Short communication — Kort berig

First record of Acanthocheilonema dracunculoides from domestic dogs in Namibia

E V Schwana* and F G Schröterb

were diagnosed on radiographic exami- ABSTRACT nation. Physical examination of Dog B Acanthocheilonema dracunculoides was diagnosed in 2 dogs from Windhoek, Namibia, by acid additionally revealed vomiting, hind leg phosphatase staining of microfilariae. This is the 1st record of A. dracunculoides in Namibia. lameness and a bilateral corneal oedema. Key words: acid phosphatase staining, Acanthocheilonema dracunculoides, dog, microfilariae, Cam’s Quick-stained thin blood films pre- Namibia. pared from peripheral blood obtained Schwan E V,Schröter F G First record of Acanthocheilonema dracunculoides from domestic from a pricked ear pinna of both dogs in Namibia. Journal of the South African Veterinary Association (2006) 77(4): 220–221 (En.). revealed the presence of isolated micro- Department of Veterinary Tropical Diseases, Faculty of Veterinary Science, University of filariae as well as a marked leukocytosis Pretoria, Private Bag X04, Onderstepoort, 0110 South Africa. and eosinophilia. Additional blood sam- ples were collected from the cephalic vein of both animals into EDTA coated vac- Acanthocheilonema dracunculoides Cobbold, tick have been uum tubes to conduct further analysis of 1870 (syn. Dipetalonema dracunculoides), identified as intermediate hosts15,17. microfilariae. Of each sample, a 2 m is a vector-borne parasite Microfilariae ingested during blood feed- aliquot was screened for microfilariae (Filarioidea: ) of the domes- ing transform into metacyclic (infective) by membrane filtration using 3.0 µm tic dog and some sylvatic carnivores L3-stages and eventually accumulate in Isopore® membrane filters (Millipore) (Proteles cristatus, aardwolf; Crocuta crocuta, the mouthparts of the respective arthro- stained with Giemsa3. Examination of the spotted hyaena; Vulpes vulpes, red fox). pods involved. Final hosts become infected Giemsa-stained membrane filters showed The parasite occurs in Europe, Asia and during blood feeding. The migrational the presence of unsheathed microfilariae. Africa28. In Africa it is known to be en- pattern and development within the final They varied in width from 4.7 µm to demic in Morocco20, Algeria24, Tunisia4,27, hosts are unknown. Similarly, the duration 5.6 µm at the widest part of the anterior Mali14,22, Niger21, Democratic Republic of of the prepatent and patent periods is end and varied in length from 218 to Congo9, Sudan2, Somalia12, Kenya15,16, unknown. Acanthocheilonema dracunculoides 243 µm. The microfilariae were eventually Tanzania26 and South Africa7, in which is regarded as largely apathogenic. How- identified by acid phosphatase staining as country it was first described by Cobbold ever, there are several reports from Spain, those of Acanthocheilonema dracunculoides, from an aardwolf. Acanthocheilonema where high prevalence rates of A. dracun- showing the typical somatic pattern of dracunculoides follows an indirect life culoides have been recorded, according to enzyme activity at the cephalic vesicle, cycle. In those carnivores, which act as which infected dogs occasionally present excretory pore, ‘Innenkörper’ (inner body) final hosts, the predilection site of the with dermal clinical signs and lesions and anal pore6,18,29 (Fig. 1). The animals male and female adult parasites is mainly ranging from pruritus, alopecia, erythema were treated with (Ivomec the peritoneal cavity19. Infection is often to skin ulcers as well as other clinical signs Injection, Merial) at 200 µg/kg once subcu- discovered accidentally during intra- such as ataxy, incoordination, cachexia taneously but could not be followed up. abdominal surgical procedures. Males are and pleural effusion5,19,25. From a differ- Both animals had never left Namibian 15–32 mm long and 0.1–0.2 mm wide, ential diagnostic point of view, A. dracun- territory. whereas females are 30–60 mm long and culoides must always be considered in Acanthocheilonema dracunculoides has 0.1–0.3 mm wide8,10,11,19,23. The male connection with canine filarioses of other never before been reported from the spicules are unequal and measure 273– aetiologies and in particular cardiovascu- domestic dog or any sylvatic carnivore in 414 and 120–165 µm in length respec- lar dirofilariosis caused by Dirofilaria Namibia. Although the species is regarded tively6,10,11,28. Sexually mature females are immitis, colloquially known as heart- as largely apathogenic in dogs, there is viviparous, i.e. they produce L1-stages, worm. This paper represents the 1st re- some evidence reported from Spain that known as microfilariae, which eventu- cord of A. dracunculoides in Namibia. The suggests that occasionally the parasite ally appear in the peripheral blood. parasite was encountered in 2 domestic may not be as innocuous as generally Microfilariae are unsheathed and mea- dogs. assumed5,19,25. Dermal clinical signs inter- sure 185–276 µm (length) by 4.2–6 µm An 8-year-old St. Bernard bitch (Dog A) preted as a result of A. dracunculoides (width)6,8,10,11,13,19,23,28. So far, the louse and a crossbred male dog of unknown infection improved following treatment fly Hippobosca longipennis and the hard age (Dog B) of different ownership were with ivermectin at a dose rate of 50 µg/kg presented to the Windhoek Veterinary administered subcutaneously or per os25. aDepartment of Veterinary Tropical Diseases, Faculty of Clinic in Windhoek, Namibia, with Whether the clinical signs or part of them Veterinary Science, University of Pretoria, Private Bag X04, Onderstepoort, 0110 South Africa. inappetence and poor appetite. Physical recorded in Dog A and Dog B are a sequel bFormerly Windhoek Veterinary Clinic–Tierklinik, PO Box examination of Dog A revealed a slightly of the filarial infection diagnosed, cannot 5030, Windhoek, Namibia elevated rectal temperature of 39.6 °C, be answered considering the scarce clini- *Author for correspondence. E-mail: [email protected] marked weight loss, inappetance and cal information available and the fact that Received: October 2005. Accepted: October 2006. ascites. Cardiomegaly and hepatomegaly the animals were not followed up.

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