Applied epidemiology and control Flashcards
Describe disease prevention, disease control and disease eradication
Disease prevention –
Avoiding disease occurrence
Reduces the incidence and prevalence of disease
Rule of thumb (ROT) - Essentially all diseases
Disease control –
Reducing the disease frequency to a tolerable level
Reduces the prevalence of disease
ROT – Diseases that are commonly found or seen, or where eradication is not possible
Disease eradication
The complete elimination of disease, or disease agent from a region
ROT - Exotic diseases, or those commonly found undergoing eradication programmes e.g. BVD in Scotland
Many factors dictate what is undertaken –
Dependent on type of disease, economic/welfare/socio-political and public health impacts
Overlap between the measures used for control, prevention (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
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
Describe environment factors of disease prevention and control
Restriction of host movement
- e.g. limited travel to Mexico during swine fever outbreak (6 day standstill in the UK for cattle and sheep movements)
Quarantine/Isolation
– e.g. norovirus - duration must exceed the incubation period (48 hours) of the disease
Control of vectors
– e.g. Ixodes ticks and Lyme disease
Biosecurity
– e.g. fomite control (management systems that reduce the risk of introducing infectious disease to a herd) – e.g. Avian Influenza 2020, 2021, 2022, 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
