Parainfluenza

The parainfluenza viruses (also, parainfluenza viruses), isolated in 1956, are a group of paramyxoviruses about 100-200 nanometers in size, with a diameter of nucleocapsid of 18 nm, which presents in the envelope two glycoproteins: HN with hemagglutinin and neuraminidase activity and F, with hemolytic and cell fusion activity.

Types of parainfluenza viruses

Four parainfluenza virus serotypes have been described, which are antigenically related to each other, to mumps viruses, and to other animal paramyxoviruses. Parainfluenza viruses types 1 and 3 belong to the respirovirus genus, while parainfluenza viruses types 2 and 4 belong to the rubulavirus genus.

• Virus parainfluenza type 1: It is related to paramixovirus Sendai, which produces infections in mice and pigs.
• Virus parainfluenza type 2: It is related to the SV-5 and SV-41 virus, and parotitis virus. It produces crup in humans.
• Virus parainfluenza type 3: Related to the SF-4 virus. It produces infections in vaults.
• Virus parainfluenza type 4: There are two serotypes 4A and 4B.

Pathogenic action

Paramyxoviruses cause frequent respiratory infections of variable severity, which depend on:

1. Types of viruses.
2. Age.
3. Primoinfection or reinfection.

• Upper respiratory tract infections: These are the most frequent infections produced by parainfluenza viruses, any serotype, and occur both as a first-infection and reinfection, both in childhood but especially in adults. They include sinusitis, rhinitis, pharyngitis, bronchitis or combinations of all (rinosinusitis, rhinopharyngitis...) and fever processes without anatomical location. Correspond to the typical common or constipated respiratory and are usually infections of good prognosis, of mild severity and that cure spontaneously after about eight days. Therefore, your treatment is directed towards the palliation of symptoms, and do not require antibiotic treatment as well as most viral infections.
• Lower respiratory tract infections: Parainfluenza viruses are responsible for 20% of these serious infections, especially in children as a first infection. Correspond to:

1. Crup or obstructive larynxitis: It is produced by all serotypes, especially type 1 and 2, being responsible for 50% of this infection. It occurs in young children, from 6 months to 6 years of age; the maximum point is at 2 years.
2. Broncholitis and pneumonia: They are rare, occur in young children, less than six months, and are mainly produced by serotype 3.