Pathophysiology
Clinical meaning
A disease outbreak is defined as the occurrence of cases of disease in excess of normal expectancy for a given population, time, and place. Outbreaks in healthcare settings may involve patients, staff, or visitors and require coordinated response from infection prevention, nursing, administration, and public health authorities. Outbreak investigation follows systematic steps: verify the diagnosis, establish case definition, identify and count cases, orient data by time (epidemic curve), place, and person, develop hypotheses, implement control measures, and evaluate effectiveness. Common healthcare-associated outbreaks involve norovirus gastroenteritis, C. difficile, influenza, MRSA clusters, and scabies. The epidemic curve (epidemiological graph of cases over time) helps identify the outbreak pattern: point source (common exposure), propagated (person-to-person), or continuous source. Nurses play a critical role in surveillance, reporting, implementing control measures, and patient cohorting.