animal health - epidemiology + control

:((((

what is epidemiology

• all aspects of studying health at a pop level:

• how disease + health related conds occur

• factors which influence it

• aims to produce factual knowledge to aid in the control of the disease or health related cond

disease distribution

• disease follows specific patterns influenced by a range of diff environmental, genetic and management factors

• if we understand the patterns - helps vets predict, prevent + control diseases

john snow

• founding farther of modern epidemiology

• 1854- investigated cholera outbreak in london + identified contaminated water pump as source

importance of epidemiology

• provides evidence for animal health decision making

• provided the evidence for gov decision making to protect public health

• identifies risk factors + T infrom preventative measures

• guides policy development + resource allocation

risk ratio

• how many times higher is the risk of the outcome among those exposed to the risk factor

• likelihood of disease in animals exposed to a risk factor compared to an unexposed group

odds ratio

• how many times higher were the odds of the outcome in those exposed to the risk factor

epidemiological study types

• descriptive

• aetiological

• evaluative

• experimental

descriptive study type

• describes health + disease + their trends over time in specific pops

aetiological study types

• searches for associative factors influencing disease - diet, microorgs, behavioural factors, age

evaluative study types

• evaluate the impact of preventative measures

experimental study types

• directly investigate causes and associations

• trial of new vaccine

• trials of treatments

essentials for epidemiology

• identification of a disease or health related state:

• entry, incubation period, spread win body, disease forms

• reliable diagnostic tests

• understanding of transmission routes:

• faecal-oral, fomites, vector borne, water born, sexual, vertical, horizontal

role of epidemiology in public health

• disease monitoring + surveillance

• outbreak investigations

• health promotion + disease prevention

• policy making

Types of disease occurrence

• endemic

• epidemic

• pandemic

• sporadic

endemic

• a disease consistently present in a pop at predictable levels

• e.g. bovine tb in certain regions

epidemic

• a sudden inc in disease cases above the normal expectation

• e.g. avian influenza outbreak

pandemic

• a disease outbreak spreading across multiple countries or continents

• e.g. foot + mouth disease

sporadic

• cases occurring irregularly + infrequently

• e.g. rabies cases in vaccinated pops

epidemiological triangle

• host

• agent

• environment

key to control

• biosecurity

• combo of diff measures implemented to red the risk of introduction + spread of disease causing agents

disease control - biosecurity

• approp biosecurity prevents the intro + spread of infectious diseases in a group of animals

• red infection pressure exerted upon the animals

• helps to red reliance on curative measures - improves production, overall health + welfare

principles of biosecurity: 1. Separation

• separate the high and low risk animals

• separate from sources of infection

principles of biosecurity 2: reduce infection pressure

• keep pressure below a level which allows nat immunity to cope

• focus on the high-risk transmission routes - probability + frequency of occurence

external biosecurity

• preventing the intro of infectious agents into an animal facility e.g.: farm, yard, kennels, exotic exhibit

• focus on the links between the facility + outside world: visitors, entrances, deliveries + intro of new animals

internal biosecurity

• prevent the spread of disease win the animal facility

• inc good disease management strats, stocking density, working lines, cleaning regimes

antiseptics + disinfectants

• diff types of disinfectants are used depending on the intended use + what org needs to be effective against

• virus, bacteria, parasites, fungi

antiseptics + disinfectants

• commercial disinfectants often have more than one type of chem agent

• some disinfectants may only be used for certain species

• certain disinfectants may have prolonged contact time to max their range of action

antiseptics - a type of disinfectants

• used topically on the skin

• can be -static - inhabits growth/multiplication of microorgs or -cidal - kills microorgs

disinfectants

• used on surfaces + inanimate objects

• static or cidal

sterilisation

• the killing of all microorgs, inc cells, spores, viruses

• causes irreversible loss of the ability to rep

• physical - dry heat, wet heat, radiation - bunsen burner/autocalve/uv light gamma rays

• chemical - sterliant - formaldehyde, beta propiolactone

antimicrobial

• agent which stops growth: weak to strong

• slows rate of microbial growth

• stops microbes from growing - static

• kills some microbes over time

• kills some microbe quickly

• kills all microbes inc spores quickly

other considerations

• hygiene

• quarantine

• transport

• ventilation

• design + layout