No evidence of endemic infection with Dirofilaria immitis in dogs

Extract

Dirofilaria immitis is periodically recorded in dogs imported from Australia into New Zealand. In this country, environmental conditions are marginal for the transmission of this species, but potential mosquito intermediate hosts are known to be present⁽¹⁾. Development in the intermediate host is temperature dependent, with most reports indicating that a mean temperature of at least 18 °C is required^(2)(3)(4). Therefore, the most likely locations in New Zealand for D. immitis to establish are the Auckland region and areas north of this.     

Dirofilaria immitis infection in foxes and coyotes in Indiana

Between October 1976 and January 1977, carcasses or hearts and lungs from 202 wild foxes and coyotes in Indiana were collected to determine the prevalence of Dirofilaria immitis infection. Three of 113 (2.7%) red foxes (Vulpes fulva), 3 of 81 (3.7%) gray foxes (Urocyon cinereoargenteus), and 1 of 8 (12.5%) coyotes (Canis latrans) were infected with D immitis. An average of 5 worms (range, 1 to 10) were recovered from foxes and 11 worms were recovered from the coyote. Worms from the coyote were of normal length and all female worms contained developing embryos and microfilariae. Worms from foxes were small, and none of the female worms contained developing embryos.     

Prevalence of Dirofilaria immitis infection among shelter cats

OBJECTIVE: To determine prevalence of Dirofilaria immitis infection among shelter cats. DESIGN: Cross-sectional study. ANIMALS: 239 cats euthanatized at an animal shelter in southeastern Michigan. PROCEDURE: A gross necropsy focusing on the thoracic cavity, heart, lungs, and pulmonary vessels was performed within 5 hours after cats were euthanatized. Blood was collected directly from the heart of cats found to be infected and tested, using a filter test for microfilariae. Serum was tested for D immitis antigens by use of 2 antigen detection kits and for D immitis-specific antibodies by use of 2 antibody detection kits. RESULTS: Cats ranged from approximately 4 months to 15 years old. Adult D immitis were found in 6 (2.5%) cats. Blood could not be recovered from 1 of the cats with heartworm infection. For the 5 other cats, results of the filter test were negative, and results of both antigen and both antibody tests were positive. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that cats living in an urban area in the northern part of the United States have a low prevalence of adult D immitis infection. However, this is likely to be an underestimate of the true prevalence of infection, because no attempts were made to identify cats infected with larval or juvenile stages of D immitis.     

Dirofilaria immitis infection in dogs: cardiopulmonary biomarker levels

Cardiopulmonary biomarkers are biological parameters that can be objectively measured and quantified as indicators of pathogenic processes (heartworm disease) or as indicators of response to therapeutic intervention. To determine levels of cardiopulmonary biomarkers in canine dirofilariasis, measurements of cardiac troponin T, cardiac troponin I, myoglobin, and D-dimer concentrations were performed for dogs with and without evidence of adult heartworm infection. The results showed that levels of cardiac troponin T were undetectable in all dogs studied while levels of cardiac troponin I were higher in dogs infected with Dirofilaria immitis. In healthy dogs, levels of myoglobin and D-dimer were below detection limits of the instrument and were significantly higher in heartworm-infected dogs, notably in microfilaremic dogs. The results suggest the possibility of using troponin I and myoglobin as markers for cardiac damage and the D-dimer as a supportive tool for a diagnosis of pulmonary thromboembolism in dogs with cardiopulmonary dirofilariasis.     

Influence of immunosuppressants against Dirofilaria immitis infection in dogs

Two immunosuppressive drugs, azathiopurine (AZP) and prednisolone (PDS), were examined on dogs experimentally infected with Dirofilaria immitis in order to estimate the involvement of immunological assail in rejecting the parasite by the host. AZP was orally administered to 3 dogs daily at a dosage of 1-10 mg/kg for a period from 3 days before infection until the end of the experiment. The dose was then varied and transiently ceased according to the severity of the side effects. PDS was subcutaneously administered daily to 2 dogs. They were administered 10 mg/kg of PDS from 3 days before infection to day 15 and 5.0-8.5 mg/kg from day 60 after infection to day 70. The serum D. immitis-specific antibody level assessed by an indirect hemagglutination test was steadily decreased in the AZP-medicated dogs. However, in the PDS-medicated dogs, the antibody titer was decreased until day 32 and, thereafter, was recovered. When all dogs were sacrificed between days 145-148, an average recovery rate of worms in both the AZP- and PDS-medicated dogs was 52.5% and 49.6%, respectively, while the controls showed 42.5%. The statistical analysis revealed no significant difference among the groups, indicating that the administration of AZP and PDS was not effective in protecting the larvae from the host's immune attack.     

Autochthonous Dirofilaria (Nochtiella) repens infection in dogs in Kuwait

Human dirofilariasis caused by Dirofilaria repens is a rare but increasingly reported zoonosis in the Middle East. However, eligible animal reservoirs seldom have been investigated in the area until now. Seven (1.8 percent) out of 381 dogs examined in Kuwait carried D. repens microfilariae showing compatible cutaneous clinical signs and positive response to the adulticide and microfilaricide therapies. This study indicates that dogs from Kuwait are natural hosts of D. repens and therefore act as an animal reservoir for the zoonotic condition.     

Glomerulonephritis associated with simultaneous canine adenovirus-1 and Dirofilaria immitis infection in a dog

This article describes a case of glomerulonephritis and immunocomplex (IgM, IgG and C3c) deposition in the mesangium and basement membranes of a 2-year-old dog with canine viral hepatitis and dirofilariasis. The deposits observed in the mesangium were in the vicinity of cells with viral replication. However, no clear relationship was found between viral replication and the deposition of immunocomplexes in the glomerular capillary basement membranes, which may be the reason why these deposits have only been tentatively related to the concomitant infestation by Dirofilaria immitis.     

Nodular skin disease associated with Dirofilaria immitis infection in the dog.

Three dogs with dirofilariasis had a dermatologic syndrome, characterized by pruritus and multifocal nodules which tended to ulcerate. The cutaneous nodules revealed angiocentric pyogranulomatous inflammation with variable numbers of eosinophils. Microfilariae were often present in the blood vessels surrounded by the pyogranulomatous process. Therapy for dirofilariasis resulted in complete resolution of the dermatitis.     

Ocular dirofilariosis by Dirofilaria immitis in a dog: first case report from Europe

A five‐year‐old, entire female mixed‐breed dog was presented with corneal oedema and episcleral hyperaemia in the left eye. The ophthalmological examination revealed the presence of a free‐swimming nematode in the anterior chamber. Circulating microfilariae were not observed by a modified Knott test nor were adult antigens detected in serum by a commercial ELISA. The parasite was surgically removed from the dog's eye, but its anterior end was damaged during the surgery. Based on the morphology of the posterior end, the nematode was preliminarily identified as a male Dirofilaria immitis. The species identification was confirmed by PCR amplification and sequencing of the mitochondrial coxI and 12S rDNA genes, using a DNA barcoding approach. Although other cases of ocular dirofilariosis by D. immitis have been previously recorded in Australia and the United States, the case reported herein is the first in a dog from Europ.     

Influence of immune treatments against Dirofilaria immitis infection in dogs

Mongrel dogs were inoculated with two kinds of antigenic substances. The first was a phosphate buffered saline extract of whole Dirofilaria immitis mixed with aluminum hydroxide gel (group 1), and the second was an orally administered live Metastrongylus apri infective larvae (L3) (group 2). Both groups were then infected with D. immitis L3. Indirect hemagglutination (IHA) tests showed that the antibody was produced by these inoculations before the infection was introduced, even in dogs inoculated with M. apri. This suggests a cross-reactivity between D. immitis and M. apri. The initial passive cutaneous anaphylaxis (PCA) antibody production was markedly delayed by about 70 days in group 2 compared with the production in the infected control dogs (group 3). The appearance of microfilaremia was also delayed by about one month in group 2 compared with that in the above control group. All dogs were sacrificed after the termination of the observation and worms recovered from the right ventricle and pulmonary arteries were counted and measured. The results indicated that immunization resulting from the homologous worm-somatic antigen might accelerate the growth of the infected larvae, whereas immunization resulting from the heterologous worm antigen, but cross-reactive to D. immitis, might disadvantageously affect the growth.