To the Editor:
Moths and butterflies are ubiquitous insects belonging to the order of Lepidoptera. Mainly, it is the caterpillar larval form that is responsible for human envenomation. Numerous species can cause local clinical manifestations following the slightest exposure to caterpillars. This is the case for species of the genus Megalopyge which has over 220 registered taxa, mostly in South but also in North America [Citation1]. The Megalopyge opercularis species is well known in the USA where it has been at the origin of numerous clinical descriptions [Citation2]. Much further south, in French Guiana, a few rare cases of envenomation caused by caterpillars of the same species have already been reported [Citation3]. We describe three new observations in the Mana district following skin contact with caterpillars of the genus Megalopyge (see and ).
Table 1. Summary of 3 cases of Megalopyge caterpillar bite collected in French Guiana.
Despite the number of species of the genus Megalopyge, only reports of envenomation caused by the M. opercularis species are found [Citation1,Citation2]. The classical clinical presentation of such incidents shows a skin reaction, in the shape of an erythematous halo that can become haemorrhagic and vesicular, and may be accompanied by an excruciating pain and systemic manifestations [Citation1,Citation2,Citation4].
The 3 Guianese cases reported here also involved caterpillars of the genus Megalopyge but in French Guiana and identified by the physician as a different species than M. opercularis. The clinical presentation presented by our 3 patients is quite atypical, with the pain being sharp and much more intense than that reported in French Guiana [Citation4], reaching a level of mobility limitation for two of the patients. Despite the intensity of this pain, no skin lesion was visible. In two of the cases the pain was so intense that an injection of local anaesthetic was necessary to relieve patients. Recovery was rapid and without any side effects for all three patients within a few hours.
The local physician who followed all 3 patients was able to obtain photographs of the caterpillar involved in the third case. There has been no formal identification of the species. Locally they call the species in question M. albicollis, but this remains to be verified given the number of species described, also those yet to be described, of this genus.
In a neighbouring country, Venezuela, an identical clinical presentation to the one observed for our 3 patients has been reported, with intense pain and minimal cutaneous reaction, also concerning a caterpillar of the genus Megalopyge. The authors stated that they think that it was the M. opercularis species in question [Citation5].
Two distinct clinical presentations seem to be found following contact with a caterpillar of the genus Megalopyge: a clearly visible cutaneous lesion with moderate pain; or an extremely intense pain and absence of a cutaneous lesion in Guiana with no formal identification and suspected implication of the M. albicollis species in Guiana.
Declaration of interest
The authors report no conflicts of interest. The authors alone are responsible for the content and writing of the paper.
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