53649 Surveillance at a glance What is surveillance? At the local level, surveillance triggers basic public health investigations of disease outbreaks and specific Health surveillance is the ongoing systematic collection, control activities predominately for infectious diseases analysis and interpretation of health data essential for and environmental hazards. The main national level planning, implementing, and evaluating public health activities are: measuring trends in risk factors and activities, closely integrated with timely dissemination disease; health planning; monitoring the effectiveness of the data to enable effective and efficient action to be of specific interventions; conducting more complicated taken to prevent and control disease. (This draws on analysis to determine risk factors; and providing the CDC and WHO definitions.) technical assistance. At intermediate levels (state, Surveillance ranges from compulsory notifiable province, etc.) public health agencies typically share diseases, specific disease registries (population- or both perspectives. hospital-based), continuous or repeated surveys of representative samples of the population, to Why invest in surveillance? aggregate data for recording trends on consumption patterns and economic activity. Relatively small investments can be very effective in reducing death, disease, and disability. Surveillance can make the health system more effective and How are health surveillance efficient, and better able to control devastating data used? epidemics. It can lead to early detection of local epidemics when control is more effective, less costly, Surveillance may be used to: and involves less loss of life. In addition to their recognize cases or clusters of cases to trigger health impact, epidemics can have a costly impact on interventions to prevent transmission or reduce productivity and other aspects of the economy: the morbidity and mortality (includes the special case 1991 cholera epidemic in Peru involved a total loss in which surveillance at the national level is of $770 million (primarily in the tourism and seafood required to recognize multi-state clusters); industries), and the plague epidemic in India is identify new health problems and emerging estimated to have cost the country $1.7 billion. diseases; Borders are ineffective in containing diseases (the 1991 assess public health impact of health events or cholera epidemic eventually spread throughout Latin determine and measure trends; America), so surveillance and timely dissemination of measure causal factors in disease (e.g., risk factors) information are wise investments for countries in which to initiate actions to prevent the onset of disease; an epidemic is or might be occurring, as well as demonstrate the need for intervention programs countries to which it might spread. and resources, and allocate resources during Surveillance is also important for controlling and health planning; preventing endemic diseases that reduce productivity monitor effectiveness and evaluate the impact of and can be costly to manage. Good surveillance prevention and control measures, intervention systems permit early identification of diseases such as strategies, and health policy changes; TB and syphilis that can be cured easily with low-cost identify high-risk population groups or geographic treatments, combined with other public health actions. areas to target interventions and guide analytic Treatment of chronic non-communicable diseases, studies; such as heart disease and diabetes and their sequelae, is costly, so prevention is a key strategy. provide data for research, and develop hypotheses Prevention and control of these diseases require that lead to analytic studies about risk factors for surveillance of associated behaviors and risk factors disease causation, propagation or progression; (e.g. smoking, physical inactivity, obesity) and actions measure progress toward Millennium Development to promote the desired changes and risk reductions. Goals, or other project or program goals, including PRSP (Poverty Reduction Strategy Paper) targets. Scarce resources for health make it essential to evaluate interventions and target resources, so that May 2006 their contribution is optimized, compared to other A key principle is to include only conditions for which possible interventions. Surveillance can provide useful surveillance can effectively lead to prevention. Another information to identify populations at greatest risk where important principle is that surveillance systems need to intervention may help most, and to gauge the reflect the overall disease burden of the community. effectiveness of interventions. Other criteria for selecting diseases include: total number of cases, incidence and prevalence; indices of severity (e.g., the case-fatality ratio); mortality rate and premature The scope of surveillance mortality; an index of lost productivity (e.g., bed- The scope of surveillance is broad, from early warning disability days); medical costs; preventability; epidemic systems for rapid response in the case of communicable potential; and information gaps on new diseases. diseases to planned response in the case of non- Surveillance can collect data on any element of the disease communicable diseases, where the lag time between causal chain--behavioral risk factors, preventive actions exposure and disease is longer than for communicable (vaccinations, pap smears), cases and program or treatment diseases. Most countries have laws or regulations on costs. The scope of a surveillance system is constrained by mandatory reporting of a list of conditions determined by the available human and financial resources. each country, primarily communicable diseases such as childhood vaccine-preventable diseases (polio, measles, tetanus, and diphtheria), TB, hepatitis, meningitis, and leprosy. Developing and expanding a Reporting may be required also for non-communicable surveillance system conditions, such as maternal deaths, injuries, and occupational and environmental diseases such as pesticide The following table presents a possible scheme for poisoning. Mandatory reporting of specific conditions is a developing a surveillance system. The minimal list of subset of surveillance. International regulations (which are diseases is a starting point. Diseases should be added as being revised) currently require reporting of three diseases to the system evolves and resources become available. The WHO: plague; yellow fever; and cholera. table suggests a second line of diseases, but these will Scheme for developing and expanding mandatory surveillance reporting Minimal list Second line Third line Internationally Cholera required* Yellow fever Plague Vaccine preventable Polio** Diphtheria Rubella Measles Pertussis Chickenpox Tetanus Mumps Communicable TB Meningitis Hepatitis Syphilis Nosocomial infections HIV/AIDS Gonorrhea/Urethritis Food borne pathogens Non-communicable Risk factors (behavioral and physiological) which predict major diseases Pesticide poisoning Injuries Specific disease incidence In endemic areas Malaria Dengue ­ especially Encephalitis Leprosy hemorrhagic Onchocerciasis* Ebola/hemorrhagic (river blindness) fevers Dracunculiasis* Rabies (guinea worm) Vital statistics Sentinel sites & Complete coverage Valid cause of death sample registration Source: World Bank, The Public Health Surveillance Toolkit * The new International Health Regulations (2005) do not limit required reporting to these 3 diseases nor define what diseases must be reported. Instead they "... require States to notify WHO of all events that may constitute a public health emergency of international concern and to respond to requests for verification of information regarding such events." **Targeted for eradication depend greatly on a country's public health priorities, its magnitude and understanding the distribution of disease burden, and the use of the data for intervention. conditions, and for tracking infant and maternal A key principle of surveillance is that it is information for mortality. Electronic systems for reporting vital data are action. In some countries (e.g., Eastern Europe/Central making this type of surveillance more timely and Asia) non-communicable diseases are a large part of the effective. Local health care providers can help ensure disease burden, making risk factor surveillance even that births and deaths (by cause) are registered. There more important than tracking some specified diseases. A should be no fees for registering births and deaths. well-developed system can include dozens of conditions Incentives (requiring death certificates for burial, birth for surveillance--third line. certificates for school enrollment and laws requiring registration) can improve vital statistic coverage. Developing a surveillance system should build on success. It is best to start slowly, and demonstrate Integrated disease surveillance is an effective, efficient and effectiveness, which builds support among those who sustainable approach to strengthen national capacity for report and use data and those who allocate resources. surveillance and response to communicable diseases. Being too ambitious initially may undermine enthusiasm Surveillance activities for different diseases involve similar for continued effort and be destructive. functions (detection, reporting, analysis and interpretation, feedback, action) and often use the same structures, Mandatory disease notification is the primary method of processes and personnel. Yet in many countries surveillance collecting timely disease information particularly for is funded and managed by different independent control communicable diseases. Other surveillance methods include: programs. An integrated approach aims to establish a well sentinel surveillance sites; periodic or ongoing surveys; coordinated, action oriented system that looks for reporting by laboratories; special registers (e.g., cancer); and opportunities to integrate functions where appropriate, secondary analysis of datasets. Depending on circumstances, maximize synergies, and build on successful initiatives. one or more of these methods may be the best choice. Where possible, countries should use a common reporting Surveillance for emerging infections such as SARS and form, a single data entry system for multiple diseases, and avian influenza is an area that is evolving and challenging common communication channels. Training and supervision public health systems. For SARS and pandemic influenza, should be integrated, a common feedback bulletin can be early warning systems for human clusters of severe used, and computers and vehicles etc can be shared. pneumonia could permit the rapid containment of new Integrating surveillance for communicable and non- cases. Syndromic surveillance of fever clusters is another communicable diseases faces serious methodological issues: approach to identifying outbreaks of emerging infections. for example, different data collection methods are usually needed for CDs and NCD risk factors, but there is good Vital statistics are the foundation of health information potential for integrating the other aspects of surveillance. and "the single most important addition that developing countries can make to their existing surveillance system" (White and McDonnell in Teutsch and Churchill 2000). DO's and DON'Ts Accurate records of all births and of deaths by cause are DO fully evaluate the existing system as part of project invaluable for monitoring trends, estimating the preparation or sector work to make things easier later. Factors that influence effectiveness of surveillance systems Factor or Element Effective: Ineffective: Number of conditions Fewer Too many Amount of information per case Little Too much Burden on reporter Small Too complex & burdensome Decision makers' interest in surveillance data High Low Goals for surveillance Clear and supported May never have been clear Reporting strategy for serious Enough information to meet Complete reporting but common conditions goals & make decisions Usefulness of data locally High Low Use is limited to analysis No, data are well used Limited use of data of data & archiving Usefulness to decision makers High Low for prevention action Involve national stakeholders in a team-based decision absolutely fundamental to effective surveillance. Give making process to determine the most appropriate and high priority to training and capacity building. suitable surveillance model. This will help to ensure DO involve all stakeholders in the design of the system better data for decision-making, and establish owner- to help ensure that the information collected is used for ship and commitment of key project implementers. making decisions on disease prevention and control. DO carefully select a manageable, limited list of DO ensure necessary laboratory support for surveillance. disease and risk factors for surveillance. Don't include Make sure that capacity and systems are in place to too many conditions for mandatory notification. provide timely, reliable confirmation of suspected cases to Additional diseases and factors can be added once those who will make decisions and take action. the system is running well and the data are being used effectively. Give priority to collecting and using vital statistics. Design a flexible system that can evolve and Key reference adapt to changing circumstances and country needs. The Public Health Surveillance Toolkit, 80 pages of DO set up a robust and accurate data transmission practical, specific, detailed information, and fundamental system, that allows data to be easily queried and concepts in public health surveillance, that draws on the corrected. experience of World Bank staff, technical experts from PAHO and the CDC, and WHO references. Also provides DO ensure that the actors have a strong sense of selected key references and websites for additional ownership of the data and that core aggregate data information, and global and regional information on on key indicators are transmitted and stored for use. outbreaks and other surveillance data. DO build local ownership and commitment to the http://www.worldbank.org/hnp > Tools & Guidelines project. It is important to visit and engage sites outside of the national capital. Involve local and intermediate Other useful references levels early on in decision-making (on design, roles and Teutsch, S. M. and R. E. Churchill, eds. 2000. Principles responsibilities) to ensure more successful outcomes. and Practice of Public Health Surveillance, 2nd edition. Include national professional associations and sectors New York: OUP. other than health, which may also benefit from a good surveillance system (tourism, agriculture, treasury, and Halperin, W., E. L. Baker, P. R. Monson, eds. 1992. Public so on). Periodic dissemination of information to the Health Surveillance. New York: Van Nostrand Rienhold. press, and involving one or two health-related http://www.who.int/csr - WHO's Communicable Disease journalists might also bring advantages in promoting Surveillance website the project. Emphasize technical aspects and also the http://www.who.int/csr/resources/publications/csrpublications process as part of the strategy for building ownership. /en/index19.html for key WHO documents on surveillance: DO involve the private sector and the community in Protocol for the Assessment of National Communicable disease surveillance. DON'T rely entirely on the public Disease Surveillance and Response Systems: Guidelines health system as the sole source of information. for Assessment Teams DO create a detailed design of the investments for WHO recommended surveillance standards, 2nd edition each level of the system. Pay close attention to what http://www.who.int/ncd/surveillance site, especially see: should be done at national, intermediate, and WHO Global NCD InfoBase municipal levels of the system. Clearly define the roles SuRF (Surveillance of Risk Factors) Report and responsibilities of the three levels of the surveillance system. Avoid task overlap. WHO STEPwise approach to Surveillance of risk factors associated with non-communicable diseases (STEPS) DO as much design as possible while planning investments. A detailed implementation plan that identifies the task, its objectives, the location, starting date People and ending date, the staff/entity responsible for World Bank: Marcelo Bortman (mbortman@worldbank.org), implementation, a description of the main steps, unit cost Anabela Abreu (aabreu@worldbank.org), and procurement procedures, and outputs is an important Mariam Claeson (mclaeson@worldbank.org), management tool for implementers and funders. Isabella Danel (idanel@worldbank.org), Joana Godinho (jgodinho@worldbank.org) DO ensure that surveillance guidelines specify "what GNV Ramana (gramana@worldbank.org) and how, when, who and where" to survey. DHHS: Steve Ostroff (sostroff@osophs.dhhs.gov), Guidelines should be revised by national health CDC: Ray Arthur (rca8@cdc.gov) surveillance officials, externally reviewed, and the David McQueen (dvmcqueen@cdc.gov) final product approved by key policy decision-makers. WHO: Ruth Bonita (bonitar@who.int), DO include the training necessary to develop Guenael Rodier (rodierg@who.int) competent and qualified personnel, who are PAHO: Marlo Libel (libelmar@Paho.org) Expanded versions of the "at a glance" series, with links to resources and more information, are available on the World Bank Health, Nutrition and Population web site: www.worldbank.org/hnp