Acute respiratory infection is the most common cause of medical treatment in infants and young children. Among them, human parafluenza Virus (HPIV) is a common pathogen of acute respiratory infection. Today we will learn about HPIV.
01 Etiology and Epidemiology
The name of parainfluenza virus is very similar to that of influenza virus. They are both enveloped single negative strand RNA viruses, but they are different in classification. HPIV belongs to the genus Paramyxovirus of the family Paramyxovirus family.
HPIV is spherical under electron microscope, with a diameter of about 150-200nm. It is divided into four types according to antigenic HPIV, among which HPIV-4 can be divided into two subtypes: HPIV-4A and HPIV-4B.
No matter which type of HPIV is transmitted through respiratory droplets, or after susceptible persons are exposed to infectious secretions, they will become infected through the "self-inoculation" method from hand to nose. The initial infection of HPIV is the nasal and oropharyngeal mucosa, which replicates in large quantities in respiratory epithelial cells, and the infection may spread to the lower respiratory tract. Viral replication reaches its peak 2-5 days after infection. Usually, the virus replication begins to decrease after 7 days, and the overall process is self-limiting.
02 Epidemic characteristics
The epidemiological characteristics of different subtypes of HPIV are different. Among them, HPIV-1 and HPIV-2 are most susceptible to preschool children aged 3 to 5 years old, and are mostly prevalent in autumn and winter; HPIV-3 detection rate is the highest, showing sporadic throughout the year, and is more common in summer, and the infection rate is the highest in infants under 1 year old. HPIV-4 is often not easily discovered in epidemiological surveillance due to mild symptoms after infection, and the detection rate in the past is relatively low. However, with the advancement of detection and monitoring technology in recent years, it has been reported that HPIV-4 often has an outbreak in autumn and winter in the United States and Japan.
03 Clinical manifestation The severity of respiratory infection caused by
HPIV infection is related to the main replication site of the virus, which is related to the subtype of HPIV. Studies have believed that common wheezing diseases in children are mainly related to respiratory virus infection, and HPIV is the culprit.
HPIV-1, HPIV-2
often causes laryngeal tracheobronchiolitis in preschool children. It usually has a more acute onset. Early infection can manifest as fever, runny nose and/or sore throat. As the condition gradually progresses, cough, wheezing, and even hypoxemia and difficulty breathing may occur. Some children need to be hospitalized for treatment.
HPIV-3
is more common in babies under 6 months of age and can lead to bronchioles or pneumonia. The clinical symptoms are similar to respiratory syncytial virus (RSV) infection, except that RSV is often "active" in winter, while HPIV-3 is more "arrogant" in summer. The respiratory symptoms of older children are often severe after they are infected with HPIV-3, which may be manifested as laryngeal tracheobronchiolitis or even pneumonia. HPIV-3 is more closely related to pneumonia than other subtypes, has a higher hospitalization rate and longer hospital stays.
HPIV-4
usually only causes mild upper respiratory tract infection symptoms, such as nasal congestion, runny nose, sneezing, etc. However, HPIV-4 in small babies and people with low immune function can also lead to severe lower respiratory diseases such as bronchioles and pneumonia.
04 Diagnosis of
There is no significant specificity in the clinical manifestations of respiratory tract infection caused by HPIV. It is usually based on the onset season and clinical symptoms. For diagnosis, it requires etiological testing. Currently, the laboratory has the following methods to find HPIV:
① Viral nucleic acid detection: Polymerase chain reaction (PCR) technology is currently a commonly used viral nucleic acid detection method. It can collect nasopharyngeal swabs or sputum from patients to detect HPIV RNA, which has high sensitivity and good specificity.
② Rapid antigen detection: collect the patient's respiratory secretions (nasopharyngeal swabs or sputum), and use direct immunofluorescence assay to detect HPIV. This method can also perform HPIV typing.
③Viral isolation and culture: It has high requirements for laboratory and is not commonly used in clinical practice.
05 Treatment and prevention of
There is currently no "special medicine" for HPIV infection, so be vigilant and the focus is on prevention! Unfortunately, there is currently no HPIV-related vaccine, so try to minimize going to public places with dense crowds, pay attention to personal hygiene, take personal protection, wash hands frequently, and strengthen ventilation in the room. This is the focus of preventing all kinds of respiratory infectious diseases.
article | Li Dan
source | Department of Infection of the Institute of Children's Research Institute
Capital Pediatrics Research Institute
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Capital Pediatrics Research Institute
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Capital Pediatrics Research Institute
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Capital Pediatrics Research Institute
Affiliated Children's Hospital
