A study of influenza A, B and respiratory syncytial virus in children with acute respiratory tract infection

A study of influenza A, B and respiratory syncytial virus in children with acute respiratory tract infection
การศึกษาหาเชื้อไข้หวัดใหญ่ ชนิด A, B และ Respiratory syncytial virus ในผู้ป่วยเด็ก ที่เป็นโรคติดเชื้อทางเดินหายใจเฉียบพลัน

Pornpimol Pruekprasert, Assoc. Prof., D. of Pediatrics, F. of Medicine, PSU.
Jintana Pradutkanchana, Medical Technologist, D. of Pathology, F. of Medicine, PSU.
Corresponding e-mail : ppornpim@ratree.psu.ac.th

Grant : Government Budget
Published : Research Report
Key words : respiratory syncytial virus (RSV), influenza virus, acute respiratory infection (ARI), shell vial technique

Introduction : Respiratory syncytial virus (RSV) and influenza virus are important pathogens causing acute respiratory tract infection in children. More data of clinical pictures and laboratory diagnoses will improve the diagnosis and control of the disease outbreat.

Objective :

1. Determined the clinical picture and epidemiology of RSV and influenza infection in children.

2. Compared RSV antigen detection by indirect immunofluorescence assay (IFA) with viral isolation by shell vial technique for diagnosis of RSV infection.

3. Compared influenza antigen detection by direct fluorescence assay (DFA) with viral isola-tion by conventional technique, and by shell vial technique for diagnosis of influenza infection.

Patients and Methods : Pediatric patients with acute respiratory infection (ARI) were pros-pectively studied in Songklanagarind Hospital, Prince of Songkla University during two periods : March, 1992 - February, 1993 and June-September 1995. Nasopharyngeal wash and throat swab specimens were collected for RSV and influenza antigen detections and viral isolations. The infection was diagnosed by positive antigen detection or viral isolation.

Results : During March, 1992 to February, 1993, 139 children less than 5 years of age with ARI were hospitalized and 31 (22.3%) were RSV positive. RSV infection was found in August to December and the peak prevalence was in October. The infection was more common in male (M : F = 1.8 : 1) and in children less than 6 months of age (P=0.01). The mean age in RSV positive and negative group were 8.2 and 15.6 months respectively. Dyspnea was found in 71% and 48% of children with RSV positive and negative respectively (P=0.04). No difference between the RSV positive and nega-tive group regarded to other clinical characteristics included fever, rhinorrhea, tachypnea and cough. Sensitivity and specificity of IFA were 81.5% and 99.1%, shell vial viral isolation technique were 100% and 100% respectively.

During June-September, 1998, 172 children less than 15 years of age with ARI were enrolled and 30 (17.4%) were influenza positive (influenza A=28, B=2). The infections were found in July (18) and Auguest (12). The mean age in influenza positive and negative were 61 and 52.8 months respectively. A significant history of ARI in household and history of sore throat were found in influenza positive group (P<0.001 and = 0.04 respectively). No difference between the influenza positive and negative group regarded to the other clinical characteristics included fever, rhinorrhea, cough and nasal congestion. Sensitivity and specificity of DFA were 12.8% and 99.6%, conventional viral isolation technique were 87.2 and 100%, shell vial viral isolation technique were 100% and 100% respectively.

Conclusion : RSV infection and influenza were common in young children with ARI. RSV occured in rainy season. We recommend the shell vial viral isolation technique to be the method for diagnosis of RSV and influenza virus infections due to its high sensitivity and specificity. For RSV infection the IFA is recommend where the cell culture for viral isolation is not available.

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