Viral Respiratory Pathogens Associated with Medically Attended Acute Respiratory Illnesses in Older Adults in Bulgaria

Acute respiratory infections (ARIs) are a major cause of morbidity and mortality among older adults This study aimed to determine the viral etiology of these infections in patients aged >= 65 years during two successive epidemic seasons in Bulgaria Nasal and throat specimens were collected from the enrolled patients during the 2015/2016 and 2016/2017 seasons The viral etiology was determined by individual Real Time PCR assays against 15 respiratory viruses Of the 160 adults examined, 74 (46 3%) were positive for at least one respiratory virus Co-infections with two and three viruses were found in 14 (18 9%) of the infected patients Influenza A(H3N2) (15 6%) and A(H1N1)pdm09 (13 1%) viruses were the predominant pathogens, followed by adenoviruses (5 6%);respiratory-syncytial virus (3 8%);metapneumovirus (3 1%);rhinoviruses (2 5%);coronaviruses - NL63 (2 5%), OC43 (1 9%), HKU1 (1 9%) and 229E (1 3%);influenza type B (1 9%);bocaviruses (1 3%) and parainfluenza viruses 1/2/3 (1 3%) At least one respiratory virus was identified in 50% and 32 3% of the patients with acute lower respiratory tract illnesses and neurological complications, respectively Respiratory viruses, especially influenza A viruses, are major pathogens of ARIs in persons aged >= 65 years Diagnostic testing for respiratory viruses using molecular methods can help in clinical decision making and may assist in measures to prevent health careassociated infections