Particularités épidémiologiques et prévention des infections nosocomiales virales

OBJECTIVES: To describe epidemiological features of viral nosocomial infections (VNI) and their prevention principles. EPIDEMIOLOGY: Many factors lead to underestimate VNI: difficulty to distinguish between community-acquired and nosocomial infections for seasonal viral diseases, incubation time leading to symptoms after patient discharge, difficulty for diagnosis. Population at high risks of VNI are the children, the elderly and the immunocompromized patients. The risk of severe diseases is high in this last population. The main reservoir of virus is infected symptomatic or asymptomatic individuals. Asymptomatic carriers, especially health care workers, are a major source of transmission. Main routes of transmission are the fecal–oral route, the respiratory route, cutaneous or mucous contact and blood and body fluids exposure. A review of the main virus involved in VNI is presented. PREVENTION: Preventive measures, such as strict adherence to standard precautions and, in some instances, to isolation procedures, are critical to control VNI. In a major outbreak situation, it may be necessary to consider cohort isolation. Specific control measures rely on immunization, antiviral drug prophylaxis (varicella–zooster, herpes, influenza, exposure to blood) and clinical and biological screening of organ, blood, tissue and cell donors.