Introduction to epidemiology Flashcards
veterinary epidemiology is…
care & treatment of animals
- the study of the FREQUENCY, DISTRIBUTION, and DETERMINANTS of health and disease in populations
- the application of this - prevent, manage, and eradicate health problems
scope of veterinary epidemiology
- study of health and disease in anima populations
- traditionally focused on disease in humans => applied to animals through ‘One Health’
- multidisciplinary => adding techniques, skills to help prevent disease
- included in One Health Systems approach: really about connections b/twn animals and humans
- scope grown and expanded across disciplines, continues to grow => mental health focus
who are epidemiologists?
a very diverse group!
Edward Jenner (1749-1843)
“Father of immunology”
- smallpox late in 18th c.
- observations: dairy maids and cowpox => those exposed to virus by cows never got smallpox
- variolation:
- infected individuals w/ smallpox material (used pus)
- some died, infected others or became infected w/ other infections
- there are some who also became immune
- the first large scale experiment to immunize healthy people against disease
James Lind (1716-1794)
Scottish doctor in Royal navy
“Father of Nautical Medicine”
- scurvy: caused by lack of vitamin c
- typical navy diet where people tend to get sick:
- breakfast: water gruwl w/ sugar
- dinner: meat broth w/ biscuits
- snacks: barley, raisins, rice, currants, wine
- first ever RANDOMIZED CONTROLLED TRIAL research study to assess if acidic fruit would cure scurvy => thought acids kill pathogens so he fed them lemons, limes, oranges etc.
Early Randomized Control Trial
- 6 groups of 2 men who received varying treatments
- one included 2 oranges and 1 lemon per day => recovered in ‘dramatic fashion’ compared to others
- and those who didn’t have scurvy didn’t get scurvy after eating them
-showed citrus fruits cured scurvy
- this is an example of black box epidemiology
- don’t know cause of disease
- investigation (observations), creative thinking, trial and error, research
John Snow (1813-1858)
Doctor & Anesthesiologist
Father of modern epidemiology
‘epidemiology of cholera’ => caused by infectious bacterial disease through drinking contaminated water supply
- looked at through population level, frequency, distribution w/n population
- also first to study anesthesia in people and animals: specified appropriate doses
- based on age
- first doses for ether and chloroform
- found out that broadstreet pump was infected w/ cholera => he traced people and tracked transmission
Veterinary medicine and epidemiology in 1st century (CE)
- increased domenstication of animals
- disease prevalent
- increased urbanization and keeping of animals = more disease
- Egyptian ‘healers’ established first vet hospitals => dedicated to improve health of animals
- techniques used to treat disease & prevent spread:
- quarantine
- slaughter
Veterinary medicine and epidemiology in 1700s-1800s
- animal plauges (notably in cattle)
- techniques to improve animal health:
- farm hygiene
- improved slaughter techniques
- used to slaughter unhealthy next to healthy and came up w/ policies to separate
Veterinary medicine and epidemiology in late 1880s-1900s
- lab diagnosis: from human medicine -> transfer knowledge to vet med
- mass immunization techniques => vaccination protocols established (particularly food animals)
- more scientific study led to improved understanding of pathogens and transmission but not that great
- evidence based medicine
Veterinary medicine and epidemiology: contemporary vet medicine (evidence based medicine)
2 major techniques to improve animal health:
- structured recording on animal health and disease: vets taught to have records
- improved analyses of disease in populations: surveillance and monitoring => important for prevention
- national and international disease reporting (World Organization for Animal Health)
OIE:
- founded in 1924
- responsible for improving animal health worldwide: keep track of outbreaks around the world
- 182 member countries, headquarters in Paris
- collaboration, share resources, codes of practice
OIE: World Animal Health information system (WAHIS)
established in 2015
- provides info on animals
- we only know 120 diseases
epidemiological investigation
tools and methods for investigating, preventing, diagnosing, reducing transmission, and treating disease in animals
Helps us understand:
- disease occurrence (where, who, when)
- causes of disease
- screening for disease: diagnostics => don’t have to wait for clinical signs
- assess effectiveness of treatments
- disease prevention, and prolongation of high quality life
Objectives of epidemiology
- investigation and controlling a disease
important for reducing spread and eradicating disease
ex: food and mouth disease in sheep
- highly contagious virus, divided hooved animals
- spread: contaminated animals, inanimate vectors
UK epidemic in 2001:
- 1st detected south east England
- epidemiological investigation through tracing animal movements
- origin was a sheep farm hundreds of miles away from region largely affected
- infected animals tracked and control measures reduced spread
- understanding natural history of a disease
- understanding how host and agent interact and co-exist w/n community of other organisms in a particular environment
- understanding why some animals get infected and others don’t
- factors impacting agent: climate, environment, geographical distribution etc
- life history, lifecycle
ex: lyme disease: caused by bacteria transmitted by ticks
1. adult tick bites and infects deer, dog, or raccoon
2. adult tick lays eggs (autumn)
3. egg hatches to larva
4. larva feeds on small mammal (summer) and leaves host and molts to nymph (spring)
5. nymph feeds on dog and transfers infection
- infected may show no clinical signs until 2-4 months later (same as humans) => can develop life long issues
6. nymph leaves host and molts to adult tick
