PARAINFLUENZA VIRUSES

Structure & Property	Transmission	Pathogenesis	Clinical findings	Laboratory diagnosis	Treatment	
Family: paramyxovirus

Size: 100-200nm

Genome: one piece of single-stranded RNA, negative polarity

Nucleocapsid: helical

Lipoprotein envelope:
- spikes consist of hemagglutinin, neuraminidase, and fusion proteins which mediate formation of multinucleated giant cells.

	Transmitted via respiratory droplets

Caused disease worldwide, primarily in winter months.	Cause upper and lower respiratory tract disease without viremia.

Large proportion of infections are subclinical.

Four serotypes:
Type 1: Croup in infants
Type 2: epidemics (winter)
Type 3: bronchiolitis and bronchopneumonia in young infants
Type 4: mild respiratory infection	Febrile common cold:
- sore throat
- cough
- hoarseness

Croup:
- acute laryngotracheobronchitis
- cough, hoarseness,
- severe: dyspnea, stridor, cyanosis, may require tracheotomy
- differential diagnosis: diphteria, haemophilus influenzae

Bronchiolitis

Bronchopneumonia	Tissue culture:
monkey kidney cells:
- CPE by type 2
- guinea pig RBC hemagglutination

Antigenic detection: IF of infected respiratory epithelial cells

Isolation:
- mouth washings
- throat swabs

Serology:
detect antibodies to:
- S (soluble) antigen: nucleocapsid – early
- V (viral) antigen – haemagglutinin & neuraminidase – late	Ventilatory support

Antibiotics for secondary bacterial infection

Sedation and hydration

No vaccine in routine use

Immunity is not long-lasting and reinfections are common.