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Description:This transmission electron microscopic (TEM) image revealed some of the nucleocapsid morphologic features displayed by the human parainfluenza virus Type-4a (HPIV-4), a member of the Paramyxoviridae family. These viruses possess a genome consisting of negative-sense single-stranded RNA ((-) ssRNA).

Each of the four HPIVs has different clinical and epidemiologic features. The most distinctive clinical feature of HPIV-1 and HPIV-2 is croup (i.e., laryngotracheobronchitis); HPIV-1 is the leading cause of croup in children, whereas HPIV-2 is less frequently detected. Both HPIV-1 and -2 can cause other upper and lower respiratory tract illnesses. HPIV-3 is more often associated with bronchiolitis and pneumonia. HPIV-4 is infrequently detected, possibly because it is less likely to cause severe disease. The incubation period for HPIVs is generally from 1 to 7 days.
Clinical features:

Human parainfluenza viruses (HPIVs) are second to respiratory syncytial virus (RSV) as a common cause of lower respiratory tract disease in young children. Similar to RSV, HPIVs can cause repeated infections throughout life, usually manifested by an upper respiratory tract illness (e.g., a cold and/or sore throat). HPIVs can also cause serious lower respiratory tract disease with repeat infection (e.g., pneumonia, bronchitis, and bronchiolitis), especially among the elderly, and among patients with compromised immune systems.

High Resolution: Click here for hi-resolution image (4.11 MB)
Content Providers(s):CDC/ Dr. Fred Murphy; Sylvia Whitfield
Creation Date:1975
Photo Credit:
Links:CDC – Nat. Center for Infectious Diseases; Respiratory and Enteric Viruses Branch; Human Parainfluenza Viruses (Common Cold and Croup)
CDC Organization
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Copyright Restrictions:None - This image is in the public domain and thus free of any copyright restrictions. As a matter of courtesy we request that the content provider be credited and notified in any public or private usage of this image.