Survillence Flashcards
(17 cards)
Surveillance
Public health surveillance is the continuous, systematic collection, analysis and interpretation of health-related data needed for the planning, implementation, and evaluation (PIE)of public health practice
Key principles: Has to be continuous, systematic collection, analysis, interpretation >have 2 System for reporting(feedback)
Surveillance is outcome oriented • (e.g., number of cases, incidence, prevalence)
Can measure frequency of an ilness or injury
Can measure severity of the condition (e.8., hospitalization rate, disability, case fatality)
Can measure impact of the condition (e.g., cost)
Orient data by person, place, and time
Uses
of
surveillance
⁃ Quantify the magnitude of health problems
- Understand the natural history of diseases (clinical spectrum epidemiology )
- Detection of epidemics, determine the Spread and distribution of health events
- Facilitate research including testing hypothesis - To define priorities in policies and resources
- Evaluation of control and prevention activities-(Including deciding on introduction of new vaccines and timing of administration of vaccines)
Effeetiveness of vaccine introduction
⁃ Monitoring changes in diseases, risk factors and health practices
- Planning and budgeting
- Anticipating changes in disease trends
Characteristics of survillence system
• Have clear objectives
• Simplicity
• Flexible
Good quality of data
• Good acceptability Availability
• Usefulness
Timeliness-to implement effective control measures
• Representation-to provide an accurate picture of the trend of the disease
• Sensitivity-to allow correct identification of individual persons with disease (to facilitate treatment; quarantine, or other appropriate control measures)
• Specificity-to exclude persons not having disease
Data Integrity & Accuracy🔥:
Good Data Quality (Reliable info?)
Sensitivity (Finds the sick?)
Specificity (Excludes the healthy?)
Mnemonic: “Q S S” - Focus on Data Quality, then the twin measures Sensitivity & Specificity.
Clear Objectives (Why?)
Usefulness (Does it work for the ‘why’?)
Timeliness (Is it useful on time?)
Representativeness (Is it useful for the whole picture?)
Mnemonic: “COURT⚖️” - The system must stand up in the ‘COURT’ of public health purpose. (C, O=Obj, U, R, T) - Slight stretch, but groups purpose.
Limitatons of
Surveillance
• Incomplete data • Overwhelming volumes of data from a variety of sources make management complex • Uneven application of information technology Timeliness • Completeness
Describe how Leptospirosis patients admitted to hospitals are reported tothe Epidemiology Unit of the Ministry ofHealth.
Process for reporting Leptospirosis patients admitted to hospitals to the Epidemiology Unit of the Ministry of Health:
- Initial Notification from Hospital: When a patient is admitted to a hospital ward with suspected Leptospirosis (a Group B notifiable disease), a Notification Card (Form H544) is filled out.
- Hospital Registers: This notification is recorded in the Ward Notification Register and the Institutional Notification Register(filled by ICNO) within the hospital.
- Notification to MOH: The H544 card is sent from the hospital to the Medical Officer of Health (MOH) office at the divisional level vis post.
- MOH Registers: The MOH office maintains its own Notification Register and an Infectious Diseases Register(H700) where the case details are entered.
- PHI Investigation (Optional/Confirmation): The area Public Health Inspector (PHI), under the MOH, may conduct a field investigation. For each confirmed case, the PHI completes Form H411, which is submitted to the MOH.
- Case Confirmation Forms: After confirmation (which may involve the PHI investigation or hospital confirmation), the MOH office completes Form H411a for each confirmed case. Additionally, the Infections Control Nurse (ICN) at the hospital fills out a specific survey form for confirmed Leptospirosis cases and sends it directly to the Epidemiology Unit.
- Weekly Reporting: The MOH office compiles a Weekly Return of Communicable Diseases (WRCD) using Form H399, summarizing all notifiable diseases reported during the week.
- Submission to Epidemiology Unit: Both the individual case form (H411a) and the weekly summary form (H399) are sent from the MOH office to the Regional Epidemiologist (RE) at the district level. The RE then forwards this information to the central Epidemiology Unit of the Ministry of Health.
- Death Reporting: In the event of a death due to Leptospirosis, the Infections Control Nurse (ICN) ensures that a death review form, filled out by the Senior Registrar (SR) or Consultant, is sent to both the Epidemiology Unit and the Regional Epidemiologist.
Basic reproduction number
R₀ is the average number of 2ry(new) infections caused by one infectious person in a totally susceptible population through the infectious period - no immunity or vaccination
Uses of basic repro number
The image describes the uses of R 0
•To determine if an emerging infection can spread to a population.
-If R 0 >1, an individual will spread the infection to more than one person.
•To determine what proportion of the population needs to be immunized.
Effective reproduction number (R) and uses
the Effective reproduction number (R) as the reproduction number when there is some immunity or some vaccination measures in place.
Its uses include:
•To describe the transmissibility of a pathogen during an epidemic.
•To reflect the effectiveness of control measures.
•To highlight when control efforts need to be intensified.
Advantages and disadvantages of Passive surveillance
Advantages
• Simple to conduct • Not a huge burden on the reporter • Low cost
Disadvantages
• vulnerable to incompleteness and variability • Under reporting • Asymptomatic patients may not be included • Depends on access to healthcare, labs
Active Surveillance
1.What
2.Adv
3.Disadv
Active Surveillance as actively looking for a particular disease in a community.
Advantages:
Achieves more complete and accurate reporting.
Disadvantages:
Requires high input for low return.
Usually limited to a specific disease for a defined period of time, or during outbreaks and epidemics.
More resource intensive.
Examples:
COVID
AFP (Acute Flaccid Paralysis)
Activated passive surveillence
Notification system in Srilanka
Sentinel site surveillance
Sentinel Surveillance:
○ Uses a limited network of carefully selected reporting sites (sentinel sites, often large hospitals) to gather high-quality data.
◦ Supplements routine notification, providing more detailed information
○ Advantages:
Improves timeliness and accuracy, signals trends, identifies outbreaks, monitors disease burden,economically, strengthens institutional capacity and inter-sectoral relationships.
○ Disadvantages:
May not detect rare diseases or those outside sentinel site catchment areas.
○ Examples in Sri Lanka: AFP, Rotavirus, Rubella, Measles, Dengue/DHF, Neonatal Tetanus, Influenza-Like lllness (ILI), Severe Acute Respiratory Illness (SARI).
Special surveillance
Special Surveillance as a combination of active, sentinel, and active lab-based surveillance.
Its characteristics and uses include:
• Obtain more detailed data which are not available through routine surveillance.
. Requires more time and resources.
Examples:
• Al EPI cases
• DF (Dengue Fever)
• DHF (Dengue Hemorrhagic Fever)
• Human rabies
• Hepatitis
• Leptospirosis
What is a Notifiable Disease?
• A disease that must be reported to public health authorities at the time it is suspected because it is potentially dangerous to human or animal health
Data Sources & Methods used for Disease Surveillance
• Indoor Morbidity & Mortality Register (IMMR)
• Notification System
• Laboratory Data Vital Statistics
• Special Disease Registries (TB, Cancer)
• Surveys
Strengths of the Notification system
• National network covering the whole island
• Availability of technical experts
• Close monitoring and evaluation
• Forecasting outbreaks
• Feedback (WER, Quarterly Bulletin)
Weaknesses
• Timeliness is not satisfactory
Reduced Integration with other vertical Disease
•
surveillance Programmes ( Eg: AMC)
• Minimum Laboratory Surveillance
• Limited to Inward cases ; minimum contribution from OPD / Private sector
• Notification on diagnosis rather than on suspicion
