Carriers

Carriers is a term used across disciplines to denote entities or materials that carry or transmit something else. The meaning varies by context, including biology, medicine, transportation, and communications.

In biology, carrier-related terms describe transport and genetic risk. Carrier proteins are membrane molecules that move ions and other substances into and out of cells. In genetics, a carrier is an individual who carries a recessive allele for a trait but does not express it. Such an individual can pass the allele to offspring, affecting inheritance patterns. Carrier status is often identified by genetic testing.

Medical epidemiology uses “carrier” to describe someone who harbors a pathogen without illness and can transmit infection. Carrier states can contribute to disease spread, especially when asymptomatic individuals interact with vulnerable populations. Public health strategies may include screening, contact tracing, and vaccination to reduce transmission from carriers.

In transportation and logistics, carriers are organizations that move goods or people. This includes airlines, shipping lines, trucking firms, and parcel services. Some jurisdictions recognize common carriers as providers obligated to offer service to the public under specified terms and non-discriminatory practices, while private carriers operate under private arrangements.

In communications, a carrier is a waveform that carries a modulated signal, such as a radio frequency used in AM or FM transmission. Carrier frequency, phase, and amplitude define the basic carrier for subsequent information encoding.