Nonsymptomatic

Nonsymptomatic refers to a person who has a disease, infection, or medical condition but does not exhibit observable symptoms at the time of evaluation. The term is often used in clinical and public health contexts to describe individuals who would not be identified by symptom-based screening alone.

In some literature, nonsymptomatic is used interchangeably with asymptomatic, though some authors distinguish: presymptomatic indicates someone who has not yet developed symptoms but will later, while nonsymptomatic/asymptomatic denotes absence of symptoms at assessment. Subclinical is another related term, often used for disease processes that are not clinically evident but detectable by tests or imaging.

Examples include individuals infected with SARS-CoV-2 who do not feel ill but can test positive, or carriers of sexually transmitted infections who show no symptoms. Nonsymptomatic conditions also occur in chronic diseases (for example, hypertension or hyperlipidemia may be present without noticeable symptoms) and in ocular, cardiovascular, or malignant diseases discovered via screening or incidental findings.

Public health implications include the potential for transmission without symptoms and the importance of screening, contact tracing, and surveillance. Clinically, recognizing nonsymptomatic disease can influence decisions about monitoring, treatment initiation, and isolation in infectious cases. However, the absence of symptoms does not guarantee the absence of disease activity, and some individuals may develop symptoms later (presymptomatic) or have non-specific symptoms that are easily overlooked.