|Year : 2014 | Volume
| Issue : 1 | Page : 46-48
Dermatobia hominis : A souvenir from Peru
Matthias Buchner, Regina Foelster-Holst
Department of Dermatology, Universitary Hospital Kiel UKSH, Allergology and Venerology, Schittenhelmstraße 7, D-24105 Kiel, Germany
|Date of Web Publication||2-May-2014|
Department of Dermatology, Universitary Hospital Kiel UKSH, Allergology and Venerology, Schittenhelmstraße 7, D-24105 Kiel
Source of Support: None, Conflict of Interest: None
A 16-year-old female with a travel history to Peru and a developing subcutanous mass previously misdiagnosed as an abscess presented in our out-patient clinic. Upon inspection a parasite was detectable at a small entrance-channel on top of the lesion. We removed the parasite after local anesthesia. It was recognized as a Dermatobia hominis larva. A sequencing analysis was also performed to confirm the exact dipteran subspecies. Infestations with D. hominis are fairly common in tropical America but rather unknown to physicians in the northern hemisphere, although they comprise up to 10% of imported diseases from overseas. A travel history and a failure of antibiotic treatment are hallmarks that led to the correct diagnosis in previous reports. As world-wide travels become even more common a detailed travel history is mandatory to consider non-resident pathogens as possible cause of diseases.
Keywords: Dermatobia hominis , paediatric dermatology, travel history
|How to cite this article:|
Buchner M, Foelster-Holst R. Dermatobia hominis : A souvenir from Peru. Indian J Paediatr Dermatol 2014;15:46-8
| Introduction|| |
Here we present a case of a common disease in a much defined area of the world, namely tropical America. It is crucial in a more and more mobile society to be aware of not only the resident parasites and pathogens, but also those of popular travel destinations.
| Case report|| |
The present case report is about a 16-year-old female in good overall health was presented by her parents with a cutaneous nodular lesion over the right scapula in our out-patient ward. She returned from a several month stay in Peru 4 weeks earlier. Due to occasional bleeding discharge she covered the lesion with a small plaster.
Upon inspection a small pore with 4 mm diameter was identified and immediately after plaster removal a small part of a parasite showed for a short moment [Figure 1]. Attempts of removing the insect with forceps failed and subsequently an excision was planned. Upon subcutaneous infiltration with local anesthesia (mepivacain 0.1%) the larva emerged far enough for removal with forceps [Figure 2] and [Figure 3].
|Figure 2: After subcutaneous anesthesia the larva left the opening far enough to be picked with forceps|
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|Figure 3: The larva split in two parts during removal: The stem (left) and rectum and spiracle (right)|
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Subsequently we treated the lesion with octenidin 0.1% disinfection and prescribed oral flucloxacillin over 7 days preventing secondary infection.
After 3 weeks only a minimal residual scarring remained [Figure 4].
For detailed diagnostics of the larva a photograph was sent to the Zoologic Institute of the local University were it was instantly recognized as a Dermatobia hominis larva. The Zoologic Institute of Munich performed a polymerase chain reaction (PCR) -analysis and confirmed the sequenced Co1-Gene of this larva to be 100% identical with the D. hominis - reference in the BOLD-database.
| Discussion|| |
Infestations with larval states of dipterans are fairly common in tropical and subtropical regions and may be due to a variety of species.  D. hominis infestations from South- and Central-America are a source of about 10% of imported diseases of far-distance travellers. ,
In the initial stage this form of infestation can be easily misdiagnosed as an abscess, unless a detailed travel history is taken or antibiotic therapy failed. ,
The keen physician has to consider also other parasitic infections upon inspection, such as tungiasis, more common in Africa, or ictus reactions to anthropoids. 
The life-circle of D. hominis begins as an egg laid on the abdomen of a hematophagial insect, e.g. a mosquito. During the bloodsucking of the mosquito the larvae hatches and can penetrate the skin along the stitch. During the 4-8 weeks of larval stage a porus is kept to the surface of the skin to provide air and for removal of excrements. In the next stage, the larva lets itself fall to the ground and pupates. After a few days the adult fly hatches. 
Diagnostic means such as computed tomography, magnetic resonance imaging, ultrasound or dermatoscopy have been described in the literature. These examinations have been performed mostly due to wrong initial diagnoses and provide only minimal practical benefit.  For exact designation of the larval subspecies a PCR and gen-sequencing should be performed in an Institute for Parasitology and Entomology, , though for pure clinical work-up it might be enough to know the species which most probably can be identified by an experienced entomologist on sight.
Diagnostic and therapeutic procedure of choice is the removal of the larva in one piece by subcutaneous injection of local anesthetics (e.g. mepivacain, lidocain) or a lavage with 1% ivermectin solution. Ultima ratio is the surgical incision. 
A local antiseptic treatment afterwards is strictly speaking not necessary due to the clean environment the larva maintains in its cave, but still recommendable to facilitate undelayed wound healing.
As a take home message we hope to increase your awareness on abscesses that do not respond to antibiotic therapy, take a travel history and insist on identifying the underlying cause. In case of D. hominis infestations these can be non-traumatically removed and should be presented to an entomologist for designation.
| Acknowledgment|| |
The Authors would like to thank Prof. Böckele, Kiel (Germany) and Dipl-Biol. Jerome Moriniere and Mr. Doczkal from the "Zoologische Staatssammlung München", Munich (Germany) for their contribution.
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[Figure 1], [Figure 2], [Figure 3], [Figure 4]