Butterflies in the stomach: a critical analysis on human scoleciasis.

Butterflies and moths have been admired for their beauty since ancient times, but even these graceful insects can pose a danger to humans, albeit rarely, mainly because of the stinging toxic hairs on the larval stage of some species. In addition to this, since the 16th century, occasional findings of caterpillars still alive after being expelled by people through vomit or faeces led prominent scientists to consider the possibility that the larvae of some species of butterflies and moths, if accidentally ingested, could survive in the human gastrointestinal tract and cause a true infestation. More recently, in the 20th century, there have been reports of caterpillars of certain moths penetrating pre-existing skin wounds under particular circumstances. The human infestation (true or alleged) with caterpillars is known as scoleciasis. The objective of this study is to provide a comprehensive review of all documented cases of human scoleciasis in the literature to date and to assess whether or not this phenomenon should be considered a true parasitosis.