Tropical Parasitology

DISPATCHES
Year
: 2020  |  Volume : 10  |  Issue : 2  |  Page : 147--149

Ophthalmomyiasis externa: A case report


Manoj Vedpathak1, Nirjhar Chatterjee2, Vasant Baradkar2, Jayanthi Shastri2,  
1 Department of Microbiology, Dr. V.M. Government Medical College, Solapur, Maharashtra, India
2 Department of Microbiology, TNMC and BYL Nair Ch. Hospital, Mumbai, Maharashtra, India

Correspondence Address:
Nirjhar Chatterjee
Department of Microbiology, College Building, 3rd Floor, TNMC and BYL Nair Charitable Hospital, Mumbai Central, Mumbai - 400 008, Maharashtra
India

Abstract

Ophthalmomyiasis is the infestation of ocular structures by fly larvae (maggots). Oestrus ovis is common among them. This is usually observed in rural areas, but a case presented here is from the urban areas. Depending on the species of larvae and ocular structure involved, manifestations vary from self-limiting condition to optic nerve involvement which may lead to blindness, and hence, identification and prompt management is necessary. This case report alerts the ophthalmologists from the urban areas to consider time management and also microbiologists for rapid identification.



How to cite this article:
Vedpathak M, Chatterjee N, Baradkar V, Shastri J. Ophthalmomyiasis externa: A case report.Trop Parasitol 2020;10:147-149


How to cite this URL:
Vedpathak M, Chatterjee N, Baradkar V, Shastri J. Ophthalmomyiasis externa: A case report. Trop Parasitol [serial online] 2020 [cited 2022 Sep 24 ];10:147-149
Available from: https://www.tropicalparasitology.org/text.asp?2020/10/2/147/307784


Full Text



 Introduction



Frederick William Hope introduced ophtalmomyiasis (OM), a zoonosis, as ocular infestation by dipterous larvae.[1] Ophthalmomyiasis externa refers to the involvement of superficial external ocular structures commonly by sheep botfly.[2],[3]

Clinical presentation varies depending on the species and location of the larvae.[4] Initially, it mimics commonly occurring inflammatory reactions of the ocular adnexa. Thorough clinical examination and laboratory corroboration are required to avoid misdiagnosis and delay in definitive treatment.[2]

The rural population is the common host. Till date, there is only one reported case from Maharashtra, a rural district of Loni.[5] This is the first reported case from urban areas of Maharashtra, namely Mumbai.

 Case Report



A 17-year-old male student presented to the ophthalmology outpatient department with a history of foreign body sensation, intense itching, reddening, and watering from the left eye.

On detailed history, it was revealed that some flying insect collided to his left eye on the previous day evening while returning home from school. He had foreign body sensations in the left eye a few minutes after the incident. As an initial remedy, he flashed his eyes with abundant water, but the symptoms failed to disappear. Later, his parents noticed a tiny white moving organism in his left eye. There was no history of surgical intervention, trauma to the other eye, diplopia, drug allergy, diabetes, immunocompromising disease, or drug intake. There were no complaints with the right eye.

On thorough examination, conjunctival congestion and excessive watering were noticed in the left eye. White twitching larvae were noticed on the palpebral conjunctiva and inner canthus [Figure 1]a. There was no corneal abrasion or perforation. On slit-lamp examination, the anterior chamber and lens appeared to be normal. Intraocular pressure was normal. The best-corrected visual acuity was 6/6. The right eye was normal.{Figure 1}

Local anesthesia using 4% topical xylocaine was given, and six maggots were removed from the left eye with forceps and cotton swab. Maggots collected in a sterile container were sent to the parasitology section.

On wet mount preparation, maggots showed typical rapid twitching movement and aversion from light. Macroscopic examination revealed about 1–2 mm length, white color larvae [Figure 1]b. Larvae were killed by formalin and seen under scanning microscope (×4); these were composed of eleven metameres, each displaying four rows of spines [Figure 2]a. The cephalic segment had two large black buccal hooks [Figure 2]b, and the posterior segment consisted of two tubercles [Figure 2]c, each containing about ten curved spines. Features were concordant with the morphological description of L1 Oestrus ovis larvae in the literature.[6]{Figure 2}

Definitive management for the patient was mechanical removal of all the larvae. The patient was discharged with a topical antibiotic (moxifloxacin) and antihistaminics to be put four times a day and asked for follow-up after 1 week. The patient reported immediate relief from foreign body sensation and itching while a resolution of other symptoms and signs took around 72 h.

 Conclusions



Myiasis is the infestation rather than infection of tissues, including organs of animals or humans by fly larvae (dipterous larvae), mostly belonging to the families of Oestridae, Calliphoridae, and Sarcophagidae.[2] These are commonly known as maggots. O. ovis (sheep botfly) is the most commonly reported cause.[2] Cases of cutaneous myiasis being commonly reported in humans, only a few reports are available for myiasis of the nose, eye, ear, genitourinary, and abdominointestinal tracts from India. Ocular involvement is seen in <5% of cases of myiasis.

On the basis of ocular structures involved, OM is classified into three types, as given in [Table 1].[3]{Table 1}

Predisposing conditions which may facilitate infestation by fly larvae include local factors such as eye infections or ocular wounds either due to surgery or trauma, advanced age, debilitation, poor general health, and poor hygiene.[2]

OM is usually observed in rural areas where O. ovis larvae parasitize the cavities of the frontal sinuses of sheep, causing sheep oestrosis from where humans get this zoonotic infestation due to close occupational contact.[1] Shepherds and farmers belonging to rural areas usually become accidental hosts.[2],[3] The first reported case from India was by Eliot in 1901.[7] Subsequently, other cases were reported from Uttar Pradesh, Karnataka, and Chandigarh.[4],[8],[9],[10],[11]

A case of human external OM is described here which is in contrast to commonly reported cases in three ways; first, the patient is a healthy young male without any debilitation, second, he is from an urban area with no rural travel history, and third, there is no occupational exposure opposing the idea of zoonosis.

Clinically, conjunctival myiasis manifests as:[1]

Superficial external forms (EOMs) classically associated with irritation, photophobia, and pain

(or)

Deep internal forms potentially associated with blindness.

Here, the clinical features corresponded with EOM.

Orbital myiasis may assume clinical pictures of varying severity from mild irritation to destructions of the orbit. In milder case, larvae deposit in the conjunctival sac and set up larval conjunctivitis. In a neglected person, the presence of a significant number of maggots and/or certain larval species such as Hypoderma (cattle grub)/reindeer fly/rodent botfly can cause serious consequences such as corneal ulcer and intraocular invasion due to the tendency to penetrate coats of the eyeball and orbit, adnexa, and optic nerve.[3],[9] Rapid laboratory identification and speciation are mandatory to avoid such consequences.

The simplest and commonly followed method of management is surgical removal under local anesthesia along with steroid and antibiotic prophylaxis.[2],[3] In our case, the patient responded to a similar line of management. Other treatment options mentioned in literature are surgical removal under local anesthesia along with systemic ivermectin[2] and liquid paraffin followed by mechanical removal and topical tobacco extract.[3] Having a propensity to invade into deeper tissue, rapid identification and thorough mechanical removal are necessary.

Ophthalmomyiasis externa is a potentially dangerous condition, for which early, prompt diagnosis and management is essential. It continues to be rarely reported from urban areas of Maharashtra, and this report would alert the ophthalmologists of the area to suspect ocular myiasis. The present case also illustrates the need for timely and correct diagnosis and rapid treatment for a favorable outcome.

Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent forms. In the form, the guardian has given the consent for images and other clinical information to be reported in the journal. The guardian understands that name and initials will not be published and due efforts will be made to conceal identity, but anonymity cannot be guaranteed.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

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