Aujeszky’s Disease

Pseudorabies, Mad Itch

Center for Food Security and Public Health, Iowa State University, 2008

OverviewOverview

• Organism• Economic Impact• Epidemiology• Transmission• Clinical Signs• Diagnosis and Treatment• Prevention and Control • Actions to Take

The Organism

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Aujeszky’s DiseaseAujeszky’s Disease

• Alphaherpesvirus−Genus: Varicellovirus

• Highly contagious• Natural hosts

−Domestic and feral swine−Attenuated strain in feral swine−Somewhat persistent in environment

Several days in environment Aerosol (under favorable conditions)

Importance

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HistoryHistory

• 1902−Aládar Aujeszky, Hungary−First identified in cattle

and dogs−Determined swine were

natural hosts• 1931: “mad itch” same as

Aujeszky’s disease• 1983 survey

−18.8% U.S. breeding swine

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History in the U.S.History in the U.S.

• 1989−National eradication program

USDA APHIS, States and producers Over 8000 herds identified

• 1992−Over 1000 herds remain

• 2004−U.S. commercial swine herds

pseudorabies free

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Economic ImpactEconomic Impact

• Trade restrictions• 1988 study – U.S. epizootic

−Newborn pig mortality 76.5% of total net losses (TNL) Estimated $24/inventoried sow/week

−Nursery pig mortality (12.6% TNL)−Sow culling and deaths (9.4% TNL)

• Hogs and Pigs, U.S., 2008−3 million head farrowed−28.1 million pig crop

Epidemiology

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Geographic DistributionGeographic Distribution

Disease Distribution from January to June, 2007

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Pseudorabies Stages in U.S.Pseudorabies Stages in U.S.

As of Feb 2008

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Morbidity/MortalityMorbidity/Mortality

• Morbidity− Up to 100% in domestic pig herds− Up to 20% abortions− Feral swine do not

develop signs of disease• Mortality

− Highest for younger animals Up to 100% - newborn piglets Up to 50% - nursery pigs

− Decreases with age 5-10% in weaner pigs 1-2% in grower/finisher pigs

− Always fatal in other animal species

Transmission

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Transmission: PigsTransmission: Pigs

• Direct Contact− Nose-to-nose contact− Reproductive

Venereal and transplacental

• Ingestion• Aerosol

− At least 55% relative humidity− Persists up to 7 hours− Can travel up to 2 km

• Fomites− Contaminated bedding and water− Meat products or carcasses

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Transmission: Other speciesTransmission: Other species

• Contact with infected pigs• Ingestion of infected meat• Rarely lateral transmission

Animals andAujeszky’s Disease

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Clinical Signs: PigsClinical Signs: Pigs

• Incubation period: 2-6 days• Piglets less than 1 week old

−Fever, listlessness, anorexia−Neurological

Tremors, paddling, seizures, Hind leg paralysis - “dog-like” position

−High mortality within 24-36 hours• Slightly older piglets

−Similar signs, lower mortality−Vomiting and respiratory signs

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Clinical SignsClinical Signs

• Weaned pigs−Respiratory illness−Neurological signs−Recover in 5-10 days

• Adult pigs−Mild or inapparent infection−Respiratory ± neurological signs−Pregnant sows: reproductive problems

• Feral swine−Asymptomatic

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Clinical Signs: Other AnimalsClinical Signs: Other Animals

• Cattle and sheep− Intense pruritus

Licking, rubbing, gnawing, self-mutilation

− Neurological signs

• Dogs and Cats− Similar to cattle and sheep− Pharyngeal paralysis and profuse salivation− Resembles rabies

• Death in a few days

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Post Mortem LesionsPost Mortem Lesions

• Serous or fibrinonecrotic rhinitis− Visible if head split and

nasal cavity opened• Pulmonary edema,

congestion, consolidation− Secondary bacterial

pneumonia• Congested and

hemorrhagic lymph nodes• Necrosis

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Post Mortem Lesions: PigsPost Mortem Lesions: Pigs

• Neurological− Nonsuppurative meningoencephalitis− Mononuclear perivascular cuffing− Neuronal necrosis− Thickened meninges

• Respiratory− Necrotic tonsillitis, bronchitis,

bronchiolitis, alveolitis

• Reproductive (fetus)− Focal necrosis of liver, spleen,

adrenal glands, lymph nodes

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Post Mortem: Other SpeciesPost Mortem: Other Species

• Edema, congestion, and hemorrhage in the portions of the spinal cord that innervate the areas of pruritus

• Cellular infiltration and neuronal degeneration

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Differential DiagnosisDifferential Diagnosis

• Pigs− Porcine polioencephalomyelitis− Classical or African swine fever− Hemagglutinating encephalomyelitis infection− Streptococcal meningoencephalitis− Swine influenza− Erysipelas− Nipah virus infection− Salt or organic poisoning

• Species other than pigs− Rabies− Scrapie in sheep

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Diagnosis: LaboratoryDiagnosis: Laboratory

• Clinical signs suggestive• Virus isolation• Detection of viral DNA or antigens

− Immunofluorescence, immunoperoxidase, virus neutralization assays, PCR

• Serology−Virus neutralization, latex agglutination,

ELISAs

Aujeszky’s Diseasein Humans

Disease has not been reported in humans

Prevention and Control

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Recommended ActionsRecommended Actions

• Notification of Authorities−Federal:

Area Veterinarian in Charge (AVIC) www.aphis.usda.gov/animal_health/area_offices/

−State veterinarian www.aphis.usda.gov/vs/sregs/official.htm

• Quarantine

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Quarantine and DisinfectionQuarantine and Disinfection

• Isolate and test− New breeding animals

• Biosecurity measures− Prevent entry

By fomites, people,roaming animals

− Double fencing

• Disinfection− Phenols and quarternary

ammonium compounds, sunlight, drying, high temps

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Quarantine and DisinfectionQuarantine and Disinfection

• Depopulation and repopulation−Premises cleaned, disinfected−Left empty for 30 days

• Test and removal −Test breeding herd monthly−Remove positive animals−Difficult to detect the latently infected

• Offspring segregation−Vaccinate breeding herd−Remove young weaned pigs

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VaccinationVaccination

• Protects pigs from clinical signs • Decrease virus shedding• Does not provide sterile immunity or

prevent latent infections• Attenuated, inactivated, gene-

deleted vaccines−Vaccinated pigs which become infected

can be detected

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Additional ResourcesAdditional Resources

• USDA-APHIS website− www.aphis.usda.gov

• World Organization for Animal Health (OIE) website− www.oie.int

• Center for Food Security and Public Health− www.cfsph.iastate.edu/DiseaseInfo/

• Food and Agriculture Organization of the United Nations (FAO) website− www.fao.org

Center for Food Security and Public Health, Iowa State University, 2008

AcknowledgmentsAcknowledgments

Development of this presentationwas funded by grants from

the Centers for Disease Control and Prevention, the Iowa Homeland Security and Emergency

Management Division, and the Iowa Department of Agriculture and Land Stewardship

to the Center for Food Security and Public Health at Iowa State University.

Authors: Katie Spaulding, BS; Anna Rovid Spickler, DVM, PhD; Reviewers: James Roth, DVM, PhD; Glenda Dvorak, DVM, MPH, DACVPM