kontaktlähte

Kontaktlähte is a term used in Finnish public health and epidemiology, translating to "source of contact" or "source of infection." In epidemiology, a kontaktlähde refers to the immediate source from which an infectious agent is transmitted to a susceptible host. The concept is central to outbreak investigations and to contact tracing, because identifying the kontaktlähde helps to interrupt transmission and prevent further cases.

A kontaktlähde can be a person (for example, a symptomatic or asymptomatic carrier), an object or surface that harbors the pathogen (a fomite), a contaminated food or water source, or, in some diseases, a vector or animal reservoir. Distinguishing the kontaktlähde from other related terms is important: the kontaktlähde is the direct source of transmission, whereas a kontaktperson is someone who has had contact with the infected person but is not necessarily the source of transmission to others.

Identification typically relies on interviews, case histories, and sometimes laboratory methods such as genomic sequencing or environmental sampling. Limitations include recall bias, asymptomatic transmission, and time lags between exposure and illness.

In practice, public health authorities use the concept of kontaktlähde to guide interventions such as isolation of cases, quarantine of contacts, decontamination of environments, and targeted measures to prevent further spread. See also infectious disease, transmission, and contact tracing.