Lecture 19 4/8/24 Flashcards
What are the four components of a transboundary disease?
-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
What are the big three transboundary diseases?
-foot and mouth disease
-African swine fever
-PPR
What are the characteristics of FMD?
-picornavirus
-highly contagious
-tremendous economic losses
-eradicated in North America and Western Europe
-list of “disease free” countries for trade purposes
Why is there not a great vaccine for FMD?
-seven distinct serotypes with no cross-immunity
-RNA virus; prone to mutation
Which species are susceptible to FMD?
-cattle: indicator species
-sheep/goats: maintenance species
-pigs: amplifier species
How is FMD transmitted?
-direct contact
-aerosols
-consumption of contaminated pork or milk
-lack of PPE
What is the pathogenesis of FMD?
-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
What are the clinical signs of FMD in cattle?
-pyrexia
-anorexia
-reduction in milk production
-drooling
-teeth grinding
-vesicles on facial mucus membranes
-lameness
-stamping/kicking
-agalactia
What are the clinical signs of FMD in sheep and goats?
-often asymptomatic or have subtle lesions
-interdigital vesicles
-oral lesions
-agalactia
What are the clinical signs of FMD in pigs?
-severe foot lesions and lameness
-vesicles at pressure points on the limbs
-knuckling
-oral lesions
-death due to myocarditis
Why is it important to know that horses cannot contract FMD?
horses CAN contract VSV, which has a very similar presentation to FMD and is still reportable
Why is FMD of importance?
-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
What can cause outbreaks of FMD?
-infected animals
-feeding contaminated garbage
-fomites
-contaminated biological products
How can FMD be controlled?
-screen new herd entries
-depopulate affected animals and carriers
-disinfect affected areas
-ring vaccination
-mass vaccination where endemic
What are the characteristics of African swine fever?
-Asfarviridae
-in wild and domestic pigs
What are the characteristics of the ASF sylvatic cycle of transmission?
-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
What are the characteristics of the ASF domestic cycle of transmission?
-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
What is the pathogenesis of ASF?
-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
What are the clinical signs of the acute phase of ASF?
-sudden death with few signs
-pyrexia
-leukopenia
-thrombocytopenia
-erythema on tips of ears, tail, distal extremities, ventrally
-anorexia
-listlessness
-cyanosis
-incoordination
-vomiting
-diarrhea
-abortion
What are the clinical signs of the chronic phase of ASF?
-weight loss
-irregular temp.
-resp signs
-skin necrosis
-skin ulcers
-arthritis
-pericarditis
-lung adhesions
-persistently enlarged LNs
How is ASF prevented/controlled?
-sanitary prophylaxis
-proper disposal of waste
-careful import policies
-rapid slaughtering of all pigs during outbreaks
-insecticides
-preventing contact between domestic and wild pigs
