases. The data are collected by Cancer Registrars. Cancer Registrars capture a complete summary of patient history, diagnosis, treatment, and status for every cancer patient in the United States, and other countries.
Other illnesses such as one-time events like stroke and chronic conditions such as diabetes, as well as social problems such as domestic violence, are increasingly being integrated into epidemiologic databases called disease registries that are being used in the cost-benefit analysis in determining governmental funding for research and prevention.
A stroke is a medical condition in which poor blood flow to the brain results in cell death. There are two main types of stroke: ischemic, due to lack of blood flow, and hemorrhagic, due to bleeding. Both result in parts of the brain not functioning properly. Signs and symptoms of a stroke may include an inability to move or feel on one side of the body, problems understanding or speaking, dizziness, or loss of vision to one side. Signs and symptoms often appear soon after the stroke has occurred. If symptoms last less than one or two hours it is known as a transient ischemic attack (TIA) or mini-stroke. A hemorrhagic stroke may also be associated with a severe headache. The symptoms of a stroke can be permanent. Long-term complications may include pneumonia or loss of bladder control.
Diabetes mellitus (DM), commonly known as diabetes, is a group of metabolic disorders characterized by high blood sugar levels over a prolonged period. Symptoms of high blood sugar include frequent urination, increased thirst, and increased hunger. If left untreated, diabetes can cause many complications. Acute complications can include diabetic ketoacidosis, hyperosmolar hyperglycemic state, or death. Serious long-term complications include cardiovascular disease, stroke, chronic kidney disease, foot ulcers, and damage to the eyes.
Systems that can automate the process of identifying adverse drug events, are currently being used, and are being compared to traditional written reports of such events.These systems intersect with the field of medical informatics, and are rapidly becoming adopted by hospitals and endorsed by institutions that oversee healthcare providers (such as JCAHO in the United States). Issues in regard to healthcare improvement are evolving around the surveillance of medication errors within institutions.
Syndromic surveillance is the analysis of medical data to detect or anticipate disease outbreaks. According to a CDC definition, "the term 'syndromic surveillance' applies to surveillance using health-related data that precede diagnosis and signal a sufficient probability of a case or an outbreak to warrant further public health response. Though historically syndromic surveillance has been utilized to target investigation of potential cases, its utility for detecting outbreaks associated with bioterrorism is increasingly being explored by public health officials."
The first indications of disease outbreak or bioterrorist attack may not be the definitive diagnosis of a physician or a lab.
Using a normal influenza outbreak as an example, once the outbreak begins to affect the population, some people may call in sick for work/school, others may visit their drug store and purchase medicine over the counter, others will visit their doctor's office and other's may have symptoms severe enough that they call the emergency telephone number or go to an emergency department.
Syndromic surveillance systems monitor data from school absenteeism logs, emergency call systems, hospitals' over-the-counter drug sale records, Internet searches, and other data sources to detect unusual patterns. When a spike in activity is seen in any of the monitored systems disease epidemiologists and public health professionals are alerted that there may be an issue.
An early awareness and response to a bioterrorist attack could save many lives and potentially stop or slow the spread of the outbreak. The most effective syndromic surveillance systems automatically monitor these systems in real-time, do not require individuals to enter separate information (secondary data entry), include advanced analytical tools, aggregate data from multiple systems, across geo-political boundaries and include an automated alerting process.
A syndromic surveillance system based on search queries was first proposed by Gunther Eysenbach, who began work on such a system in 2004.Inspired by these early, encouraging experiences, Google launched Google Flu Trends in 2008. More flu-related searches are taken to indicate higher flu activity. The results closely match CDC data, and lead it by 1–2 weeks. The results appeared in Nature. More recently, a series of more advanced linear and nonlinear approaches to influenza modelling from Google search queries have been proposed. Extending Google's work researchers from the Intelligent Systems Laboratory (University of Bristol, UK) created Flu Detector; an online tool which based on Information Retrieval and Statistical Analysis methods uses the content of Twitter to nowcast flu rates in the UK.
Influenzanet is a syndromic surveillance system based on voluntary reports of symptoms via the internet. Residents of the participant countries are invited to provide regular reports on the presence or absence of flu related symptoms. The system has been in place and running since 2003 in the Netherlands and Belgium. The success of this first initiative led to the implementation of Gripenet in Portugal in 2005 followed by Italy in 2008 and Brasil, Mexico, and the United Kingdom in 2009.
Some conditions, especially chronic diseases such as diabetes mellitus, are supposed to be routinely managed with frequent laboratory measurements. Since many laboratory results, at least in Europe and the US, are automatically processed by computerized laboratory information systems, the results are relatively easy to inexpensively collate in special purpose databases or disease registries. Unlike most syndromic surveillance systems, in which each record is assumed to be independent of the others, laboratory data in chronic conditions can be theoretically linked together at the individual patient level. If patient identifiers can be matched, a chronological record of each patient's laboratory results can be analyzed as well as aggregated to the population level.
Laboratory registries allow for the analysis of the incidence and prevalence of the target condition as well as trends in the level of control. For instance, an NIH-funded program called the Vermedx Diabetes Information Systemmaintained a registry of laboratory values of diabetic adults in Vermont and northern New York State in the US with several years of laboratory results on thousands of patients. The data included measures of blood sugar control (glycosolated hemoglobin A1C), cholesterol, and kidney function (serum creatinine and urine protein), and were used to monitor the quality of care at the patient, practice, and population levels. Since the data contained each patient's name and address, the system was also used to communicate directly with patients when the laboratory data indicated the need for attention. Out of control test results generated a letter to the patient suggesting they take action with their medical provider. Tests that were overdue generated reminders to have testing performed. The system also generated reminders and alerts with guideline-based advice for the practice as well as a periodic roster of each provider's patients and a report card summarizing the health status of the population. Clinical and economic evaluations of the system, including a large randomized clinical trial, demonstrated improvements in adherence to practice guidelines and reductions in the need for emergency department and hospital services as well as total costs per patient. The system has been commercialized and distributed to physicians, insurers, employers and others responsible for the care of chronically ill patients. It is now being expanded to other conditions such as chronic kidney disease.
A similar system, The New York City A1C Registry,is in used to monitor the estimated 600,000 diabetic patients in New York City, although unlike the Vermont Diabetes Information System, there are no provisions for patients to have their data excluded from the NYC database. The NYC Department of Health and Mental Hygiene has linked additional patient services to the registry such as health information and improved access to health care services. As of early 2012, the registry contains over 10 million test results on 3.6 million individuals. Although intended to improve health outcomes and reduce the incidence of the complications of diabetes, a formal evaluation has not yet been done.
In May 2008, the City Council of San Antonio, Texas approved the deployment of an A1C registry for Bexar County. Authorized by the Texas Legislature and the state Health Department, the San Antonio Metropolitan Health Districtimplemented the registry which drew results from all the major clinical laboratories in San Antonio. The program was discontinued in 2010 for lack of funds.
Laboratory surveillance differs from population-wide surveillance in that it can only monitor patients who are already receiving medical treatment and therefore having lab tests done. For this reason, it does not identify patients who have never been tested. Therefore, it is more suitable for quality management and care improvement than for epidemiological monitoring of an entire population or catchment area.
Influenza vaccines, also known as flu shots or flu jabs, are vaccines that protect against infection by influenza viruses. New versions of the vaccines are developed twice a year, as the influenza virus rapidly changes. While their effectiveness varies from year to year, most provide modest to high protection against influenza. The United States Centers for Disease Control and Prevention (CDC) estimates that vaccination against influenza reduces sickness, medical visits, hospitalizations, and deaths. When an immunized worker does catch the flu, they return to work half a day sooner on average. Vaccine effectiveness in those under two years old and those over 65 years old remains uncertain due to a lack of high quality research. Vaccinating children may protect those around them.
Community health is a branch of public health which focuses on people and their role as determinants of their own and other peoples's health in contrast to environmental health which focuses on the physical environment and its impact on peoples health.
Swine influenza is an infection caused by any one of several types of swine influenza viruses. Swine influenza virus (SIV) or swine-origin influenza virus (S-OIV) is any strain of the influenza family of viruses that is endemic in pigs. As of 2009, the known SIV strains include influenza C and the subtypes of influenza A known as H1N1, H1N2, H2N1, H3N1, H3N2, and H2N3.
Flu season is an annually recurring time period characterized by the prevalence of outbreaks of influenza (flu). The season occurs during the cold half of the year in each hemisphere. Influenza activity can sometimes be predicted and even tracked geographically. While the beginning of major flu activity in each season varies by location, in any specific location these minor epidemics usually take about 3 weeks to peak, and another 3 weeks to significantly diminish.
Influenza (H1N1) virus is the subtype of influenza A virus that was the most common cause of human influenza (flu) in 2009, and is associated with the 1918 outbreak known as the Spanish flu.
A chronic condition is a human health condition or disease that is persistent or otherwise long-lasting in its effects or a disease that comes with time. The term chronic is often applied when the course of the disease lasts for more than three months. Common chronic diseases include arthritis, asthma, cancer, chronic obstructive pulmonary disease, diabetes and some viral diseases such as hepatitis C and acquired immunodeficiency syndrome. An illness which is lifelong because it ends in death is a terminal illness. It is possible and not unexpected for an illness to change in definition from terminal to chronic. Diabetes and HIV for example were once terminal yet are now considered chronic due to the availability of insulin and daily drug treatment for individuals with HIV which allow these individuals to live while managing symptoms.
Disease surveillance is an epidemiological practice by which the spread of disease is monitored in order to establish patterns of progression. The main role of disease surveillance is to predict, observe, and minimize the harm caused by outbreak, epidemic, and pandemic situations, as well as increase knowledge about which factors contribute to such circumstances. A key part of modern disease surveillance is the practice of disease case reporting.
The Situational Awareness and Preparedness for Public Health Incidences and Reasoning Engines (SAPPHIRE) is a semantics-based health information system capable of tracking and evaluating situations and occurrences that may affect public health. It was developed in 2004 by Dr. Parsa Mirhaji at the University of Texas Health Science Center at Houston using the Semantic Web technologies.
mHealth is an abbreviation for mobile health, a term used for the practice of medicine and public health supported by mobile devices. The term is most commonly used in reference to using mobile communication devices, such as mobile phones, tablet computers and PDAs, and wearable devices such as smart watches, for health services, information, and data collection. The mHealth field has emerged as a sub-segment of eHealth, the use of information and communication technology (ICT), such as computers, mobile phones, communications satellite, patient monitors, etc., for health services and information. mHealth applications include the use of mobile devices in collecting community and clinical health data, delivery of healthcare information to practitioners, researchers and patients, real-time monitoring of patient vital signs, the direct provision of care as well as training and collaboration of health workers.
Influenza-like illness (ILI), also known as flu-like syndrome/symptoms, is a medical diagnosis of possible influenza or other illness causing a set of common symptoms.
The 2009 flu pandemic or swine flu was an influenza pandemic that lasted from early 2009 to late 2010, and the second of the two pandemics involving H1N1 influenza virus, albeit in a new version. First described in April 2009, the virus appeared to be a new strain of H1N1 which resulted when a previous triple reassortment of bird, swine and human flu viruses further combined with a Eurasian pig flu virus, leading to the term "swine flu". It is estimated that 11-21% of the global population contracted the illness, and 151,000-579,000 died.
Social distancing is a term applied to certain nonpharmaceutical infection control actions that are taken by public health officials to stop or slow down the spread of a highly contagious disease. The objective of social distancing is to reduce the probability of contact between persons carrying an infection, and others who are not infected, so as to minimize disease transmission, morbidity and ultimately, mortality.
The Pandemic H1N1/09 virus is a swine origin Influenza A virus subtype H1N1 virus strain responsible for the 2009 flu pandemic. For other names see the Nomenclature section below.
The 2009 flu pandemic was a global outbreak of a new strain of influenza A virus subtype H1N1, first identified in April 2009, termed Pandemic H1N1/09 virus by the World Health Organization (WHO) and colloquially called swine flu. The outbreak was first observed in Mexico, and quickly spread globally. On 11 June 2009, WHO declared the outbreak to be a pandemic. The overwhelming majority of patients experience mild symptoms", but some persons are in higher risk groups, such as those with asthma, diabetes, obesity, heart disease, or who are pregnant or have a weakened immune system. In the rare severe cases, around 3–5 days after symptoms manifest, the sufferer's condition declines quickly, often to the point respiratory failure.
Infoveillance is a type of syndromic surveillance, which focuses on public health related concerns, that utilizes online information and content. The term was coined by Gunther Eysenbach in 2004 for the first time along with coining, Infodemiology, a new branch of science-based research.
Google Flu Trends (GFT) was a web service operated by Google. It provided estimates of influenza activity for more than 25 countries. By aggregating Google Search queries, it attempted to make accurate predictions about flu activity. This project was first launched in 2008 by Google.org to help predict outbreaks of flu.
H7N9 is a bird flu strain of the species Influenza virus A. Avian influenza A H7 viruses normally circulate amongst avian populations with some variants known to occasionally infect humans. An H7N9 virus was first reported to have infected humans in March 2013, in China. Cases continued to be reported throughout April and then dropped to only a few cases during the summer months. At the closing of the year, 144 cases had been reported of which 46 had died. It is known that influenza tends to strike during the winter months, and the second wave, which began in October, was fanned by a surge in poultry production timed for Chinese New Year feasts that began at the end of January. January 2014 brought a spike in reports of illness with 96 confirmed reports of disease and 19 deaths. As of April 11, 2014, the outbreak's overall total was 419, including 7 in Hong Kong, and the unofficial number of deaths was 127.
Infodemiology is a term coined by Canadian researcher Gunther Eysenbach. Eysenbach defines infodemiology as a new area of science research that focuses on scanning the internet for user-contributed health related content, with the ultimate goal to improve public health
John Brownstein is a Canadian epidemiologist and Professor of Medicine at the Harvard Medical School as well as the Chief Innovation Officer at Boston Children’s Hospital. His research focuses on development of computational methods in epidemiology for applications to public health also known as computational epidemiology or e-epidemiology He is also the founder of several global public health surveillance systems including HealthMap. He is most known for his work on global tracking of disease outbreaks.