Determination of the frequency of human bocavirus and other respiratory viruses among 0-2 years age group children diagnosed as acute bronchiolitis

Abstract

Acute bronchiolitis, mostly seen in infants and younger children, is a lower respiratory tract infection frequently caused by viral agents. We aimed to determine the frequency of a broad panel of respiratory viruses including human bocavirus (HBoV) and to assess the clinical characteristics of acute bronchiolitis in a group of children under 24 months of age. A total of 62 children (45 male, 17 female; age range: 0-2 years) with the initial diagnosis of acute bronchiolitis and 33 healthy children (21 male, 12 female; age range: 0-2 years) as control group who were admitted to the Pediatrics Department of Mersin University Hospital, southern Turkey, from January to July 2010 were included in the study. Nasopharyngeal aspirates were collected from the study groups and the detection of respiratory viruses [respiratory syncytial virus (RSV) A & B; rhinovirus (RV); human metapneumovirus (hMPV) A & B; influenza virus type A [H1N1, H3N2, H1N1v], B & C; parainfluenza virus (PIV) type 1, 2, 3 & 4A/B; adenovirus (AdV); HBoV; coronavirus (CoV 229E); enterovirus (EV)], were performed by using a commercial system namely CLART®Pneumovir (Clinical Array Technology, Genomica, Spain) based on the principle of multiplex polymerase chain reaction (M-PCR) and DNA microarray. Demographic features, clinical and laboratory findings of the patients, treatment protocols and the relationship between the length of hospitalization and the viral agents determined were also evaluated. Of the 62 samples collected from bronchiolitis cases, at least one virus was detected in 52 (83.9%) and viral co-infections were detected in 31 (50%) of them. Including the co-infections, RSV was the most commonly identified virus (n= 21; 33.9%), followed by influenza A [H1N1] (n= 18; 29%), RV (n= 18; 29%), hMPV (n= 13; 21%), PIV (n= 10; 16.1%), AdV (n= 5; 8%), HBoV (n= 3; 4.8%) and EV (n= 1; 1.6%). Of the 33 samples from healthy children, at least one virus was detected in 21 (63.6%) and viral co-infections were detected in seven (21.2%) samples. Including the co-infections, the most commonly detected virus was RV (n= 10; 30.3%), followed by influenza A [H1N1] (n= 6; 18.1%), AdV (n= 6; 18.1%), RSV (n= 4; 12.1%) and PIV (n= 3; 9%), however HBoV and hMPV were not detected in the control group. The differences of demographic features (age, gender, history of atopy, exposure of smoking, length of breast-feeding, presence of school-age sibling) and frequency of virus detection (83.9% and 63.6%, respectively) between the patient and control groups were not statistically significant (p> 0.05). The most common complaints of patients on admission were cough (100%), runny nose (82.3%) and respiratory difficulty (71%), whereas fever was present in 21 (33.9%) patients. The most common findings on physical examination were prolonged expirium (98.4%), rhonchi (98.4%), rales (80.6%), tachypnea (71%) and tachycardia (67.7%). Pulmonary graphies revealed that diffuse air trappings were more common in virus-associated bronchiolitis (36/52; 69.2%) cases, on the other hand infiltrations were more common (6/10; 60%) in patients who were virus-negative (p< 0.05). The demographic features, clinical and laboratory findings, clinical severity scores, hospitalization rates and duration of hospitalizations in bronchiolitis cases did not show statistically significant differences between the viral agents (p> 0.05 for each parameter). However the rates of antibiotic and steroid use in hospitalized patients (24/34 and 5/34, respectively) were significantly higher than those of outpatients (7/28 and 0/28, respectively) (p= 0.001 and p= 0.03). Our data indicated a high rate (~84%) of respiratory viruses in children with bronchiolitis in the Mersin province and the detection of hMPV (21%) and HBoV (4.8%) only in the patient group encouraged their roles in the etiology of acute brochiolitis. It was concluded that viral etiology should be investigated in selected cases to prevent unnecessary antibiotic treatment and to initiate appropriate antiviral therapy when necessary.