Case Review: Parasitosis that Wasn't Delusional

While we have previously written about delusional parasitosis, which is more of a psychiatric than an infectious disease diagnosis, there is a situation where a patient’s complaints of parasites climbing out of their skin is worth looking into. Here is a case review. 

The patient returned from a trip to Belize in early July. Shortly thereafter he developed swelling, pain and redness over the left lower face just lateral to the side of his mouth. This lesion had a dimple in it that periodically drained serous to purulent material. He was treated with doxycycline and subsequently Bactrim with minimal improvement. A limited I and D was performed without much improvement. A culture did not show any pathogens. A dermatology e-consult the patient suggested it was an infected cyst.  An ultrasound was done which showed: “Complex subcutaneous lesion in the left cheek with a linear tract extending to the skin surface may represent a sebaceous cyst with internal debris” After about eight weeks, the patients lesion spontaneously ruptured emitting what the patient initially thought was a gummy bear but ultimately was found to be a fly larva. The patient slowly healed thereafter.

The key issue here that differentiates this from delusional parasitosis is the history of a recent trip to a tropical site and a persistent abscess-like lesion. Human furuncular myiasis is caused by Dermatobia hominis or the New World botfly in the Americas, particularly Latin America and the Caribbean and Cordylobia species in Africa. Infestation commonly occurs while sunbathing without insect repellent and may be on any exposed part of the body.

The vector may be a mosquito with botfly eggs implanted on it by a botfly in midflight (nature is infinitely industrious). The presentation is very much as described above. The classic treatment is blocking the dimple in the furuncle that allows the parasite to respirate with Vaseline, fingernail polish or the like, and hope the parasite is coaxed out. Lidocaine injection may also be helpful. Ultimately, surgical extraction may be necessary, followed by wound cleansing, tetanus prophylaxis as needed, and bacterial superinfection treatment if present. 

Not everyone who comes in with concerns of skin parasites is necessarily delusional.