Efficacy of a single administration of a spot-on solution containing imidacloprid 10%/moxidectin 2.5% in eliminating Dirofilaria repens microfilariae in naturally infected dogs

In the past decade reports of canine subcutaneous dirofilariosis, caused by the mosquito-transmitted nematode Dirofilaria repens, increased in number in several countries in Europe, along with a rise of human cases. Given the merit to the new approaches for the control and treatment of this infection, the present study evaluated the efficacy of a single application of the spot-on formulation containing imidacloprid 10%/moxidectin 2.5% (Advocate(?), Bayer Animal Health) in the elimination of D. repens microfilariaemia in naturally infected dogs. In September 2009, 18 dogs with a natural infection by D. repens were enrolled in the study. In October 2009 all the dogs were treated once with Advocate(?) and the presence/absence of circulating MF and skin lesions after treatment was evaluated monthly until April 2010. From November 2009 to April 2010 15 dogs scored negative for D. repens while one dog remained negative till March 2010 when it died. Two dogs had a recurrence of microfilariaemia in December 2009 and January 2010 respectively. Nine infected dogs showed skin lesions at the beginning of the trial, which disappeared after treatment in 7 dogs, whereas the other two symptomatic dogs did not show any dermatological improvement until the end of the trial even though they scored negative for D. repens microfilariae. This study demonstrated that a single dermal administration of Advocate(?) is effective in eliminating microfilariae of D. repens and likely has a certain degree of activity in killing subcutaneous adult worms as well. This study demonstrates the efficacy of Advocate(?) in the treatment of dermatitis caused by D. repens. Also, these results are of importance towards further control programs aiming to reduce the number of bites infectious for mosquitoes and the risk of infection for both humans and dogs.     

Dirofilaria repens infection in a dog: diagnosis and treatment with melarsomine and doramectin

Therapy of canine dirofilariois due to Dirofilaria repens is indicated for dogs suffering from clinical signs of this disease, such as dermal swelling, sub-cutaneous nodules and pruritus. It is also important in order to decrease the risk of infection to other dogs and humans in the vicinity of the infected animal when suitable mosquito vectors are present. Combined therapy with the arsenic adulticide melarsomine and the avermectin microfilaricidal doramectin was effective in clearing infection with D. repens in a dog. The number of microfilariae dropped from 17 microl(-1) blood pre-treatment to 7 microl(-1) following the first adulticide injection and reached 0 a day after the microfilaricidal administration. The dog remained negative for D. repens microfilaremia during a follow-up period of 90 days. Euthanasia and necropsy performed 3 months after the initiation of therapy due to a progressive neoplastic disease revealed no evidence of filariae.     

A prevalence survey and risk analysis of filariosis in dogs from the Mt. Vesuvius area of southern Italy.

A dog microfilariae prevalence and risk factor survey was conducted in 51 contiguous municipalities of the Mt. Vesuvius area (Campania region, southern Italy) in order to add data to the limited epidemiological information available regarding filarial worms in this zone. Between May 1999 and June 2000, blood samples were collected from 351 asymptomatic dogs. Blood samples were examined using a modified Knott's technique and histochemical staining in order to count and identify microfilariae. The results were subjected to statistical analysis and choroplethic municipal maps (MMs) were drawn by a geographical information system (GIS) software. Microfilariae were detected in 63 of the 351 dogs surveyed, constituting a total filarial prevalence of 17.9%. In particular, 56 dogs (15.9%) showed only microfilariae of Dipetalonema reconditum; three dogs (0.8%) only microfilariae of Dirofilaria repens; two dogs (0.6%) microfilariae of both D. reconditum and D. repens and two dogs (0.6%) microfilariae of both Dirofilaria immitis and D. repens. High D. reconditum prevalence was associated with hunting practice, masculine gender and older dogs. There was also a tendency to find high prevalence in dogs sampled in the afternoon.In conclusion, the presence of microfilariae of D. reconditum in 92% of microfilaraemic dogs indicates that this filarial worm was the predominant filarial species in dogs in the Mt. Vesuvius area.In addition, the general trends of the MMs showed that D. immitis and D. repens were present only in a few municipalities, whereas D. reconditum was widely and homogeneously spread throughout the entire study area.     

Canine dirofilariosis in two cities of southeastern Spain

Several cases of human subcutaneous/ocular dirofilariosis caused by Dirofilaria repens from an area in the southeastern Spain where previous epidemiological studies have shown a very low prevalence of this species in dogs, have been studied in our laboratory. Since the prevalence of this species in dogs did not correspond to the incidence of human cases in the zone studied, a preliminary epidemiological survey was carried out on 114 dog blood samples from two kennels and one veterinary clinic. Knott, polymerase chain reaction (PCR) with specific primers for Dirofilaria immitis and D. repens, and ELISA with adult E/S D. immitis and adult somatic D. repens antigens for the detection of specific IgG, were used. Fifty-three out of the 114 samples analyzed were positive for Knott and/or PCR to D. immitis or to D. repens. D. repens was the species with the highest prevalence, 84.6 and 37.1%, respectively, in each kennel. IgG antibodies against D. immitis and D. repens, were detected in 11 samples which gave negative results to both Knott and PCR. These results demonstrate a very high prevalence of D. repens that could be associated with the increasing incidence of human subcutaneous/ocular cases recently detected in this zone.     

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).     

Retrospective study on the presence and pathogenicity of Dirofilaria repens in 5 dogs and 1 cat from Aosta Vally

Aosta Valley is the only region of Italy free of reported human cases of dirofilariosis due to Dirofilaria repens. Nonetheless, the retrospective analysis of five locally acquired D. repens infections in dogs, seems to indicate that an animal reservoir exist in the area. A feline case imported from Camargue, France, is also described. The most common dermatological signs were erythema, alopecia, crusting, papulae and nodules. All patients had lesional pruritus and dogs were affected by concurrent babesiosis. Eradication of the underlying condition, followed by a therapy with the specific adulticide and microfilaricide drugs led to a complete recovery of microfilaraemia. Increased pet travel and ecological changes are extending the ranges of vector borne, parasitic and zoonotic diseases. This fact pose a unique diagnostic challenge for the veterinarian, since the index of suspicion may be absent outside endemic areas.     

Canine dirofilariasis in the canton of Ticino and in the neighboring areas of northern Italy

The distribution of canine dirofilariosis in Southern Ticino (Switzerland) and in the neighbouring provinces of Varese and Como (Italy) was investigated. Blood samples were collected from 308 dogs which had remained in the local area and were outdoor-housed, older than 1.5 years and had not been treated previously with preventive or microfilaricidal drugs. Microfilariae of Dirofilaria immitis and D. repens were found in 33 (10.7%) and 17 (5.5%) dogs, respectively. Ten more dogs (3.2%) tested positive for circulating antigens. Four infected dogs lived in Southern Ticino: two harboured D. immitis, one D. repens and one had a mixed infection. In addition, 3887 mosquitoes were captured in five sample sites by means of dog-baited traps. Culex pipiens, Aedes geniculatus and Ae. vexans were the most abundant species. Infective stages of D. immitis were observed in local strains of Ae. geniculatus and Cx. pipiens, following engorgement on a microfilaraemic dog and the successive rearing in laboratory conditions. A chemo-prophylactic scheme in four administrations between July and October is recommended for Southern Switzerland.     

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.     

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.     

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.     

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.     

Changing climate and changing vector-borne disease distribution: the example of Dirofilaria in Europe

Climatic changes, together with an increase in the movement of dogs across Europe, have caused an increase in the geographical range of Dirofilaria infections. The present paper is focuses on northeastern European countries, where survey data have shown an increase of Dirofilaria repens infections both in animals and humans. A growing degree day-based forecast model has been developed to predict the occurrence. The model is based on evidence that there is a threshold of 14 °C below which Dirofilaria development will not proceed in mosquitoes, there is a requirement of 130 growing degree-days (GDDs) for larvae to reach infectivity, and there is a maximum life expectancy of 30 days for a mosquito vector. The output of this model predicted that the summer temperatures (with peaks in August) are sufficient to facilitate extrinsic incubation of Dirofilaria even at latitudes of 56 °N and longitudes of 39 °E. Despite the fact that both Dirofilaria immitis and D. repens have the same temperature requirement for extrinsic incubation in mosquitoes, empirical data has shown that D. repens is the main cause of dirofilarial infections in both humans and animals. Clinical signs are absent in most canine infections with D. repens. Furthermore, diagnosis is problematic and in-clinic serological tests, such as those for D. immitis, do not exist. Therefore, most infections go undiagnosed, allowing the infection to spread undetected.     

Discrimination between six species of canine microfilariae by a single polymerase chain reaction

Canine dirofilariasis caused by Dirofilaria immitis is usually diagnosed by specific antigen testing and/or identification of microfilariae. However, D. immitis and at least six other filariae can produce canine microfilaremias with negative heartworm antigen tests. Discriminating these can be of clinical importance. To resolve discordant diagnoses by two diagnostic laboratories in an antigen-negative, microfilaremic dog recently imported into the US from Europe we developed a simple molecular method of identifying different microfilariae, and subsequently validated our method against six different filariae known to infect dogs by amplifying ribosomal DNA spacer sequences by polymerase chain reaction using common and species-specific primers, and sequencing the products to confirm the genotype of the filariae. We identified the filaria in this dog as D. repens. This is the first case of D. repens infection in the United States. Additionally, we examined microfilariae from five additional antigen-negative, microfilaremic dogs and successfully identified the infecting parasite in each case. Our diagnoses differed from the initial morphological diagnosis in three of these cases, demonstrating the inaccuracy of morphological diagnosis. In each case, microfilariae identified morphologically as A. reconditum were identified as D. immitis by molecular methods. Finally, we demonstrated that our PCR method should amplify DNA from at least two additional filariae (Onchocerca and Mansonella), suggesting that this method may be suitable for genotyping all members of the family Onchocercidae.     

Subcutaneous dirofilariosis in South-East Serbia--case report

Human dirofilariosis is a relatively rare infection caused by filarial worms of the genus Dirofilaria. We herein report the first case of human subcutaneous dirofilariosis in the southeastern part of Serbia. A complete alive nematode was removed from a nodule in the periorbital region of a 50-year-old woman. The nematode was morphologically identified as a D. repens-like immature female. The diagnosis was confirmed with molecular methods. The patient was probably infected in the South-East Serbia as she had not travelled abroad, nor in other parts of Serbia such as Vojvodina, recently identified as a hyperendemic area for D. repens infection of dogs.     

A simple molecular method for discriminating common filarial nematodes of dogs (Canis familiaris)

Accurate diagnosis of canine filariosis is essential for choosing correct therapeutic approach. Therefore, reliable methods for discriminating among the different filarial infections in dogs are needed. The authors report simple and highly specific molecular methods that identify the three most common filarial nematodes of European dogs: Dirofilaria immitis, D. repens and Acanthocheilonema (syn. Dipetalonema) reconditum, based on (1) PCR amplifications of mitochondrial DNA (12S rDNA and coxI) with general filarial primers followed by digestion with restriction enzymes that generates band polymorphisms clearly discriminating the three species and (2) PCR amplifications with species-specific primers to support the restriction analysis, in particular in the case of multiple infections.     

Dermatitis associated with Dirofilaria repens microfilariae in three dogs in Saudi Arabia

The presence of microfilariae of the zoonotic nematode Dirofilaria repens is reported in three dogs from Saudi Arabia, manifesting as pruritic dermatitis with signs including erythema, alopecia, papules, crusting and hyperkeratosis. All dogs were found to have concurrent babesiosis. Specific treatments against the two conditions led to complete clinical recovery and disappearance of microfilariae from the blood one month later.     

12个多年生牧草品种在迪庆高寒地区的引种评价

为筛选出适宜云南迪庆高寒地区种植的多年生牧草品种,本研究开展了12个多年生牧草品种引种适应性的比较,并采用灰色关联度综合评价法对其生产性能进行了综合评价。结果表明,12种牧草生产性能的高低顺序为紫花苜蓿牧歌401+Z(Medicago sativa cv.Amerigraze401+Z)菊苣将军(Cichorium intybus cv.Commander)鸭茅安巴(Dactylis glomerata cv.Anmba)多年生黑麦草雅晴(Lolium perenne cv.Yatsyn)白三叶铺地(Trifolium repens cv.Prop)红三叶(T.pratense)白三叶海法(T.repens cv.Haifa)紫花苜蓿游客(Medicago sativacv.Eureka)紫花苜蓿WL-525(Medicago sativacv.WL-525)扁穗雀麦草地麦特(Bromus catharticus cv.Grasslands Matua)紫花苜蓿猎人河(M.sativacv.Hunterriver)老芒麦同德(Elymus sibiricus cv.Tongde)。其中,牧歌401+Z紫花苜蓿、将军菊苣、安巴鸭茅、雅晴多年生黑麦草、铺地白三叶、普通红三叶、海法白三叶在当地适应性较好,生产性能相对较高,可作为当地建植栽培草地及改良天然草地的优选品种。研究结果对解决当地饲草匮乏、促进当地草地畜牧业的可持续发展具有重要的意义。     

Characterization of Trypanosoma (Trypanozoon) evansi from dromedary camels in Kuwait by isoenzyme electrophoresis

Blood from 115 camels in Kuwait was examined for blood parasites. Two camels of a local herd (1.7%) were found to be infected with Trypanosoma (Trypanozoon) evansi and three camels (2.6%) with microfilarial nematodes. The Trypanosoma stocks isolated from these two camels were screened for isoenzyme patterns of 10 enzymes using thin-layer starch-gel electrophoresis. The results revealed that these two stocks were identical to camel stocks of T. evansi from certain countries in Africa, as well as to two stocks isolated from dogs in Kuwait. This is the first record of Trypanosoma (Trypanozoon) evansi isolates and microfilariae from camels in Kuwait.     

Effects of an extract of Serenoa repens on dogs with hyperplasia of the prostate gland

OBJECTIVE: To determine effects of an extract of Serenoa repens on dogs with prostatic hyperplasia. ANIMALS: 20 mature male dogs with benign prostatic hyperplasia. PROCEDURE: Dogs were assigned to 3 comparable groups on the basis of prostatic volume per kg of body weight and degree of prostatic hyperplasia determined histologically. Dogs in 2 groups were treated for 91 days (8 received 500 mg, PO, q 8 h [1,500 mg/d], and 6 received 100 mg, PO, q 8 h [300 mg/d]). The control group of 6 dogs did not receive medication. Effects of treatment on prostatic volume, prostatic weight, prostatic histologic characteristics, radiographic and ultrasonographic assessment of prostatic size, results of CBC, serum biochemical analyses, and urinalysis, serum testosterone concentration, and semen characteristics were determined. At the termination of the study, all dogs were euthanatized, and necropsies were performed. Investigators conducting tests and interpreting results were not aware of treatment group of each dog. RESULTS: Treatment did not affect prostatic weight, prostatic volume, or prostatic histologic scores, libido, semen characteristics, radiographs of the caudal portion of the abdomen, prostatic ultrasonographs, or serum testosterone concentrations. Results of CBC, serum biochemical analyses or urinalysis, and body weights did not change during treatment. CONCLUSIONS AND CLINICAL RELEVANCE: Treatment with an extract of S repens for 91 days did not significantly affect the prostate gland of dogs. Adverse effects were not evident. Although products containing extracts of S repens are widely advertised for men with prostatic hyperplasia, beneficial or harmful effects of this plant extract were not found in dogs with prostatic hyperplasia.