Parainfluenza Virus

The human parainfluenza virus (HPIV) is an enveloped, negative-sense, single-stranded RNA virus that belongs to the family of  It is classified into four serotypes numbered from 1 to 4 (HPIV-1, HPIV-2, HPIV-3, and HPIV-4). Serotype 4 can even be more subdivided into HPIV-4A and HPIV-4B. HPIV can cause both upper respiratory tract infection (URTI) and lower respiratory tract infection (LRTI) in children usually under the age of 5, adults, immunocompromised adults, and the elderly. It is one of the major causes of morbidity and mortality in infants worldwide. These respiratory viruses were first observed in the late 1950s when they were isolated from children with croup and were known as croup-associated viruses.  Although HPIV demonstrated a resemblance to the influenza virus, HPIV is unique and can be easily and simply separated from the myxoviruses (influenza virus). The parainfluenza virus shared some characteristics with the influenza virus, including few antigenic sites, as well as their poor growth in embryonated eggs. In 1959, the fourth serotype was discovered that shared the same criteria with the 3 parainfluenza serotypes previously demonstrated, and a new family of viruses was created called "parainfluenza viruses".