Onchocerca lupi infection in Turkey: A unique case of a rare human parasite

Abstract

Onchocerpa lupi was first isolated from a wolf in Russia. Since then, canine ocular onchocercosis has been increasingly reported, particularly in Europe and the United States. It is thought that blackflies and midges are the vectors of transmission, and it is possible that these vectors could transmit the parasite to humans. The first human case of O. lupi in Turkey was reported in 2011. In this report we present the third human case of O. lupi infection in Turkey. Our patient was a 28-year-old male who displayed a painless, immobile mass under the conjunctiva. The mass measured 10 x 12 mm in size. Pathological examination of the surgically excised tissue was suggestive of infection by a filarial nematode. Subsequently, the parasite was identified as O. lupi through molecular analysis. All of the previously reported cases of O. lupi in both humans and dogs were more symptomatic than in our patient, Onchocerca infection should not be ruled out during the differential diagnosis of the subconjunctival and orbital cystic mass in instances where there is little to no inflammation. It is important to consider biopsy and carry out molecular analysis to identify the parasite.

Human case of Onchocerca lupi infection, Germany, August 2014

“…The zoonotic significance of O. lupi was first highlighted in 2002 in two suspected human cases from Albania and Russia [3] that had occurred close to regions where the parasite had been described in a wolf and dogs [4]. Only recently, further and definitive human infections have been described from 2011 onwards in Turkey [5][6][7], Iran [8], Tunisia [7], and the US Figure 2 Molecular phylogeny of various Onchocerca species and other filaria species pathogenic for humans based on partial sequences of parasite 12S rRNA genes…”

“…[9,10]. The clinical picture in humans is characterised by the development of a bulbar subconjunctival nodule [5][6][7]10]. In one case also multiple eye nodules were observed [8].…”

Case report of an epidural cervical Onchocerca lupi infection in a 13-year-old boy

“…No other Onchocerca species have been reported to infect the intradural or extradural space of the cervical spine. [4][5][6]9,15,16,21,23 No prior reports have documented the treatment of CNS O. lupi infections in humans; however, ivermectin has been demonstrated to kill O. volvulus larvae and promote the death of adult worms when administered 4 times per year. The first patient diagnosed with O. lupi infection of the epidural cervical spine was also treated with ivermectin, 5 and interestingly, was also a Native American residing in northeastern Arizona.…”

“…While isolated spinal cysticercosis without intracranial involvement is rare, patients with spinal echinococcosis present more often with primary spinal infection. 1,3,5,[7][8][9][10][11][12][13][14][17][18][19][20]22 In a recent review of 467 cases of spinal echinococcosis by Neumayr et al, 13 17.9% were primary spinal infections without intracranial involvement.…”

“…Onchocerca is a genus of nematodes with 34 different species, which primarily parasitize nonhuman hosts. 9 The only well-established species known to cause human infection is O. volvulus, which causes onchocerciasis or "river blindness," primarily in Africa. 2 O. lupi is the only other species that has been reported to infect humans (7 cases total).…”