Baylisascaris procyonis and Herpes Simplex Virus 2 Coinfection Presenting as Ocular Larva Migrans with Granuloma Formation in a Child

Case Report

The patient was a 12-year-old female born and raised in the Bronx, New York City, in an area bordering the suburban County of Westchester. She presented to the emergency department of the Jacobi Medical Center, Bronx, New York City, complaining of “redness and pain” in and about her right eye after reportedly being “poked” in that eye 5 days before. Her medical history included perinatal exposure to human immunodeficiency virus (HIV), bronchiolitis, attention deficit hyperactivity disorder, and she wore corrective glasses for astigmatism from age 2 to 7 years. There was a puppy in the household and she reported having played with several stray cats and had seen raccoons in the neighborhood. There was no history of pica and the remainder of the review of systems was negative.

Initially, her best corrected visual acuity was finger counting at two feet in the right eye and 20/200 in the left eye at distance. There was no afferent papillary defect. The right eyelid showed mild periorbital edema, with 2+ injection of her conjunctiva. Anterior segment exam revealed endothelial keratic precipitates and 3+ cells without flare in the anterior chamber. Intraocular pressures were 10 and 12 in the right and left eyes, respectively. On dilated funduscopic examination, a hazy view with approximately 3+ vitritis prevented visualization of the right fundus. Ultrasound confirmed a dense vitritis. The left eye posterior segment had a quiescent chorioretinal scar inferotemporally, approximately 1.5 disc diameters in size, without any overlying vitritis. The anterior segment of the left eye was normal. No nematode larvae were visualized in the eyes.

The patient was initially treated for presumed ocular toxoplasmosis with trimethoprim–sulfamethoxazole and prednisone. In addition, she was given a topical regimen of prednisolone acetate 1% and cyclogyl 1%. Serum serology was done for Toxocara, Toxoplasma, HSV, and syphilis, and later for Baylisascaris. Angiotensin-converting enzyme, human leukocyte antigen B-27, and rheumatoid factor were negative. C-reactive protein and the erythrocyte sedimentation rate were within normal limits and eosinophilia was absent. The chest X-ray and tuberculin skin test were negative.

On multiple subsequent visits, her anterior segment exam improved, but the dense vitritis persisted, and her vision just before surgery was hand motion in the right eye. On a subsequent exam, a membrane extending from the posterior pole near the optic nerve to the periphery was noted (Figure 1), raising the suspicion for Toxocara OLM despite the negative serology. She was treated for Toxocara with albendazole 200 mg twice daily, the trimethoprim–sulfamethoxazole was discontinued and the topical regimen was continued. Subsequent serum serology for Baylisascaris was positive (optical density [OD] = 0.476; positive > 0.250; serum dilution 1:200). Because of her non-clearing vitritis and suspicious-appearing retinal membrane, she had a pars plana vitrectomy with membrane dissection of the right eye. Undiluted vitreous fluid was obtained by aspiration and submitted for PCR for HSV, and for herpes zoster virus (HZV) Cytomegalovirus and Toxoplasma, serology for Toxocara and Baylisascaris, and for routine cytology and culture. After adequate core vitrectomy, visualization of the fundus revealed extensive membrane formation above a large retinal fold extending nasal from a granuloma at the posterior pole (Figure 1). Careful minimal dissection of the membranes was performed. Also noted was a mild amount of subretinal fluid in the peripapillary region. Vitreous fluid was PCR-positive for HSV-2 DNA as well as being seropositive for Baylisascaris (OD = 0.286; positive > 0.250; fluid dilution 1:10). There was no histopathology performed and the cytology of the vitreous fluid revealed benign squamous cell and lymphocytes. Serum serology detected both HSV-1- and HSV-2-specific antibodies. Albendazole, acyclovir, and corticosteroids were given by mouth. Acyclovir was administered for 1 year. The patient's visual acuity remained at counting fingers.

Photo of the fundus of the right eye: (A) note the peripheral granuloma (arrow) extending from optic nerve to periphery (see B). (B) Peripheral view of the right eye (note the optic nerve at the lower left corner) showing a posterior pole granuloma. (C) A view of the far periphery of the right eye showing proximal extent of the posterior pole granuloma causing a tractional retinal detachment.

Citation: The American Society of Tropical Medicine and Hygiene 93, 3; 10.4269/ajtmh.15-0272

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Photo of the fundus of the right eye: (A) note the peripheral granuloma (arrow) extending from optic nerve to periphery (see B). (B) Peripheral view of the right eye (note the optic nerve at the lower left corner) showing a posterior pole granuloma. (C) A view of the far periphery of the right eye showing proximal extent of the posterior pole granuloma causing a tractional retinal detachment.

Citation: The American Society of Tropical Medicine and Hygiene 93, 3; 10.4269/ajtmh.15-0272

• Download Figure
• Download figure as PowerPoint slide

Photo of the fundus of the right eye: (A) note the peripheral granuloma (arrow) extending from optic nerve to periphery (see B). (B) Peripheral view of the right eye (note the optic nerve at the lower left corner) showing a posterior pole granuloma. (C) A view of the far periphery of the right eye showing proximal extent of the posterior pole granuloma causing a tractional retinal detachment.

Citation: The American Society of Tropical Medicine and Hygiene 93, 3; 10.4269/ajtmh.15-0272

• Download Figure
• Download figure as PowerPoint slide

Discussion

This case represents the first confirmed case of baylisascariasis presenting as classic end-stage OLM with granuloma formation rather than the more commonly associated lesions of DUSN. Despite the fact that a larva could not be visualized in the eye, of particular interest was the observation of a positive Baylisascaris serology in the vitreous fluid, in addition to being seropositive in the serum. This has not been reported previously in cases of Baylisascaris OLM–DUSN, but is well-known for Toxocara infections. Often in cases of toxocaral OLM, and also presumably with Baylisascaris OLM, patients may be seronegative in serum but positive for antibodies in ocular fluid. This is related to low-level infection, with chance migration of a larva into the eye, where it incites a localized response.1–3 This underscores the fact that in OLM cases it is more diagnostic to perform serology on both fluids. Ocular antibodies in toxocaral OLM are often much higher than the serum titer, and may be detected even though the serum is negative4; this would also apply to some cases of Baylisascaris OLM, but in our patient both compartments were seropositive. Examination of the right eye revealed peripheral posterior pole granuloma with a membrane extending from the optic nerve to the periphery, as well as a tractional retinal detachment. Retinal detachment has not been reported previously in Baylisascaris infection but is well-known to occur in some Toxocara infections with granuloma formation. Retinal necrosis rather than retinal detachment is typically observed in HSV-2 infections5; however, this child did not have retinal necrosis clinically.

Baylisascaris procyonis is the most common cause of the “large nematode variant” of DUSN,1–3 a type of OLM with progressive visual loss secondary to inflammation of the retina, retinal vessels, and optic nerve.6,7 DUSN is manifested by the early loss of central vision, inflammation of the vitreous fluid, and edema of the optic disc. In addition, there are recurrent crops of gray–white lesions that affect the outer retina and pigment epithelium.6,7 These are considered to be inflammatory migration tracks associated with migrating larvae,8 and were also seen in experimentally infected primates.9,10 There is also inflammatory sheathing of retinal vessels. Eventually, there is optic atrophy, narrowing of retinal vessels, hypopigmentation, and visual field loss.6,7 These findings appear to be the result of eosinophilic inflammation stimulated by migrating larvae, with subsequent infiltration and degranulation of eosinophils resulting in ocular tissue damage.8,9 Migrating larvae release highly antigenic excretory–secretory products including enzymes and wastes that trigger the eosinophilic inflammatory reaction.4,8 There may be a sudden decrease in vision in one eye. Larvae that are observed in the retina are much larger than those of Toxocara, and are best treated by laser photocoagulation.2,3,11 The infection is also treated using steroids to reduce inflammation and albendazole to kill the parasites. The visual loss encountered with this infection is variable and in most cases treatment has not resulted in any significant improvement. In cases of heavier infection, B. procyonis typically produces meningoencephalitis, which is often irreversible, and may include concomitant ocular involvement with DUSN.2,3

All reported cases of Baylisascaris OLM in humans to date have had lesions of DUSN associated with active migration of intraocular larvae. Although granuloma formation and associated retinal detachment would be expected in B. procyonis OLM (as seen in OLM due to Toxocara species), before this case it has not been reported. However, intraocular granulomas were noted in nonhuman primates and rodents experimentally infected with B. procyonis, along with lesions of DUSN.9,10

There is a plausible explanation for the coexisting HSV-2 infection in the right eye. This girl was born to an HIV-infected mother and most likely acquired an asymptomatic neonatal HSV-2 infection, which at age 12 was reactivated in the eye. Eight similar published cases exist of HSV-2 reactivation in the eye in children and young adults with asymptomatic perinatal HSV-2 infections.5 All eight cases had retinal necrosis, a clinical diagnosis for which a biopsy is routinely performed. In the absence of clinical findings of retinal necrosis in this case, neither retinal biopsy nor HSV testing was immediately performed. It is believed that the Baylisascaris infection was responsible for the chronic damage to the eye of this patient, and that she acquired the infection in the urban environment of New York City, similar to what occurred in two other cases.11,12 Raccoon sightings are common in the part of New York City where the patient resides and raccoons in the northeastern United States are commonly infected with B. procyonis.1

This case demonstrates that patients with infectious uveitis may harbor more than one infectious agent, so comprehensive evaluations are essential even in the setting of classic presentations. This case further illustrates that even in an urban setting, Baylisascaris OLM infections should be considered in the differential diagnosis, and that patients can have an atypical presentation with other ocular lesions present besides those of DUSN.