Public Health Surveillance

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Public Health SurveillancePresenter: Dr. Uroosa FarooqDepartment of Community Medicine ,SKIMS ,Srinagar India.

Table of contents:Introduction.


Uses of surveillance.

Types of surveillance.



Steps of an outbreak investigation.

Success stories about surveillance.

The first recorded epidemic in history was the great pestilence in Egypt during 3180 BC.

This was the starting point of collecting and organizing data.

Some of the major epidemics in the history of public health are summarized in table below:Historical origins of surveillance:

CDC defines epidemiological surveillance as the ongoing and systematic collection, analysis and interpretation of health data essential to planning, implementation and evaluation of public health practice and programmes closely integrated with timely dissemination of these data to those who need to know. SURVEILLANCE IS- INFORMATION FOR ACTION


The idea of collecting data, analysing them, and considering a reasonable response stems from Hippocrates, a Greek physician who lived between 460 370 BC. In his book, On Airs, Waters and Places, when writing on disease occurrence, Hippocrates made a distinction between the endemic state as the steady state of the disease, and the epidemic as the abrupt change in incidence of disease.

John Graunt (1620-1674) introduced systemic data analysis.

Samuel Pepys (1633-1703) started epidemic field investigation.

William Farr (1807-1883) founded the modern concept of surveillance.

John snow (1813-1858) linked data to intervention .

Alexander Langmuir (1910-1993) gave the first comprehensive definition of surveillance.(Bernard C. K. 2012)

In 1741, the legislation for surveillance was first introduced in America, when Rhode Island passed an act requiring tavern keepers to report contagious disease among their patrons.

Regular reporting of smallpox, yellow fever, and cholera was made an act. France was the first country to make health of people as the responsibility of state. Legislations for surveillance :

1.To determine incidence of disease.

2.To know the geographical distribution or spread of disease/event.

3.Identify population at risk of that disease/event.

4.To capture the factors and conditions responsible for occurrence and spread of a disease.USES OF EPIDEMIOLOGICAL SURVEILLANCE:

6. To predict the occurrence of epidemic and control epidemic.

7. To evaluate the effectiveness of an intervention or programme .

8. To assess the disease burden in the community or health needs of community.5.Monitor trend of disease over a long time period.

1.Detection and notification of health event.

2.Investigation and confirmation (epidemiological , clinical, laboratory).

3. Collection of data.

4. Analysis and interpretation of data.

5. Action to be taken

6. Feed back and dissemination of results.

Steps of Surveillance system:

1. Community level surveillance.2. Routine reporting system.3. Active and passive surveillance .4. Sentinel surveillance.5. Surveys and special studies.6. Case and outbreak investigation.7. Verbal autopsy.8. Laboratory surveillance.9. Entomological surveillance. A .Surveillance methods for data collection:

ASHAs, Anganwadi workers, Self help groups , village panches

Report births, deaths, outbreaks and unusual events

Informants at community level need to be contacted on regular basis.1.Community level surveillance:

Health staff collects information about number of cases of reportable diseases and deaths that occur in relation to all national health programmes .

This system relies on government established system of sub centres , PHCs, CHCs and hospital data.

Whosoever comes to these facilities are recorded and reported .Thus called passive routine reporting system.2.Routine reporting system:

3.Active surveillancePassive surveillance1.Means actively looking or searching for a particular type or group of diseases, is useful in detecting these unreported cases.Collection of data from persons, themselves reporting to a facility (hosp., clinic, sub Centre, PHC and CHC,)2.It involves active participation of health personals as well as the community .At times during outbreak investigator may conduct what is sometimes called stimulated or enhanced passive surveillance by sending a letter describing the situation and asking for reports of similar cases.3.Degree of reporting is more complete.4.Important strategy for small pox and guinea worm.5.Its importance for malaria control is still going on strong.6.It has also been undertaken for acute flaccid paralysis.

A small number of health units are selected to report cases of diseases and deaths that are seen or diagnosed at their facility.

These sentinel sites also collect and report additional information such as age , immunization status and other details.

Staff at sentinel sites is given special training and supervised to ensure that reporting is complete and accurate.4.Sentinel surveillance:

Hospital( infectious diseases, TB, Pediatric hospital)

Health centre

Antenatal clinics

STD clinic


Rehabilitation centre which attend large number of particular type of cases can be considered as a possible sentinel site.Common sentinel sites:

Large attendance of patients with particular disease.

Diagnosis is reasonable ,accurate and laboratory support is available.

Good recording and reporting facilities available.

Willingness to submit regular report.Minimum criteria need to be observed in selection of sentinel Centre :

Sample surveys or disease surveys is an active and efficient method of surveillance, which can complement the other methods.

Two surveys done at an interval of several years apart may be able to demonstrate changes in disease incidence.

The first survey for collecting reliable baseline epidemiological information and the subsequent one for evaluation of the control programme or intervention. e.g., 5. Surveys and special studies:

Survey on blindness at different points in time in India provides information on prevalence of blindness and effect of interventions on blindness.National oral health survey and fluoride mapping provides useful information on oral health status and problems.Survey of risk factor for non-communicable diseases is being undertaken at 3-5 years interval under IDSP .

Surveys are difficult to conduct .

Relatively expensive .

Highly skilled persons with organizational abilities are required.

The sample size, questionnaires and forms must be well designed to avoid bias and misinterpretation of data.

Some diseases require laboratory back-up for accurate diagnosis, which make the surveys even more difficult. Limitations:

6. Case and outbreak Investigation:

An out break investigation is an investigation of many cases . However , when the occurrence of a particular disease is very low, Polio for example , even one case can be considered as an out break.Case investigation is an investigation of a single case of a disease or death.

7.Verbal Autopsy:It is a special technique for investigation of cause of death.

Trained worker or investigator conducts an in-depth investigation of the death ( maternal or infant or any other death) through interviews with the mother or any one else who was a witness to the death and the circumstances leading up to it.

The investigations are done on a standard designed format or protocol.

Purpose:To ascertain the most probable cause of death.

Whether the death could have been prevented or avoided by timely and appropriate measures.

Workers can educate community as to how to prevent deaths as also common causes of death in the community .

Laboratory testing confirms the syndromes of presumptive cases and helps in diagnosis of cases for case management.8. Laboratory surveillance :Regular surveillance for vectors of disease under national vector born disease control programme is being done to know vector density and sensitivity to insecticides.9. Entomological surveillance:

B. Compilation and transmission of data:

The cases that have been detected and recorded need to be compiled and transmitted to the next level on regular basis once a week or daily .

This could be done on a fixed date from each type of unit . All reporting units/centres will provide zero reporting if no cases were detected.

The designation of the person responsible for data compilation and transmission at each level has been identified (pharmacist, computer statistical officer , lab technician and medical officer).

The health workers, medical officers of PHCs and sentinel private practitioners will provide regular reports on prescribed formats on every Monday.

C. Analysis and interpretation:

The analysis should be encouraged at each level of surveillance system. Data are analyzed by count, divide and compare principles and then displayed by time, place and person analysis .

The workers should learn to interpret the data they are collecting and thereby they will have better understanding of the needs of their community .

The surveillance data can be easily tabulated in three ways: summary tables, disease charts and maps , which show the number of cases of disease for each reporting week and month. Data after analysis becomes useful information for action.

D. Action:Surveillance w