Ultrasonography of the paralumbar muscles as a new aid during melarsomine treatment in canine heartworm disease. Description and illustration of the method - A preliminary study.

Melarsomine is used intramuscularly to destroy adult heartworms when treating canine heartworm disease (HWD). This drug is highly irritative and can elicit local complications. Therefore, melarsomine should be injected into the paralumbar muscles by strictly adhering to the manufacturers' prescriptions. However, it is not known how to determine the optimal location of the needle during the injection process. Ultrasonography (US) of the epaxial (paralumbar) musculature was used as a new method to measure the cross-sectional diameter of the paralumbar musculature, to determine the required location of the injection needle, and to study the local side effects in two dogs with HWD. The macroscopic appearance of the melarsomine solution during injection was demonstrated by video imaging. Melarsomine was not fully gravitating, but its majority was spreading along the thickest fascia of the musculature. Three minutes thereafter, no ultrasound signs of the melarsomine solution were seen, suggesting a full absorption at least ultrasonographically. This procedure was simulated in vitro with methylene blue solution having the same appearance. Removing the injection needle only after 5 min post-injection could prevent undesirable leakage of the drug through the injection channel into the subcutaneous tissue. Ultrasonography can be a useful aid during the treatment of HWD with melarsomine according to this preliminary study.

Selected advanced imaging techniques were unable to quantify in vivo parasitic burden in heartworm-infested dogs.

This prospective exploratory study aimed to determine whether certain noninvasive advanced imaging techniques could estimate parasitic burden in heartworm-infested dogs; a noninvasive method is needed for ethical considerations and permitting longitudinal drug studies. Three cardiac-gated and respiratory-gated 3T MRI techniques and CT pulmonary angiography (CTPA) were performed in three healthy beagles to optimize imaging techniques. Once the imaging techniques were established, a pilot study was performed to determine which one of the MRI techniques would be used in an observer comparison study. Ultimately, spoiled gradient recalled (SPGR)-cine-MRI and CTPA were performed in four and five heartworm-infested dogs, respectively. Heartworms were detected in the pulmonary arteries in all dogs during SPGR-cine-MRI and in no dog during CTPA. However, counting the number of worms was unsuccessful. In conclusion, CTPA and SPGR-cine-MRI were unable to replace necropsy for quantifying parasitic burden in heartworm-infested dogs.

Verminous myelopathy secondary to aberrant Dirofilaria immitis migrans was detected in the cervical subarachnoid space of four dogs using MRI and CT.

Aberrant Dirofilaria immitis migrans is a rare cause of neurologic signs in dogs, however, published studies describing the computed tomographic (CT) and magnetic resonance imaging (MRI) characteristics of this problem are currently lacking. The objective of this retrospective case series study was to describe the clinical and imaging findings for four adult dogs with verminous myelopathy due to aberrant Dirofilaria immitis migrans within the cervical subarachnoid space. All dogs were toy breeds, were heartworm antigen positive, had neurologic signs (ranging from cervical hyperesthesia to tetraparesis), and similar MRI findings. In two patients additionally imaged with CT, findings were variable. On MRI, each dog had a single large, dorsal- to laterally located, intradural-extramedullary, fusiform mass with characteristic stippled, mixed T2-weighted and T1-weighted signal intensity, hypo-to-iso T1-weighted signal intensity, and spinal cord compression. Nematodes were identified as serpentine or circular subarachnoid structures with low T2-weighted and T1-weighted signal in the sagittal and transverse image planes, respectively. CT (n = 2 dogs) demonstrated focal regions of mildly enhancing intradural-extramedullary spinal cord compression in 1 dog. Dorsal laminectomy and durotomy were performed in two dogs at C3-C4. A C4-5 hemilaminectomy with durotomy and dural biopsy was performed in one dog. Extraction of live, immature adult, female D. immitis worms was performed in three dogs. Operated dogs had complete post-surgical resolution of clinical signs. One dog was euthanized without surgery; necropsy revealed an adult heartworm in the spinal subarachnoid space at C2. Findings indicated that cervical spinal subarachnoid D. immitis aberrant migration should be considered as a differential diagnosis for dogs with this combination of clinical and CT/MRI imaging findings, and that the prognosis may be good with early detection and surgical removal.

Multidetector computed tomographic pulmonary angiography in a cat with fatal heartworm disease.

A 17-month-old neutered male domestic shorthair cat was referred for a computed tomographic (CT) study of the thorax due to respiratory distress. Multidetector CT angiography showed a multifocal interstitial ground glass opacity, tortuous and blunted pulmonary arteries consistent with thromboembolism with perivascular lung infiltration and hypoventilation in multiple lung lobes. A blood antigen test was positive for Dirofilaria immitis. The cat's clinical condition rapidly declined and the owners elected euthanasia. The histopathologic examination confirmed heartworm disease with parasitic pulmonary thromboembolism.

Periocular dirofilariasis: A case series.

OBJECTIVE: To cite a series of patients presenting with complaints of a lid swelling associated with preseptal cellulitis. METHODS: Three patients on three different occasions came with complaints of a unilateral lid swelling associated with preseptal cellulitis. Examination showed palpable mass in the upper eyelid localized, firm in consistency and was freely mobile and occasionally disappeared during palpation. CT scan showed nonspecific preseptal inflammation. A trial of antibiotics was given in each of the cases with temporary reduction in the swelling but a consecutive flare up following which patient was subjected to excision biopsy. Each of the biopsies was subjected to histopathological and microbiological examination. RESULTS: On excision biopsy in all the three cases it was reported to be a parasitic infestation belonging to the genus Dirofilaria. CONCLUSIONS: Dirofilariaiasis is a common zoonotic infection among wild animals but rarely infects human beings with ocular involvement. Hence dirofilariasis should be considered as a differential diagnosis for migratory subcutaneous swellings and conjunctival nodules in the southern belt of India.

Thirty cases of human subcutaneous dirofilariasis reported in Rostov-on-Don (Southwestern Russian Federation).

INTRODUCTION: Different species of the genus Dirofilaria, mainly D. immitis and D. repens, are responsible for emergent vector borne transmitted zoonotic diseases in the Old World. Human D. repens infections are characterized by the appearance of benign subcutaneous nodules that mimic skin malignant tumors or due to live worms in the ocular area. METHODS: Thirty patients presenting superficial or deep nodules were treated at the Rostov Regional Diagnostic Center (Southwestern Russian Federation). Anatomical characteristics of the nodules were studied by non-invasive ultrasound and color and power Doppler techniques. Worms were surgically removed from every nodule and their DNA analyzed by polymerase chain reaction (PCR). RESULTS: Twenty-four out of the 30 nodules were located in the hypodermis, two in a retro-ocular location and four in scrotal location. Image techniques allowed the identification of the helminthic origin of all nodules, based on their oval and regular shape, peripheral vasculature, and the existence of internal linear winding hyperechoic structures with or without movements, indicating the presence of live or dead worms, respectively. Specific adscription to D. repens was achieved by the PCR analysis. CONCLUSION: The series described in the present paper confirms the increasing risk of infection by D. repens in humans living in endemic areas of Eastern Europe. The use of non-invasive ultrasounds and Doppler techniques can contribute to an appropriate management of human dirofilariasis. Moreover, awareness of the medical community in the endemic areas influences the report of cases, and consequently the current epidemiological picture of human dirofilariasis.

Dirofilariasis of the breast: sonographic appearance.

Human dirofilarial infections characteristically manifest as pulmonary "coin" lesions or as subcutaneous nodules. A case of subcutaneous Dirofilaria infection of the breast involving a 25-year-old woman with a painful breast lump is presented. The patient had not traveled anywhere and did not have any animals, but provided a history of being bitten by mosquitoes. The suspicion of a parasitic infection was raised by the presence of rod-like structures within a hypoechoic nodule on sonography; movement within the nodule was detected during the examination. Histopathological examination revealed viable, adult female Dirofilaria repens, a nematode that is commonly found in dogs, cats, and wild mammals throughout parts of Europe, Africa, and Asia. © 2014 Wiley Periodicals, Inc. J Clin Ultrasound 42:433-435, 2014.

Subcutaneous dirofilariasis in a 25-year-old male patient in Belgium on ultrasonography: a case report.

BACKGROUND: Subcutaneous dirofilariasis is a parasitic zoonosis commonly described in Canidae but rarely seen in humans. Most physicians are unfamiliar with this disease, especially in nonendemic areas, which can lead to medication error and diagnostic and treatment delay. To the best of our knowledge, no previous case of subcutaneous dirofilariasis preoperatively diagnosed on ultrasound has been described in Western Europe. CASE PRESENTATION: A 25-year-old Belgian male patient presented with a subcutaneous nodule in the epigastric region. Ultrasound investigation showed a typical cystic lesion with an internal serpiginous structure with echogenic lines, and there was active twirling movement of this serpentine structure during investigation, pathognomonic for subcutaneous dirofilariasis. Surgical extirpation was performed, and the diagnosis was histopathologically confirmed. CONCLUSION: Subcutaneous dirofilariasis has a characteristic appearance on ultrasound but is not well known in nonendemic areas, often leading to diagnostic delay and initial incorrect treatment. More knowledge of this disease and of its characteristic ultrasound appearance will hopefully lead to better patient care.

Imaging Findings of Subcutaneous Human Dirofilariasis.

Dirofilariasis is an emerging helminthic zoonosis seldom reported. Humans are accidental hosts and rarely affected. We report a case of dirofilariasis presenting as a subcutaneous nodule in the uncommon location in the thigh with concealed history of dog meat handler. Of the cases published in literature, imaging findings of this disease have been few and far between. In this article, we describe multimodality imaging findings of dirofilariasis in the thigh.

Intracardiac heartworms in dogs: Clinical and echocardiographic characteristics in 72 cases (2010-2019).

BACKGROUND: Heartworms, a cause of pulmonary hypertension (PH) in dogs, can migrate from the pulmonary arteries into the heart resulting in life-threatening caval syndrome (CS). OBJECTIVES: To describe clinical and echocardiographic characteristics in dogs with intracardiac heartworms including estimated heartworm burden and frequency of PH and pigmenturia. ANIMALS: Seventy-two client-owned dogs with heartworms. METHODS: Retrospective study. Data collected from an electronic medical records search for dogs with intracardiac heartworms included clinicopathologic, echocardiographic, and procedural findings. Dogs with heartworms isolated to the pulmonary arteries were excluded. RESULTS: Estimated intracardiac heartworm burden was low in 14 of 72 (19%) and high in 58 of 72 (81%) dogs. The majority were small breed (54/72; 75%; 29/72; 40% Chihuahuas) and had a high likelihood of PH (67/72; 93%). Pigmenturia was the second most common clinical finding (31/72; 43%) after lethargy (32/72; 44%). Anemia (37/55; 36%), pigmenturia (30/58; 52%), and bilirubinuria (28/36; 78%) were significantly more common in dogs with a high worm burden (P < .05). Based on the presence of anemia, pigmenturia, and clinical signs, 18 of 72 dogs (25%) were considered to have CS. CONCLUSIONS AND CLINICAL IMPORTANCE: Although the majority of dogs with intracardiac heartworms had a high worm burden and high likelihood of PH, only 25% had clinical evidence of CS. Echocardiography is a useful tool to identify intracardiac heartworms, detect likelihood of PH, and could be useful for staging heartworm positive small breed dogs for intracardiac heartworm migration.

Clinical and diagnostic imaging findings in 37 rescued dogs with heartworm disease in Germany.

Canine dirofilariasis is currently uncommon in Germany, but its prevalence appears to be increasing due to rehoming of dogs from endemic areas. As part of staging of the disease, this case series describes clinical, radiological and echocardiographic findings in 37 dogs tested positive for Dirofilaria immitis between October 2016 and January 2019. Clinical history revealed 12 (32 %) asymptomatic and 22 (59 %) symptomatic dogs, with most of the dogs showing exercise intolerance, coughing or breathlessness. Thoracic radiographs were performed in 34 dogs and showed parenchymal lesions in 14 (41 %) and bulging of the main pulmonary artery (MPA) in 8 (23,5 %). Enlarged peripheral pulmonary arteries were noted in 22 (65 %) dogs, mainly affecting caudal peripheral pulmonary arteries. In 12 (24 %) of dogs with echocardiographic findings, thoracic radiographs were unremarkable. Echocardiographic examination was performed to assess secondary pulmonary hypertension (PH), identification of worm burden and dilation of pulmonary arteries. RPAD was applied for grading of PH in 34 dogs. Normal values (RPAD > 35 %) were detected in 11 (32 %) dogs, mild PH (RPAD 28-35 %) in 12 (35 %), moderate PH (RPAD 23-27 %) in 5 (15 %), and severe PH (RPAD < 23 %) in 6 (18 %) dogs. Severe systolic PH was confirmed by pressure gradient of tricuspid regurgitation in two dogs. Pressure gradients of pulmonary insufficiency were suggestive of diastolic PH in 5 dogs and correlated with RPAD < 23 %. Right ventricular hypertrophy was observed in 6 dogs with severe PH, flattening of the interventricular septum in 5 dogs. Right ventricular systolic time intervals showed a short acceleration time (<80 ms) and AT/ET of <0.31 in all dogs with severe PH. MPA dilation, defined as the ratio of MPA to aorta (MPA/Ao) exceeding 1.0 was found in 16 (43 %) dogs. Right pulmonary artery (RPA) dilation, defined as the ratio of RPA to aorta (PRA/Ao) exceeding 0.5 was detected in 25 (68 %) dogs. Double, linear parallel objects (DL) suggestive for macrofilaria were found in 28 (76 %) dogs. Of these, 7 (19 %) had a high worm burden occupying RPA and MPA. Six months after the 3rd Melarsomine injection a follow up examination was performed in 21 dogs. Main findings included persistent dilation of RPA in 11 (52 %), as well as RPAD indicative of PH in 11 (52 %) dogs. This case series demonstrates that>70 % of dogs had at least one relevant finding suggestive of PH prior to starting adulticide treatment. Therefore, thoracic radiographs as well as a thorough echocardiographic examination are recommended in all dogs that test positive for D. immitis. Echocardiography should focus on presence and severity of PH, for which RPAD has been proven to be useful. A follow up examination after adulticide treatment should be performed, which provides comparative assessment of presence and severity of PH. Dogs with persistent moderate to severe PH may benefit from long-term monitoring and medical management.

Case Report: Successful Treatment of a Patient with Microfilaremic Dirofilariasis Using Doxycycline.

We report the case of a 56-year-old woman with microfilaremic dirofilariasis due to Dirofilaria repens, which is a very rare condition in humans. Of note, just one of six large-volume blood samples of this patient was positive for microfilariae. Polymerase chain reaction (PCR) and sequencing of the parasite gene determined the geographic origin of the causative helminth. The patient was treated successfully with doxycycline. This drug was chosen because of the patient's reluctance to the use of ivermectin and to provide an anthelmintic effect by targeting the bacterial endosymbiont Wolbachia present in most filarial species.

Encapsulated living worms due to periorbital dirofilariasis: detection with high-resolution sonography.

Sonography (US) is commonly required when a superficial lump appears. We present the case of a patient for whom US was highly suggestive of living worms causing a recurrent periorbital mass. After surgery, the final diagnosis was a nodule composed of dirofilariasis larva.

The Diversity of Human Dirofilariasis in Western Sri Lanka.

BACKGROUND: Human dirofilariasis is an emerging zoonosis in many countries. Dirofilariasis caused by Dirofilaria repens may present with diverse clinical manifestations in humans due to aberrant localization of worm lesions causing diagnostic dilemmas. The aim of this retrospective study was to describe and update the demography and clinical spectrum of human dirofilariasis in western Sri Lanka. Nematode or nematode fragments isolated from excision biopsies that were confirmed as D. repens at the Department of Parasitology, Faculty of Medicine, University of Kelaniya, Sri Lanka, between 2012 and 2018 were included. Data on age, gender, and clinical details were obtained from case files. Identity of worms was established by morphometry and cuticle characteristics on wet-mount preparation. Specimens from unusual case presentations were further analyzed by PCR with specific primers for internal transcribed spacer region 2 (ITS2) of the ribosomal DNA. RESULTS: Sixteen nematode specimens isolated from subconjunctiva (n=2), subcutaneous (n=13) and intramuscular (n=1) locations were identified as D. repens by morphometry (average length 11.5 cm) and the characteristic longitudinal striations on cuticle visualized by microscopy. The age distribution of cases ranged from 1 to 65 years with a mean of 21.5. Females were more frequently affected (n=10, 62.5%) and worm locations were commonest in the orbital region (5/16) and scrotum (3/16). Imaging techniques were of use in detecting infections in deeper tissue levels. PCR analysis of DNA extracted from a worm in an intramuscular granuloma of the temporal region elicited the expected band at 484bp for D. repens. CONCLUSIONS: Human dirofilariasis is on an upward trend in incidence. Imaging techniques were of use in clinical diagnosis and molecular speciation in establishing the species identity in unusual case presentations. We suggest a more conservative approach in the management of human dirofilariasis and recommend a one health approach for control.

Clinical evolution and radiographic findings of feline heartworm infection in asymptomatic cats.

Clinical manifestations of heartworm disease in cats are variable; most cats seem to tolerate the infection well for extended periods. Heartworm-infected cats may undergo spontaneous self-cure due to the natural death of parasites without any symptomatology, or they may suddenly show dramatic and acute symptoms. Sudden death in apparently healthy cats is not a rare event. Thoracic radiographs are important tool for the diagnosis of cardiopulmonary disease. However, thoracic abnormalities are often absent or transient and highly variable in heartworm-infected cats. Findings, such as enlargement of the peripheral branches of the pulmonary arteries, with a varying degree of pulmonary parenchymal disease and hyperinflation, are the most typical features consistent with infection. A field study was performed for cats referred to the Veterinary Hospital Città di Pavia from January 1998 to December 2001 for routine health examinations and procedures to evaluate the clinical evolution and radiographic findings of feline heartworm infection. Thirty-four asymptomatic cats diagnosed with feline heartworm infection by antibody and antigen tests together with an echocardiogram that allowed worm visualization were included in the follow-up study. Cats were routinely examined every 3 months from the time of heartworm diagnosis until the outcome (self-cure or death). Self-cure was defined as no positive serology for heartworm antigens and no visualization of worms by echocardiography. A final examination for antibodies was carried after 12 months as a final confirmation of self-cure. Twenty-eight cats (82.4%) self-cured; including 21 that showed no clinical signs of infection throughout the study. Six cats died. The most common clinical features observed were acute respiratory symptoms and sudden death. Infection lasted over 3 years in the majority of the cats enrolled in the study. Thoracic radiograph appearance was variable, and the most commonly observed findings were focal and diffuse pulmonary parenchymal abnormalities.

Echocardiographic quantification of Dirofilaria immitis in experimentally infected cats.

The safety of heartworm preventives in heartworm-positive cats has traditionally been evaluated using adult Dirofilaria immitis removed from infected dogs and surgically implanted into the cats. An alternate study model uses infective larvae to establish adult infections in cats. Unfortunately, the number of adult worms resulting from the latter method varies widely from none to more than 30, both unacceptable for studies of natural heartworm infection and for studies evaluating product safety in heartworm-infected cats. We sought to determine infection severity in experimental infections via echocardiography to reduce the chances of enrolling uninfected and heavily infected cats into a study. Eighty adult cats were each inoculated with 60 infective D. immitis larvae and maintained for 8 months to allow for the development of adult worms. Antigen and antibody testing, as well as echocardiographic imaging, were performed to confirm and estimate adult worm burdens. Approximately 8 and 12 months post-infection, echocardiographic examination was performed to confirm and enumerate adult D. immitis populations in the cardiovascular system. Worm burdens were stratified as 0, 1-3, 4-11, and > 11 adults, with 0 being considered uninfected and more than 11 considered too heavily infected to be relevant for anthelmintic studies. Cats with clinically relevant infections (1-10 adults) subsequently received multiple treatments with the investigational drug, and worm burdens were confirmed by necropsy 30 days following the final treatment. Worm burden estimated with echocardiography correlated well, but not precisely, with post-mortem counts (p < 0.001, r2 = 0.67). Echocardiography under-, over-, and exactly estimated heartworm burden 53%, 27%, and 22% of the time, respectively. Although the correct category (0-4) was determined by echocardiography in only 54% of cats, positive cats were distinguished from negative cats 88% of the time and the heaviest infections (> 11) were correctly categorized 95% of the time. Both false negative and false positive results were observed. We conclude that echocardiography is useful for detecting mature experimental heartworm infections, identifying cats that have rejected mature infection, and detecting very heavy heartworm burdens, but it is only moderately accurate in classifying lesser burdens. While echocardiography cannot be relied upon to consistently determine the exact heartworm burden in experimentally infected cats, it is useful in stratifying worm burdens for anthelmintic safety studies.

High-resolution CT evaluation of bronchial lumen to vertebral body, pulmonary artery to vertebral body and bronchial lumen to pulmonary artery ratios in Dirofilaria immitis-infected cats with and without selamectin administration.

Objectives The bronchial lumen to pulmonary artery (BA) ratio is utilized to evaluate pulmonary pathology on CT images. The BA ratio may be unreliable when changes are present in bronchial and pulmonary arteries concurrently. Bronchial lumen to vertebral body (BV) and pulmonary artery to vertebral body (AV) ratios have been established in normal cats and may serve as an alternative. This study aimed to evaluate the BV, AV and BA ratios in cats before and after infection with Dirofilaria immitis, with and without selamectin administration, and to characterize the distribution of disease. Methods Archived CT images were reviewed from three groups of cats: D immitis-infected untreated (n = 6); infected pretreated with selamectin (n = 6); and uninfected untreated (n = 5). The BV, AV and BA ratios were calculated for all lung lobes for baseline (D0) and day 240 (D240) postinfection. Ratios and percentage change from baseline were compared between lobes and between groups. Results BV and AV ratios were more consistent in identifying abnormalities when disease was present in bronchial and arteries concurrently than BA ratios. Infected untreated cats had significant changes in both BV and AV ratios and percentage change from baseline. Abnormal BV and AV ratios were noted in the infected selamectin group, although less widely distributed. Conclusions and relevance The BV and AV ratios more accurately identified bronchial and pulmonary artery abnormalities in D immitis-infected cats. Both bronchial and pulmonary artery changes were present in infected cats, decreasing the diagnostic application of the BA ratio. Pulmonary artery changes were more widely distributed than bronchial changes in the lung. Heartworm-infected cats receiving selamectin had bronchial and pulmonary artery changes but to a lesser extent than untreated heartworm-infected cats. The CT-derived BV and AV ratios are a useful measure to evaluate lung disease of cats.

Heartworm Removal Guided by Transesophageal Echocardiography in a Dog with Naturally Acquired Caval Syndrome.

A 14 mo old shih tzu was referred for dyspnea, hemoptysis, and hematuria. Heartworm disease with caval syndrome was diagnosed by laboratory tests, thoracic radiography, and transthoracic echocardiography. The minimally invasive heartworm removal procedure was performed using flexible alligator forceps guided by transesophageal echocardiography. The procedure was successfully performed removing over 94% of heartworms displayed echocardiographically without any intraoperative complication.

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.