Aujeszky’s Disease (Pseudorabies) in Animals
Introduction
Aujeszky’s disease, also known as Pseudorabies, is a highly contagious viral disease affecting pigs and several other animal species. It is caused by a herpesvirus and is characterized by severe neurological, respiratory, and reproductive disorders depending on the age and species affected. Pigs are the natural host and reservoir, while other species often develop fatal disease.
Etiology
Causative Agent
Aujeszky’s disease is caused by Suid herpesvirus 1 (SuHV-1), a member of the family Herpesviridae, subfamily Alphaherpesvirinae.
Virus Characteristics
- Enveloped, double-stranded DNA virus
- Neurotropic (affects nervous tissue)
- Establishes lifelong latency in infected pigs
- Can reactivate under stress conditions
Epidemiology
Species Affected
- Pigs (primary host and reservoir)
- Ruminants (cattle, sheep, goats) – dead-end hosts
- Carnivores (dogs, cats) – highly susceptible and usually fatal
- Wild boar (important wildlife reservoir)
Transmission
- Direct contact with infected pigs
- Nasal and oral secretions
- Inhalation of aerosols
- Ingestion of contaminated tissues (especially in carnivores)
Risk Factors
- High-density pig farming
- Poor biosecurity
- Mixing of age groups
- Stress (transport, overcrowding)
Pathogenesis
Entry and Replication
The virus enters via mucosal surfaces (respiratory or oral) and replicates in epithelial cells and regional lymphoid tissue.
Spread in Pigs
- Primary replication in respiratory tract
- Viremia leads to systemic spread
- Infection of nervous system and other organs
Latency
Like other herpesviruses, SuHV-1 establishes latency in sensory ganglia (especially trigeminal ganglia) and can reactivate later.
Clinical Signs
In Pigs
Neonatal Piglets
- Severe neurological signs
- Tremors and incoordination
- High mortality
Growers and Finishers
- Respiratory disease (coughing, dyspnea)
- Fever
- Reduced growth rate
Sows
- Reproductive failure (abortions, stillbirths)
- Mummified fetuses
In Other Species
- Severe pruritus (itching) in carnivores
- Neurological signs (aggression, seizures)
- Rapid death (especially dogs and cats)
Summary for Practitioners
Aujeszky’s disease should be suspected in pigs with respiratory and reproductive signs and in carnivores showing severe pruritus and neurological disease after exposure to pigs or pork products.
Postmortem Findings
Gross Lesions
- Respiratory tract inflammation
- Necrotic tonsils and pharynx
- Pneumonia in young pigs
- Fetal lesions: mummification, autolysis
Microscopic Lesions
- Non-suppurative encephalitis
- Neuronal degeneration
- Intranuclear inclusion bodies (herpesvirus feature)
Diagnosis
Clinical Diagnosis
Based on species affected, neurological signs in young animals, and reproductive failure in breeding pigs.
Laboratory Diagnosis
- PCR for viral DNA detection
- Virus isolation
- Serology (ELISA for antibody detection)
Differential Diagnosis
- Classical swine fever
- Porcine reproductive and respiratory syndrome (PRRS)
- Rabies (in carnivores)
- Canine distemper (in dogs)
Summary for Practitioners
Laboratory confirmation is essential due to overlap with other viral diseases. Herd-level testing is important in pig populations.
Treatment
General Consideration
There is no specific antiviral treatment for Aujeszky’s disease.
Management
- Supportive care for affected animals (limited effectiveness)
- Euthanasia in severe cases (especially non-porcine species)
Summary for Practitioners
Treatment is not practical in most cases. Control and prevention are the primary approaches in managing this disease.
Control and Prevention
Biosecurity
- Strict control of pig movements
- All-in/all-out production systems
- Quarantine of new animals
Vaccination
- Marker (gE-deleted) vaccines used in control programs
- Allows differentiation between infected and vaccinated animals (DIVA strategy)
Eradication Programs
- Testing and removal of infected animals
- Surveillance and certification schemes
Wildlife Control
- Monitoring wild boar populations as reservoirs
Summary for Practitioners
Successful control relies on vaccination combined with strict biosecurity and surveillance. Many countries have successfully eradicated the disease using coordinated national programs.
Zoonotic Importance
Aujeszky’s disease is not considered zoonotic, and there is no significant risk to humans.
Economic Importance
The disease causes major economic losses in pig production due to mortality, reproductive failure, reduced growth rates, and trade restrictions.
Summary
Aujeszky’s disease is a herpesvirus infection of pigs characterized by respiratory, neurological, and reproductive disorders. It is highly fatal in non-porcine species. Control depends on biosecurity, vaccination, and eradication programs.
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