Intravitreal Onchocerca sp. With Concomitant Cerebral MRI Lesion: A Case Report

BACKGROUND Onchocerca lupi is a zoonotic filarial nematode that primarily infects canids. Human infection is rare and typically involves the eye or subcutaneous tissue. O. lupi infection should be considered in cases of unresolved uveitis or neurological symptoms. We report a diagnostically challenging case of human ocular O. lupi infection with possible neurological involvement. CASE REPORT A 24-year-old man from Jakarta, Indonesia, presented with a 1-month history of blurred vision, floaters, left ocular discomfort, and intermittent headaches. He did not respond to initial treatment for uveitis. Further examination revealed a mobile, thread-like, whitish worm in the left vitreous. Pars plana vitrectomy enabled removal of an intravitreal worm morphologically most consistent with adult male O. lupi, although definitive species-level confirmation was not possible in the absence of molecular testing. The patient's ocular inflammation resolved postoperatively, but his visual acuity remained poor. Due to persistent headaches, brain magnetic resonance imaging (MRI) was performed; a T1-hypointense and T2-weighted fluid-attenuated inversion recovery (FLAIR)-hyperintense white matter lesion was evident in the left parietal lobe. The lesion persisted on 9-month follow-up MRI, and its etiology was uncertain; a causal relationship with the parasitic infection could not be established. CONCLUSIONS We describe the first reported case of intravitreal O. lupi infection with a concurrent cerebral MRI lesion. This infection should be considered in the differential diagnosis of unresolved uveitis in endemic areas to facilitate timely diagnosis and help prevent irreversible visual damage.