Respiratory Viral Infection in Nursing Home Slovenia

This study will be conducted in a 208-bed nursing home in Maribor. The investigators will observe a group of a 100 nursing-home residents and 50 health care workers- employees in the nursing home- in a six months period.Influenza vaccination status will be recorded in all participants at the beginning. At the beginning and at the end of the study the blood samples for vitamin D concentration determination and nasopharyngeal swabs for molecular detection of respiratory viruses will taken in all of the participants. The study will observe number of viral respiratory tract infection in participants and identify the viral etiology of infections during 6 months observational period.Nasopharyngeal swab and blood sample will be taken in each of the participant who will suffer an acute respiratory tract infection (upper or lower respiratory tract infection) and viral agents of respiratory tract diseases will be searched for. The investigators will try to detect different viral agents of respiratory tract infection: human rhinoviruses, enteroviruses, influenza A, B, parainfluenza 1-4, respiratory syncytial virus, human coronaviruses, human metapneumovirus, adenoviruses and human bocavirus with newer molecular methods (real-time polymerase chain reaction, real-time reverse transcriptase polymerase chain reaction) in nasopharyngeal swab and in blood sample of the participants. During the study period the investigators will monitor the daily number of visitors (adults, preschool children and pupils) in each nursing home room. The epidemiological aspect of respiratory viral infection will be assessed. Our study hypothesis is that lower respiratory tract infections in elderly can be caused by viruses other than influenza. The investigators would like to know if hypovitaminosis D is a risk factor for respiratory tract infections in nursing home residents and employees. The investigators would also like to know if the number of respiratory tract infections in elderly correlat