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HRVs linked to severe respiratory disease in very low birth weight infants

Miller EK. Pediatrics. 2011;doi:10.1542/peds.2011-0583.

Human rhinoviruses were linked to severe respiratory infections in very low birth weight infants, whereas bronchopulmonary dysplasia and the absence of breast-feeding presented additional risk factors for hospitalization, according to a study published in the Dec. 29 issue of Pediatrics.

Researchers enrolled 119 infants and children at high risk for pulmonary disease from June 1, 2003, to May 31, 2005, at the Garrahan Children’s Hospital and the Maternidad Sarda High Risk Clinics in Buenos Aires, Argentina. Patients were managed monthly and with every acute respiratory illness during the first year of life. Researchers acquired nasal wash samples during each respiratory episode and tested for human rhinovirus (HRV), respiratory syncytial virus (RSV), human parainfluenza viruses, influenza viruses and human metapneumovirus using reverse transcriptase-polymerase chain reaction.

During the course of the study, 303 episodes of acute respiratory illness were identified in 119 infants. One hundred twenty-five (41%) episodes were linked with HRV, of which there were 11 coinfections: seven with RSV; two with human parainfluenza virus 3; and two with human metapneumovirus. Twenty (7%) episodes were associated with RSV, 12 (4%) with human parainfluenza virus type 3, seven (2%) with human metapneumovirus, five (2%) with seasonal influenza virus A and three (1%) with human parainfluenza virus 1. Among the study group, 55% were found to have HRV-associated acute respiratory illnesses — HRV also was associated with 12 of 36 hospitalizations (33%) compared with RSV, which was linked to nine of 36 hospitalizations (25%).

Among all infants with HRV, adjusted RRs for HRV-associated hospitalizations vs. HRV-associated episodes were lower for breast-fed infants (RR=0.26; 95% CI, 0.07-0.98). Upon further analyses, which excluded coinfection episodes, none of the seven hospitalized patients with at least 1one HRV-only episode was breast-fed; however, 40 of 58 non-hospitalized infants with at least one HRV-only–associated episode were breast-fed (P<.001). Six of the seven patients who had at least one HRV-only–associated episode and were hospitalized had bronchopulmonary dysplasia, whereas 23 of 58 infants who had at least one HRV-only–associated episode and were not hospitalized had bronchopulmonary dysplasia (P=.039).

Limitations of the study included not testing healthy control participants in tandem to investigate the incidence of asymptomatic HRV infection to link causality more strongly. Researchers, however, performed molecular testing for a spectrum of viruses known to cause lung disease in infants and did not detect a coinfecting virus in 91% of HRV-positive cases, which suggested that HRV was the causative pathogen. Researchers said the low-income study population had higher rates of bronchopulmonary dysplasia than those often reported in industrialized nations or for higher-income groups in developing countries.

Disclosure: The researchers report no relevant financial disclosures.

Miller and colleagues conducted a prospective cohort study on the molecular etiology of acute respiratory illness (ARI) in very low birth weight infants in Buenos Aires, Argentina. A virus was identified in 172 (56.7%) of 303 ARI episodes with human rhinovirus (HRV) and respiratory syncytial virus (RSV) being detected in 125 and 20 cases, respectively. HRV (n = 12) and RSV (n = 9) were the principal viruses identified at hospitalization (n = 36). Bronchopulmonary dysplasia was a risk factor while breastfed was associated with protection against HRV hospitalization. A concern is the high percentage of ARI episodes without an identifiable pathogen. This is particularly noticeable in the winter months and raises a question on the specimen collection method and/or molecular diagnostic assay. On the other hand, this article adds to the growing evidence of HRV being a major contributor to acute respiratory disease burden in infants and the potential benefit of breast feeding.

Pedro A. Piedra, MD
Infectious Diseases in Children Editorial Board

Disclosure: Dr. Piedra reports no relevant financial disclosures.

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