Lecture 19 4/8/24

Question 1

What are the four components of a transboundary disease?

Answer 1

-cause high morbidity and/or mortality in animals
-highly contagious/potential for rapid spread
-persistent threat to livelihood of livestock farmers
-often cause epidemics and affect multiple nations

Question 2

What are the big three transboundary diseases?

Answer 2

-foot and mouth disease
-African swine fever
-PPR

Question 3

What are the characteristics of FMD?

Answer 3

-picornavirus
-highly contagious
-tremendous economic losses
-eradicated in North America and Western Europe
-list of “disease free” countries for trade purposes

Question 4

Why is there not a great vaccine for FMD?

Answer 4

-seven distinct serotypes with no cross-immunity
-RNA virus; prone to mutation

Question 5

Which species are susceptible to FMD?

Answer 5

-cattle: indicator species
-sheep/goats: maintenance species
-pigs: amplifier species

Question 6

How is FMD transmitted?

Answer 6

-direct contact
-aerosols
-consumption of contaminated pork or milk
-lack of PPE

Question 7

What is the pathogenesis of FMD?

Answer 7

-adheres to mucosa of resp. tract
-macrophages transport virus to epithelium, mucosa, and myocardium (secondary sites)
-replicates at secondary sites and develops vesicles
-secondary infection can lead to chronic lameness

Question 8

What are the clinical signs of FMD in cattle?

Answer 8

-pyrexia
-anorexia
-reduction in milk production
-drooling
-teeth grinding
-vesicles on facial mucus membranes
-lameness
-stamping/kicking
-agalactia

Question 9

What are the clinical signs of FMD in sheep and goats?

Answer 9

-often asymptomatic or have subtle lesions
-interdigital vesicles
-oral lesions
-agalactia

Question 10

What are the clinical signs of FMD in pigs?

Answer 10

-severe foot lesions and lameness
-vesicles at pressure points on the limbs
-knuckling
-oral lesions
-death due to myocarditis

Question 11

Why is it important to know that horses cannot contract FMD?

Answer 11

horses CAN contract VSV, which has a very similar presentation to FMD and is still reportable

Question 12

Why is FMD of importance?

Answer 12

-ulcers are very painful to animal
-affected animals do not eat, nurse, or move
-tremendous losses in body weight and milk production
-often cannot fully recondition a recovered animal
-disease of LOST PRODUCTION

Question 13

What can cause outbreaks of FMD?

Answer 13

-infected animals
-feeding contaminated garbage
-fomites
-contaminated biological products

Question 14

How can FMD be controlled?

Answer 14

-screen new herd entries
-depopulate affected animals and carriers
-disinfect affected areas
-ring vaccination
-mass vaccination where endemic

Question 15

What are the characteristics of African swine fever?

Answer 15

-Asfarviridae
-in wild and domestic pigs

Question 16

What are the characteristics of the ASF sylvatic cycle of transmission?

Answer 16

-maintenance cycle
-asymptomatic infection in wild pigs and soft ticks
-young warthogs develop viremia, allowing for infection of more ticks
-older warthogs persistently infected, but not viremic

Question 17

What are the characteristics of the ASF domestic cycle of transmission?

Answer 17

-ticks or consumption of contaminated tissues lead to outbreaks in Africa
-direct contact and aerosols lead to outbreaks in Europe and Asia
-mechanical spread via people, vehicles, and fomites

Question 18

What is the pathogenesis of ASF?

Answer 18

-enters via aerosol, direct contact, etc.
-infects macrophages/monocytes
-infects liver, LN, lungs, blood, other tissues with macrophages
-acute phase involves cytokine storm, endothelial damage, thrombosis, organ failure, and hemorrhage
-persistence can occur due to lower virulence variants
-can produce proteins that inhibit apoptosis
-can cause lifelong carriers

Question 19

What are the clinical signs of the acute phase of ASF?

Answer 19

-sudden death with few signs
-pyrexia
-leukopenia
-thrombocytopenia
-erythema on tips of ears, tail, distal extremities, ventrally
-anorexia
-listlessness
-cyanosis
-incoordination
-vomiting
-diarrhea
-abortion

Question 20

What are the clinical signs of the chronic phase of ASF?

Answer 20

-weight loss
-irregular temp.
-resp signs
-skin necrosis
-skin ulcers
-arthritis
-pericarditis
-lung adhesions
-persistently enlarged LNs

Question 21

How is ASF prevented/controlled?

Answer 21

-sanitary prophylaxis
-proper disposal of waste
-careful import policies
-rapid slaughtering of all pigs during outbreaks
-insecticides
-preventing contact between domestic and wild pigs