Jasna Čepin-Bogović

Adenovirus respiratory infections in hospitalized children: clinical findings in relation to species and serotypes.

Background: There are >50 adenovirus (ADV) serotypes that are divided into 7 species (A–G). The aim of this study was to characterize ADV serotypes and species in hospitalized infants and children in the City of Zagreb and Zagreb County and to describe clinical features and laboratory findings of ADV infections according to the causative ADV serotype. Methods: During the 3-year period from January 2006 to November 2008, 135 children (<10 years of age) with ADV respiratory infection, based on virus isolation, were treated at 2 hospitals in Zagreb. Demographics, clinical presentations and laboratory findings were evaluated. Results: Of the 135 ADV isolates, 77 (57.0%) were type 2, followed by 26 (19.3%) of type 1, 15 (11.1%) isolates of type 3, 2 (1.5%) of type 6 and only 1 (0.7%) was type 7. Male-to-female ratio was 3.2:1 (103 boys and 32 girls). The mean age was 22.9 months. The most common symptoms were fever (98%), rhinorrhea (89%) and cough (71%). The mean peak body temperature was 39.8°C. Tonsillitis was present in 79 (59%) and acute otitis media in 37 (28%) patients. Leukocytosis (>15.0 × 109/L) was noted in 103 (77%) patients. Serum C-reactive protein was >40 mg/L in 74 patients (56%). The erythrocyte sedimentation rate was ≥30 mm/h in 91 (71%) of the 127 patients tested. Conclusions: In this study, the most common isolated serotype was ADV type 2. Most affected children were younger than 3 years. ADV infections in young children can present with prolonged fever, leukocytosis and significantly elevated C-reactive protein and erythrocyte sedimentation rate, mimicking bacterial infections.

Decreased Toll-like receptor 8 expression and lower TNF-alpha synthesis in infants with acute RSV infection

BackgroundToll-like receptors (TLRs) are part of the innate immune system, able to recognize pathogen-associated molecular patterns and activate immune system upon pathogen challenge. Respiratory syncytial virus (RSV) is a RNA virus particularly detrimental in infancy. It could cause severe lower respiratory tract disease and recurrent infections related to inadequate development of anti-viral immunity. The reason could be inadequate multiple TLRs engagement, including TLR8 in recognition of single-stranded viral RNA and diminished synthesis of inflammatory mediators due to a lower expression.MethodsIntracellular TLR8 expression in peripheral blood monocytes from RSV-infected infants was profiled and compared to healthy adults and age matched controls. Whether the observed difference in TLR8 expression is a transitory effect, infants in convalescent phase (4-6 weeks later) were retested. Specific TLR8-mediated TNF-α production in monocytes during an acute and convalescent phase was analyzed.ResultsRSV-infected and healthy infants had lower percentage of TLR8-expressing monocytes than healthy adults whereas decreased of TLR8 protein levels were detected only for RSV-infected infant group. Lower protein levels of TLR8 in monocytes from RSV-infected infants, compared to healthy infants, negatively correlated with respiratory frequency and resulted in lower TNF-α synthesis upon a specific TLR8 stimulation. In the convalescent phase, levels of TLR8 increased, accompanied by increased TNF-α synthesis compared to acute infection.ConclusionsLower TLR8 expression observed in monocytes, during an acute RSV infection, might have a dampening impact on early anti-viral cytokine production necessary to control RSV replication, and subsequently initiate an adaptive Th1 type immune response leading to severe disease in infected infants.

Does the viral subtype influence the biennial cycle of respiratory syncytial virus

BackgroundThe epidemic pattern of respiratory syncytial virus (RSV) is quite different in regions of Europe (biennial epidemics in alternating cycles of approximately 9 and 15 months) than in the Western Hemisphere (annual epidemics). In order to determine if these differences are accounted for by the circulation of different RSV subtypes, we studied the prevalence of RSV subtype A and B strains in Zagreb County from 1 January 2006 to 31 December 2007.ResultsRSV was identified in the nasopharyngeal secretions of 368 inpatients using direct fluorescence assays and/or by virus isolation in cell culture. The subtype of recovered strains was determined by real-time PCR. Of 368 RSV infections identified in children during this interval, subtype A virus caused 94 infections, and subtype B 270. Four patients had a dual RSV infection (subtypes A and B).The period of study was characterized by two epidemic waves of RSV infections-one, smaller, in the spring of 2006 (peaking in March), the second, larger, in December 2006/January 2007 (peaking in January). The predominant subtype in both outbreaks was RSV subtype B. Not until November 2007 did RSV subtype A predominate, while initiating a new outbreak continuing into the following calendar year.ConclusionThough only two calendar years were monitored, we believe that the biennial RSV cycle in Croatia occurs independently of the dominant viral subtype.

Detection of genetic lineages of human metapneumovirus in Croatia during the winter season 2005/2006.

Human metapneumovirus (HMPV) is an important respiratory pathogen, especially among young children. The genetic characteristics of HMPV circulating in Croatia have not been studied so far. The aim of this study was to determine the incidence of HMPV infection in hospitalized children with acute respiratory tract infection (ARTI) in the season 2005/2006 in Croatia, as well as to perform the genotypic analysis of detected HMPV strains. From December 1 to March 31 nasopharyngeal secretions (NPSs) were collected from 402 inpatients up to 5 years of age with ARTI. NPSs were tested by real‐time RT‐PCR assay targeting the nucleoprotein (N) gene of HMPV. HMPV infection was detected in 33 patients (8.2%). To perform the phylogenetic study, partial nucleotide sequences were obtained for HMPV fusion (F) gene of 30 HMPV positive samples. Phylogenetic analysis showed the circulation of two main genetic lineages (A and B), with B lineages being prevalent. It also showed the existence of two sublineages within the group B (B1 and B2) and three subclusters within lineage A (A1, A2a and A2b). Further molecular analysis revealed point mutations in HMPV strains of sublineage B1. J. Med. Virol. 80: 1282–1287, 2008.

The Relationship Between Gastroesophageal Reflux and Chronic Unexplained Cough in Children

The aim of this study was to assess the association between chronic cough and acid or weakly acid gastroesophageal reflux (GER) determined by 24-hour multichannel intraluminal impedance-pH monitoring and to assess whether the association is age dependent. Overall 150 children (mean age 7.5 years; range 0.3-18.0 years; male/female 90/60) were enrolled. Median of 87.5% (0% to 100%) of all cough episodes were associated with reflux; 9% (0% to 100%) with acidic and 60% (0% to 100%) with weakly acidic episodes. In 52 children (34.7%), all cough episodes were associated with GER (100% association). Children younger than 2 years had significantly higher number of cough episodes associated with total (P = .03) and weakly acidic GER (P = .01). Binary logistic regression confirmed that only increase in age decreases the risk for complete (100%) association between cough episode and GER. Cough is significantly associated with weakly acidic GER and children of younger age are at higher risk.

Seasonal occurrence of human metapneumovirus infections in Croatia.

Background: Human metapneumovirus (HMPV) is 1 of the commonest causes of viral ARI especially among pediatric patients. Its incidence varies from year to year in countries belonging to moderate climate zone. The aim of this study was to investigate epidemiologic characteristics of HMPV infections in Croatia. Methods: During a 4-year period (January 1, 2009, through December 31, 2012), nasopharyngeal aspirates were collected from 2610 children <10 years who were admitted to hospitals with acute respiratory infections. Direct immunofluorescence assay was used to detect the virus from clinical samples. Demographics and clinical data were also analyzed. Results: HMPV was detected in 8.4% of patients. While many of HMPV-infected children were 13–24 months of age (30.9% of all proven HMPV infections), the highest incidence of HMPV infection was recorded in 2- to 5-year-old children (11.4% of all children in this age group). HMPV caused 7.1% of upper respiratory tract infections and 11.7% of lower respiratory tract infections. Annual prevalence rates of HMPV infection varied significantly from year to year (P < 0.001). Peak incidence was detected in spring or winter months, depending on the year. Conclusions: This study indicates that HMPV infections in Croatia show a biennial outbreak pattern characterized by alternation of winter and spring activity. HMPV outbreaks alternate with respiratory syncytial virus outbreaks.

Etiology and clinical characteristics of single and multiple respiratory virus infections diagnosed in Croatian children in two respiratory seasons.

The aim of this study was to determine the causative agent of acute respiratory infection (ARI) in hospitalized children, as well as investigate the characteristics of ARIs with single and multiple virus detection in two respiratory seasons. In 2010 and 2015, nasopharyngeal and pharyngeal swabs from a total of 134 children, admitted to the hospital due to ARI, were tested using multiplex PCR. Viral etiology was established in 81.3% of the patients. Coinfection with two viruses was diagnosed in 27.6% of the patients, and concurrent detection of three or more viruses was diagnosed in 12.8% of the patients. The most commonly diagnosed virus in both seasons combined was respiratory syncytial virus (RSV) (28.6%), followed by parainfluenza viruses (PIVs) types 1–3 (18.4%), rhinovirus (HRV) (14.3%), human metapneumovirus (10.1%), adenovirus (AdV) (7.1%), influenza viruses types A and B (4.8%), and coronaviruses (4.2%). In 2015, additional pathogens were investigated with the following detection rate: enterovirus (13.2%), bocavirus (HBoV) (10.5%), PIV-4 (2.6%), and parechovirus (1.3%). There were no statistical differences between single and multiple virus infection regarding patients age, localization of infection, and severity of disease (P > 0.05). AdV, HRV, HBoV, and PIVs were significantly more often detected in multiple virus infections compared to the other respiratory viruses (P < 0.001).