Neuroinvasive Onchocerca lupi Infection in a Ten-Year-Old Girl

Abstract

The nematode Onchocerca lupi is an emerging human pathogen. Though its life cycle is not well studied, it likely infects humans after a bite from a black fly vector, which in turn acquires infective microfilariae from an infected canid. These microfilariae mature into an infective larval stage within the fly. Among six reported cases in the United States, five involved children, and all occurred in the southwest. In this report, we present a case of O. lupi infection with cervical spine invasion in a healthy 10-year-old girl. She presented with five months of neurological symptoms from a rural and medically underserved area, highlighting a need for clinical vigilance in such settings for this emerging infectious threat in the American southwest.

Figure 1

Sagittal T1-weighted preoperative MRI with contrast showing an anterior intradural extramedullary mass, measuring 1.6 × 0.9 × 2.8 cm (blue arrow). The mass is centered at C5 and spans from C4-6 with what appears to be a dural tail. The mass shows significant compression of the spinal cord.

Figure 2

Longitudinal section revealing degenerating Onchocerca lupi nematode encased in inflamed, dense fibrous tissue. Lillie–Twort Gram stain, original magnification ×25.

Figure 3

Trichrome-stained sections of O. lupi revealing relevant morphological features ((a) 200x magnification and (b) 400x magnification). Arrows indicate external cuticular ridges, and arrowheads indicate internal striae.