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4/14/2017
1
Infectious animal diseases Epidemiology and control measures
Katsuaki Sugiura
Global Animal Resource Science
Nogaku Kokusai Tokuron 1 2017_0421
AGENDA :
• What are infectious diseases
• Interventions for the control of infectious
animal disesases
• Foot and mouth disease
• Rabies
• African swine fever
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What are infectious diseases
• Diseases caused by infection
• Infection is the invasion of the host animal by micro-organisms (viruses, bacteria, fungi and parasites) and their multiplication.
Disease cycle
Exposure
Incubation period
Latency period
Prodromal period
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Incubation period
Disease Incubation period
Influenza 1-3 days
HIV 2-3 months or longer
Measles 9-12 days
Rabies 1-3 months but varies from <1 weeks to >1 year
Foot and month disease 2-14 days
Rinderpest 3-15 days
African swine fever 3-15 days
BSE 2-9 years
Three factors involved in transmission of infectious diseases
Host (susceptible animals)
Pathogen (infected animals)
Environment (transmission media)
Direct transmission
Indirect transmission
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Transmissible diseases
Mode of transmission Examples
Direct contact Indirect contact Vector
Contagious ○ ○
○
African swine fever
○
○
FMD, Rinderpest
○ ○
Equine infectious anemia
○ Rabies
○ Strongylosis
Non-contagious
○ Arboviruses
Genetic defects
Epidemic patterns
8
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Basic reproduction number (Ro)
• Number of infections produced on average by an infected animal during its infectious period (generation time), when all contacts are susceptible.
• When Ro>1, epidemic occurs, and when Ro<1 epidemic does not occur.
• The value of Ro depends on the infectiousness of the disease, contact rate between animals, generation time.
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Basic reproduction number (Ro)
Human disease Transmission R0
Measles Airborne 12–18
Diphtheria Saliva 6–7
Smallpox Airborne droplet 5–7
Polio Fecal-oral route 5–7
Rubella Airborne droplet 5–7
Mumps Airborne droplet 4–7
HIV/AIDS Sexual contact 2–5
Pertussis Airborne droplet 5.5[2]
SARS Airborne droplet 2–5[3]
Influenza (1918 pandemic strain)
Airborne droplet 2–3[4]
Ebola (2014 Ebola outbreak)
Bodily fluids 1.5-2.5[5
Basic reproduction number (Ro)
Animal disease Transmission Ro
Foot-and-mouth disease
Air-borne 38.5
1964 UK epidemic
BSE Feed-born 400 1983-1988 UK epidemic
Rabies Saliva 1.05 1950 Tokyo epidemic
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Reproduction number changes
Impact by various diseases
Public health Spread Cost Trade
FMD - +++ +++ +++ Rabies +++ + + + BSE +++ + +++ +++ ASF - +++ +++ +++
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AGENDA :
• What are infectious diseases
• Interventions for the control of infectious
animal disesases
• Foot and mouth disease
• Rabies
• African swine fever
Possible interventions in free countries
• Import restriction policy for animals and animal products
• Disposal of waste food from international aircraft or ships
• Disinfection of international travelers' footwear
• Warning people • Early detection of infected
animals • Vaccination of susceptible
animals
Avoid pathogens and transmission
Immunize hosts
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Possible interventions in outbreaks
• Killing of infected animals • Cleaning and disinfection • Surveillance of infected area • Movement control of
susceptible animals • Avoid contact between
susceptible animals and vectors
• Vaccination • Treatment with
antimicrobials • ・・・
Combat pathogens
Avoid transmission
Immunize or treat hosts
Vaccination is not perfect
• Good vaccines provide long and strong protection.
• For diseases with a single antigenic type (e.g. rinderpest, rabies), vaccines produced with one simple strain of the pathogen is capable of conferring protection against any of the other strains of the same pathogen.
• Some vaccines only protect animals from the disease not from infection.
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Pros and cons of vaccination
(Pros)
• Provide clinical protection;
• Reduce circulation of the pathogen;
(Cons)
• Induce incidents or accidents;
• Interfere with screening techniques;
• Costly
Epidemiological structures that influences the vaccination result
• Single domestic species with no wild species or vector
• Several domestic species with no wild species or vector
• Several domestic and wild species with no vector
• Several domestic and wild species with vector
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Epidemiological context of rabies in Europe
Cattle
Foxes
Dogs Cats Other
Humans
Vaccination of foxes
Vaccination of humans
Vaccination of domestic animals
Wildlife cycle
Spillover
Domestic relay
AGENDA :
• What are infectious diseases
• Interventions for the control of infectious
animal disesases
• Foot and mouth disease
• Rabies
• African swine fever
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What is FMD
• A viral disease
• 7 serotypes
• Cloven-hoofed animals (cattle, sheep, goats, pigs, etc.) are susceptible
• Highly contagious
• Vaccines available (protect animals from the disease but not from infection)
What is FMD
• A viral disease
• 7 serotypes
• Cloven-hoofed animals (cattle, sheep, goats, pigs, etc.) are susceptible
• Highly contagious
• Vaccines available (protect animals from the disease but not from infection)
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Three factors involved in transmission of FMD
Host (susceptible animals)
Pathogen (infected animals)
Environment (transmission media)
Direct transmission
Indirect transmission
Contaminated hands, footwear, clothing, vehicles; Contaminated meat products, milk; Contaminated semen;
Contact between animals
Contaminated aerosols; Airborne; Humans.
Interventions taken in free countries without vaccination
• Import restriction policy for animals and animal products
• Disinfection of international travelers' footwear
• Warning people not to visit farms
• Maintenance of early detection capability
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Interventions taken in free countries and zones with vaccination
• Import restriction policy for animals and animal products
• Maintenance of early detection capability of infected animals
• Vaccination of pigs, cattle and sheep
Possible interventions taken in outbreaks
• Killing of infected and contact animals
• Destruction of contaminated goods
• Movement control of animals, animal products
• Disinfection of vehicles, equipment and people
• Vaccination of animals at risk
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AGENDA :
• What are infectious diseases
• Interventions for the control of infectious
animal disesases
• Foot and mouth disease
• Rabies
• African swine fever
What is rabies?
• A viral disease
• All mammals are susceptible
• Transmit by direct contact
• 100% lethal
• Vaccine available
• PEP available
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Rabies free countries/areas
Three factors involved in transmission of Rabies
Host (susceptible animals)
Pathogen (infected animals)
Environment (transmission media)
Direct transmission
Indirect transmission
Contact between animals
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Interventions taken in rabies free countries
• Import restriction policy for animals
• Capability maintenance of early detection of infected animals and surveillance
• Registration of dogs
• Vaccination or no vaccination but with vaccine reserve
Interventions taken in rabies infected countries
• Vaccination of dogs (and wild animals)
• Registration of dogs
• Capturing of wild and free roaming dogs
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AGENDA :
• What are infectious diseases
• Interventions for the control of infectious
animal disesases
• Foot and mouth disease
• Rabies
• African swine fever
What is African Swine Fever
• A viral disease
• Pigs, warthogs, wild boars and some ticks are susceptible
• Highly contagious
• High mortality in pigs
• Resistant pathogen
• No vaccine available
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Direct transmission
Indirect transmission
Sucking Sucking
Ticks
Pigs Wild boars
How is ASF transmitted
Warthogs
Sucking
Direct and indirect transmission
ASF is maintained in Africa
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Sources of ASF infection from African continent into free areas
Transmission route Location and date of occurrence
Raw pork waste at airport/port
Lisbon, 1957 Sao Tome, 1979 Madagascar, 1998 Georgia, 2007
Movement of pork or pig product
Portugal, 1960
Sources of ASF infection into other countries
Transmission route Location and date of occurrence
Raw pork waste at airport/port
Malta, 1978 Sardinia, 1978 Dominican Rep., 1978 Cuba, 1980
Movement of pork product
Spain, 1960* France, 1964* Italy, 1983 Belgium, 1985*
Natural ranging of infected wild boar
Russia, 2007 Lithuania, 2014 Poland, 2014 Latvia, 2014 Estonia, 2014
Movement of pigs Haiti, 1978
*Smuggling of pig products
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European situation
0
50
100
150
200
250
300
2007 2008 2009 2010 2011 2012 2013 2014 2015
1 7
18 22 14 9 13
261
166
18
39 35
54 50 58 57
75
13
Nº
of
anim
als
infe
cted
Wild boar
Domestic swine
Three factors involved in transmission of ASF
Host (susceptible animals)
Pathogen (infected animals)
Environment (transmission media)
Direct transmission
Indirect transmission
Infected pork products Ticks Premises, people and trucks
Contact between animals
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Interventions taken in countries free from ASF
• Import restriction policy for animals and animal products
• Disposal of waste food from international aircraft or ships
• Sterilization of garbage
• Maintenance of early detection capability
Possible interventions taken in outbreaks
• Killing of infected and contact animals
• Destruction of contaminated goods
• Movement control of animals, animal products
• Disinfection of vehicles, equipment and people
• Avoid contact between pigs and tick vectors (endemic African countries)