Etiology:  Parainfluenza viruses (PI-1, -2 and -3) are enveloped RNA viruses.

Transmission:  Transmission occurs by direct contact and aerosol.

Incidence:  The incidence of infection with Parainfluenza viruses is rare.

Clinical signs:  PI-1 (Sendai virus) produces transient infection and generally subclinical disease, but rhinitis has been noted in experimental infection.

PI-2 (SV5 virus) has only been documented by seroconversion.

PI-3 has been recovered from research guinea pigs and produces subclinical transient infection.

Diagnosis:  Diagnosis is made by serology (MFI, IFA).