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

Jonathan H. Lai,a Noreen M. G. Walsh,a Bobbi S. Pritt,b Lynne Sloan,b Lawrence E. Gibson,c,d Leon Desormeau,e David J. M. Haldanef

Division of Anatomical Pathology, Department of Pathology and Laboratory Medicine, Capital District Health Authority and Dalhousie University, Halifax, NS, Canadaa;Division of Infectious Diseases and Clinical Microbiology, Department of Pathology and Laboratory Medicine, Mayo Clinic, Rochester, Minnesota, USAb; Division ofAnatomical Pathology, Department of Pathology and Laboratory Medicine, Mayo Clinic, Rochester, Minnesota, USAc; Department of Dermatology, Mayo Clinic, Rochester,Minnesota, USAd; Department of Pathology and Laboratory Medicine, St. Martha’s Regional Hospital, Antigonish, NS, Canadae; Division of Microbiology, Department ofPathology and Laboratory Medicine, Capital District Health Authority and Dalhousie University, Halifax, NS, Canadaf

A 65-year-old male with known hypertension and hypercholesterolemia sought medical attention because of a 3-month historyof skin swelling on his upper back. Histopathology and molecular techniques were employed and identified an organism in theOnchocerca genus. This represents a very uncommon example of cutaneous infection by a zoonotic Onchocerca species.

CASE REPORT

A65-year-old Caucasian man from rural Nova Scotia soughtmedical attention because of a sudden onset of localized

swelling of the skin in the inferior left scapular area. He had noteda small, mildly tender pruritic papule one morning, measuringless than 1 cm, which he regarded as a possible insect bite. Over thecourse of 1 day, the lesion enlarged to form a nodule measuringapproximately 4 cm in diameter. Medical attention was sought.The patient was given a 10-day course of antibiotics which causedthe swelling to decrease in size, but the nodule did not resolvecompletely. Elective surgical excision was undertaken.

Within the previous 5 years, the patient had traveled to Florida inApril 2009 and had been working in Ontario until 31 May 2010.While in Ontario, he had been in charge of maintaining a high-riseapartment block in Windsor for 12 years. Prior to this, he had workedin the automotive industry. There was no history of foreign travel.During the previous 3 years, the patient had resided in rural NovaScotia, where he had a pet dog with a free range in an open hayfieldwhere contact with wild animals was minimal. The dog showed nosymptoms of infection during this period and remains healthy to thepresent day. The patient’s medications included 12.5 mg hydrochlo-rothiazide once daily for hypertension and 20 mg simvastatin oncedaily for hypercholesterolemia. He was otherwise healthy. There wasno history of immunosuppression.

On examination, an erythematous nodule was evident on the leftupper back just inferior to the scapula. This area had been covered byclothing, and the patient could not recall any history of an arthropodbite. No other skin lesions were detected. Preliminary blood work wasnot performed. Following excision, the specimen was submitted tothe laboratory for processing. Clinically interpreted as a cyst, the sub-mitted sample consisted of an ellipse of skin and subcutaneous adi-pose tissue measuring 1.4 by 0.3 by 1.3 cm. It was serially sectionedand submitted in total. Histopathologic examination revealed adense, nodular, superficial and deep, perivascular lymphocytic infil-trate with abundant eosinophils in the dermis and superficial pannic-ulus. Small foci of interstitial granulomatous inflammation werenoted (Fig. 1A and B). Close to the edge of the biopsy specimen, inassociation with the inflammatory infiltrate, cross sections of a nem-atode were noted (Fig. 1C).

A microbiological consultation confirmed the presence of anematode measuring 60 by 68 �m. There were no lateral alae, and

the cuticle was smooth, with a 3-�m thickness. The lateral cordshad 2 cells with prominent nuclei, but the dorsal and ventral lineswere not prominent. A muscular layer was present internal to thecuticle. An esophagus and possibly a reproductive system werepresent, although a double uterus was not observed. No ova orlarvae were seen within the organism. Based on the microbiolo-gist’s evaluation, certain organisms were excluded, includingStrongyloides stercoralis, hookworm, Toxocara canis or Toxocaracati, Gnathostoma spp., and Baylisascaris procyonis. Candidate or-ganisms included Brugia spp., Mansonella spp., and Acanthochei-lonema delicata. A trichrome stain was not performed, and un-stained slides were not available for examination.

Because the nematode could not be further identified by con-ventional microscopic examination, the specimen was referred inconsultation to the Mayo Clinic in Rochester, MN. There, a mo-lecular approach to identification of the organisms was under-taken. PCR using primers for the mitochondrial NADH dehydro-genase subunit 5 gene of Onchocerca species was employed (1).Sequence analysis of the amplified product (174 b) in conjunctionwith a query in the public NCBI (National Center for Biotechnol-ogy Information) Nucleotide database enabled identification ofthe nematode as an Onchocerca species, with the closest (96%)homology to O. volvulus, O. dukei, and O. linealis.

The localized clinical lesion was considered to be a result of acci-dental inoculation by a zoonotic species, without further implicationsfor the patient’s health. Excision was regarded as curative, and thepatient remains well 10 months after excision of the lesion.

Filariasis is a parasitic infection caused by nematodes (round-worms) belonging to the family Filarioidea. When filariae that

Received 10 December 2013 Returned for modification 31 December 2013Accepted 29 January 2014

Published ahead of print 5 February 2014

Editor: M. J. Loeffelholz

Address correspondence to David J. M. Haldane,David.Haldane@cdha.nshealth.ca.

Copyright © 2014, American Society for Microbiology. All Rights Reserved.

doi:10.1128/JCM.03358-13

CASE REPORT

1768 jcm.asm.org Journal of Clinical Microbiology p. 1768 –1770 May 2014 Volume 52 Number 5

on February 2, 2019 by guest

http://jcm.asm

.org/D

ownloaded from

normally infect animals infect humans, the condition is termedzoonotic filariasis. These are often transmitted by bloodsucking ar-thropod vectors, such as black flies and mosquitoes. Zoonotic filari-asis has been reported worldwide, with variable clinical presentationsranging from an asymptomatic state to a serious illness with wide-spread dissemination of the organism. Zoonotic filariasis of the skin ismost commonly caused by filariae of the Dirofilaria, Onchocerca, andBrugia genera. In this report, we have described an inflammatory skinlesion in an adult male which was caused by a zoonotic Onchocercaspecies acquired in Nova Scotia, Canada.

Zoonotic filariae are occasionally identified in biopsy spec-imens or removed intact from superficial sites, such as the orbitor conjunctiva (2). The site of human infection is often analo-gous to the site of infection in the native mammalian host (2).In humans, zoonotic nematodes have typically been found inthe subcutaneous tissue, heart, lungs, eyes, lymphatic system,brain, and spinal cord (2). Zoonotic filariae that have beenisolated in humans include Dirofilaria, Brugia, Onchocerca, Di-petalonema, Loaina, and Meningonema (2). While many filariaespecies can cause infections in birds, reptiles, and amphibians,only filariae with natural mammalian hosts cause zoonotic fi-lariasis in humans (2).

Human infection occurs by way of an arthropod vector whichhad previously ingested a blood meal from an animal with anactive filarial infection. During their development, filarial larvaeelicit a minimal host response, with the exception of colonizationof sensitive areas like conjunctiva (2). However, due to the incom-patibility of the host, the larvae inevitably die and generate anintense host inflammatory response to the organism (2). Whyhumans mount a host response only when the larvae die is un-clear. It is known that larvae live for an extended period of timewithin their natural hosts without generating a host response (2).Rarely, filariaemia is seen in zoonotic filariasis (2). Removal of theparasite is therapeutic.

Onchocerca are natural parasites of animals, often cows andhorses (2). Many species of Onchocerca can be found within con-nective tissues of wild and domestic animals worldwide (3). Intropical areas where Onchocerca volvulus is endemic, human in-fection is quite common. Human onchocerciasis, also known asriver blindness, manifests as intense pruritis, skin depigmenta-tion, and ocular scarring due to migration of the microfilariae (3).The adult filariae are stationary in the human host and are foundwithin a subcutaneous nodule. In our case, it is unclear what thevector might have been. Certainly, the pet dog could be suspected,although this is unlikely given that the dog showed no symptomsof infection and remains healthy to this day. Previous reports sug-gest that Simulium spp. (blackflies) are often implicated as vectorsin zoonotic onchocerciasis (4, 5).

To date, 16 cases of zoonotic filaria by Onchocerca spp. whosenatural hosts are animals have been reported outside their areas ofendemicity (Table 1). All cases but one were infected by a singlefemale worm. The remaining patient, who had systemic lupuserythematosus and was on immunosuppressive therapy, had mul-tiple lesions and multiple worms on the face and neck (1). Theadult forms of Onchocerca spp. have a marked predilection forconnective tissues and often assume a coiled nodular appearance,a characteristic seen also in their natural hosts (2). Histomorpho-logic assessment of the parasite may allow accurate identificationto the genus level. Features of relevance include cuticle thickness,musculature development, hypodermis development, lateral

FIG 1 (A) Elliptical excision of skin and panniculus, at scanning magnifi-cation, shows a superficial and deep perivascular inflammatory infiltrateextending to the panniculus. There are no epidermal changes. Hematoxylinand eosin (H&E) staining and �5 magnification were used. (B) Higher-power view of the infiltrate reveals a predominantly lymphohistiocyticpopulation with numerous eosinophils, along with a focal interstitial his-tiocytic component. H&E, �72. (C) Adjacent to the interstitial histiocyticinflammatory infiltrate, cross sections of a larval nematode are seen (H&E,�400). Note the unevenly thick cuticle, the small number of weak musclecells, and the absence of reproductive tubes, consistent with diagnosis of anOnchocerca sp. larva.

Case Report

May 2014 Volume 52 Number 5 jcm.asm.org 1769

on February 2, 2019 by guest

http://jcm.asm

.org/D

ownloaded from

chords, and a vestigial digestive system. Determining the species ofzoonotic Onchocerca organisms, however, is often difficult andrequires molecular ancillary techniques, namely, DNA sequenc-ing. In our case, histomorphology was inconclusive and PCR andsequence analysis were required for identification. By utilizingprimers for the mitochondrial NADH dehydrogenase subunit 5gene, we were able to determine that this organism was of theOnchocerca genus. However, an attempt at species determinationutilizing primers for the 18S gene provided by the Centers forDisease Control and Prevention was unsuccessful. We surmisethat this may have been due to the fragmented nature of DNA informalin-fixed, paraffin-embedded tissue.

Conclusion. Although it is rare, pathologists and dermato-pathologists should be aware of zoonotic filariasis. Usually, a thor-ough clinical history with a focus on recent exposure to animalsand/or arthropod bites is helpful in establishing the correct diag-nosis. Immunosuppression may lead to more severe infections,although this needs to be further investigated. Consultation with amicrobiologist is particularly valuable in this type of setting. Spe-cific identification to the genus and species level may require an-cillary molecular techniques.

ACKNOWLEDGMENT

We acknowledge Mark Eberhard, from the Division of Parasitic Diseasesand Malaria, Centers for Disease Control and Prevention, Atlanta, GA, forhis assistance with this case.

REFERENCES1. Koehsler M, Soleiman A, Aspock H, Auer H, Walochnik J. 2007.

Onchocerca jakutensis filariasis in humans. Emerg. Infect. Dis. 13:1749 –1752. http://dx.doi.org/10.3201/eid1311.070017.

2. Orihel TC, Eberhard ML. 1998. Zoonotic filariasis. Clin. Microbiol. Rev.11:366 –381.

3. Gutierrez Y. 1984. Diagnostic features of zoonotic filariae in tissue sec-tions. Hum. Pathol. 15:514 –525. http://dx.doi.org/10.1016/S0046-8177(84)80004-0.

4. Takaoka H, Fukuda M, Otsuka Y, Aoki C, Uni S, Bain O. 2012. Blackflyvectors of zoonotic onchocerciasis in Japan. Med. Vet. Entomol. 26:372–378. http://dx.doi.org/10.1111/j.1365-2915.2012.01023.x.

5. Otranto D, Sakru N, Testini G, Gurlu VP, Yakar K, Lia RP, Dantas-Torres F, Bain O. 2011. Case report: first evidence of human zoonotic

infection by Onchocerca lupi (Spirurida, Onchocercidae). Am. J. Trop.Med. Hyg. 84:55–58. http://dx.doi.org/10.4269/ajtmh.2011.10-0465.

6. Azarova NS, Miretskii O, Sonin MD. 1965. 1st case of human infectionby the nematode Onchocerca Diesing, 1841 in the USSR. Med. Parazitol.(Mosk.) 34:156 –158. (In Russian.)

7. Siegenthaler R, Gubler R. 1965. Para-articular nematode granuloma(indigenous Onchocerca). Schweiz. Med. Wochenschr. 95:1102–1104. (InGerman.)

8. Beaver PC, Horner GS, Bilos JZ. 1974. Zoonotic onchocercosis in aresident of Illinois and observations on the identification of Onchocercaspecies. Am. J. Trop. Med. Hyg. 23:595– 607.

9. Ali-Khan, Z. 1977. Tissue pathology and comparative microanatomy of On-chocerca from a resident of Ontario and other enzootic Onchocerca species fromCanada and the U.S.A. Ann. Trop. Med. Parasitol. 71:469–482.

10. Beaver PC, Yoshimura H, Takayasu S, Hashimoto H, Little MD. 1989.Zoonotic Onchocerca in a Japanese child. Am. J. Trop. Med. Hyg. 40:298 –300.

11. Takaoka H, Bain O, Tajimi S, Kashima K, Nakayama I, Korenaga M,Aoki C, Otsuka Y. 1996. Second case of zoonotic Onchocerca infection ina resident of Oita in Japan. Parasite 3:179 –182.

12. Burr WE, Jr, Brown MF, Eberhard ML. 1998. Zoonotic Onchocerca (Nema-toda:Filarioidea) inthecorneaofaColoradoresident.Ophthalmology105:1494–1497. http://dx.doi.org/10.1016/S0161-6420(98)98035-6.

13. Pampiglione S, Vakalis N, Lyssimachou A, Kouppari G, Orihel TC. 2001.Subconjunctival zoonotic Onchocerca in an Albanian man. Ann. Trop. Med.Parasitol. 95:827–832. http://dx.doi.org/10.1080/00034980120111163.

14. Wright RW, Neafie RC, McLean M, Markman AW. 2002. Zoonoticonchocerciasis of the shoulder. A case report. J. Bone Joint Surg. 84-A:627– 629.

15. Takaoka H, Yanagi T, Daa T, Anzai S, Aoki C, Fukuda M, Uni S, BainO. 2005. An Onchocerca species of wild boar found in the subcutaneousnodule of a resident of Oita, Japan. Parasitol. Int. 54:91–93. http://dx.doi.org/10.1016/j.parint.2004.08.003.

16. Sallo F, Eberhard ML, Fok E, Baska F, Hatvani I. 2005. Zoonoticintravitreal Onchocerca in Hungary. Ophthalmology 112:502–504. http://dx.doi.org/10.1016/j.ophtha.2004.10.036.

17. Hira PR, Al-Buloushi A, Khalid N, Iqbal J, Bain O, Eberhard ML. 2008.Zoonotic filariasis in the Arabian Peninsula: autochthonous onchocercia-sis and dirofilariasis. Am. J. Trop. Med. Hyg. 79:739 –741.

18. Uni S, Boda T, Daisaku K, Ikura Y, Maruyama H, Hasegawa H, Fukuda M,Takaoka H, Bain O. 2010. Zoonotic filariasis caused by Onchocerca dewitteijaponica in a resident of Hiroshima Prefecture, Honshu, Japan. Parasitol. Int.59:477–480. http://dx.doi.org/10.1016/j.parint.2010.05.006.

19. Eberhard ML, Sims AC, Bishop HS, Mathison BA, Hoffman RS. 2012.Ocular zoonotic onchocerca infection in a resident of Oregon. Am. J.Trop. Med. Hyg. 87:1073–1075. http://dx.doi.org/10.4269/ajtmh.2012.12-0469.

TABLE 1 Previously reported zoonotic filariasis by Onchocerca species outside areas of endemicity

Age (yr)/genderof patient Anatomical site Geographic location Species Reference

15/female Tendon of oculomotor muscle Russia Onchocerca species 625/male Knee Switzerland Onchocerca species 748/female Wrist Illinois Onchocerca species, most likely O. cervicalis 843/female Wrist Ontario, Canada Onchocerca species 92/female Left foot (plantar aspect) Oita, Japan Onchocerca species 1057/female Wrist Oita, Japan Onchocerca species, most likely O. gutturosa 1152/female Right cornea Colorado Onchocerca species, most likely O. cervicalis 1216/male Subconjunctival area Albania Onchocerca species 1350/female Left subdeltoid mass Minnesota O. gutturosa 1469/female Right infraclavicular region Oita, Japan O. dewittei japonica 1565/male Anterior vitreous cavity Hungary Onchocerca species 1659/female Multiple nodules on face and neck USA O. jakutensis 112/female Suprapubic skin nodule Kuwait Onchocerca species 1770/male Subcutaneous nodule left knee Hiroshima, Japan O. dewittei japonica 1818/female Left subconjunctival area Edirne, Turkey O. lupi 556/male Left anterior chamber of eye Oregon Onchocerca species 19

Case Report

1770 jcm.asm.org Journal of Clinical Microbiology

on February 2, 2019 by guest

http://jcm.asm

.org/D

ownloaded from