Principles of disease control Flashcards
What are the routes a pathogen can spread?
- direct contact
- aerosol
- orofecal
- vectors
- transplacental
- fomites
Name 2 control measures that can be used to prevent/limit spread?
- prevent entry into the country
- prerequisites
How can disease be prevented entry into a country?
- import controls such as certification, inspections, testing
- quarantine (pre/and or post importation)
vector control
What prerequisites can be used to control disease?
- border security
- traceability
- biosecurity
What is the definition of eradication?
- elimination of pathogen or reduction to negligible levels
What is a notifiable disease and what can they be classed as?
- disease one is legally obliged to report
may be:
* endemic
* exotic
* zoonotic
what is the definition of control?
- reduction to prevalence below a certain level - live with it
Name 2 eradication options?
- test and slaughter - positives removed/slaughtered e.g. TB
- culling of entire group/herd - stamping out - e.g. brucellosis
Name some control options?
- vaccinations (usually where prevalence >5% and insufficient ability to eradicate)
- statutory controls ( isolation, culling, testing, movement restrictions, disinfection)
- active or passive surveillance to detect disease
- treatment
- slaughter and decontamination
What is an inactivated vaccine?
- pathogen treated so cannot replicate when administered
what is a modified live vaccine?
- Low virulent mutant, stimulated antibody response but not disease
What is a subunit vaccine?
- purified parts of organism that stimulate immune response
What is a disease free status?
-“A self-declaration of disease freedom is a documented statement from the Delegate of the OIE Member Country regarding the absence of one or several diseases in a country, zone or compartment”
What organisations are involved in international issues?
- WTO - World Trade Organisation
- WHO - World Health Organisation
- WOAH - World Organisation for Animal Health
What are obstacles are there for disease control?
- deficient measures
- neglected zoonotic disease
- global transport
- reservoir hosts and insect vectors
- nature of the organism
- pathogen mutation
- vaccine failure
Why is deficient measures an issue?
- funding
- infrastructure
- political will
What is a neglected zoonotic disease?
- Zoonotic diseases where control is sub-optimal, usually occurring in poor and marginalised populations in low-resource situations
Why is global transport an issue?
- the world is a small place disease can travel quickly
why are reservoir hosts and insect vectors an issue?
- Reservoir host – carries pathogen, no symptoms, role in onward transmission
- insect vectors – must control to eradicate the disease
Why is the nature of an organism an issue?
- Some – long incubation period – must not exceed quarantine period
- Some – latency – may not show symptoms for years
Why is pathogen mutation an issue?
- viruses can mutate
- new strains can beat vaccines
when can vaccine failure arise?
- Doesn’t protect against all the relevant strains
- Isn’t correctly stored or administered (“cold-chain”)
- Insufficient number of animals vaccinated
- Wrong animals vaccinated (e.g. too young, already infected etc)
What is an endemic?
- refers to the constant presence and/or usual prevalence of a disease or infectious agent in a population within a geographic area
Define sporadic
- refers to a disease that occurs infrequently and irregularly
What is an hyperendemic?
- refers to persistent, high levels of disease occurrence
What is an epidemic?
- refers to an increase, often sudden, in the number of causes of a disease above what is normally expected in that population in that area
What is an outbreak?
- same definition as epidemic but often used for a more limited geographic area
What is a cluster?
- refers to an aggregation of cases grouped in place and time that are suspected to be greater than the number expected, even through the number expected may not be known
What is a pandemic?
- refers to an epidemic that has spread over several continents, usually effecting a large number of people
