one health lecture 5- surveillance Flashcards
what is monitoring in surveillance?
-Routine collection of information on disease
-Often a defined population and time period
-More descriptive and less systematic than surveillance
-Doesn’t necessarily lead to action
what is the difference between eradication and elimination?
Eradication - permanent and global, only happened twice
-Smallpox
-Rinderpest
Elimination - restricted to a specific geographic area
when is a disease confirmed as eliminated?
-no cases for over 10 years but is this due to lack of detection or true absence?
what are the types of surveillance?
-passive
-active = of notifiable diseases and target diseases
-syndromic
what is active surveillance?
-health department (or other authority) proactively contacts health care providers or laboratories requesting information about specific diseases
-more costly and labour-intensive
-tends to provide a more complete estimate of disease frequency
what are notifiable disease?
-Legal duty to report
-Within 24-72 hours, depending on level of urgency
-Diseases with high public health or economic implications
-Often “exotic” (transboundary diseases)
-On basis of clinical suspicion
-Urgent 0 within 24 hours
-Routine – within 3 days
what is bovine tuberculosis?
endemic – already present in the UK, such as bovine TB; Scotland officially free since 2009
Transmission can occur through nose to nose contact and also through contact with saliva, urine, faeces and milk.
exotic – not normally present in the UK, such as foot and mouth disease
Contingency plans…
what is targeted surveillance?
-Directed at particular at-risk individuals
Example: cancer screening for those with family history
-Helps improve health outcomes
Early detection ~ more effective treatment options
what is passive surveillance?
Regular reporting of observed cases but no active search
-minimum standard, present in most countries
-relatively cheap
-expect underreporting
In contrast to active surveillance (which aims to determine true incidence)
Includes “ad-hoc” reporting (e.g. citizen science)
what are the challenges with wildlife disease surveillance?
-Observing and reporting of cases
-Remoteness
-Scavengers
-Topography (landscape) Etc.
what is syndromic surveillance?
-Look for rise in the number of people reporting particular types of symptoms, e.g. febrile illness (fever)
-Syndromic surveillance systems monitor data from school absenteeism logs, emergency call systems, hospitals’ over-the-counter drug sale records
-Monitor trends on web or other data collection platforms => “nowcasting”
what is laboratory based surveillance?
-Diagnostic confirmation of aetiology (cause) of disease
-More specific than syndromic surveillance
Can detect:
-Pathogen (culture)
-Nucleic acid (PCR)
-Antibodies (ELISA) –> exposure
what are the 2 hypotheses about where our own pathogens come from?
1- Co-evolution: pathogens inherited from our ancestors
2- Cross-species transmission: more recent introductions from other species
For most human infectious diseases, genetic data support the second hypothesis
what are the 2 ways to predict zoonotic disease emergence?
1- Cataloguing all wildlife pathogens and identify the ones most likely to emerge
2-Better surveillance systems (especially in high-risk regions) to detect emergence as it happens
why do surveillance?
1- Gaining basic understanding of epidemiology
2- Early warning system (detect outbreaks)
3- Tracking interventions (assess impact)
4- Inform policy and practice
5- Monitoring variants (e.g. drug resistance)
what is the example of anthrax?
~400 cases confirmed in 3 years of active case investigation and sampling vs. < 10 in previous years
BUT
Number of cases greatly affected by completeness of reporting
what is the example of wildlife as sentinels of zoonotic disease risk?
-Reports of dead crows were useful in defining the geographic and temporal limits of a West Nile virus outbreak in north-eastern US in 1999
-Health department received over 17,000 dead bird reports in 2nd half of year
Suggestion: surveillance system based on bird deaths may provide sensitive method of detecting WN virus
what is the problem with syndromic surveillance, with the risk of mis-diagnosis?
Malaria uncommon overdiagnosed
Invasive bacterial, mycobacterial, fungal infections high
-bacterial zoonoses common yet unrecognized
-mismatch between clinical diagnoses with actual diagnosis – implications for patient care
what does integrating genomics into surveillance allow?
Overall, integrating genomics into surveillance enhances the ability to detect, monitor, and control infectious diseases, improving public health outcomes and response times.
