Respiratory syncytial virus: viral load, viral decay, and disease progression in children with bronchiolitis

Abstract

Acute viral bronchiolitis is the major cause of hospital admissions in children under 2 years of age, and respiratory syncytial virus (RSV) can be responsible for up to 80% of these infections. We aimed to describe RSV dynamics among hospitalized children with bronchiolitis. Upper respiratory samples of 101 hospitalized patients were collected and submitted to RSV detection by a quantitative real-time RT-PCR to assess viral load (Log₁₀ RNA copies/mL). Seventy-two patients were positive for RSV infection, of which 38 (52.7%) could be followed up until RSV was no longer detected. The first RSV RT-qPCR was carried out on average on the 5th day of symptom onset. Thirty-six patients (94.7%) were still shedding RSV after 7 days, and 9 (23.6%) after 14 days of symptoms onset. Only 2 patients (5.2%) were still shedding RSV after 21 days. Only 7 of the followed patients (18.9%) were submitted to intubation. There was no difference between the viral load of the first collected sample and the viral persistence of patients with comorbidities, who needed intensive care unit and who needed intubation. These data could help understand RSV dynamics and future studies and treatments to come.

Keywords: Bronchiolitis; Respiratory syncytial virus; Viral decay; Viral load.

Fig. 1

Flow diagram of the study

Fig. 2

Individual patients viral load: patients 1 to 8, non-intubated. The black vertical lines indicate the patient’s hospitalization period, and the yellow band indicates ICU treatment. (1): Patient 6 started to show symptoms of RSV infection during hospitalization for other medical issues; for practical reasons, we only show the black vertical line representing the hospital discharge

Fig. 3

Individual patients viral load: patients 9 to 16, non-intubated. The black vertical lines indicate the patient’s hospitalization period, and the yellow band indicates ICU treatment. (2): Patient 9 started to show symptoms of RSV infection during hospitalization for other medical issues and was kept hospitalized long after; for practical reasons, we chose not to show the entire period of his/her hospitalization. (3): Patient 12 started to show symptoms of RSV infection during hospitalization for other medical issues; for practical reasons, we only show the black vertical line representing the hospital discharge

Fig. 4

Individual patients viral load: patients 17 to 24, non-intubated. The black vertical lines indicate the patient’s hospitalization period, and the yellow band indicates ICU treatment

Fig. 5

Individual patients viral load: patients 25 to 31, non-intubated. The black vertical lines indicate the patient’s hospitalization period, and the yellow band indicates ICU treatment. (4): Patient 27 was discharged without the acknowledgment of our team, which explains the lack of a sample on the day of discharge

Fig. 6

Individual patients viral load: patients 32 to 38, intubated. The black vertical lines indicate the patient’s hospitalization period, the yellow band indicates ICU treatment, and the red band indicates intubation

Fig. 7

Viral load of each sample collected per day of the analyzed patients after the onset of the symptoms