Molecular characterization of human rhinovirus in Portugal: 2014-2015 season

Cristóvão, Paula; Pechirra, Pedro; Conde, Patrícia; Costa, Inês; Guiomar, Raquel

http://hdl.handle.net/10400.18/4210

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Background: Human rhinoviruses (HRV) frequently cause mild upper respiratory tract infections and more severe disease manifestations such as bronchiolitis and pneumonia. Plays an important role in asthma and chronic lung disease exacerbations. Genetic characterization of HRVs detected by molecular methods has revealed much greater diversity, enabling the identification of three species (HRV-A, HRV-B and HRV-C) and a great number of types. The aim of this study is to characterize HRV detected in respiratory specimens from influenza-like illness cases (ILI), received in the scope of the Portuguese Influenza Surveillance Program, during 2014-2015 season in Portugal. Methods: During the 2014 - 2015 season, 411 nasopharyngeal swabs negative for influenza were tested for HRV in a multiplex PCR [1]. 18% (75/411) of the samples were positive for HRV, and from these 83% (62) were sequenced by a nested RT-PCR [2]. Nucleotide sequences of the VP4/VP2 region were used for genotyping and phylogenetic tree construction in Mega 6.0. Demographic and clinical data (according EU ILI case definition) were recorded in a questionnaire,. Results: HRV were detected throughout the study period, between week 40/2014 (October) and week 9/2015 (March) with a peak in January 2015. Phylogenetic analysis showed that 45% (28/62) strains belonged to species HRV-A, 15% (9/62) to species B and 40% (25/62) to species C. Overall were identified 35 different types. All species co-circulated in Portugal with the exception of the Algarve and Açores, being HRV-A predominat in north region and HRV-C predominant in Alentejo. HRV positives cases had a median age of 42,5. HRV-C were the most frequently detected in all age groups, apart from young adults aged 15 to 44. In this age group HRV-A were identified in 73% (16/22). HRV-B was detected sporadically in all age groups, except in children (5-14 years old). HRV was found in similar proportions in both genders (52% in female; 48% in male). Data on influenza vaccination was reported in 51 HRV positive cases, but only 9 (18%) had been previously vaccinated. Information on chronic diseases was reported in 54 cases, of these 15 (28%) had a chronic disease (mainly cardiovascular or diabetes). HRV was detected in 4 pregnant women, 14% (4/28). Cough, myalgias, weakness and fever were the most frequent symptoms reported by HRV confirmed cases. Conclusions: During 2014-2015 was observed a co-circulation of the three species of HRV (A, B and C) with a predominance of HRV-A followed by the recently identified specie C. A wide genetic diversity of 35 types was identified, with a higher diversity among HRV-A. HRV was most frequently diagnosed in adults. Our study included few children under 5, preventing conclusions about this group. Diabetes and cardiovascular disease were found has a possible risk for HRV infection, highlighting the relevance of respiratory disease prevention measures that should be undertaken. This was the first study to attempt the gentic diversity of rhinovirus circulating in Portugal during a winter season in ILI cases. Further studies in the general population and in high risk groups for severe respiratory disease will aid knowledge in HRV epidemiology and exarcebation of respiratory infections.