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Integrated Health Management > Emerging Infectious Diseases > Flashcards

Emerging Infectious Diseases Flashcards

1
Q

How many emerging pathogens are zoonotic?
How many emerging zoonotic pathogens are vector transmitted?
How many emerging/re-emerging diseases affecting humans have originated in animals (21st century)

A
  • 75%
  • 70%
  • 75%
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2
Q

What are emerging infectious diseases

A

= diseases that have recently
~ increased in incidence
~ spread geographically - e.g. due to climate change, mosquitos survive in more contries due to rise in temperature
~ infected a new species or population

  • diseases caused by new varients assigned to known pathogen e.g. avian influenza
  • pathogens newly resistant to antibiotics
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3
Q

Why are their more EID in developed countries

A
  • more people/livestock so more human-animal contact
  • building people areas in close quarters to animals
  • pasture next to arable crop (maximising land space, little gap between areas) - ecotones allow for lots of wildlife to live between different crops and spread disease
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4
Q

What are the biggest problems that cause EID

A

vectors and wildlife

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5
Q

Major global health threats

A
  • pandemic risks and other EIDs in humans and animals
  • pathogens turning more virulent = infect more easily and have bigger impact on individual affected
  • existing pathogens moving into novel areas and hosts
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6
Q

Global challenges to health maanegment

A
  • increased productivity demand
  • education (lack)
  • increase population
  • land use
  • anthropogenic effect on nature (human impact e.g. deforestation)
  • globalisation
  • poverty
  • increase demand for food
  • natural disasters
  • climate change
  • movement over boarders
  • gov one healthlack cooperation
  • increase no. companion animals
    antibiotic resistance
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7
Q

Major drivers of EIDs (3 catagories and dirvers)

A
  • drivers that enhance disease spread by existing pathogens into new areas
    (increase animal pop, land use, climate change, increased pop density, globalisation, natural resource management challenges)
  • drivers that increase pathogen virulence
    (mass-rearing, use of antibiotics)
  • drivers of emergance of novel pathogens
    (increase human-animal contact, globalisation)
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8
Q

Modelling the rate of EIDs

A
  • the SIR model
  • susceptible, infectives and removed
  • necessary to determine:
    ~ factors that increase susceptability (compromised immune system, increase stocking density
    ~ factors that increase risk of exposure (movement)
    ~ factors that increase how infectious individual is (e.g. ringworm = only pass by direc contact, TB = aerosol, airborn = very transmissible
    ~ rate at which susceptible organisms get infected
    ~ rate at which infected individuals recover or die
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9
Q

Factors that increase susceptability

A
  • new pathogen in previously uninfected area (trade, infected vector or contaminated products)
  • movement of naieve individuals where pathogens exist (migration, expanse of agriculture, exploitation of natural resources)
  • if existing population are immunosuppressed (aging, poor vaccination program, poverty, undernutrition)
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10
Q

Factors that increase the risk of exposure

A
  • climate change
  • high animals density and population
  • increased no. of vectors
  • industrilisation of animal production
  • reduced food safety
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11
Q

Factors that impact infectivity

A
  • compromised immune system (aging, polution, malnutrition, water scarcity)
  • inadequate access to veterinary/medical care (lack of funding, remote areas)
  • ## excess use of antibiotics = resistant pathogens
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12
Q

Bluetongue Virus - about

A
  • non-contageous vector borne virus
  • 27 strains
  • emerged from east asia over 1000 years ago
  • transmitted via midgies on the wind = Culicoides spp
  • host to host transmission = biting midgies
  • historically confined to tropical and subtropical areas
  • goats ancestral host
  • climate change and trade patterns lead to outbreaks on tempret regions
  • 9 strains in europe
  • UK BT free but risk of midgies
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13
Q

Bluetongue - epidemic 2006-2008

A
  • 2006 ~ BT virus serotype 8 (BTV-8) invaded areas substantially further north than previously
  • 2000 cases confirmed end 2006
  • queit until June 16th 2007 in germany (virus overwintered)
  • rapid spread nov 2007 = 45000 cases
  • sept 15th 2007 = first case in UK suffolk (came with animal in fleese = low temperature)
  • dec 2007 = 66 cases in east england
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14
Q

Analysis if BTV-8 in france 2007-2008 - 5 themes, 16 variables

A
  • Host availability (density dairy, density of beef cattle, sheep density,)
  • Vaccination (No. of vaccinated animals)
  • Elevation (metres above sea level) may affect vector abundance
  • Landscape-related variables (proportion of area covered by pastures, arable land or forests)
  • Meteorological-related variables (average rainfall and temperature 1 month, and 2 months prior to first outbreak)
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15
Q

Analysis if BTV-8 in france 2007-2008 - factors affecting disease emergance and spread (velocity)

A
  • elevation reduced velocity the most followed by vaccination = 4.3km/day
  • weather lag increased velosity (spread) the most = 5.3km/day
  • average velosity = 4.9km/day
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16
Q

Analysis if BTV-8 in france 2007-2008 - impact of land related variables

and impact of climate

A
  • 10% increase in % of pastures or arable land increased velocity by 0.04km/day
  • highest BTV spread in areas with:
    ~ highest % of pastures or arable land
    ~ highest edge densities between forest-pasture or forest-arable

(Pioz et al 2012)

  • ecological variables related to Culicoides vectors (elevation temperature and rainfall) were the main factors influencing velocity
  • velocity lowest = high rainfall (84.5-324mm/month) and low temperature (4.5-19 degrees)
  • velocity highest = low rainfall (13.1-42.8mm/month) and high temperature (23.1-25.8 degrees)
17
Q

Blue tongue threat 2018

A
  • germany
  • outbreak 17th dec 2017
  • 28 cases by 3rd wk of jan 2018
  • 28 cases SW germany
  • 28 cases north (luxembourg, netherlands, belgium at risk)
  • large scale vaccination in 2006-08 controlled BTV-8 outbreak
  • outbreak re-emerged = large no. unvaccinated animals
  • require >95% vaccination of susceptible animals for 5 years to eliminate virus in N.europe
  • new cases emerging at time when vector populations low
  • vector season = late spring/summer so season has ended and cold in germany
  • likly an effect of movement of cattle
  • advised vaccination (not manditory)
  • at least 80% vaccination required to prevent outbreak
18
Q

Bluetongue threat 2019 and 2020

A
  • dec-mar 2019 = 50 outbreaks in germany
  • 1 in belgium feb 2019, 3 in march
  • march-july = 4 outbreaks in germany
  • macedonia = 404 sheep infected
  • greece first reported case in 2020 (277 total)
  • 118 cases italy
19
Q

Buetongue threat 2021 and why five fold increase on numbers compared to same 5 months of 2020

A
  • 140 cases from 1st jan - 31st may 2021
  • 83 italy
  • 1 germany
  • risk to UK via importation
  • uk farmers must vaccinate agaist BTV-8/4 if transporting animals to infected zones and traveling back to BTV free zone
20
Q

Challenges in management strategies - Global Public Good concept

A
  • the increase in population and more people shifting from poverty to middle class cause increase in food demand and causes increased globalisation
  • refers to goods whose benefits extend to all countries
  • depend on each other around animal disease control
21
Q

Management strategies to reduce impact on EID on animal health - European Union and Animal Health Law

A
  • common market in European union huge challenge for animal health policy = eliminates trade barrier for goods and labor, allows free movement of animals and people without restrictions, increase risk of disease spread
  • new laws move away from finatial losses by animal disease and focuses on funding ways to prevent
    (e. g. increase biosecurity, managing diseases control)
  • introduction of the Animal Health Law in 2016
    ~ greater use of new technology for animal health activities such as survalence of pathogens
    ~ earlier detection and control of emerging diseases
    ~ flexibility to adjust rules to local circumstance (outbreaks)
    ~ legal basis to monitor animal pathogens resistnt to antimicrobial agents
22
Q

Neglected zoonotic diseases

A
  • dont cross international boaders easity but spread localy
  • affect poor/disadvantaged people
  • neglected by research
  • considerable impact on morbidity/mortality
    (e. g. bovine tuberculosis)
  • diseased under control in most parts of world but remain in developing world
  • impacts livestock owners and families through infection of animals, diminishing productivity which contributes to circle of poverty
23
Q

Bluetongue - vaccines

A
  • live attenuated vaccines introduced in early 1900s but genetic diversity continued to peak
  • indroduced recombinant vaccines in 1990s = substancial decline in genetic diversity
  • but still continuous emergance of new strains = vaccine development barely keeps up
24
Q

Bluetongue - migration of disease

A
  • migration between asia and austrailia = started mid 1500s
  • migration between asia and europe = late 1700s
  • Europe primary source of BTV into Africa in 17/1800s = colonisation and export of livestock
25
Q

Why is geography and climate strong influence on spread/transmission
(Pioz et al 2012)

A
  • many Culicoides life cycle parameters related to temperature, humidity and windspeed
  • temp influences activity, survival and development of Culicoides
  • flying activity inhibited by heavy rainfall = decreased velocity
  • elevation = found lowest velocities at highest elevation range
  • dairy cattle density = higher density meant slower velocity
    ~ housed in buildings so discontinous host pattern, limited active dispersion of Culicoisdes, spread less to cattle compared to through diffusion ouside
    ~ less exposed to biting midges (milked in afternoon and housed all night)
26
Q

Global drivers of disease emergence - Globalisation

A

= the spread of products and people across national boarders

  • millions animals transported anually, affect wildlife and trade with exotic/pet animals = one of causes behind spread of amphibian chytridomycosis
  • brings in new pathogens and vectors to naieve populations
  • pathogens dont need dont need to be transported within host (e.g. ballast water = cholera)
  • facilitates world wide spread of disease
  • essential for trade and economies and desired for part of population for traveling
27
Q

Global drivers of disease emergence - Deforestation and reforestation

A
  • deforestation creates more larval habitats = incrase no. vectors
  • most mosquitos oppertunistic, adapt to new hosts in these new areas = introduction of new disease cause other animals to be resevoirs
  • increases risk of viral transmission = require long time to prob and salivate more which is how they spread the disease, spread more pathogen
  • reforestation in suburban/rural areas lacks the high biodiversity in natural forests
  • increased transmission of vector borne pathogens due to disaperance of hosts, not amplifying virus = reduce dilution effect cased by non- reservoir animals eng infected by vectors
  • reforrestation associated with increased wildlife but less predators
  • dominated by wild animals that benefit from fragmented habitats (e.g. squirrels, mice)
  • reduction in species non-competent (not infectious) hosts for lyme disease and increase in resevoires = caused lyme disease to increase with increased reforestation
28
Q

Global drivers of disease emergence - Hunting and bushmeat

A
  • increases interface between humans and wildlife
  • expose humans to wildlife vectors
  • impact biodiversity = decrease disease resevoirs
    or increase resevoirs in predator removed
  • wild meat consuption risk factor for disease transmission
  • improtant food source (proteins)
  • ## trade involves direct contact with multiple people alongside pathogens of wild animals
29
Q

Global drivers of disease emergence - Population growth and urbanisation

A
  • > 50% pop live in urban areas
  • migrate to better job/lifestyle
  • cities higher temperatures and less varied seasons = increase risk of disease
30
Q

Global drivers of disease emergence - Irrigation and dams

A

= agricultural process of applying controlled amounts of water to land to assist in the production of crops
- contributed to 40% global crop production, increased outputs and crops beneficial to health
- association between increased irrigation and increased incidence of disease = Japanese encephalitis virus
~ density of rice fields shown to be positively associated with Culex tritaeniorhynchus ( main vector for JEV

31
Q

Global drivers of disease emergence - livestock intensification and extensification and adv/dis for both in terms of disease management

A
  • increasing demand for production of animal products in developing countries
  • more animals kept in commercially, highly productive envrironment
  • demand for organic products and higher animal welfare in developed countries = extensification
  • increased indoor pig keeping reduced Toxoplasma gondii parasites compared to free range fams which showed re-emergance
  • intensified production causes increased contactbetween animals, many that are geneticly similar, bred for other purposes rather than disease management and kept in stressful environments = increase risk of disease spread, high no.s carrying zoonotic pathogens
  • intensive systems lack ventilation and safe disposal of manure
  • industrialised systems cause increase segrigation of animals and their vectors
  • extensive systems associated with disease risk
    ~ avian influenza outbreak in southeast asia dependant on rice production, duck densities and human pop density
    ~ backyard poultry keeping in poor/rural areas as well as small flocks in urban areas = biosecurity measures/awarness limited

Integrated Health Management (15 decks)

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