Which of the following is a key trigger of an outbreak?

A sudden cluster of infections is a key trigger of an outbreak because it indicates an unusual increase in the number of infections within a specific timeframe and geographical area. This sudden rise may suggest that there is a common source or mechanism of transmission that is facilitating the spread of infection among individuals, particularly in vulnerable settings like nursing homes. Identifying this pattern is critical for timely intervention and control measures to prevent further spread.

Contrasting with stable infection rates or a decrease in infection rates, which suggest that infections are under control, a sudden cluster alerts healthcare providers to the need for immediate investigation and response. Routine hand hygiene compliance is vital for infection prevention, but it is not, by itself, a trigger for an outbreak; rather, it is a preventive measure to help mitigate the risk of infection.