Massive Orbital Myiasis Infestation

Infestation by dipterous fly larvae in ocular and orbital tissues (ophthalmomyiasis) occurs throughout the world, mostly in children and older people and, depending on the genus of the fly, the infestation can be by single or multiple larvae.¹ We report a case of orbital myiasis in a man who had more than 100 larvae removed, followed by orbital exenteration.

A 54-year-old man had severe pain and swelling in his right orbital region. The sensation was noted 4 hours prior to examination, just after waking up from an estimated 24-hour sleep in a countryside house after ingesting a bottle of a sugarcane alcoholic beverage. The patient reported undergoing exeresis of a suspected skin cancer in his right inferior eyelid a few years previously that then recurred with an exudative inferior eyelid lesion. In addition, alcoholism of 30 years' duration was mentioned.

Findings from examination revealed periorbital edema, erosion of the skin and conjunctiva of the inner canthus of his right orbit, and a wound full of larvae that displaced the eye globe to the outer canthus. Findings from gross examination revealed a hypotonic eye, an inflamed conjunctiva, and a severely swollen cornea. Visual acuity OD was no light perception (Figure 1 and Figure 2).

The patient underwent orbital exenteration under general anesthesia (Figure 3) and more than 100 larvae of Cochliomyia hominivorax (Coquerell) (Diptera: Calliphoridae) were removed. Findings from histological analysis of the specimen showed the presence of basal cell carcinoma in the eyelid with infiltration into the muscle layer; the margins were free of neoplasm. This patient's oculoplastic aspect has been followed up periodically to provide a satisfactory cosmetic result. In addition, a psychiatrist was enrolled to provide needed assistance.

Ophthalmomyiasis is considered a rare, life-threatening condition. Mechanical removal with or without chemical immobilization of the larvae are the options of treatment, depending on the time and degree of infestation. The preservation of larvae in ethanol for genus identification may be useful for epidemiological purposes and the subsequent application of large-scale measures to reduce the fly population. Outbreaks of C hominivorax have been reported, and although considered to be confined to the New World, reports have identified the parasite in Africa and Asia.²

The massive infestation seen here may have been precipitated by an open wound caused by basal cell carcinoma in the nasal canthus. This hypothesis is based on previous observations that adult flies of C hominivorax locate their hosts via visual and olfactory stimuli and are strongly stimulated by fresh blood, usually present in this type of skin neoplasia.³ Alcoholism and the prolonged state of unconsciousness in a rural location contributed to the fast destruction of the orbit of our patient. Exenteration was conducted to prevent intracranial progression.

Although there is no method for completely protecting against myiasis, prevention may be conducted on a local scale by practicing adequate personal hygiene and proper care of wounds. To our knowledge, this is the first reported case of ophthalmomyiais caused by C hominivorax in which exenteration was necessary to contain the progression of the infestation.

Corresponding author: Eduardo M. Rocha, MD, Faculty of Medical Sciences, State University of Campinas (UNICAMP), Rua Alexandre Fleming, s/n, Campinas, SP, CEP 13081-970, Brazil (e-mail: emrocha@unicamp.br).