Infection vs. inflammation
Infection and inflammation are two concepts that are often linked, but they are not synonymous.
Infection means that tissues in the body have been colonized by microorganisms (bacteria, fungi, viruses or protozoa), which continue to multiply and cause tissue damage. If the microorganism in question does not cause damage, but belongs to the normal flora and is perhaps even useful for its host animal, one should instead speak about colonization.
Inflammation is the body's defense reaction to an attack of microorganisms or an injury (eg, stroke, heat, cold or allergy). Some diseases can also cause inflammation. The body's defense reactions are characterized by, among other things, the peripheral blood vessels being widened to become permeable to blood plasma and immune cells (white blood cells), which can then leave the bloodstream and seek out and disarm microorganisms or repair damage to the body's cells.
In the case of ectoparasites, one sometimes sees the concept of infestation instead of infection and, particularly in American literature. However, this expression should be avoided as it may cause confusion.