1.0 Public Health Surveillance

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1 Pubic Heath Surveiance Pubic Heath Surveiance 1.1 Overview Historicay, disease surveiance in the Caribbean had been primariy focussed on morbidity reporting of communicabe diseases. Reports of disease events were often made after epidemics had occurred and they were recognized as such. Surveiance to detect new cases and interventions to contro and prevent further disease spread was ony then activey pursued. In many instances, active surveiance was undertaken after the epidemic had peaked. Resuting morbidity and mortaity may therefore have been avoided, had active surveiance systems been in pace as part of a systematic routine. Numerous positive changes have taken pace within recent years. Athough this manua focuses on communicabe diseases, surveiance activities have been expanded to incude non-communicabe chronic diseases, injuries, such as, those due to motor vehicuar accidents, nutrition and behavioura risk factors. Pubic Heath Surveiance has been defined as the ongoing, systematic coection, coation, anaysis, interpretation and dissemination of heath data essentia to the panning, impementation and evauation of pubic heath practice. The utimate objective of surveiance activities is its appication to disease prevention and contro. This definition of surveiance embraces a concept that is wider than the simpe reporting of disease occurrence. Heath information incudes data such as the immunization status of popuations, the identification of risk factors, as we as demographic and other data usefu in disease prevention and contro programmes. Surveiance can aso incude procedures to determine other baseine data such as disease incidence and prevaence; and vector distribution and densities, using data generated in day-to-day heath programmes. The parameters of surveiance data can therefore be expanded and appied to a number of other areas of heath care deivery. An appreciation and knowedge of risks can hep to determine vunerabiity/susceptibiity factors, to which interventions can be appied. For exampe, in the case of zoonoses and arthropod borne diseases, appropriate strategies to contro the vector can be impemented, whie measures reated to water quaity, environmenta, veterinary and other heath factors may be pertinent to the prevention and contro of food-borne inesses. Risk data appropriatey presented can faciitate the panning process and the evauation of preventive heath care, as we as the optimization of scarce resources through panned intersectora coaboration, incuding both the pubic and private sectors. Pubic heath action woud require prioritization on the basis of criteria such as urgency, the severity and extent of probems and adverse effects, identified within the context of avaiabe resources. In the case of vaccine-preventabe diseases, where the popuation has been A Caribbean Communicabe Disease Surveiance Manua for Pubic Heath Action, CAREC October 1999

2 2 Pubic Heath Surveiance protected by immunization, the probem may not be as great as in the case of nonimmunizabe diseases. Specia mention shoud aso be made of the need to maintain active surveiance in situations where diseases may have been eiminated. Vigiance is often diminished when a disease has been eiminated, or its prevaence is significanty reduced. Whie economic and socia considerations pay a major roe, reduced vigiance and increased compacency are factors contributing to the phenomenon of re-emerging diseases now being experienced in many countries. Maaria, for exampe, can be re-introduced and remain unrecognized unti secondary cases prompt further investigation. Re-activated cases of tubercuosis can ead to an insidious resurgence of a disease that may once have been under contro. It is therefore important that surveiance systems shoud be designed to identify probems of re-emerging diseases eary, in order to faciitate timey impementation of contro and prevention measures. Another area of growing concern is that of newy emerging diseases, sometimes referred to as exotic diseases. These diseases pose a specia pubic heath probem because of imited information on their aetioogy, pathogenesis and mode of transmission, a of which are essentia to impementation of effective prevention and contro measures. A usefu approach to monitoring both newy emerging and re-emerging disease situations woud be to augment disease-specific surveiance with the monitoring of syndrome compexes. This is important within the context of modern day trave, through which, for exampe, maaria can be re-introduced into a country from which it had been eradicated. The Pasmodium parasite can be imported either by visitors from countries where maaria is endemic, or by residents returning home after visits abroad. Simiary, one of the newy emerging diseases coud be imported and remain unrecognized, unti an epidemic of an unusua disease syndrome is identified because of associated morbidity or mortaity. Surveiance of pyrexias of unknown origin [PUOs] as we as of unusua syndromic presentations shoud therefore incude information on trave history. Sentine surveiance coud pay a key roe in this activity. The main uses of surveiance data are to: Estimate the size of a heath probem (Figure 2) Detect outbreaks of communicabe diseases (Figures 3 and 5) Characterize disease trends (Figure 4, 6) Evauate interventions and preventive programmes (Figure 1) Provide information for use in heath panning Identify training needs in terms of categories and eves Identify and prioritize research needs Some of these uses are iustrated in the accompanying figures. A Caribbean Communicabe Disease Surveiance Manua for Pubic Heath Action, CAREC October 1999

3 Pubic Heath Surveiance 3 FIGURE 1 12 REPORTED MEASLES CASES AND VACCINATION COVERAGE RATES BY YEAR ENGLISH SPEAKING CARIBBEAN & SURINAME M e ase s v accination cov e rage 100 NO. OF REPORTED CASES [000s] Catch-up Campaign Foow -up Campaign VACCINATION COVERAGE [PERCENTAGE] Surve iance YEARS Source : M inistrie s of He ath re ports to SVI/EPI/CAREC M eases cases 0 FIGURE 2 REPORTED TUBERCULOSIS INCIDENCE RATES PER 100,000 POPULATION CAREC MEMBER COUNTRIES INCIDENCE RATES YEARS A Caribbean Communicabe Disease Surveiance Manua for Pubic Heath Action, CAREC October 1999

4 4 Pubic Heath Surveiance FIGURE 3 REPORTED DENGUE FEVER INCIDENCE RATES PER 100,000 POPULATION CAREC MEMBER COUNTRIES INCIDENCE RATES YEARS FIGURE 4 REPORTED LEPROSY INCIDENCE RATES PER 100, 000 POPULATION CAREC MEMBER COUNTRIES INCIDENCE RATES YEARS A Caribbean Communicabe Disease Surveiance Manua for Pubic Heath Action, CAREC October 1999

5 Pubic Heath Surveiance 5 FIGURE 5 30 REPORTED RUBELLA INCIDENCE RATES PER 100,000 POPULATION CAREC MEMBER COUNTRIES INCIDENCE RATES YEAR FIGURE 6 REPORTED MENINGOCOCCAL INFECTION INCIDENCE RATES PER 100,000 POPULATION CAREC MEMBER COUNTRIES INCIDENCE RATES YEARS A Caribbean Communicabe Disease Surveiance Manua for Pubic Heath Action, CAREC October 1999

6 6 Pubic Heath Surveiance With particuar reference to communicabe diseases, surveiance is a key activity in nationa, regiona and internationa contro programmes, requiring the coordinated triad of epidemioogica, cinica and aboratory inputs. Since inadequate financing is a common probem, it is perhaps best to deveop the surveiance system using cost-effective modification of existing infrastructure in terms of faciities and human resources. Improvements, modifications and extensions to these may be taiored to the needs of individua countries, provided the basic essentias of effective surveiance are not compromised. Finay, it shoud be recognised that the avaiabiity of new information technoogies can greaty enhance the efficiency and effectiveness of the very abour intensive surveiance process of coection, coation and anaysis of data and the dissemination of information. Modern informatic technoogy can hande repetitive actions, store, process and disseminate data rapidy, compementing the core activities in pubic heath surveiance. The computer s critica roe in the area of information management is undisputed. However, adequate attention must be given to the potentia probems in the impementation of new technoogies. Issues such as standardization, security of data, verification of the output of systems and the amendment of system or process-reated poicies to accommodate new procedures must be addressed to ensure the efficacy of technoogy. 1.2 Essentia Components and Requirements of a Genera Communicabe Disease Surveiance System An efficient communicabe disease surveiance system is based on three essentia components and requirements which are: 1. AN ORGANISATIONAL STRUCTURE 2. A FUNCTIONAL FRAMEWORK 3. OPERATIONAL STEPS The first component is an organisationa structure (1.2.1) with ceary defined eves of responsibiity and channes of communication. Leve 1 represents the first point of contact with the disease under surveiance. Heath faciities ranging from district heath centres to arge hospitas are incuded in this category, the main function of which is case detection and reporting. Leve 2 is ocated at the district, parish or regiona heath faciity and performs manageria and supportive functions within the system. It is the crucia ink between the case detection and poicy making eves of the system. Leve 3 represents the centra eve which coordinates activities on a nationa scae, formuates poicy and is responsibe for inter-ministeria and internationa coaboration. A Caribbean Communicabe Disease Surveiance Manua for Pubic Heath Action, CAREC October 1999

7 Pubic Heath Surveiance 7 The aboratory serves as a supportive piar in the entire structure for those diseases requiring aboratory confirmation for fina case cassification and definitive action. The aboratory may aso serve as a primary generation of surveiance data in areas such as anti-microbia resistance, which is monitored as a guide to cinica management. The second component is a functiona framework (1.2.2) which outines the primary foci of the surveiance eements, the personne avaiabe and their activities in the routine and outbreak contro situations. The smooth functioning of a surveiance system depends on many enabing activities such as training and the provision of the necessary toos. The third requirement is an awareness of the operationa steps (1.2.3) commencing with case detection through case investigation and case confirmation to the desired pubic heath action. The detaied requirements of each step must be carefuy considered and appropriate systems estabished which incude panning, designation of responsibiity, and monitoring of performance. Centra to the success of a disease surveiance system is the cose interaction of three major eements - the cinica, the diagnostic and the anaytica, represented by the cinician, the aboratory scientist and the epidemioogist, respectivey. It is essentia that each understands and appreciates the functions of the others. TRIAD OF COLLABORATION CLINICIAN EPIDEMIOLOGIST LABORATORY SCIENTIST A Caribbean Communicabe Disease Surveiance Manua for Pubic Heath Action, CAREC October 1999

8 A Caribbean Communicabe Disease Surveiance Manua for Pubic Heath Action, CAREC October 1999 CASE REPORTS LEVEL 2 Case reporting Case cassification Data anaysis District-eve action Management DISTRICT REGION PARISH COUNTY LEVEL 1 Case detection and reporting Community action HEALTH FACILITY HOSPITAL SENTINEL PHYSICIAN LABORATORY (Loca, Nationa, Reference) Diagnostic testing for case confirmation CASE REPORTS EPIDEMIOLOGICAL DATA SUMMARY DATA seected diseases LEVEL 3 Nationa and internationa action; Poicy formuation; Funding; Pubic Information; Anaysis and dissemination of data through nationa Epidemioogic buetin EPIDEMIOLOGY CHIEF MEDICAL OFFICER MINISTER OF HEALTH Note: Athough three generic eves are shown on this diagram, individua countries may expand or contract them depending on their specific needs Key Data Feedback Specimen Lab Resuts CAREC, PAHO/WHO FUNDING AGENCIES OTHER MINISTRIES NGOs STRUCTURE COMMUNICABLE DISEASE SURVEILLANCE SYSTEM: ORGANISATIONAL 8 Pubic Heath Surveiance

9 A Caribbean Communicabe Disease Surveiance Manua for Pubic Heath Action, CAREC October 1999 System Leve Surveiance Node Primary Focus Leve 1 Heath Centre Community heath service Leve 1 Hospita - Genera and Speciaised Leve 1 Leve 1 Sentine Physician University medica centre Curative medicine Curative medicine Community heath service for the university popuation Operating Personne Nurses, Physicians, Pubic Heath workers Physicians, Nurses, Surveiance and infection contro officers Physicians Nurses, Physicians Routine Activities Toos Needed Outbreak Contro Activities Routine surveiance; Case detection and reporting; Heath education; Immunisation Case detection and reporting; Case investigation; Specimen coection and referra; Cinica management Case detection and reporting; Cinica care and referra; Specimen coection Cinica care and referra Case definitions; Disease fact sheets; Reporting, specimen referra and case investigation forms; Specimen coection kits and instructions Case definitions and detaied cinica profies; Reporting, specimen referra and case investigation forms; Specimen coection kits and instructions Case definitions and detaied cinica profies; Reporting forms and specimen kits Case definitions; Disease fact sheets; Reporting forms and specimen kits Specimen coection and referra; Case investigation; Case searches; Community mobiisation; Mass immunisation; Environmenta monitoring. Specimen coection and referra with necessary data; Case investigation Specimen coection and referra with necessary data Case investigation and case searches; Studies of case series; Specimen coection and referra; Community education; Immunisation COMMUNICABLE DISEASE SURVEILLANCE SYSTEM: FUNCTIONAL FRAMEWORK Pubic Heath Surveiance 9

10 A Caribbean Communicabe Disease Surveiance Manua for Pubic Heath Action, CAREC October 1999 System Leve Leve 2 Leve 3 Laboratory Surveian ce Node District, Parish or Regiona Heath Authority Nationa Heath Authority Laboratory, Pubic, private or University Primary Focus Community heath management Nationa heath management Diagnostic testing on cinica materia Operating Personne Medica officers; Data cerks; Statisticians; Managers Pubic Heath Nurses Medica and Statistica officers; Epidemioogists Laboratory technoogists; scientists Routine Activities Toos Needed Outbreak Contro Activities Receipt of reports and tabuation of data; Management of case investigation and active case search; Forwarding of ine-isted data and anaysis to nationa eve; Suppy of disease information and specimen kits to Leve 1 Receipt of data from district eve; Monitoring and feedback of disease trends; Assessment of resource needs; Sourcing of funds and personne; Nationa poicy Provision of information on specimen coection and transport; Suppy of transport media; Testing and Reporting Referra to Reference aboratory as appropriate Case definitions; Disease fact sheets; Case investigation, specimen referra and ine-isting forms; Popuation data; Epidemioogica information; District maps; Epi-anaysis software; Specimen coection suppies for distribution A above pus: Outbreak investigation guideines; Epi-anaysis software; Nationa disease situation data; WHO reporting requirements Technica information on specimen referra, atest aboratory techniques and kits; Resuts interpretation. Suppy of Media, Reagents and suitabe Equipment Epidemioogica investigation. Specific containment activities incuding immunisation and vector contro; Management of specimen referra and aboratory resuts; Estimation of resources needed; Procurement and channeing of resources Dissemination of action pan and monitoring of impementation; Liaison with nationa and internationa funding sources; Nationa community awareness; Internationa and Regiona reporting; Pan of further containment measures. Receipt of specimens and testing by appropriate methods; Prioritisation of tests; Rapid feedback of resuts with interpretation; Assessment of needs COMMUNICABLE DISEASE SURVEILLANCE SYSTEM: FUNCTIONAL FRAMEWORK 10 Pubic Heath Surveiance

11 Pubic Heath Surveiance COMMUNICABLE DISEASE SURVEILLANCE SYSTEM: OPERATIONAL STEPS 1. CASE DETECTION 2. CASE INVESTIGATION 3. CASE CONFIRMATION (CLINICAL, EPIDEMIOLOGICAL OR LABORATORY) 4. APPROPRIATE PUBLIC HEALTH ACTION There are specific requirements for the efficient operation of each of these steps. 1. Case detection requires: a) Faciities that interact cosey with the community, providing both curative and preventive services. It is important to incude different types of heath faciities in order to obtain a broady based system covering different sectors of the community. Bearing in mind that many of these are short-staffed, the number of diseases under routine surveiance shoud be kept to a minimum. b) Cear, simpe case definitions that wi ensure consistent standardised reporting and reiabe information on disease occurrences and trends over time. These must be readiy avaiabe at a Leve 1 sites. c) A standardized reporting system that is manageabe over the ong term by those who wi be using it. Existing communication inks, even if unsophisticated, shoud be retained unti newer systems have proven themseves. d) Nationa feedback to stimuate routine reporting and to motivate staff. 2. Case investigation requires: a) Reporting within the agreed time frame. Cass 1 diseases, (see 2.2), are immediatey reportabe and require prompt case investigation and rapid response. b) Trained investigators, who wi obtain accurate responses and the essentia items of information. c) We-designed investigation data forms, arranged in a ogica format and compatibe with manua or computer data anaysis. d) Coordination of the activities of Leve 1 where the investigation begins and Leve 2 where it is competed with the addition of epidemioogica, cinica and aboratory data. e) Coordination with the aboratory to ensure that resuts are sent to the origina referring ocation and accuratey recorded on the appropriate case investigation form. Unique case identification numbers used on the case investigation, aboratory request and aboratory resut forms are invauabe in the reconciiation of data. A Caribbean Communicabe Disease Surveiance Manua for Pubic Heath Action, CAREC October 1999

12 12 Pubic Heath Surveiance 3. Case confirmation requires: Cinica case confirmation is based on the accurate use of the case definition and may suffice where the symptoms are highy specific, or where there are inadequate aboratory faciities, or during an outbreak, where the first few cases have been aboratory confirmed. Laboratory case confirmation is based on: a) Specimens that are appropriatey coected, stored and transported. The vaidity of most test resuts requires that these conditions be satisfied. Resuts reported on the assumption that specimens were propery handed may be quite erroneous since organisms may have been destroyed and antibody degraded. Both genera and specific guideines are required. b) Specimen referra forms with adequate data. The minimum data set shoud incude - dates of onset of iness and specimen coection; main cinica findings; antimicrobia therapy; type of specimen; immunization history of the patient. These are a important in interpreting test resuts. c) Technica proficiency of aboratory staff arrived at through constant training and proficiency testing, and adequate supervision. d) Prompt reporting of resuts through agreed channes. Late reporting of resuts frustrates the purpose of surveiance since it causes deayed pubic heath action which may then be ineffective. Epidemioogicay inked confirmation requires that a cinica case is inked in time, pace or circumstances to a aboratory confirmed case. This cassification requires carefu investigation and recording of trave and exposure histories, and anaysis of a epidemioogica data. Note: In an epidemic situation, pubic heath action does not require aboratory confirmation of every case. Once the cause of the outbreak has been estabished by aboratory confirmation of the initia cases, it can be managed on the basis of cinica confirmation. 4. Pubic Heath Action requires: a) Disease contro guideines, that shoud be present at every decision-making node of the surveiance network. b) Case confirmation by cinica criteria, positive aboratory tests or epidemioogica inkage to a confirmed case. A Caribbean Communicabe Disease Surveiance Manua for Pubic Heath Action, CAREC October 1999

13 Pubic Heath Surveiance 13 c) Coation and anaysis of epidemioogica data to identify the popuations affected or at risk, to define the mode of transmission, to decide on the strategies most ikey to minimise the effect of disease on the community. d) Formuation of a pan of action with specific activities and a time frame. e) Identification of human and financia resources f) Impementation of designated functions at a eves with supervision and monitoring according to performance criteria. g) Competion and writing of surveiance reports. h) Evauation of each pubic heath exercise and feedback to a eves of the system SENTINEL SURVEILLANCE Sentine Surveiance is a sensitive method of obtaining eary warning of, or prompt information on, a imited number of diseases through seection of sites which have a high probabiity of detecting cases and the abiity to rapidy and accuratey report through designated channes. 1. Why do we need Sentine Surveiance? a) As a parae system to estimate the competeness of reporting of the routine system and to vaidate its sensitivity and specificity. The accuracy and consistency of reporting in the routine system may apse with time and this may be undetected without a sentine standard of comparison. b) To expand the detection network in the eary stages of an outbreak. One exampe of this is dengue fever, which occurs in many Caribbean countries, causing considerabe morbidity and requiring prompt pubic heath action for its contro. A widespread aert prior to the season of high incidence wi provide eary warning of its emergence and aow effective contro. c) To detect the introduction of a disease occurring in other countries, e.g. choera, hepatitis E. Current goba information on the occurrence of communicabe diseases is now easiy avaiabe. Pubic heath authorities are therefore aware of potentia threats to their popuations and are in a position to assess their reative importance and seect those which warrant specia surveiance. d) To obtain information on diseases not incuded in the routine surveiance system, e.g. varicea and conjunctivitis. Conducting a status assessment on certain diseases is a necessary first step in defining the need for contro activities such as A Caribbean Communicabe Disease Surveiance Manua for Pubic Heath Action, CAREC October 1999

14 14 Pubic Heath Surveiance vaccination, for modifying existing strategies or for determining the impact of an intervention. e) To detect the re-emergence of diseases which have been eradicated or eiminated, e.g. poiomyeitis. Diseases no onger occurring in the region may be subject to Sentine Surveiance to detect any recrudescence in particuar areas or high-risk popuations. f) To detect the emergence of diseases which may appear due to a change in risk factors, e.g. Arbovira diseases foowing dam construction. The possibe adverse heath consequences of any panned and deveopment or popuation movement shoud be assessed before changes are made, and efforts shoud be made to minimise these. However, it is desirabe to monitor the popuation during and after the change to detect expected or unexpected heath probems, and to seek eary soutions. 2. Who are the potentia participants and how are they seected? a) Heath Centres, serving a specific catchment area, may be asked to conduct sentine surveiance for a disease which may appear in that area. An exampe of this is yeow fever surveiance in viages on the periphery of a forested area known to be enzootic for the virus. b) Private medica practitioners may be recruited depending on ocation, scope and type of practice. Exampes woud incude paediatric practices for surveiance of respiratory or diarrhoea disease in infants, or famiy practices for dengue. c) Pubic and private aboratories which perform the required tests in sufficient voume and to an adequate standard may be asked to participate in, for exampe, a programme to coect information on the different types of vira hepatitis. d) Specia institutions and popuation groups provide information on a defined community which may be appropriate for certain types of surveiance. Exampes of this category are University faciities, serving a young adut community drawn from different countries; Medica faciities of the protective services, serving an adut, predominanty mae group distributed throughout the country; Prison medica services, serving a group of incarcerated aduts with specia heath risks; Hote staff and guests; a dua community exposed for varying periods to the same environment. e) Hospitas, both genera and speciaised, are a source of information on the more severe cases of any disease under sentine surveiance. Specific departments may report directy to the system manager, but care shoud be taken to avoid dupicate reporting of cases detected at heath centres or in private practice and referred to hospita. A Caribbean Communicabe Disease Surveiance Manua for Pubic Heath Action, CAREC October 1999

15 Pubic Heath Surveiance How are sentine sites inked to the pubic heath system? With whom do they interact? The operation of the routine surveiance system is we estabished and understood by a. In setting up a sentine system additiona reporting sites are recruited or staff of existing faciities are asked to carry out additiona duties. Care must be taken to carify reporting channes and points of contact with those responsibe for data management and pubic heath action. Arrangements are needed for: a) Reporting either to the district (eve 2) or to a designated person in the epidemioogy unit (eve 3). b) Suppy of iterature, reporting and case investigation forms. c) Coection and referra of aboratory specimens. This may be the responsibiity of the person reporting or may be handed by the routine system. d) Feedback from the nationa Heath Authority. This shoud be an active system with frequent status buetins to maintain interest. e) Educationa activities. Cinica updates and seminars and patient management information wi hep to raise awareness and encourage cooperation. 4. Who switches the system on and off? Sentine surveiance systems are set up for a specific purpose on the authority of the Nationa Leve (e.g. the Chief Medica Officer or Epidemioogist). If a time-imited system is no onger needed, or is no onger serving its purpose, it shoud not be eft to peter out but shoud be officiay terminated. This can be done by a fina summary report which shoud incude action taken as a resut of the activity, and a statement of the current status of the disease. This shoud be disseminated to a participants. A etter of appreciation from the Nationa Leve wi eave the door open for further coaboration REPORTING OF DISEASE SYNDROMES Disease specific surveiance invoves the foowing: Case detection based on a cinica case definition that is simpe and sensitive Extensive case investigation that introduces some specificity Confirmation of a specific disease based on a combination of cinica, epidemioogica and aboratory data A Caribbean Communicabe Disease Surveiance Manua for Pubic Heath Action, CAREC October 1999

16 16 Pubic Heath Surveiance This procedure frequenty resuts in deayed reporting since considerabe decision making is required at the periphera eve before the Pubic Heath system even becomes aware of a potentia threat. The effectiveness of pubic heath action is sometimes compromised by the perceived need to await definitive confirmation of aetioogy which can ony be provided by aboratory tests not avaiabe in-country. In an effort to overcome these difficuties a system of syndromic disease reporting has been proposed by the Word Heath Organization as a means of rapidy detecting syndromes/disease events that may cause a significant internationa pubic heath probem. Syndromic notification wi be foowed by disease-specific information as soon as it becomes avaiabe. A WHO sponsored piot study of this internationa system is underway and, unti it is assessed, the reporting of choera, pague and yeow fever remains an obigation under the present Internationa Heath reguations. (For further information see Section 6 of this Manua). In parae with this internationa initiative it is considered advisabe to introduce syndromic reporting as part of the nationa surveiance systems in the Caribbean. The syndromes presented in Tabe 1 are easiy recognised and can be prompty reported, aerting the pubic heath system to the possibiity of one or more diseases. In some cases action can be taken prior to a definitive diagnosis, but in any event expert assistance can be enisted at an eary stage. Reporting of disease syndromes may be used in different ways depending upon the needs of each country: a) As a sensitive screening patform from which to focus attention on specific diseases. b) As a rapid reporting suppement to existing disease-specific nationa surveiance activities c) As an aternative system to be used where medicay trained heath workers and adequate aboratories are not avaiabe to support specific disease reporting. The foowing eight syndromes (Tabe 1) are proposed as covering a the important communicabe diseases which may be a threat to pubic heath and which are under surveiance in CAREC Member countries. Receipt of a syndromic report shoud trigger a response from eve 2 which starts with case investigation using the appropriate forms. This wi serve to narrow the ist of possibiities to one or two diseases, based on additiona cinica and epidemioogica information. A Caribbean Communicabe Disease Surveiance Manua for Pubic Heath Action, CAREC October 1999

17 Pubic Heath Surveiance 17 Requests for further aboratory, medica or epidemioogica assistance can then be made through the nationa authorities who wi decide on immediate contro activities It is important to provide feedback on the fina diagnosis to eves 1 and 2 and to inform them of ong range pans for contro and prevention of the disease. A Caribbean Communicabe Disease Surveiance Manua for Pubic Heath Action, CAREC October 1999

18 18 Pubic Heath Surveiance TABLE 1: SYNDROMIC CHARACTERISTICS AND SPECIFIC DISEASES ASSOCIATED SYNDROME CHARACTERISTICS SELECTED DISEASES WITHIN THESE SYNDROMES 1. Febrie systemic disease Sudden onset of fever, headache, musce and joint pain; occasionay gastrointestina symptoms; may be biphasic or recurrent Bruceosis, Dengue fever, Leptospirosis, Maaria, Typhoid fever 2. Fever with rash Onset with fever and systemic symptoms; generaised eruption (macuar, papuar, vesicuar) or eruption ocaised to parts of the skin and/or mucous membranes Dengue fever, Meases, Rubea 3. Fever with respiratory symptoms Fever with aryngitis, pharyngitis, cough, thoracic pain, pumonary edema, fatigue, puruent or bood-stained sputum Diphtheria, Hantavirus pumonary syndrome, Legionnaires disease, Pertussis, Pneumococcus infection, Pague (pneumonic), Tubercuosis 4. Gastrointestina symptoms with or without fever Nausea, vomiting, abdomina cramps, diarrhoea with or without mucus or bood Choera, Foodborne iness, Gastroenteritis, Samoneosis, Shigeosis 5. Fever with jaundice Acute or insidious onset of fever, headache, backache, anorexia, maaise, fatigue, nausea, abdomina pain or discomfort, vomiting, jaundice Leptospirosis, Vira hepatitis, Yeow Fever 6. Fever with haemorrhagic symptoms Onset of fever with systemic symptoms; second phase after 3-5 days with cutaneous beeding (petechiae, ecchymoses); interna beeding (haematemesis, meena, haematuria); sometimes jaundice, shock Dengue Haemorrhagic fever, Leptospirosis, Yeow Fever 7. Fever with neuroogica symptoms Fever with systemic symptoms, headache, vomiting, neck stiffness and/or pain; confusion, disorientation, anxiety, hyperactivity, tremors, spasticity, convusions, coma Meningitis/Encephaitis, bacteria or vira, Poiomyeitis, Rabies, Tetanus, 8. Genita discharge or ucer Urethra or vagina discharge, itching, burning, dysuria, genita or periana ucers in maes or femaes, papue, bubo, skin rash Sexuay transmitted diseases incuding Chamydia, Gonorrhoea, Syphiis, Herpes A Caribbean Communicabe Disease Surveiance Manua for Pubic Heath Action, CAREC October 1999

19 Pubic Heath Surveiance REQUIREMENTS OF A SPECIALISED SURVEILLANCE SYSTEM Meases is used as an exampe. This approach may be adapted for other diseases. Speciaised surveiance systems are estabished for diseases with ceary defined regiona or goba goas of disease reduction, eimination or eradication. The emphasis is on high quaity surveiance which is assured through the estabishment of performance standards for every procedure and maintained by constant monitoring of performance indicators. A high degree of standardization is needed for inter-country coation of data. In 1991, Caribbean Heath Ministers adopted a goa of meases eimination by the year 2000, and began impementation of the PAHO strategies of mass immunization to interrupt transmission foowed by high routine coverage and sensitive, case-based surveiance to detect introduction or recrudescence of the disease. Speciaised surveiance systems shoud, as far as possibe, be integrated into routine disease surveiance systems, and shoud serve to enhance the quaity of case detection, reporting and investigation. Characteristics of speciaised systems are: 1. Simpe cinica criteria for case detection and reporting The aim of this simpicity is high sensitivity of case detection, with the responsibiity for case confirmation (specificity) resting on eve 2 or 3. Every case of meases must be identified, and cassified as indigenous or imported in order to determine the circuation of meases virus in the community. Meases is a febrie rash disease which is detected and reported on the basis of the foowing cinica case definition. Meases Case Definition: Any person with fever and a macuopapuar rash or any person in whom a cinician suspects meases infection. Suspect meases is immediatey reportabe (within 24 hours) to the district eve, and every effort is made to enist the non-pubic heath sector through paediatric and University associations. 2. Rapid and standardised case investigation Suspect cases are investigated within 48 hours of notification using a standard case investigation form. (See for a sampe form). A unique identifying number is assigned to each case (the EPID number). This is used aong with demographic information to positivey identify the case and to ink cinica, epidemioogica and aboratory data. A Caribbean Communicabe Disease Surveiance Manua for Pubic Heath Action, CAREC October 1999

20 20 Pubic Heath Surveiance A items on the investigation form are needed for accurate interpretation of aboratory resuts and fina case cassification. Particuary important are dates of onset and specimen coection, immunization history and trave history. 3. Laboratory confirmation Case investigation incudes aboratory investigation of every case to excude the many other causes of fever and rash. These incude rubea, dengue fever, eary chicken pox, enterovirus infections, scaret fever and roseoa. Athough many methods of aboratory confirmation are avaiabe, for a speciaised surveiance system ony one or two are seected based on a baance between sensitivity and practicabiity. Ony designated aboratories shoud be used since these are required to adhere to stringent aboratory protocos of testing and interpretation of resuts. Training is given and specific reagents are recommended or provided. The recommended test for meases is the ELISA for Meases-specific IgM antibodies. An adequate specimen is coected from every case of suspected meases. With reference to meases surveiance, an adequate specimen is a bood sampe taken within 3 to 28 days of rash onset. (However, it is recommended that a bood sampe be coected on first contact, to ensure that every case is tested). The accompanying aboratory request form shoud state the dates of onset and coection. The bood sampe is transported rapidy to the aboratory where the Meases IgM test is done within 3 days, and resuts reported to the sender of the specimen and to the programme manager. 4. Effective pubic heath action A confirmed case, or a custer of cases, indicates circuation of the meases virus in the community. The pubic heath options incude intensive house-to-house mop-up vaccination in the affected district or a country-wide keep-up campaign of a chidren born since the initia mass campaign, to reduce the number of accumuated suseptibes. 5. Monitoring of performance indicators The quaity of surveiance is assessed by performance indicators such as: Proportion of reporting sites that report each week (target 80%), Proportion of sites reporting at east one suspected meases case per year (80%) Proportion of cases investigated within 48 hours of notification (target 80%) Proportion of cases with adequate specimens or epidemioogic inkage to a aboratory confirmed meases case (target 80%) Proportion of tota aboratory confirmed cases with source of infection identified target (80%). A Caribbean Communicabe Disease Surveiance Manua for Pubic Heath Action, CAREC October 1999

21 Pubic Heath Surveiance Data anaysis and the production of status reports The effectiveness of speciaised surveiance is measured by on-going data anaysis at the nationa eve, the eve which interacts with PAHO/WHO and funding agencies. Monthy status reports are produced to document progress or highight areas of weakness. Such reports incude: Meases immunization coverage by district Competeness of weeky reports by district Cinica and aboratory confirmed cases by district Immunization status of confirmed cases Confirmed cases by age at rash onset Cases with surveiance faiure (ate notification/investigation; no adequate specimen) 1.3 Essentia Attributes of a Surveiance System The utimate objective of a surveiance system is its appication to disease contro and prevention. Within each system, there are eements which have specific objectives. The combination of these eements determines the overa strength or weakness of the system. In order to meet its specific objectives and maximize the effectiveness of the system, there are certain essentia attributes which shoud characterize a stages of the process. These attributes may be quaitative or quantitative. Among the quaitative attributes that shoud be considered in the organisation of a surveiance system simpicity, fexibiity and acceptabiity are of specia importance QUALITATIVE AND QUANTITATIVE ATTRIBUTES Simpicity of a system refers to its structure and its ease of operation, both of which are interreated. As a genera principe, the structure design and size of the system shoud be as simpe as the requirements for meeting its objective woud aow. In sma systems in which data handing and two-way fow of information are streamined, high eves of compiance in reporting and other associated areas are usuay achieved. Simpe systems are aso ess costy to maintain than arger compex ones. On the other hand, the objectives of the system are the key considerations against which expected returns shoud be measured, and shoud be used as a guide in the fina determination of its structure and size. Consideration shoud be given to the quantity and type of data required; the mechanisms for coecting, coating, anayzing, disseminating and using the data generated by the system; the infrastructure required to ensure cost-effective operation of the system. Disease surveiance is a dynamic process. Trends change, new diseases appear, methods of diagnosing, reporting, controing and preventing diseases change over time. To maintain effectiveness, fexibiity shoud be a buit-in attribute of any surveiance system. This woud faciitate prompt responses to changing disease conditions, incuding corresponding demands for changes in appropriate pubic heath action. A Caribbean Communicabe Disease Surveiance Manua for Pubic Heath Action, CAREC October 1999

22 22 Pubic Heath Surveiance Surveiance requires the participation of contributors and users and the eve of this participation is to a arge degree a refection of the acceptabiity of the system. Inputs by participants into practica aspects of the design/modification of the system are therefore important. One measure of acceptabiity is the eve of compiance at the various points of interaction between the system and its participants. Accuracy ensures that a the information is vaid and correcty documented. Timeiness may be viewed from two aspects. One is the promptness of reporting in terms of meeting specific deadines. The other aspect of timeiness, reates to the interva between any two or more steps in a surveiance system. e.g. time between disease occurrence, diagnosis and receipt of report and appropriate pubic heath intervention. Deay in this case, is assessed by its reevancy to the urgency of the probem in reation to the required response. Competeness requires that a reevant information is coected, incuding negative reports. Representativeness is important in that a surveiance system shoud provide reiabe and unbiased information on the occurrence of a heath event over time, and its distribution in the popuation by pace and person. This can be assessed to some degree either by comparing the characteristics of reported events with those of a such events that occurred, or through the use of specia studies conducted in a representative sampe of a popuation. Sensitivity of a surveiance system describes the abiity of a system to detect the cases or other heath events that it is intended to detect. Sensitivity aso refers to the system s abiity to detect epidemics and other changes in disease occurrence. Many surveiance systems detect ony a sma proportion of the cases that actuay occur, and whie it may not be cost efficient to achieve 100% sensitivity as regards individua cases ascertainment, there is need to ensure nonetheess that the system is sufficienty sensitive to identify community-wide probems. Predictive Vaue Positive is defined as the proportion of reported cases who actuay have the condition being monitored or the proportion of reported epidemics which were actuay epidemics. That is, it is a measure of the predictive vaue of a reported case or epidemic. We measure predictive vaue positive by investigating whether the reported cases and epidemics meet our definition for a true case or rea epidemic. The more fasepositive reports there are in a surveiance system, the ower the predictive vaue of the reports. These resut in unnecessary investigations, wastefu aocation of resources, and especiay for fase reports of epidemics unwarranted pubic anxiety SURVEILLANCE PROCESS Surveiance activities incude a number of monitoring functions e.g. of contacts of cases of communicabe diseases, of the environment and other factors affecting disease transmission. Perhaps the most important feature of the communicabe disease surveiance process is data management which incudes: A Caribbean Communicabe Disease Surveiance Manua for Pubic Heath Action, CAREC October 1999

23 Pubic Heath Surveiance 23 Coection of data Coation Anaysis and interpretation Dissemination of information Data anaysis, however, is the most prominent feature. Epidemioogists use surveiance data for monitoring the heath status of popuations. Thus, describing a heath probem or event and defining its magnitude and trend in popuations over time are two important ongoing surveiance functions. In order to understand the basic dimensions of a heath probem or event, we usuay anayse the data by time, pace and person. Hence, for exampe, during the conduct of an outbreak investigation, we create a ine isting of information incuding data on age, gender, time and date of onset of iness, pace of residence or empoyment, etc of affected cases. Simiary, from our surveiance data, we must be abe to document the incidence or prevaence rate of the heath probem by month or year; to graph the number of reported cases of a heath event occurring over time using histograms, epidemic curves, etc; and to group affected cases by their age, immunisation status, common exposure etc. The organisation and presentation of such data is very important for communicating effectivey with poicy makers, poiticians,etc and other stakehoders SOURCES OF SURVEILLANCE DATA There are at east ten major sources or kinds of data reevant to disease surveiance. They are: Mortaity reports Morbidity reports Epidemic reports Reports of aboratory utiisation Reports of individua case investigations Reports of epidemic investigations Specia surveys (e.g. of hospita admissions, disease registers, and seroogic surveys) Information on anima reservoirs and vectors Demographic data Environmenta data Mortaity reports the usefuness of mortaity data as a surveiance too in disease contro is imited by severa characteristics. Data from death certification gives ony a cause of death and is not aways accurate in terms of refecting underying disease; there can be ong deays (severa months or onger) in accessing the data; some communicabe diseases have a very ow fataity rate, and in those with a high fataity rate the interva between onset and death may be proonged. Morbidity reports despite the fact that certain diseases are notifiabe by aw, most countries share a common experience of under-reporting. Lists of notifiabe disease may be too ong; the system of data coection may be unsatisfactory; and very often there is A Caribbean Communicabe Disease Surveiance Manua for Pubic Heath Action, CAREC October 1999

24 24 Pubic Heath Surveiance a breakdown in feedback to the contributors with a resuting oss in interest. Athough the true extent of disease occurrence cannot be determined by reports from this source, Sentine reporting is usuay accurate and timey and can provide an indicator of increase or decrease in disease occurrence. If carefuy seected, this source can aso provide some indication of distribution. Epidemic reports these may be received from a variety of sources: Medica officers at region, parish or county eves; epidemioogists investigating outbreaks; hospitas or other heath institutions at which a arge number of persons are seen in a custer e.g. presenting with gastro-intestina disturbances; community sources. Reports often appear in the media, and whie these may be inaccurate they shoud be subject to at east preiminary investigation. Laboratory reports aboratories shoud report to the surveiance system, to which they shoud be integray inked. Reports of individua case investigations eary diagnosis and contro measures may prevent outbreaks. They may aso be usefu in detecting weaknesses in immunization programmes, especiay in the EPI. Reports of epidemic investigations surveiance and investigation procedures may be improved upon by critica reviews of such reports. Reports of actua investigations are usefu toos in training programmes. Specia surveys these are used to provide information needed for specia purposes which are not avaiabe from routine surveiance data. Information on anima reservoirs and vectors has practica appication in the impementation of prevention and contro measures against vector borne diseases. Demographic data obtained from officia popuation census and used as baseine data in epidemioogica anayses. Environmenta data monitoring of these data provides information on eves of risk factors for certain communicabe diseases and is of specia importance in disaster situations. After coation and anaysis, data interpretation shoud be presented in a form upon which pubic heath action can be based. Finay, to achieve the end point of the system, adequate mechanisms for the prompt feedback of processed data must be in pace to faciitate impementation of the required pubic heath response. Feedback shoud be at periodic intervas, determined to some extent by particuar disease situations, and recipients shoud incude both contributors to, as we as users of the system. Co-ordination at Country eve shoud be the responsibiity of the Designated Nationa Epidemioogist, and a personne invoved in the system shoud be famiiar with a aspects of procedures to be foowed. Particuar roes/functions within the system shoud be cear, and ongoing reevant training shoud be an integra eement of the system. A Caribbean Communicabe Disease Surveiance Manua for Pubic Heath Action, CAREC October 1999

25 Diseases and Conditions under Surveiance Diseases and Conditions Under Surveiance The Communicabe diseases which have been seected for surveiance in the Caribbean, and which wi be discussed in detai in Section 3 of this manua, can be arranged into categories which justify their incusion. 2.1 Categories of diseases under surveiance. a) Diseases subject to the Internationa Heath Reguations Choera, pague and yeow fever. b) Diseases under internationa surveiance AIDS, maaria and infuenza c) Diseases of the Expanded Programme on Immunization Tubercuosis, diphtheria, pertussis, tetanus, poiomyeitis, meases, mumps, rubea and congenita rubea syndrome. d) Diseases of interest in the Region of the Americas Meningococca infection (Neisseria meningitidis), eprosy, dengue fever, dengue haemorrhagic fever/dengue shock syndrome. e) Diseases of interest in the Caribbean Typhoid fever, food borne iness, vira hepatitis A and B, rabies in humans, eptospirosis, samoneosis, shigeosis, gastroenteritis, sexuay transmitted diseases and vira meningitis/encephaitis. f) Diseases of nationa interest Meningitis due to H. infuenzae and invasive pneumococca disease. g) Other diseases of potentia concern Legionnaires disease, hantavirus pumonary syndrome and bruceosis in humans 2.2 Reporting casses of seected diseases These are further cassified for reporting purposes according to the practica benefit that can be derived from reporting. A Caribbean Communicabe Disease Surveiance Manua for Pubic Heath Action, CAREC October 1999