Viral pathogens and epidemiology, detection, therapy and resistance

Worldwide community-acquired pneumonia (CAP) is one of the most frequent infectious diseases and a leading cause of death. Several studies have shown that a pathogen could be identified only in 50 to 60% of all patients, although in children < 6 month infectious agents can be detected in about 90%. Viral infections are most frequent in children < 2 years (80%), whereas bacterial infections increase with age. RSV, influenzaviruses, rhinoviruses, parainfluenzaviruses and adenoviruses are the most common viruses associated with CAP in children. Among adenoviruses a predominance of adenovirus 7 has been reported in several countries with emergence of highly pathogenic variants with significant lethality in young children. Many childhood respiratory infections are caused by more than one pathogen and up to 30% mixed viral / bacterial infections can be observed. CAP in immunocompetent adults is rare, whereas persons with underlaying diseases have an increased incidence of CAP. In the elderly, RSV, influenzaviruses, parainfluenzaviruses and less frequent adenoviruses are predominant viruses causing pneumonia. Less frequently associated with CAP are the newly discovered human metapneumovirus and the coronaviruses NL63 and HKU1. Hantaviruses, involved in the hantavirus pulmonary syndrome, belong to the emerging pathogens to date in North, Middle and South America. For optimum diagnosis the whole spectrum of potential respiratory viral agents should be included and multiple diagnostic techniques have to be used. In view of the high relevance of influenzavirus for CAP influenza vaccination is highly advisable for prevention of CAP, especially in high-risk groups.