Applied epidemiology and control Flashcards
Describe disease prevention, disease control and disease eradication
Prevention: Avoids disease occurrence; reduces incidence/prevalence. Applies to almost all diseases.
Control: Reduces disease to a tolerable level; for common or endemic diseases where eradication isn’t feasible.
Eradication: Complete removal of disease/agent from a region. Usually for exotic or targeted diseases (e.g. BVD in Scotland).
Choice depends on disease type, economics, welfare, politics, and public health.
Measures often overlap between prevention, control, and eradication
How is disease prevention and control achieved
Host - Increased resistance/decrease susceptibility of host
- Modification of host resistance
- Vaccination
Environment – Decrease pathogen transmission
- Restriction of host movement
- Quarantine/Isolation
- Control of vectors
- Biosecurity
Pathogen – Decrease pathogen population
- Therapeutics - drugs
Describe host factors of disease prevention and control
Give examples.
Improve host resistance
- e.g. National Scrapie Plan e.g. ARR/ARR resistant genotypes
Vaccination
- Strategic vaccination – e.g. Emergency vaccination in an outbreak (swine flu)
- Blanket vaccination – e.g. Rabies and travelling pets on Pet Passport Scheme
What environmental factors help with disease prevention and control? Give examples.
Movement restrictions: Limit host movement to reduce spread
- e.g. 6-day standstill for cattle/sheep in UK, swine fever travel limits to Mexico
Quarantine/Isolation: Separate infected or exposed individuals
- e.g. Norovirus isolation for >48 hrs (exceeds incubation period)
Vector control: Target & reduce disease-carrying vectors
- e.g. Ixodes ticks for Lyme disease
Biosecurity measures: Prevent disease entry/spread via fomites or visitors
- e.g. Avian Influenza outbreaks (2020–2023)
What is contact tracing in disease prevention and control
Identification of those needing to be restricted - Test and trace systems (‘contact tracing’)
Aim is to identify infected individuals before they are able to transmit disease to others
Requirement for isolation for infected individuals, quarantine for those in close contact with infected individuals
What are pathogen factors of disease prevention and control
Decrease pathogen load - Therapeutics
- Not always effective e.g. nitazoxanide for Cryptosporidium in people
- OK at individual animal/farm level, but poor regionally/nationally
- Expensive
- ?Antimicrobial resistance & anthelmintic resistance
Describe methods of disease eradication and give examples for each
Test and removal
- Animals testing positive are removed and slaughtered
- E.g. Bovine tuberculosis
Pre-emptive
- Animals that have been exposed to infection are slaughtered
- E.g. Pre-emptive culling in the UK for Avian Influenza 2020
Blanket culling
- Animals on contiguous premises surrounding an infected farm are culled
- E.g. Killing domestic pigs in Asia to stop African swine fever spread - 2019
‘Stamping out’
- Combination of one of the above with other preventive measures
- E.g. disinfection, burning of carcasses, dangerous contacts culled during FMD 2001 outbreak
What are communicable diseases
Communicable, or infectious diseases, are caused by microorganisms such as bacteria, viruses, parasites and fungi that can be spread, directly or indirectly, from one person to another. Some are transmitted through bites from insects while others are caused by ingesting contaminated food or water
What is an outbreak
A disease outbreak is the occurrence of cases of disease in excess of what would normally be expected in a defined community, geographical area or season.
Outbreaks are maintained by infectious agents that spread directly from person to person, from exposure to an animal reservoir or other environmental source, or via an insect or animal vector.
Human behaviours nearly always contribute to such spread
What is the role of an outbreak control team (OCT)?
The outbreak control team (OCT) is in charge of investigating, controlling and managing an outbreak.
Their primary objective is to protect the public health by identifying the source and etiology of infection as well as the transmission dynamics and to put in place control measures to prevent the spread
Name the members of an OCT
