The patient was instructed to complete a regimen of oral azithromycin as prescribed the previous evening and to increase the frequency of the erythromycin ointment to every hour. The next day, when the patient returned for follow-up evaluation, there was significant improvement in the periorbital edema and erythema. Visual acuity was unchanged. A dilated fundus examination was performed at this visit, revealing healthy internal ocular structures. The patient continued to show improvement with complete resolution within 1 week.
The reported Middle Eastern cases of myiasis are from the Baghdad area of Iraq, southern Iran, Kuwait, Oman, Saudi Arabia, Jordan, Israel, and Egypt. All the reported cases from this region seem to have occurred between April and September. The case reported here accounts for the northernmost report of myiasis caused by O. ovis in the Middle East region and is also the case that occurred latest in the calendar year, a time that coincides with population peaks of sheep bot flies.31
When dipteran larvae infect a human, the disease is referred to as human myiasis. When the eye is involved, the disease is called ophthalmomyiasis, and distinction may be made as to whether the parasite is located in external or internal ocular tissues.38,39 External ophthalmomyiasis is typified by mild to acute conjunctivitis, pseudoorbital cellulitis, and superficial punctate keratitis.9,12,38 Engelbrecht et al.40 reported on the occurrence of a preseptal cellulitis secondary to Cuterebra sp. larval infection of a patient in North Carolina. If the larvae penetrate the globe, the host may have a poor visual outcome.25,41 In addition to O. ovis other dipteran larvae that have been reported to be the etiologic agents of ophthalmomyiasis include Hypoderma bovis, Hypoderma lineatum, Edemagena tarandi, Cuterebra sp., Gastrophilus intestinalis, Cochliomyia macellaria, and Rhinoestrus purpureus.42,43 Although O. ovis is the most common etiologic agent of ophthalmomyiasis on a global basis, Goodman et al.44 report that the human bot fly Dermatobia hominis is the most common cause of cutaneous myiasis in Central and South America. The disease ranges from being seasonal in dry arid environments to continuous throughout the year in more humid temperate areas.41
Untreated cases of ophthalmomyiasis externa do not always produce serious eye damage unless secondary bacterial complications ensue. Therefore, unidentified, untreated cases can resolve and go unreported. The authors believe that only a small proportion of actual human eye infestations are reported and that the few reports in the literature are reflective of the lack of definitive diagnosis of ophthalmomyiasis caused by larva of O. ovis or other species of flies.
Management of superficial infections includes antibiotic therapy and corticosteroids to alleviate the inflammatory response. It is advisable to use a topical anesthetic when removing the larvae from the ocular surface not only for the benefit of the patient but also to loosen the larval attachment to the ocular surface. Because the larvae migrate along the mucous tissue of the conjunctiva, it is necessary to double evert the eyelids to ensure that all the larvae have been removed. The inflammatory state of the conjunctiva is usually resolved within a few days, but if signs and symptoms persist for more than 1 week, a deeper penetration into the ocular tissues needs to be considered.
Myiasis is generally considered an occupational risk of raising sheep or goats. In this case, the intermediate human host was an American soldier serving at a post in Mosul, Iraq near the Tigris River. There were many sheep in the general area, but none were inside the military compound. With the increased frequency and length of deployments of our military around the world, it is important for all health care providers, military and civilian alike, to be aware of the increased risk of exposure to a wide variety of conditions, such as ophthalmomyiasis, that may otherwise not be on the providers’ list of differential diagnoses.
We thank the U.S. 101st Airborne Division for its cooperation.
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