Marked subcutaneous mast cell and eosinophilic infiltration associated with the presence of multiple Dirofilaria repens microfilariae in 4 dogs

Dirofilaria repens is a parasitic nematode in the subcutaneous tissue of carnivores, including dogs and cats, transmitted by mosquitoes. Human beings may be accidental hosts. Infection of a dog with D repens was first reported in Palestine in 1934, and 2 additional cases were reported in dogs in Israel to date. This report describes D repens infection in 4 dogs in Israel that presented with subcutaneous masses, which were cytologically characterized by marked mast cell and eosinophil infiltration. In 3 cases, multiple microfilariae were present in the lesions; rare microfilariae were present in the 4^th case. In all 4 dogs, PCR of fine‐needle aspirates from the lesions were positive for D repens. The mast cells observed in all lesions were uniform and highly granulated, and with the presence of the microfilariae, a mast cell tumor was considered less likely. This report suggests that D repens infection‐associated subcutaneous lesions, characterized cytologically by massive mast cell and eosinophil infiltration, should be considered a differential diagnosis for mast cell tumor, especially in geographic locations endemic for this nematode. Notably, all 4 dogs were infected with D repens despite a routine prophylactic doramectin therapy administered every 3 months, probably due to the relatively long time interval between treatments.     

Dermatitis associated with Dirofilaria (Nochtiella) repens microfilariae in dogs from central Italy

Pruritic dermatitis associated with Dirofilaria (Nochtiella) repens microfilariae in the blood was diagnosed in 22 dogs from Fermo (Central Italy). According to the history, previous unsuccessful treatments with corticosteroids, antibiotics, restricted diet, flea control, levamisole and ivermectin were recorded in 17 dogs (77.3%). The combined filtration tests and antigen tests, performed during the study, were negative for Dirofilaria immitis and Acanthocheilonema reconditum in each case. Dermatological lesions included erythema, papules, single or multifocal alopecia, eczema, lichenification, crusting and nodules. All dogs had pruritus. Concurrent babesiosis was diagnosed in the blood smears of each case (100%), and 60% of the dogs were found to be carriers of canine granulocytic ehrlichiosis (CGE). Three dogs (13.6%) were positive for leishmaniosis. Eradication of the concurrent infections followed by specific macro- and microfilaricide treatment led to complete recovery from the dermatological syndrome. The main conclusion of the study is that D. repens infection can be more pathogenic than is currently considered, and it is apparently an opportunistic disease with serious dermatological consequences.     

Nodular presentation of Dirofilaria repens infection in a cat mimicking a fibrosarcoma

A cat with multiple subcutaneous nodules suggesting a soft tissue sarcoma by physical and computed tomographic examination was diagnosed as being affected by subcutaneous filariosis based on cytologic and ultrasonographic assessments. Nodules were surgically removed and extracted nematodes were identified by PCR as Dirofilaria repens. Furthermore, DNA of Dipetalonema dracunculoides (syn. Acantocheilonema dracunculoides) was detected by PCR, with no evidence of circulating microfilariae. To the best of the authors' knowledge, this represents the first report describing adults of D repens in multiple subcutaneous nodules in a cat. Cytopathologic examination allowed characterization of the parasitic nature of the nodules. Veterinary practitioners should be aware of the possible nodular presentation of D repens in cats and should include D repens in the differential diagnosis of subcutaneous neoformations in the cat.     

Preliminary findings on the efficacy of selamectin in the treatment of dogs naturally infected with Dirofilaria repens

Subcutaneous dirofilariosis caused by Dirofilaria repens is common in dogs and it is an emerging helminthozoonosis in Europe, Asia, Africa and also in Hungary. Macrocyclic lactones are used for preventing the infection; however, their activity against the microfilariae and mature stages of this species is questionable. Selamectin is widely used for the prophylaxis of heartworm (D. immitis) infection. The objective of the present study was to test the microfilaricidal efficacy of the topical formulation of selamectin in dogs naturally infected with D. repens . A total of 78 Beagle dogs were examined for the presence of circulating microfilariae by Knott's test. Twenty-three of the microfilaraemic dogs were divided into four groups and included in the trial. The dogs received monthly or biweekly selamectin treatment and were subjected to monthly blood testing for a period of 252 or 336 days. At the end of the study, 65% of the dogs were not microfilaraemic and the rest had low number of microfilariae in their blood. These results indicate that chronic spot-on selamectin treatment may be a useful tool also in the control of canine subcutaneous dirofilariosis.     

A duplex real-time polymerase chain reaction assay for the detection of and differentiation between Dirofilaria immitis and Dirofilaria repens in dogs and mosquitoes

This study describes a duplex real-time polymerase chain reaction (PCR) assay for the detection and differentiation between Dirofilaria immitis and Dirofilaria repens in dog blood and mosquitoes. Regions of a cytochrome oxidase 1 (cox1) mitochondrial DNA fragment and the second internal transcribed spacer (ITS-2) of nuclear ribosomal DNA were amplified from microfilariae and adult worm samples, using a sensitive SsoFast? EvaGreen(?) based real-time PCR method coupled with melting-curve analysis. The limit of the real-time PCR in detecting microfilaria and adult worm DNA was also tested both in dog blood and in artificially infected microfilarial. Two peaks at different melting temperatures (T(m)) for D. immitis (mean ± SD=75.7 ± 0.3°C) and D. repens (mean ± SD=70 ± 0.7°C), respectively, were obtained for microfilarial and adult positive controls of both species when examined separately and together. The real-time PCR protocol was also efficient in detecting microfilarial and adult DNA of both species when tested in samples spiked with DNA from Aedes albopictus, in Aedes aegypti experimentally infected by D. repens and in Culex pipiens naturally infected by D. repens and D. immitis. The high sensitivity of real-time PCR confirmed its reliability in detecting small amounts of genomic DNA either in dog blood or mosquitoes (2.5 pg/μl and 3 × 10(-1)pg/μl for D. immitis and D. repens, respectively). This assay is proposed as a tool for the epidemiological surveillance of the two most important Dirofilaria species in areas where they are endemic and sympatric.     

Autochthonous canine Dirofilaria repens in the vicinity of Warsaw

In 2009 microfilaremia was recognized in ten dogs living in five distinct districts located near Warsaw, the capital of Poland. Based on PCR results, all the animals were found to be infected with Dirofilaria repens. Nine of the infected dogs have never travelled outside the country and it was assumed that the cases were native. Monitoring the infection in the European countries should be introduced to establish the actual geographic range of dirofilariosis.     

Cutaneous lesions in dogs with Dirofilaria (Nochtiella) repens infestation and concurrent tick-borne transmitted diseases

A pruritic dermatitis characterized by the presence of erythema, papules, focal or multifocal alopecia, crusting and nodules was seen in 28 dogs with Dirofilaria repens microfilariae infestation in an endemic area in north-west Italy. Previous unsuccessful nonspecific antipruritic treatments, flea control and restricted diet were recorded in 53.6% of the patients. Both the Knott and the antigen tests were negative for Dirofilaria immitis and Acanthocheilonema reconditum. Concurrent babesiosis and/or canine granulocytic ehrlichiosis was also diagnosed in many affected dogs. Preliminary treatment of the concurrent diseases was followed by specific filaricide treatment. The cutaneous lesions, although slightly improved with the initial treatment, resolved completely with macro- and microfilaricide treatment. Although D. repens may be an opportunistic pathogen, this parasite should not be considered as harmless as previously thought and its potential pathogenic role in causing cutaneous lesions in dogs should be considered. Furthermore, it has a zoonotic importance as human cases have been reported worldwide.     

Comparison of the acid-phosphatase staining and polymerase chain reaction for detection of Dirofilaria repens infection in dogs in Korea

This study was performed to compare acid-phosphatase staining with polymerase chain reaction (PCR) analysis for the diagnosis of Dirofilaria repens infection. The infection of D. repens was confirmed in Korean reared German shepherd dogs. Knott's tests were carried out for the detection of microfilaria in 543 Korean reared German shepherd dogs (255 females and 288 males). Eighty four of the 543 dogs (15.5%) showed microfilaria-positive reactions with the modified Knott's test, and the test-positive microfilariae were then examined by both acid phosphatase staining and PCR analysis. Six (7.1%) and 17 (20.2%) of the 84 microfilaria-positive samples, by the Knott's tests were positive to D. repens by acid-phosphatase staining and in D. repens-specific PCR analysis, respectively. All samples found to be positive by the acid-phosphatase staining were also found to be positive by PCR analysis. Therefore, we conclude that PCR analysis (20.2%) is more valuable for the diagnosis of D. repens infection than acid-phosphatase staining (7.1%) (p<0.001).     

Adult Dirofilaria repens in a subcutaneous granuloma on the chest of a dog

A 10-year-old, 9 kg, intact male crossbred dog was treated for nasal mites with milbemycin oxime using a dose of 1 mg/kg bodyweight orally, three times at 10-day intervals. One month after the initiation of this treatment a subcutaneous nodule developed on the sternum of the dog. The nodule was removed and found to contain a single, 82 mm long, thread-like nematode. Several exotic parasites were suspected as possibilities because the dog had been imported to Norway from South Africa. Microfilariae were not detected in the blood and heartworm antigen tests were negative. The worm was identified morphologically as an adult, female Dirofilaria repens. This is the first report of D repens from Norway. The case is of interest because of the differential diagnostic problem it posed and because infestation was recognised following treatment of another parasitic condition with a broad-spectrum, antiparasitic drug. In addition, the case provides a reminder of the necessity to be aware of geographical differences in disease occurrence which can produce unexpected disease in non-endemic areas as a consequence of increased international travel with pets.     

Molecular survey of Dirofilaria immitis and Dirofilaria repens by direct PCR for wild caught mosquitoes in the Republic of Korea

Adult mosquito collections using New Jersey light traps and Black-hole light traps were conducted to determine the potential vectors and the relative mosquito infection rates of Dirofilaria immitis and Dirofilaria repens in Gyeonggi and Gangwon Provinces, Republic of Korea, 2005. Dirofilaria spp. were confirmed by polymerase chain reaction (PCR) using species-specific primers for D. immitis and D. repens. Minimum field infection rates (MFIR) [MFIR = (number infected pools/total number of mosquitoes) x 1000] of 12 pools/2059 total number mosquitoes (5.8) and 21 pools (10.1) of the wild caught mosquitoes were positive by PCR for D. immitis and D. repens, respectively. Dual infections of both D. immitis and D. repens were detected by PCR in eight pools (3.9). Anopheles sinensis sensu lato (includes An. sinensis s.s., An. pullus, An. kleini, An. belenrae, and An. lesteri), An. sineroides, Aedes vexans nipponi, Culex pipiens and Armigeres subalbatus were found to be infected and are potential vectors of D. immitis and D. repens in Korea. Infections observed in mosquitoes represent potential health risks for domestic animal and human populations.     

Prevalence of Dirofilaria immitis infection in dogs from Dandong, China

The aim of the present study was to estimate the prevalence and risk factors of Dirofilaria immitis infection in dogs from Dandong, China. A total of 886 dogs were examined for D. immitis infection by microscopic examination and PCR, indicating that the prevalence was 16.6% (213/886) and 24.0% (147/886), respectively. The odds of infection were significantly higher in older dogs and dogs sheltered in outdoor, compared to the younger ones and ones sheltered in indoor. No significant difference of infection was observed in different genders, and between pure breed and cross-breed dogs in the same rearing conditions. These results indicated that the risk of exposure to D. immitis in dogs is high in Dandong, China, and prophylaxis against the parasite is advisable to decrease the incidence of canine dirofilariosis.     

Saccadic oscillations in 4 dogs and 1 cat

Disorders affecting the control of saccadic eye movements result in involuntary saccadic oscillations and are widely reported in human medicine. Information regarding the occurrence and potential importance of saccadic oscillations in veterinary medicine is currently limited. The clinical histories of three dogs and one cat displaying involuntary eye movements consistent with opsoclonus are presented, with final diagnoses including idiopathic generalized tremor syndrome and neuronal ceroid lipofuscinosis (NCL). A dog with eye movements closely resembling macrosaccadic oscillations is also presented, for which a final diagnosis of NCL was made. All animals had clinical signs of cerebellar disease. As in human medicine, recognition of these forms of involuntary eye movement might suggest a cerebellar neuroanatomic localization. Opsoclonus and macrosaccadic oscillations are forms of involuntary saccadic eye movement that are both unrecognized and under‐reported in veterinary medicine.     

Sero-epidemiological study of the presence of hantaviruses in domestic dogs and cats from Belgium

Hantaviruses are worldwide rodent-borne pathogens infecting humans and other animals mainly through inhalation of aerosols contaminated with rodent excreta. Few data are available on hantavirus serology and geographical distribution in dogs and cats. We therefore screened sera from pet dogs (N=410) and cats (N=124) in two regions of Belgium, using IgG ELISA and IFA. We analysed the effect of the owner's address as well as pet gender and age on hantavirus status. Hantavirus antibodies were found in both species with a significantly higher seroprevalence in cats than in dogs (16.9% vs. 4.9%, P=0.001). More dogs were infected in highly forested southern Belgium (harbouring more rodents) than in northern Belgium (10.5% vs. 3.0%, P=0.002). In the south, hantavirus sero-positive cats were found in more densely forested localities than sero-negatives ones were (P=0.033). These results are consistent with the ecological variations of hantavirus risks in humans.     

Surgical transplantation of adult Dirofilaria immitis to study heartworm infection and disease in dogs

Heartworm infections were established in dogs by surgical transplantation of adult heartworms into the external jugular vein. The heartworms were obtained from donor dogs that had been infected with large numbers of infective larvae. This heartworm model standardized the infection with a known number of heartworms of a known age and sex. This paper presents the methods for obtaining heartworms from donor dogs, for selection of recipient dogs, and for transplantation of heartworms.