An apparently pharyngeal myiasis in a patient caused by Oestrus ovis (Oestridae: Diptera)

Incidence of myiasis among humans-a review

Myiasis, the infestation of tissues of live humans and other vertebrate animals with dipteran larvae (maggots), is a phenomenon of widespread occurrence throughout the tropical regions of the world. It is commonly seen in domestic and wild animals but occurs rarely in man also. The tissue invasion in man by maggots is generally a well-recognized complication of neglected wounds. The condition may be asymptomatic but occasionally results in more or less severe problems and even death when larvae invade body cavities or areas that forbid their direct visual examination. Many cases of myiasis, however, usually do not reach the attention of medical practitioners because of the tendency of the mature larvae to migrate out of the lesion for pupation. In the present study, the authors reviewed the past literature describing the cases of human myiasis, causative fly species and predisposing factors for the onset of the same. The aim of the present manuscript is to provide a database for the future reference of medical entomologists, medical practitioners and veterinarians. Review of literature revealed that 37 fly species belonging to ten families were responsible worldwide for the onset of human myiasis. The incidence of myiasis among humans can be correlated to increasing fly populations, poor hygienic conditions and presence of domestic animals in the close vicinity. Other factors responsible for myiasis include neglected open wounds and foul-smelling discharge from natural body openings. Moreover, ignorance plays a key role in its occurrence since people are generally unaware about the actual cause and often correlate the condition to their superstitious beliefs. It is emphasized that the patients should not neglect their wounds and should take proper medical care; otherwise, myiasis may supervene.

Diagnosis of ophthalmomyiasis externa by dermatoscopy

Ophthalmomyiasis in humans caused by the larvae of the sheep nasal botfly (Oestrus ovis) and is a rare phenomenon in Israel. We describe the utilization of the dermatoscope as a diagnostic tool for the facilitation of early diagnosis of conjunctivitis due to the infestation of the eyes by the sheep nasal botfly in two patients. After the physical removal of the larvae with the help of a cotton swab applicator under a slit lamp examination and the topical use of antibiotics, the clinical symptoms improved within 1-2 days. Undoubtedly the dermatoscope played a crucial role leading to the definitive diagnosis and immediate therapeutic intervention.

Ophthalmomyiasis caused by the sheep bot fly Oestrus ovis in northern Iraq

Myiasis is the feeding of fly larvae on vertebrates. The sheep bot fly larva of Oestrus ovis is a mammalian parasite of the skin, nose, ears, and eyes. When the larvae infest and feed on the structures of the eye, the condition is termed ophthalmomyiasis. Most often this infestation is limited to the external structures of the eye and is referred to as ophthalmomyiasis externa. The features of this condition are severe local inflammation, positive foreign body sensation, erythema, and lacrimation. Vision may or may not be reduced, depending on involvement of the cornea. A 20-year-old white male soldier sought treatment for an inflamed eye and an irritated cornea OS. His eyelids were swollen with marked periorbital edema and conjunctival erythema OS. On slitlamp examination, small whitish organisms were viewed on the conjunctiva OS. The organisms were removed, preserved, and sent to Nova Southeastern University where they were identified as O. ovis first-stage larvae. The patient was treated with antibiotic ointment, and the inflammation resolved within 1 week. O. ovis has a worldwide distribution, and although sheep are the preferred host, humans may also serve as an intermediate host in the organism's life cycle. This case represents one of several reports of ophthalmomyiasis in the Middle East caused by O. ovis. U.S. troops stationed in Iraq and surrounding areas are vulnerable to eye infestation by fly larvae, and health care providers need to include this condition in their differential diagnosis of anterior segment inflammatory disorders.