Detection of Canine Vector-Borne Filariasis and Their Wolbachia Endosymbionts in French Guiana

In French Guiana, canine heartworm disease is well known, but the diversity of filarial parasites of dogs remains largely unknown. A total of 98 canine blood samples from Cayenne and Kourou were assessed by a blood wet mount preparation, heartworm antigen test and molecular exploration of filarioid and Wolbachia DNAs, followed by a multiplex species-specific qPCR’s identification and a subsequent sequencing analysis. Thereafter, a phylogeny based on maximum likelihood was carried out to facilitate specific identification. Five dogs were microfilaremic. Heartworm antigens were detected in 15 (15.3%) dogs. Of these, six (6.1%) were considered as occult infections as neither microfilariae nor Dirofilaria immitis DNA were detected. The 11 (11.2%) D. immitis isolates corresponded to a low virulent strain. Six of the D. immitis isolates were positive for Wolbachia endosymbionts of D. immitis belonging to the clade C DNA. Acanthocheilonema reconditum DNA was detected in 3 (3.1%) samples. Of these latter, one was found co-infected with the Brugia sp. genotype and the DNA of the clade D of the Wolbachia endosymbiont of Brugia species. This latter was also detected in two filarioid DNA-free samples. Finally, two samples were positive for Cercopithifilaria bainae genotype, which is distinct from those identified in Europe. The present study highlights the urgent need to implement chemoprophylaxis associated with anti-Wolbachia drugs to control these potential zoonoses.

Activation of mosquito immunity blocks the development of transmission-stage filarial nematodes

Mosquito-borne helminth infections are responsible for a significant worldwide disease burden in both humans and animals. Accordingly, development of novel strategies to reduce disease transmission by targeting these pathogens in the vector are of paramount importance. We found that a strain of Aedes aegypti that is refractory to infection by Dirofilaria immitis, the agent of canine heartworm disease, mounts a stronger immune response during infection than does a susceptible strain. Moreover, activation of the Toll immune signaling pathway in the susceptible strain arrests larval development of the parasite, thereby decreasing the number of transmission-stage larvae. Notably, this strategy also blocks transmission-stage Brugia malayi, an agent of human lymphatic filariasis. Our data show that mosquito immunity can play a pivotal role in restricting filarial nematode development and suggest that genetically engineering mosquitoes with enhanced immunity will help reduce pathogen transmission.

Red foxes (Vulpes vulpes) and coyotes (Canis latrans) in an urban landscape: prevalence and risk factors for disease

Urbanized areas contain fragmented landscapes and abundant resources, resulting in concentrated and increased wildlife populations in relatively close contact with other wildlife species, humans, and their domestic pets, thereby posing novel disease risks and facilitating inter-specific disease transmission. We trapped and radio-collared 15 red foxes (Vulpes vulpes) and 14 coyotes (Canis latrans) in the urban landscape of Madison, Wisconsin, to determine the prevalence of disease among these canids and to examine how these canids were using the landscape. Using Fisher’s exact probability tests, we found that coyotes had a significantly higher seroprevalence of Lyme disease (P = 0.002) and a higher prevalence of canine heartworm disease (P = 0.02) than foxes. Red foxes did not select specific habitat types in the urban landscape, but coyotes selected for forest and grass cover types, and avoided developed sites. Understanding the prevalence of disease in urban canid populations is important because diseases affecting urban canids cause morbidity and mortality and are transmissible to domestic dogs, and vice versa. Additionally, urban canids may serve as sentinels for zoonotic diseases such as Lyme disease and leptospirosis.

Approaches to Canine Heartworm Disease Treatment Among Alumni of a Single College of Veterinary Medicine

ABSTRACT This descriptive study was designed to ascertain the current heartworm treatment strategies employed by veterinary graduates of a single college of veterinary medicine, to assess the frequency with which each of these treatment strategies is prescribed, and to report the motivation behind the use of these treatment strategies. A survey containing a combination of multiple-choice and open-ended questions was distributed via e-mail with an online link during 2013 to graduates of the University of Georgia College of Veterinary Medicine. Demographic data and opinions regarding treatment for cases of canine heartworm disease (HWD) were obtained, and motivation for recommending different treatment strategies was assessed. Nearly all 170 respondents (99%) indicated that they recommend melarsomine dihydrochloride for first-line treatment of canine HWD. Exercise restriction (80%) and monthly heartworm preventive (75%) were components of the treatment approach to HWD with no clinical signs. The majority of respondents (74%) indicated that when first-line treatment recommendations were declined, they endorsed long-term administration of ivermectin (i.e., “slow-kill” method) despite current American Heartworm Society guidelines that recommend against the use of long-term macrocyclic lactone administration for the monotherapy treatment of canine HWD. Respondents also indicated that owners’ financial concerns frequently result in modification of HWD treatment. Routine inclusion of exercise restriction is commonly, but not universally, utilized and may represent an opportunity for improvement in the management of this disease. In addition, when first-line recommendations for heartworm disease treatment are declined, a two-dose melarsomine protocol instead of the slow-kill method should be considered.

In Iraq,The First Application of Serological SNAP ELISA Technique In Detection of Canine Heartworms (Dirofilariaimmitis) In Herder Dogs of Al-Qadisiyah and Dhi-Qar Provinces

Canine heartworm disease is one of the most pathogenic parasitic infections in the temperate countries,which had importance large effects on public health as could be infecting human. Serologically,this study is the first one in Iraq,which dealt with detection of the disease in dogs by using of SNAP ELISA technique. The overall seroprevalence for (172) herder dogs submitted to this study,was (40.12%),comprising (42.48%) and (35.59%) in Al-Qadisiyah and Dhi-Qar provinces,respectively. Also,the severity of infection in seropositive dogs had been estimated as (42.59%) for low infection level and (53.62%) for high D. immitis infection level. In association with the sex factor,the seropositive rates were (39.53%) for females and (41.86%) for males. Whilst,in relation to age factor, (32.35%) of less than 4 years dogs and (45.19%)of more than 4 years dogs,were infected,serologically. Statistically,the significant differences were showed between the seropositive results of examined provinces,intensity of infection,as well as the risk factors (age and sex) at a level of P£ 0.05.

Τreatment and prevention of canine heartworm disease (dirofilariosis): what is new?

Canine heartworm disease (dirofilariosis) is a frequent parasitic disease in Greece and other para-Mediterranean countries. Immediate adulticide therapy, followed by administration of microfilaricidals, has been the mainstay of heartworm treatment. However, a more recent approach has included the requirement to killing microfilariae and Wolbachia pipientis prior to adulticide treatment. Administration of prophylactic doses of milbemycin, moxidectin, ivermectin or selamectin for 2 to 3 months, as well as of doxycycline (10 mg kg-1 bw, per os, twice daily) for a month, seems to negate the ‘susceptibility gap’ and to decrease the possibility of pulmonary thromboembolism. Moreover, an alternative protocol of adulticide therapy (2.5 mg kg-1 bw of melarsomine, intramuscularly, followed by two further injections, 24-hours apart, a month later) is considered superior to the classical one, regardless of the clinical stage of the disease.Treatment of potential complications (right heart failure or vena cava syndrome) includes administration of heart failure medication and surgical removal of adult worms. Strict exercise restriction seems to play the most important role in reducing the possibility of pulmonary thromboembolism. Alternative protocol melarsomine administration, after treatment with macrocyclic lactones and doxycycline, increases the therapeutic effect and improves prognosis in earlier stages of the disease. Continuous (or at least during the warm period of the year) preventive administration of microfilaricidals coupled with annual serological testing of animals is important for effective disease control.

Διροφιλαρίωση του σκύλου: παθογένεια και διάγνωση ενός πολυδιάστατου νοσήματος

Canine heartworm disease (dirofilariosis) caused by Dirofilaria immitis is a parasitic disease frequently occurring in the para-Mediterranean countries. Global climate changes, animal transportation and inappropriate implementation of preventive measures in companion animals are some factors that have contributed to expansion of the disease in the last decades. Transmission of the parasite is carried out by mosquitoes, whilst the final hosts are members of the Canidae family or occasionally other animal species and humans. Apart from the endothelial lesions caused by the adult filariae, the endosymbiotic bacterium Wolbachia pipientis appears to play a role in the pathogenesis of the disease, through endotoxin production and production of specific IgG responses by the host against the bacterium’s surface proteins. Based on clinical and laboratory findings, dogs with the disease can be categorized into one of four clinical stages, ranging from asymptomatic to caval syndrome. Diagnosis of the disease can be reached after evaluation of clinical findings, in conjunction with paraclinical examinations, e.g., microfilarial and antigen testing, diagnostic imaging, haematological and blood biochemical examination.