Larvae under the skin

The image shows two carbuncles in the buttock region of a patient who had been on holiday in West Africa. In the centre of the carbuncles are 3 mm holes that lead down to channels 1–2 cm deep. The patient noticed the swellings during the journey home, when they became tender, itchy and started to ooze. Two days after returning home, the patient discovered yellow-white larvae crawling out of the wounds (see video). The wounds were cleaned and checked for more larvae. They healed without becoming infected, and the itching subsided.

The patient had classic furuncular myiasis caused by Cordylobia anthropophaga fly larvae, commonly known as the mango fly or tumbu fly. Tumbu is the most common cause of human myiasis in Africa (1). The fly lays eggs in damp soil or clothing (1–3). When human skin comes into contact with the eggs, the larvae hatch and burrow under the skin. They develop for 8–12 days before leaving the host and pupating. The larvae need an air hole, which appears as a visible opening in the swelling above them.

Treatment involves removing the larva. One method is to seal the air hole with oil and wait for the larva to come out in search of air (this can take 24 hours), after which it can be removed. Alternatively, the larva can be surgically removed (1–3). A tetanus vaccine is recommended.

Facultative myiasis is the predominant form observed in Norway, involving fly larvae species that can consume necrotic tissue in poorly managed chronic wounds. The reindeer warble fly (Hypoderma tarandi) causes specific myiasis in reindeer but has also caused several cases of human myiasis in Finnmark (4). The diagnosis is clinical. If identification of the exact fly species is required, the larva can be placed in ethanol and sent to a microbiology laboratory for microscopic examination.