Hyönteisvälitys

Hyönteisvälitys, also known as insect-borne transmission or vector-borne transmission by insects, refers to the process by which an insect transmits a pathogen or parasite to a host. This is a common mode of disease spread in both humans and animals. The insect acts as a vector, meaning it carries the infectious agent from one organism to another.

There are two primary mechanisms of hyönteisvälitys. Mechanical transmission occurs when an insect's body, such as its legs or mouthparts, comes into contact with a pathogen, and then subsequently touches a host, transferring the pathogen directly. For example, houseflies can pick up bacteria from feces and transfer them to food.

Biological transmission is more complex and involves the pathogen developing or multiplying within the insect vector. This can happen in several ways. Some pathogens are ingested by the insect while it feeds on an infected host and are then transmitted to a new host when the insect feeds again, often through saliva injected during feeding. Malaria, transmitted by mosquitoes, is a classic example of this type of transmission. Other pathogens may encyst in the insect's body and are later released when the insect defecates near a wound or entry point, or when the host scratches the bite wound, introducing the pathogen. Fleas transmitting plague to humans is an example of this latter mechanism. Understanding hyönteisvälitys is crucial for disease control and prevention strategies, often involving measures to control insect populations or prevent insect bites.