Introduction

• Cause: cytomegalovirus (CMV) a species-specific herpesvirus.
• Signs: usually asymptomatic.
• Diagnosis: at necropsy, histopathology: intranuclear and intracytoplasmic inclusion bodies in affected cells. Serology.
• Treatment: none.
• Prognosis: CMV in natural infections is usually subclinical, and will be carried latently for the life of the animal.

Pathogenesis

Etiology

• Guinea pig cytomegalovirus; Herpesviridae.

Predisposing factors

General

• Many colonies have this as a subclinical, latent infection. Usually is considered an incidental finding at necropsy.
• CMV may be inoculated as it is used as a model for human CMV.
• Associated with immunosuppression.

Specific

• Lesions produced in inoculated weanlings, pregnant guinea pigs.
• Immunocompromized animals may get systemic infection with lesions when inoculated.

Pathophysiology

• In natural infections, primary target organs are salivary glands, liver, kidney.
• In experimental disease (inculation subcutaneously):
  • Focal lesions with intranuclear inclusion bodies in salivary gland, liver, spleen, lung, and kidney.
  • Produces lymphoproliferative disease with mononucleosis-like syndrome and lymphadenopathy.
• Reported infection of young, naive animals introduced into a conventional colony having focal destructive lesions with large intranuclear and cytoplasmic inclusion bodies in various tissues:
  • Spleen.
  • Liver.
  • Kidney.
  • Lung.
• In natural infections, lesions are usually regarded as an incidental finding. Primarily confined to ductal epithelial cells of the salivary glands.
• In acute systemic form: interstitial pneumonitis. Multifocal areas of necrosis in lymph nodes, spleen, liver, kidney, lung and other viscera.
• Virus is shed in urine, saliva, or transplacentally.

Timecourse

• Natural infection: may take prolonged time period.
• Experimental infections: fairly acute, immune status may affect; consider within 2-4 weeks.

Epidemiology

• Conventional colonies: most are subclinically infected.
• Transmission is through urine, saliva or transplacentally.
• For animal model work: usually inoculated subcutaneously.

Diagnosis

Treatment

Prevention

Outcomes