Subconjunctival zoonotic Onchocerca in an Albanian man

Confirmed cases of human Onchocerca lupi infection: a systematic review of an emerging threat

Diverse Onchocerca species are present mostly parasitizing ungulates, with the exception of Onchocerca volvulus (O. volvulus) in humans and O. lupi in canids and cats. The human cases due to the O. lupi have been more highlighted during last years. So, the present review was performed to determine the detailed characteristics of confirmed human O. lupi case reports documented worldwide. Hence, a systematic search was done using English international databases (Scopus, PubMed, Web of Science, Embase, ProQuest, and Google Scholar). Totally, 14 confirmed human cases were documented during the last decade, mostly from the USA and Turkey with 7 and 3 cases, respectively. Most cases (7 individuals) were male with the age range of 22-month-old to 54-year-old. The parasite was frequently isolated from the right eye (5 cases), followed by the left eye (4 cases), cervical spinal canal (3 cases), scalp, and right forearm (one case each). Molecular identification of the isolated agent was the preferred way of diagnosis in most cases (9 records). In conclusion, human O. lupi cases have been more highlighted in recent years, whether due to the improved diagnostics and/or host-switching phenomenon, and both veterinarians and healthcare authorities should be alerted.

Zoonotic Ocular Onchocercosis by Onchocerca lupi

The parasitic filarioid Onchocerca lupi causes ocular disease characterized by conjunctivitis and nodular lesions. This nematode was first described in 1967 in a wolf from Georgia, and since then cases of infection from dogs and cats with ocular onchocercosis and sporadically from humans also with subcutaneous and cervical lesions caused by O. lupi have been reported from the Middle East, Europe, and North America. Due to its zoonotic potential, this parasitic infection has gained attention in the past 20 years. Phylogenetic studies have highlighted the recent divergence of O. lupi from other Onchocerca spp. and the importance of domestication in the evolutionary history of this worm. Moreover, the finding of an O. lupi genotype associated with subclinical and mild infection in the Iberian Peninsula, raises important questions about the pathogenicity of this presently enigmatic parasite.

Zoonotic Implications of Onchocerca Species on Human Health

The genus Onchocerca includes several species associated with ungulates as hosts, although some have been identified in canids, felids, and humans. Onchocerca species have a wide geographical distribution, and the disease they produce, onchocerciasis, is generally seen in adult individuals because of its large prepatency period. In recent years, Onchocerca species infecting animals have been found as subcutaneous nodules or invading the ocular tissues of humans; the species involved are O. lupi, O. dewittei japonica, O. jakutensis, O. gutturosa, and O. cervicalis. These findings generally involve immature adult female worms, with no evidence of being fertile. However, a few cases with fertile O. lupi, O. dewittei japonica, and O. jakutensis worms have been identified recently in humans. These are relevant because they indicate that the parasite’s life cycle was completed in the new host—humans. In this work, we discuss the establishment of zoonotic Onchocerca infections in humans, and the possibility of these infections to produce symptoms similar to human onchocerciasis, such as dermatitis, ocular damage, and epilepsy. Zoonotic onchocerciasis is thought to be an emerging human parasitic disease, with the need to take measures such as One Health Strategies, in order to identify and control new cases in humans.

Onchocerca jakutensis ocular infection in Poland: a new vector-borne human health risk?

BACKGROUND

Zoonotic onchocerciasis is a vector-borne disease, which involves many animal species, including large ungulates, boars, dogs, and sporadically, humans. So far, 39 cases of zoonotic onchocerciasis have been reported worldwide, 30 of which have been found in the last 20 years. Onchocerca nematodes are transmitted to humans by blood-sucking vectors during a blood meal. The following species have been responsible for zoonotic infections: Onchocerca cervicalis, O. dewittei japonica, O. gutturosa, O. jakutensis and O. lupi. In humans, the worms have usually been found in the subcutaneous tissues where they form subcutaneous nodules, induce inflammation of musculature, or penetrate the eye. Thirteen ocular zoonotic onchocerciasis cases have been reported so far. In the eye, nematodes were localized in the subconjunctival space, anterior chamber and within the vitreous body.

METHODS

In a 39-year-old male patient, a writhing worm in the vitreous body of the left eye was detected and surgically removed. Laboratory identification of the worm was based on macroscopic and molecular identification, based on sequencing of the cytochrome c oxidase subunit 1 gene (cox1). Phylogenetic analysis of the first 250 nucleotide sequences showing the highest levels of similarity with the present isolate in a BLAST analysis was performed.

RESULTS

Here, we report the first case worldwide of human ocular infection with O. jakutensis, a natural parasite of red deer. By exploiting a PCR assay, we detected the sequence almost identical to O. jakutensis (GenBank: KT001213.1; positions 1-650) with a single mismatch G/A at position 622. The sequence reported in this paper was deposited in the GenBank database under the accession number MK491767.

CONCLUSIONS

Our case together with the previous case reports indicate that zoonotic Onchocerca worms exhibit no tissue specificity and an eye infection has been described in over one third of human zoonotic onchocerciasis cases. In terms of the growing number of cases of zoonotic onchocerciasis in Europe, the USA and Japan, attention should be paid to the diagnosis of subcutaneous nodules and eye infestations.

First molecular detection of Onchocerca flexuosa (Wedl, 1856) in red deer in Slovakia

The present paper deals with the post-mortem diagnostics of onchocerciasis and the molecular detection of causative agents of this disease in wild ruminant ungulates (Cervus elaphus, Dama dama and Capreolus capreolus). The animals were shot in hunting seasons 2017 and 2018, in two regions of the Eastern Slovakia. The total number of examined skins was fifty-eight. The presence of subcutaneous nodules was confirmed in 27.59% (95% CI 16-39) of animals. All positive skins belonged to red deer individuals (47.06%; 95% CI 30-64). The nodules were present mainly in the back area and in the lumbar area, and their sizes ranged from 2.9 to 24.1 mm, with the average count of 10 nodules per animal. Thirteen worms, isolated from the nodules collected from 13 animals, were subjected to molecular identification. Applying the standard PCR method, targeting the mitochondrial 12S rRNA, 16S rRNA and NADH-dehydrogenase gene, and subsequent sequencing, all the worms were identified as Onchocerca flexuosa Wedl, 1856. The sequences were submitted to GenBank under specific accession numbers. Two samples were identified as Onchocerca flexuosa haplotype B, in which T176A and A177T were present. Despite the presence of mutations in the 12S rRNA of the Onchocerca flexuosa, the standardized PCR remains to be a very specific and sensitive method that uses this fragment as a selectable marker for the detection of the studied parasite.

The Emergence of Zoonotic Onchocerca lupi Infection in the United States--A Case-Series

This case-series describes the 6 human infections with Onchocerca lupi, a parasite known to infect cats and dogs, that have been identified in the United States since 2013. Unlike cases reported outside the country, the American patients have not had subconjunctival nodules but have manifested more invasive disease (eg, spinal, orbital, and subdermal nodules). Diagnosis remains challenging in the absence of a serologic test. Treatment should be guided by what is done for Onchocerca volvulus as there are no data for O. lupi. Available evidence suggests that there may be transmission in southwestern United States, but the risk of transmission to humans is not known. Research is needed to better define the burden of disease in the United States and develop appropriately-targeted prevention strategies.

Onchocerciasis caused by Onchocerca lupi: an emerging zoonotic infection. Systematic review

Globalization has increased circulation of people, their food, livestock and pets in the world, and changes in the environment, climate and human behaviour have led to the rapid expansion of emerging infections throughout the world. One of the reasons of a new pathogen affecting humans is the passage from an animal to a human being. Onchocerca (O.) lupi, a filarial worm first described in a wolf in 1967, is an emerging pathogen which has been incriminated as the etiological agent for 205 canine, 2 feline and 18 human infections in Europe, Tunisia, Turkey, Iran and the USA. Most frequent findings in animals and humans are monolateral or asymmetrical variably painful subconjunctival swellings and nodules containing immature or mature worms affecting the eye and/or adjacent tissues accompanied by conjunctival hyperemia. Occasionally, subcutaneous nodules and masses affecting the spinal cord have been observed in humans. Diagnosis of O. lupi is achieved by microscopy of excised adult female worms which exhibit a particular cuticular structure and molecular analysis. Treatment consists in worm removal accompanied by antihelminthic, antibiotic and anti-inflammatory therapy.

Intraocular localization of Onchocerca lupi adult worm in a dog with anterior uveitis: A case report

OBJECTIVE

Canine ocular onchocercosis may represent an important ocular disease with zoonotic potential and widespread geographical distribution. An uncommon localization of Onchocerca lupi adult worm in the anterior chamber of the eye is described for the first time.

ANIMAL STUDIED

A 4-year-old, intact, male, mixed-breed dog was admitted with profuse lacrimation and severe squinting. On the right eye, there were mucopurulent discharge, chemosis, and all typical signs of anterior uveitis which were attributed to the presence of a moving filarial worm within the anterior chamber.

PROCEDURE

Removal of the parasite from the anterior chamber by a limbal incision revealed a mature adult male, 7.65-cm-long O. lupi worm. Periocular skin scrapings for the corresponding microfilariae were negative. Postoperatively, apart from systemic prednisolone and doxycycline hyclate and a topical antibiotic/steroid solution, parenteral melarsomine, followed by ivermectin, was given until the complete disappearance of the ocular lesions.

CONCLUSIONS

Intraocular onchocercosis should be included in the differential diagnosis of canine anterior uveitis in endemic areas. This case highlights the atypical localization of O. lupi in the canine eye emphasizing on the possibility for a complete cure after the surgical removal of the parasite and the filaricidal medication subsequently applied.

Cutaneous manifestations of a zoonotic Onchocerca species in an adult male, acquired in Nova Scotia, Canada

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.

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

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 × 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.

Zoonotic Onchocerca lupi infection in a 22-month-old child in Arizona: first report in the United States and a review of the literature

A 22-month-old girl presented with neck pain and stiffness and magnetic resonance imaging showed an extradural mass extending from C2 through the C4 level with moderate to severe compression of the cord. A left unilateral C2-C4 laminectomy was performed revealing an extradural rubbery tumor; a small biopsy was obtained. Examination of stained tissue revealed the presence of a parasitic worm that was identified as a gravid female Onchocerca lupi. A magnetic resonance imaging at 7 weeks follow-up showed a significantly decreased size of the enhancing lesion and the patient's symptoms gradually resolved. This is the first report of zoonotic O. lupi in the United States. The parasite has been reported in dogs and cats in the western United States, and from people in four cases reported from Europe. A great deal more needs to be learned, including full host range and geographic distribution, before we fully understand O. lupi infections in animals and man.

Blackfly vectors of zoonotic onchocerciasis in Japan

Studies of blackfly vectors of Onchocerca dewittei japonica Uni, Bain & Takaoka (Spirurida: Onchocercidae), a parasite of wild boar implicated in the aetiology of zoonotic onchocerciasis in Japan, and six other zoonotic Onchocerca species of this country are reviewed. Molecular identification of infective larvae found in wild-caught female blackflies showed that Simulium bidentatum (Shiraki) (Diptera: Simuliidae) is a natural vector of O. dewittei japonica, and also Onchocerca sp. sensu Fukuda et al., another parasite of wild boar. Inoculation experiments demonstrated that Simulium arakawae Matsumura and four other Simulium species are putative vectors. Similarly, S. arakawae, S. bidentatum and Simulium oitanum (Shiraki) are putative vectors of Onchocerca eberhardi Uni & Bain and Onchocerca skrjabini Rukhlyadev, parasites of sika deer. Morphometric studies of infective larvae indicated that Onchocerca lienalis Stiles, a bovine species, is transmitted by S. arakawae, Simulium daisense (Takahasi) and Simulium kyushuense Takaoka, and that Onchocerca sp. sensu Takaoka & Bain, another bovine species, is transmitted by S. arakawae, S. bidentatum, S. daisense and S. oitanum. Prosimulium sp. (Diptera: Simuliidae) and Simulium japonicum Matsumura are suspected vectors of Onchocerca suzukii Yagi, Bain & Shoho and O. skrjabini [Twinnia japonensis Rubtsov (Diptera: Simuliidae) may also transmit the latter], parasites of Japanese serow, following detection of the parasites' DNA genes in wild-caught blackflies.

Onchocerca lupi causing ocular disease in two cats

Although canine ocular onchocerciasis has been well described as an emerging pathogen of dogs in Europe and North America over the past 20 years, there are no previous reports of feline ocular onchocerciasis. This report details the clinical, histopathologic, and molecular diagnosis of two domestic short hair cats residing in the United States infected with Onchocerca lupi causing episcleritis and orbital cellulitis. The results of this report suggest that O. lupi is a newly recognized disease of domestic cats.

Zoonotic helminths affecting the human eye

Nowaday, zoonoses are an important cause of human parasitic diseases worldwide and a major threat to the socio-economic development, mainly in developing countries. Importantly, zoonotic helminths that affect human eyes (HIE) may cause blindness with severe socio-economic consequences to human communities. These infections include nematodes, cestodes and trematodes, which may be transmitted by vectors (dirofilariasis, onchocerciasis, thelaziasis), food consumption (sparganosis, trichinellosis) and those acquired indirectly from the environment (ascariasis, echinococcosis, fascioliasis). Adult and/or larval stages of HIE may localize into human ocular tissues externally (i.e., lachrymal glands, eyelids, conjunctival sacs) or into the ocular globe (i.e., intravitreous retina, anterior and or posterior chamber) causing symptoms due to the parasitic localization in the eyes or to the immune reaction they elicit in the host. Unfortunately, data on HIE are scant and mostly limited to case reports from different countries. The biology and epidemiology of the most frequently reported HIE are discussed as well as clinical description of the diseases, diagnostic considerations and video clips on their presentation and surgical treatment.

Case report: First evidence of human zoonotic infection by Onchocerca lupi (Spirurida, Onchocercidae)

In the past decades, cases of canine ocular onchocercosis have been reported worldwide, particularly in the United States and Europe. Onchocerca lupi, originally described from a wolf, has been implicated in some of these cases, and its zoonotic role has been hypothesized on the basis of the reexamination of two cases of human ocular onchocerciasis. In the present study, we describe, for the first time, the occurrence of O. lupi in the subconjunctival region of the human eye in a patient from Turkey. The nematode was identified as O. lupi based on its morphology and molecular phylogenetic analysis of partial cox1 and 12S ribosomal DNA genes. The results suggest that O. lupi should be considered in the differential diagnosis of other eye parasitic infections in humans. The role of dogs as natural hosts of O. lupi and the vectors of this zoonotic parasite need to be investigated.

Onchocerca jakutensis filariasis in humans

We identified Onchocerca jakutensis as the causative agent of an unusual human filariasis in a patient with lupus erythematosus. To our knowledge, this is the first case of human infection with O. jakutensis and the first human case of zoonotic onchocercosis involving >1 worm.

Zoonotic intravitreal Onchocerca in Hungary

OBJECTIVE

To report the case of a 65-year-old male patient from western Hungary who presented with rapidly progressive peripheral visual field (VF) loss and the sensation of an actively moving object in his central VF.

DESIGN

Interventional case report. METHOD/INTERVENTION: A live nematode was removed from the anterior vitreous cavity by pars plana vitrectomy.

RESULTS

The worm was successfully removed surgically, and the patient had an uneventful recovery. The nematode was identified as an immature filaria, most likely a member of the genus Onchocerca.

CONCLUSIONS

Only 3 previous reports exist of human infection of the eye caused by zoonotic Onchocerca, 2 involving the subconjunctiva and 1 the cornea. Although rare, zoonotic onchocercal infection of the eye must be considered a differential diagnostic entity even in temperate climates.

An Onchocerca species of wild boar found in the subcutaneous nodule of a resident of Oita, Japan

Histological examination and dissection of a subcutaneous nodule removed from the right infraclavicular region of a 69-year-old woman from Oita, Kyushu, Japan, revealed a young female of Onchocerca dewittei japonica, a common parasite of wild boar in the Oita region. Distinctive morphologic characteristics of this Onchocerca species include the thick cuticle with very prominent and straight transverse ridges overlapping at the lateral sides, the lack of inner striae (scalloping) of the inner cuticle layer, the dorso-ventral symmetry, and the thick somatic muscles. Jointed with previous reports in the past decade, this case confirms the occasional transmission of the parasite from wild boar to humans in Oita.

Subconjunctival zoonotic onchocerciasis in man: aberrant infection with Onchocerca lupi?

In the past few decades, 10 cases of cryptic, zoonotic onchocerciasis, including two subconjunctival infections, have been reported in man. In the majority of cases, Onchocerca cervicalis, O. gutturosa or O. dewittei, which normally infect horses, cattle and wild boar, respectively, were responsible for the lesions. However, the taxonomic status of the parasites involved in the two subconjunctival infections, both of which were European, has never been unambiguously determined. In such infections, the acute phase appears to be characterized by conjunctivitis. A single, strongly coiled, immature, female worm was found incorporated in a large granulomatous nodule, in the ocular and peri-ocular tissues, in the chronic stage of each of the two eye infections. Several, patent, sporadic cases of subconjunctival O. lupi infection have recently been reported in dogs. In terms of the location of the worms, clinical signs and histopathology, these canine infections were very similar to those seen in the two human patients with eye infection. When the parasites recovered from human eyes were compared morphologically with the Onchocerca spp. infecting animals in Europe, they appeared to be most similar to O. lupi. Although O. lupi is normally a parasite of dogs, it may thus also be responsible for aberrant, zoonotic, subconjunctival infections in man.