Report of Dirofilaria immitis infection with acute cardiopulmonary complications in a cat from Northeastern Brazil

Dirofilariasis is a zoonotic disease caused by Dirofilaria immitis, a nematode found mainly in the pulmonary artery and right chambers of the heart, lungs, and large vessels of dogs. This parasitism also occasionally occurs in cats, causing an amicrofilaremic and asymptomatic infection, resulting in severe illness and rapid death. In this case report, it was described acute clinical signs and histopathological alterations in a domestic cat with heartworm disease from the city of Mossoró, the Rio Grande do Norte, Brazil. The nematode species, D. immitis, was confirmed by morphological and molecular analyses. This is the first documented and full report of feline heartworm disease in northeastern Brazil.

Differential diagnosis of Dirofilaria immitis nematodes (Nematoda, Onchocercidae)

Heartworm disease is a widespread anthropozoonotic disease of carnivorous animals, as well as humans. It is caused by nematodes belonging to the suborder Filariata, family Onchocercidae, genus Dirofilaria. There are about 26 species of heartworms in nature, the most common and pathogenic species in dogs and cats in most countries is Dirofilaria immitis Leidy, 1856. Mature helminths parasitize in the right ventricle and pulmonary arteries, large veins of animals and cause heart and vascular disorders, and death. Therefore, the aim of the study was to investigate the features of morphological and metric structure of adult nematodes of D. immitis isolated from the heart of dogs. Morphological studies have shown that in males the most characteristic differential features are the presence of two unequal spicules, specifically positioned relative to each other, as well as well-defined preanal and less pronounced adanal and postanal papillae. In female heartworms, the characteristic morphological features are the shape and location of the vulva. There is a difference in the structure of the esophagus in males and females. In females, the anterior and posterior parts of the esophagus are well expressed, with enlargements, in males these divisions are not pronounced. To increase the efficiency of species identification of D. immitis nematodes, it is proposed to use metric parameters that characterize the overall body size, body and width of esophagus in different areas, length of esophagus, and the location of the nerve ring. In males, 11 indicators are also suggested that characterize the size of the spicules and the location of the cloaca. In females, seven additional parameters are pointed out that characterize the location of the vulva, anus and body width in these areas. The obtained data expand the already existing data on the peculiarities of the morphological structure of parasitic nematodes of the species D. immitis and their identification.

Canine and Feline Dirofilariasis Currently Spreads in Indonesia Damaging Pulmonary Arteries and Lungs: A Literature Review

Dirofilariasis, caused by Dirofilaria immitis, mostly known as heartworm disease, is an important mosquito-borne nematode zoonosis that naturally infects canids and other species such as cats, ferrets, and humans. There have been reports of heartworm infection from many countries in worldwide. Researchers have reported D. immitis is widely distributed in Southeast Asia because this parasitic zoonosis disease lives in temperate, tropical, and subtropical areas and can be found in colder regions. Therefore, the authors intended to provide an overview of Dirofilariasis cases in Indonesia from a global perspective. The published articles of dirofilariasis were collected and retrieved by an electronic literature search of three databases, including Google Scholar, PubMed, and Science Direct. The literature presented is intended to enhance our current understanding of the overview of D. immitis infection and its prevalence in Indonesia from a global perspective. D. immitis infection can cause caval syndrome in dogs as well as a cardiopulmonary syndrome known as Heartworm-Associated Respiratory Diseases (HARD), which can become fatal as the number of worms infecting the host increases. Whereas in cats, although the number of worms in the host are very few (one to six worms) they can cause pathological changes in the pulmonary arteries which result in a more serious infection than in dogs and endanger life.

First Autochthonous Infection of a Cat with Dirofilaria immitis in Austria

This case report is about a seven-year-old male neutered European Shorthair cat infected by Dirofilaria immitis as the first reported autochthonous Dirofilaria immitis infection in Austria. There was no history of periods abroad. Echocardiography showed suspected D. immitis in the right cardiac chamber with increased pulmonary pressure and ascites. Surgical removal of the heartworms was performed. Twenty adult heartworms were removed by transvenous jugular approach under general anesthesia and stored in 4% formalin. Five out of 20 specimens were examined via light and stereomicroscopy and feline heartworm infection was confirmed. Amplification of a 203 bp or 724 bp fragment of the cytochrome c oxidase subunit I gene was unsuccessful. After surgery the cat developed acute renal failure but recovered quickly. One year later, the cat underwent a control examination including echocardiography and blood work. There were no more D. immitis detectable at echocardiography. Lung pressure was mildly increased. Complete blood count and creatinine were unremarkable. The Knott’s test and Dirofilaria-Antigen-test produced negative results. The cat did not show any clinical signs during the follow-up period. The aim of this case report is to highlight the growing risk of acquiring infection with D. immitis not only for Austrian dogs, but also for cats. This case report represents the first report of autochthonous D. immitis infection in Austria. Moreover, even if the prognosis in cats with caval syndrome due to feline heartworm disease is guarded to poor, surgical removal of the filariae can be a successful treatment option.

Monitoring of parasitic diseases of dogs

During the study, dogs were diagnosed with the following helminthic diseases: toxocariasis, echinococcosis, uncinariosis, trichuriasis, capillariosis, dipilidiosis, which took the form of mono and mixed invasions. The aim of this study was to identify the intensity of helminth infestation of dogs of different ages and methods of keeping. Materials and methods. Experimental studies were conducted during 2018–2020 on the basis of the laboratory “Innovative technologies and safety and quality of livestock products” and “Veterinary Pharmacy” of the Department of Veterinary Examination, Microbiology, Zoohygiene and Safety and Quality of Livestock Products; epizootology and parasitology of the Faculty of Veterinary Medicine of Sumy National Agrarian University. In cities and villages, faecal samples were taken from dogs, taking into account the method of keeping (tethered or untethered) and their use (office, hunting, decorative, etc.), which were placed in airtight containers, labeled samples and sent to the laboratory for the research. The object of clinical and laboratory research were dogs aged one to seven years, admitted to veterinary clinics in the period from 2018 to 2020, with suspected helminthic diseases. Testing of dogs was performed by collecting medical history and clinical examination. Results. According to the results of the research, it was established that among helminthic diseases during 2018–2020 the following diseases were registered: toxocariasis, cestodes, uncinariosis of dogs. Among the blood-parasitic diseases for the period 2018–2020 were diagnosed with heartworm disease, babesiosis of dogs. Among ectoparathyroidism, the laboratory diagnosed demodectic mange, otodectosis, canine sarcoptosis, and carnivorous syphonepterosis. A total of 513 surveys were conducted in 2018, of which 80 were positive; for 2019–509, of which positive – 58; for 2020 – 488, of which 62 are positive. Conclusions. Intestinal helminthiasis has been found to account for the lowest proportion (11 %) of carnivorous parasitic diseases compared to blood parasitic diseases (19 %) and ectoparasitosis (70 %), but they are of great interest for study because of their significant epidemiological significance and may be the cause of disease in humans. It has been proven that helminthic diseases of dogs run as mixed invasion, and a minority of cases 31.7 % of cases run as mono invasion. Of the total number of patients with helminthic diseases, 73.4 % of the total number of animals were accompanied by other diseases of infectious and non-infectious ethology

Episootic situation of dirofilariasis in dogs in Kiev

In most countries, dogs are more likely to have two types of heartworm pathogens: Dirofilaria repens ‒ localized in the subcutaneous tissue and causes skin lesions and Dirofilaria immitis ‒ parasitizes in the right ventricle and pulmonary arteries and is accompanied by cardiovascular disorders in animals. The increase in the number of dogs infected with heartworms occurs with increasing age, depending on the sex and breed of animals. Laboratory tests are important in diagnosing heartworm disease because the clinical signs are nonspecific. Heartworm disease is a global disease, the geographical area of which continues to increase The aim of the study was to clarify the epizootic situation regarding heartworm disease of dogs in Kyiv, to study the dynamics of the disease for the period 2017-2020, depending on the age of dogs, economic use in the city of Kiev, also to analyze the similarity of pathological and anatomical changes of affected animals by parasites Dirofilaria immitis. The material for the epizootic situation were reports on the results of studies of dogs in Kyiv for 2017-2020 and the results of our own research. Pathological and anatomical examinations were performed in the section hall of the Research Pathomorphology Department of the State Research Institute for Laboratory Diagnostics and Veterinary Sanitary Examination. The object of research is 96 dogs of different ages: puppies up to 1 year, dogs from 1 year to 12 years. Autopsies were performed according to generally accepted methods. According to official research results in Kyiv for 2019 - 2020, heartworm disease has decreased significantly (8 - 5.7%). The highest rate of invasion was in 2017 (29.6%) and with each passing year the percentage of the disease decreased, reaching 5.7% in 2020. This situation may be due to changes in weather and climate conditions (reduced rainfall), timely prevention, treatment and treatment of animals from mosquitoes. According to the results of pathological and anatomical studies, it was found that dogs under 1 year of age were not infested, and with increasing age in animals the incidence rate begins to increase and reaches the highest percentage of infestation in adult animals aged 10-12 years to ‒ 60%. Which is due to biological vectors (infested mosquitoes) and reduced resistance of animals. Pathological autopsy was performed on dogs of different breeds. However, 16 dogs were infected, including: German Shepherds ‒ 7, mestizos ‒ 4, outbred ‒ 5. In general, it is not the breed that affects dogs, but the conditions of keeping and economic use. The intensity of the invasion among service dogs ‒ 12,5%, domestic ‒ 18,2%, among homeless dogs were not found, which indicates a higher resistance of the body to this disease. According to the results of pathological and anatomical autopsies in the corpses of 16 affected animals with heartworms, similar postmortem changes were observed: 1. The presence of parasites Dirofilaria immitis approximately 20-30 cm long of light yellow color in the lumen of the right ventricle in aorta and pulmonary artery in 16 corpses ‒ 100% cases; 2. Acute venous hyperemia and pulmonary edema in 12 corpses ‒ 75% of cases; 3. Dilatation of the right ventricle of the heart in 9 corpses ‒ 56.3%; 4. Aneurysm and thrombosis of the pulmonary artery adjacent to the right ventricle of the heart was found in 8 corpses ‒ 50% probability; 5. Myocardial dystrophy among 8 corpses ‒ 50%; 6. Pericarditis was found in 3 carcasses of animals ‒ 18.8%; 7. Endocarditis in one dog, i.e. ‒ 6.3%; 8. With myocarditis one corpse ‒ 6.3%; 9. Gastro-enteritis was observed in 12 corpses in the total number ‒ 75%, but: catarrhal in 8, catarrhal-hemorrhagic in 3, hemorrhagic in 1; 10. Pneumonia in 3 corpses ‒ 18.8%, distinguishing interstitial, serous-catarrhal, catarrhal-purulent in one case. Own research has established the infestation of dogs with parasites, and the similarity of pathological and anatomical changes at the autopsy of animals depending on age, breed and economic use. In the future, it is planned to conduct histological and histochemical studies of organs in which the presence of helminths Dirofilaria immitis was detected in order to study the characteristic morphological changes.

Field study to investigate the effectiveness and safety of a novel orally administered combination drug product containing milbemycin oxime and lotilaner (Credelio® Plus) for the prevention of heartworm disease (Dirofilaria immitis) in client-owned dogs in the USA

Background Dirofilaria immitis, a globally distributed filarial parasite of dogs, is known to cause serious or fatal cardiopulmonary disease. Client-owned dogs were enrolled in a clinical field study in the USA to evaluate the clinical effectiveness and field safety of an orally administered combination investigational product (IP) containing milbemycin oxime and lotilaner (Credelio® Plus) as compared to a control product (CP) for the prevention of heartworm disease when administered monthly for 11 consecutive months. Methods In this 11-month field study, 319 dogs ≥ 8 weeks old confirmed to be heartworm-negative were enrolled from eight geographically distinct US veterinary clinics, including sites in the southern USA and Mississippi River Valley. The dogs were treated with either the IP combination product at 0.75–1.53 mg/kg milbemycin oxime and 20–41.5 mg/kg lotilaner (n = 159) or the CP (Sentinel® Flavor Tabs®; milbemycin oxime/lufenuron) at the label-recommended dose rate (n = 158.) On day 330, effectiveness was evaluated in each dog using antigen and microfilarial (modified Knott’s) testing to assess the establishment of any patent adult heartworm infections. Results All dogs treated with the IP combination product and the CP tested negative (100% prevention) for heartworm infection on day 330. The IP combination product tablets containing milbemycin oxime and lotilaner were well tolerated based on the safety assessments in all treated dogs. Conclusions This multi-site clinical study using client-owned dogs demonstrated that monthly use of flavored, chewable tablets containing a combination of milbemycin oxime and lotilaner administered orally under end use conditions is safe for dogs. None of the enrolled dogs developed heartworm infections. Eleven consecutive monthly treatments of the IP provided 100% prevention of heartworm disease caused by D. immitis. Graphic Abstract

Pharmacoeconomic Analysis of Heartworm Preventive Compliance and Revenue in Veterinary Practices in the United States

Background: Heartworm disease (HWD) is a potentially fatal condition caused by the nematode Dirofilaria immitis. It is endemic in North America, and the American Heartworm Society recommends that owned dogs be on a Food and Drug Administration-approved HWD preventive year-round. The objective of this study was to compare the 12-month HWD preventive purchase compliance rates of injectable moxidectin (ProHeart® 6) and the dose equivalent in monthly HWD preventives and their associated economic value to the veterinary hospital.Methods: This study used retrospective anonymized transactional data of 7,926,392 unique dogs from 3,737 companion animal practices across the US for the period 2014–2017. Compliance was defined using American Heartworm Society guidelines. Comparisons were purchases of a 6-month moxidectin injection or six doses of any monthly HWD or HWD combination preventive product, tracked for the next preventive purchase 5–7 months later. Total revenue, HWD prevention cost, 12-month repurchase compliance, and patient retention were calculated. Data were expressed on an annualized basis. Compliance comparisons were calculated based on proportion analysis with the SAS ProbNorm function (SAS 9.4, Cary, NC), using a two-sided t-test, at the 5% level of significance (P < 0.05).Results: At 51.7%, annual compliance with injectable moxidectin was higher than the dose equivalent in monthly HWD preventives, which was 24.4% (P = 0.0001). Eighty-five percent of patients on injectable moxidectin recorded additional transactions during the first visit (average invoice of $161), compared with only 55% of pet owners who purchased monthly HWD prevention (average invoice $141) or monthly HWD combination (average invoice of $171). The average costs of 6 months of HWD preventives were as follows: injectable moxidectin, $48 (29.7% of the total visit invoice); monthly HWD prevention, $45 (31.0% of the total invoice); and monthly HWD combination, 95 (55.6% of the total visit invoice). Finally, dogs receiving injectable moxidectin had a higher proportion of patients with repeat injections within 12 months between 2014 and 2017, with 68% retention rate after 4 years. In comparison, the six-dose monthly HWD cohort retention rate dropped to 55% by 2017.Conclusions: Dogs receiving injectable moxidectin had higher HWD preventive compliance, generated more practice revenue, and had a higher rate of practice retention compared with monthly HWD products.