Sir,
Verma P reported a 1-year-old infant having cerebral palsy, from a slum area in Delhi, India, with a diagnosis of furuncular myiasis due to Dermatobia hominis.[1] According to this report, the larvae of D. hominis (human botfly) were extracted from inflammatory nodules occupying the scalp with central discharging pores in this case.
As per literature, D. hominis is a causative agent for furuncular myiasis and is endemic in South and Central America.[2] There are also cases reported from other countries in travellers returning from these endemic areas. After searching in PubMed with key words DERMATOBIA HOMINIS, HUMAN BOTFLY and FURUNCULAR MYIASIS and to the best of our knowledge, there are no previous reports of furuncular myiasis due to D. hominis from India. In our opinion, diagnosis of furuncular myiasis due to D. hominis in India should be reported with caution based on travel history and thorough evaluation of clinical characteristics and based on the taxonomic identification by an entomologist. We believe that this was certainly performed in this case; however, some of the findings reported seem to be contradictory to the known characteristic diagnostic patterns. We are adding some of our observations.
D. hominis causes a furuncular lesion, usually single, with a central pore with sero-purulent discharge through which the posterior end of the larva can be seen.[3]
In this case, there are multiple nodular swellings.
The larva typically develops through three instars stages. The second instars have a characteristic flask shape, while the mature third instars have a characteristic fusiform shape but the larva depicted in the report lacks these features.
The mature third stage larva has parallel rows of posterior directed hooks which resist its extraction and the posterior protruding end of the larva usually has a pair of respiratory spiracles which are not evident from the image.
The gross appearance of the larva given in the report does not fit the standard characteristics and appears to be that of a different species. Species specific microscopic taxonomic characteristics of D. hominis are not clearly articulated in the report. We believe that wound myiasis due to Chrysomya bezziana (the Old World screwworm fly), a common species in the Indian subcontinent, also needs to be considered in this case.[4,5] DNA bar-coding has recently emerged as an easier, standard and more reliable technique of identifying insect species and this methodology has been found very useful for species identification of Dipterans in India.[6] Author could have used this tool as a confirmatory test in this case. Based on the observations cited above, a diagnosis of furuncular myiasis due to D. hominis in the reported case has to be reconsidered or requires substantiation with precise definition of larval morphology and DNA bar-coding.
References
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