Human parainfluenza viruses

Human Parainfluenza Viruses (HPIVs)

Microscopic image of Paramyxoviridae, the family to which HPIVs belong.

Human Parainfluenza Viruses (HPIVs) are a group of viruses that cause respiratory infections in humans. They belong to the Paramyxoviridae family and are a paraphyletic group consisting of four distinct single-stranded RNA viruses.

Classification

HPIVs are classified into four types based on their genetic and antigenic properties:

• HPIV-1
• HPIV-2
• HPIV-3
• HPIV-4

Each type is known to cause different patterns of respiratory illness.

Structure and Genome

Diagram showing the typical structure of a single-stranded RNA virus.

HPIVs are roughly 150–250 nm in size and contain negative-sense RNA. Their genome encompasses about 15,000 nucleotides. The virus structure includes a lipid envelope and surface proteins essential for infection of host cells.

Diseases Associated with HPIVs

HPIVs are primarily associated with respiratory diseases, including:

• Croup, most commonly caused by HPIV-1
• Bronchiolitis and pneumonia, often linked to HPIV-3
• Mild to severe respiratory illnesses caused by HPIV-2 and HPIV-4

These viruses can affect individuals of all ages but are particularly severe in infants, young children, the elderly, and immunocompromised patients.

Diagnosis and Treatment

Diagnosis is typically based on the presentation of symptoms and can be confirmed through laboratory testing. Treatment is mainly supportive, as there are no specific antiviral therapies for HPIVs.

External Links

• Centers for Disease Control and Prevention - Human Parainfluenza Viruses
• World Health Organization - Influenza (Seasonal)