Smitteveje

Smitteveje, often translated as routes of transmission, are the pathways by which infectious agents spread from one host to another. In epidemiology, identifying smitteveje helps explain how diseases propagate, assess risk, and guide control measures. Transmission routes depend on properties of the pathogen, including its survival outside the host, the infectious dose, and the mode by which it enters new hosts.

Major routes include direct contact, such as skin-to-skin or sexual contact; indirect contact via fomites, or objects that carry pathogens; droplet transmission from close-range respiratory secretions; and airborne transmission through smaller particles that may remain suspended and travel longer distances. Vector-borne transmission occurs when arthropods or other vectors transfer pathogens. Common vehicle transmission involves contaminated food or water or other shared materials. Other routes include vertical transmission from mother to fetus or newborn and parenteral transmission through contaminated needles or blood products.

Pathogens often can exploit more than one smittevej, and the relevance of each route depends on the environment, behavior, and host susceptibility. Understanding smitteveje supports targeted interventions, such as hand hygiene and ventilation to reduce contact and airborne risk, vaccination to block specific pathways, safe sex practices, safe handling of food and water, vector control, and proper sterilization of medical equipment. Public health strategies combine measures across multiple routes to interrupt transmission effectively.