Cutaneous Manifestations of a Zoonotic Onchocerca Species in an Adult Male, Acquired in Nova Scotia, Canada

Abstract

A 65-year-old male with known hypertension and hypercholesterolemia sought medical attention because of a 3-month history of skin swelling on his upper back. Histopathology and molecular techniques were employed and identified an organism in the Onchocerca genus. This represents a very uncommon example of cutaneous infection by a zoonotic Onchocerca species. CASE REPORTA 65-year-old Caucasian man from rural Nova Scotia sought medical attention because of a sudden onset of localized swelling of the skin in the inferior left scapular area. He had noted a small, mildly tender pruritic papule one morning, measuring less than 1 cm, which he regarded as a possible insect bite. Over the course of 1 day, the lesion enlarged to form a nodule measuring approximately 4 cm in diameter. Medical attention was sought. The patient was given a 10-day course of antibiotics which caused the swelling to decrease in size, but the nodule did not resolve completely. Elective surgical excision was undertaken.Within the previous 5 years, the patient had traveled to Florida in April 2009 and had been working in Ontario until 31 May 2010. While in Ontario, he had been in charge of maintaining a high-rise apartment block in Windsor for 12 years. Prior to this, he had worked in the automotive industry. There was no history of foreign travel. During the previous 3 years, the patient had resided in rural Nova Scotia, where he had a pet dog with a free range in an open hayfield where contact with wild animals was minimal. The dog showed no symptoms of infection during this period and remains healthy to the present day. The patient's medications included 12.5 mg hydrochlorothiazide once daily for hypertension and 20 mg simvastatin once daily for hypercholesterolemia. He was otherwise healthy. There was no history of immunosuppression.On examination, an erythematous nodule was evident on the left upper back just inferior to the scapula. This area had been covered by clothing, and the patient could not recall any history of an arthropod bite. No other skin lesions were detected. Preliminary blood work was not performed. Following excision, the specimen was submitted to the laboratory for processing. Clinically interpreted as a cyst, the submitted sample consisted of an ellipse of skin and subcutaneous adipose tissue measuring 1.4 by 0.3 by 1.3 cm. It was serially sectioned and submitted in total. Histopathologic examination revealed a dense, nodular, superficial and deep, perivascular lymphocytic infiltrate with abundant eosinophils in the dermis and superficial panniculus. Small foci of interstitial granulomatous inflammation were noted ( Fig. 1A and B). Close to the edge of the biopsy specimen, in association with the inflammatory infiltrate, cross sections of a nematode were noted (Fig. 1C).A microbiological consultation confirmed the presence of a nematode measuring 60 by 68 m. There were no lateral alae, and the cuticle was smooth, with a 3-m thickness. The lateral cords had 2 cells with prominent nuclei, but the dorsal and ventral lines wer...

Zoonotic Implications of Onchocerca Species on Human Health

“…Among these cases in humans, O. lupi was the most prevalent species identified, followed by O. dewittei japonica and, to lesser extent, O. jakutensis, O. gutturosa, and O. cervicalis. Moreover, there are several cases where Onchocerca parasites infecting animals were found in humans, but the species was not identified [127][128][129][130][131][132][133] or was only suspected without confirmation [134][135][136]. The first human case unequivocally caused by O. lupi was found infecting the subconjunctival region of a person in Turkey [76].…”