Swine Lecture 14 - Foreign Animal Diseases and Zoonotic Diseases PDF

Swine Lecture 14 Foreign Animal Diseases and Zoonotic Diseases  Swine Lecture 14 Foreign Animal Diseases and Zoonotic Diseases OBJECTIVES: n To be able to describe the typical clinical signs, epidemiology, pathogenesis, diagnosis, of Pseudorabies and the n Clinical signs and...

Swine Lecture 14 Foreign Animal Diseases and Zoonotic Diseases  Swine Lecture 14 Foreign Animal Diseases and Zoonotic Diseases OBJECTIVES: n To be able to describe the typical clinical signs, epidemiology, pathogenesis, diagnosis, of Pseudorabies and the n Clinical signs and post-mortem findings for: n Foot and Mouth Disease n Hog Cholera n African Swine Fever n To recall and list potential zoonotic diseases  Major concerns for the Canadian Swine Industry What are major areas of concern for the Canadian swine industry in the event of an outbreak of foreign animal disease? n Economics n Shut down exports – 50% of production exported n Restrict farm-to-farm movement n Multi-site production, pig flow affected n Disposal of carcasses n Mental health Foreign Disease Threats What major foreign animal disease(s) is/are the “most likely” to occur in the Canadian pig population?  Pseudorabies (Aujeszky’s Disease) Etiology n Pseudorabies virus n suid herpesvirus 1 (suHV-1) n can persist in latent state n resulting in carrier animals and subclinical infections n Moderately resistant outside of the host n Probably doesn’t survive much longer than 2 weeks outside of host n Can be destroyed by disinfectants n Marker vaccines make it possible to distinguish vaccine titres from natural virus antibody levels  Pseudorabies (Aujeszky’s Disease) Epidemiology n Excreted in large numbers in saliva, nasal secretions, urine and feces (for up to 2 weeks) n Persists in tonsil for several weeks n Latent in CNS for many months n Other animals dead-end hosts – causes fatal neurologic disease (rabies-like signs) and severe itching (mad-itch) n Dogs, cats, cattle mice, racoons, mink, foxes…. n Found in most countries except: Canada, Greenland, Australia. n USA – eradicated from commercial herds 2004  Pseudorabies (Aujeszky’s Disease) Transmission n Highly contagious, spreads through herd rapidly n Mainly spread through respiratory route, oral-nasal n pig-to-pig via oral and nasal secretions n Also, transplacental, milk, vaginal mucosa, semen n Possibly airborne n Fomites Transmission  Pseudorabies Pathogenesis: varies depending on the viral strain, age of pig, and viral load n Inhalation or ingestion n Replicates in upper respiratory tract epithelium n Spreads to LN then, CNS: spinal cord and brain n Localizes in many areas forms intranuclear inclusion bodies n Localizes in Tonsil primary site n Causes inflammation and necrosis of tissue n Respiratory tract, bronchial tree, alveoli, endometritis, vaginitis, necrotic placentitis, fetus  Pseudorabies: clinical signs Pig Clinical Signs: n Three ‘overlapping’ syndromes n Age-dependant n Infectious dose and strain dependant n CNS, respiratory and reproductive  Pseudorabies: clinical signs NEONATES: n Ill within 2-4 days after exposure n High mortality ~100% usually within 1-3 days n Sometimes sudden death n Listless, anorexic, and pyrexia n Neurological signs n depression, tremors, convulsions, incoordination, dog-sitting posture, coma and death Weaned pigs: n Similar signs but mortality is usually much lower  Pseudorabies: clinical signs Grow-Finish pigs: n Primarily respiratory signs n Coughing, sneezing, nasal discharge n Loss of body condition n Pyrexia, anorexia, depression n +/- CNS signs: tremors, convulsions n High morbidity and low mortality n many recover in 7-10 days  Pseudorabies: clinical signs Adult swine n Pyrexia, anorexia n Respiratory signs n sneezing and coughing and laboured breathing n Most recover n Abortions, returns, stillbirths, weak pigs  Pseudorabies Other Species: n Dead-end hosts n All livestock mammals, and cats, dogs, raccoons, skunks n Infected animals die within 1 to 2 days before shedding virus – always fatal n Intense pruritis (mad itch) n Neurological signs (rabies-like)  Pseudorabies Tonsil Gross lesions: n fibrinonecrotic rhinitis n necrotic tonsillitis n foci of necrosis in liver (neonate), spleen, lung n aborted fetuses n microscopic lesions in nervous tissue Histology: n intranuclear inclusion bodies Severe necrotizing rhinitis Photo: Halbur via AASV  Pseudorabies Diagnosis and control: n History: including death of cats and dogs, high mortality in neonates, abortions, neurologic signs n Many tests: FA, IHC, PCR, HISTOLOGY n Eradication in U.S. (2004) n DIVA Vaccine (gene-deleted) n Vaccine highly efficacious n No treatment n Inform CFIA of suspected cases – REPORTABLE!!  Vesicular Diseases n Foot-and-Mouth Disease (Picornaviridae, Aphthovirus) n Swine Vesicular Disease (Picornaviridae, Enterovirus) n Seneca Virus A Cases in USA, and identified in Ontario sourced pigs n Vesicular Stomatitis (Rhabdoviridae, Vesiculovirus) n Vesicular Exanthema: San Miguel sea lion viruses n (Calicivirus)  Foot-and-mouth disease (FMD) Etiology and Epidemiology n Picornaviridae n Many strains - differ antigenically, limited cross protection n Transmitted through respiratory droplets and nose-to-nose contact n 50km aerosol n Affects most ruminants and pigs (cloven-hooved animals) n Horses resistant n Canada 1952 & USA 1929 Multi species – HIGHLY contagious. VERY RESISTANT TO DISINFECTANTS, SURVIVES IN ENVIRO FOR LONG TIME  Foot-and-mouth disease (FMD) n Last outbreak in Canada n Saskatchewan 1951-1952 n Delayed confirmation (3 months) n 25 farms affected n cost ~6.6 Billion in today’s dollars n Not accounting for trade  Foot-and-mouth disease (FMD) n Pigs n Lower infectious dose for oral route of exposure relative to ruminant n Relatively resistant to airborne infection n Excretion by air n Infectious pig = 400M infectious doses/day n Infectious ruminant = 120K infectious doses/day n Carrier stage n Cattle – up to 3.5 years n Small ruminants up to 9 months n Pigs = 28 days n Incubation n 2-14 days  FMD n Acute lameness - often first sign noticed n 1-5 days after infection n Pyrexia – slobbering, salivating and chomping n Start as small, blanched foci in skin vesicles on lips and tongue, teats, and udder n High morbidity, mortality ~5% but higher in younger piglets  FMD - Piglets n Vesicles similar to sows n High mortality n Vesicles at coronary bands, hooves may fall off  FMD Status Map https://www.woah.org/app/uploads/2024/06/fmd-world-eng-2024.png  What would happen if outbreak occurred? n Humane destruction of all infected and exposed animals n Tracing to identify locations of potentially infected or exposed animals n Quarantine – and restricted movements n Zoning to define infected and disease-free areas Seneca Virus A (Seneca valley virus)  Vesicular Diseases n Look like Foot and Mouth Disease Vesicles on snout Changing trends in FAD investigations (USDA data) Changing trends in FAD investigations (source: USDA) By species in 2012 vesicular stomatitis By species in 2018…..  Systemic Viral Diseases n Hog Cholera (classical swine fever) n Flaviviridae, Pestivirus n African Swine Fever – African swine fever virus n Japanese B encephalitis - Flavivirus n Blue eye disease - Paramyxoviridae, (Rubulavirus) n Teschen and Talfan - Enterovirus  Large numbers of stillborns Hog Cholera (CSF) can be seen with hog cholera - Pestivirus n Strains vary in virulence n Eradicated from USA in 1970’s Clinical Signs (varies with virulence of virus) 1. Lethargic, depressed, appear chilled 2. High fever, conjunctivitis, +/- constipation 3. Severe watery diarrhea, vomiting 4. Gaunt, weak, posterior paresis, cyanosis 5. Sudden outbreak of high mortality 6. Clinical signs include fever, lethargy, cyanotic extremities Hog Cholera - lesions button ulcers in cecum enlarged spleen with infarction of the spleen “turkey egg kidneys” Petchechia (hemorrhages) in kidney and lymph nodes  What diseases in swine may have similar clinical signs? Cyanotic extremities Ears, Legs Enlarged - infarction of the spleen  African Swine Fever n Asfarviridae n Enveloped DNA virus n Transmitted by arthorpods n Highly contagious viral disease of swine n Isolates vary in virulence n High: up to 100% mortality n Low: seroconversion  ASF n Highly resistant warthog n Killed by high temperatures and some disinfectants n Affects domestic and wild pigs bush pig n May be asymptomatic in wild pigs n No treatment, no vaccine in NA! n FDA vaccine press release Oct 1, 2021 n Viet Nam collared peccary  History n Kenya early 1900s n Spread to Europe n Vector identified/described 1963 n Emergence in western hemisphere 1971 (Cuba) n Recent outbreaks n Africa, Russia, Western Europe, China 2018, Belgium 2018, Dominical Republic 2021!!  ASF Transmission n Direct contact an adult Ornithodoros n Usually oronasal secretions soft tick n Indirect n Uncooked garbage, fomites, bite of infected tick, biting insects n Is found in all tissues and body fluids n Incubation thought to be 5 to 19 days  ASF Clinical Signs Acute disease n Incubation 5-19 days, but can be < 5 days after exposure to tick n Pyrexia, anorexia, erythema, cyanosis n Recumbency n Bloody diarrhea n Abortion n Sudden death  ASF Clinical Signs Chronic disease n Multi-focal erythema n Ears, abdomen n Raised or necrotic areas n Low fever n Painless joint swelling n Emaciation n Death  Post mortem lesions Highly variable lesions but, most common are: Hemorrhagic n Spleen n Enlarged n Friable n Dark red, black n Lymph nodes n Kidneys n Heart  ASF - Differential Diagnosis n Classical swine fever – clinically indistinguishable n Acute PRRS n Porcine Dermatopathy and nephropathy syndrome n Erysipelas n Salmonellosis n Actinobacillosis n Glasser’s disease n Pseudorabies n ………warfarin poisoning, heavy metal toxicosis, thrombocytopenia, generalized septicemic or hemorrhagic conditions  Zoonotic diseases n Many POTENTIAL pathogens n In North America most agents: n Not present or very rarely cause problems n However, may be of importance to young children, those with compromised immune systems  Leptospira pomona Transmitted by urine and infected water Bacterial contact with mucus membranes, skin, eyes Leptospirosis in human – Splenomegaly, hepatitis, nephritis Recommendations 1. Vaccinate sows against Lepto 2. Use gloves when assisting with dystocia  Strep. suis type 2 Widespread among pig population Septicemia, meningitis, balance disorders, hearing loss in people Occupational disease: about 100 cases/yr Low infectivity Most common in abattoir workers and in people in developing countries eating pigs with clinical signs of Strep suis  Toxoplasma gondii Infection via undercooked/uncooked meat Cats excrete oocysts in feces Pigs become infected by consuming oocysts Low prevalence in Ontario herds (1%) and Ontario pigs (0.1%) Control measures - cat & rodent control Persist in tissues of pigs for long periods  Salmonella spp Food-borne human health risk Farm-to-fork continuum Control at abattoir and in kitchen Improved hygiene and management  Others… Influenza viruses of swine Campylobacter Yersinia Listeria