Infection Magic

Infection Magic (Kansen majutsu) is one of two broad categories of magic, the other is Imitative Magic. It was first introduced in Shinyaku Toaru Majutsu no Index and used by Tsuchimikado Motoharu.

Principles
Magic of the infection category could use object such as hairs, fingernails, or other parts of the body such an eye. The most popular forms of curse magic would remotely attack the target by destroying a piece of one's target using a special method.

Agitate Halation Arc
In his quest for revenge, Motoharu comes upon Kumokawa Seria and is dominated by her through her superior analysis of his capabilities. Knowing that she is unaware of magic, Motoharu plucks one of her eyes out, though she is unperturbed by this, and merely shoots him on his side. Thinking that Motoharu's cards are spent, she suddenly feels an unpleasant pressure in her chest that she cannot ascertain. She collapses and it is revealed that Motoharu used a modified Ushi no Koku Mairi curse, a simple curse that can be countered by any decent magician, but not those who know nothing of magic.

Trivia

 * Infection Magic is similar to the real-life magical concept, which states that things which have once been in contact with each other supposedly continue to act on each other at a distance even after physical contact has been severed.