Evaluation of feline heartworm disease based on gross necropsy, serology, pulmonary histopathology, and radiographic evidence in adult shelter cats in northeastern Alabama

BACKGROUND

Veterinary knowledge regarding feline heartworm has been increasing significantly over the past two decades. Necropsy surveys of shelter cats have shown feline adult heartworm infection prevalence to be 5-20% of the rate in unprotected dogs; however, other studies have shown feline heartworm antibody prevalence up to 33%, reflecting higher exposure rates and potential immature adult infections. Thus, the true prevalence of feline heartworm infection is likely underestimated due to the limitations of current diagnostic techniques, inadequate testing protocols, and the high likelihood of cats exhibiting transient clinical signs or dying without confirmation of infection. Diagnosing Feline Heartworm Disease (FHWD), also referred to as Heartworm Associated Respiratory Disease (HARD), is one of the conundrums of veterinary medicine. The purpose of this study was to evaluate and characterize the occurrence of Heartworm Associated Respiratory Disease [HARD] in shelter cats, naturally-infected with D.immitis.

METHODS

Fifty shelter cats slated for euthanasia between December 2009 and June 2010 were investigated by gross necropsy, radiography, serology, and lung histopathology using techniques that have been established in experimental models of cat heartworm infection. The relationship between pulmonary vascular disease and serological markers for heartworm was also examined using correlations and statistical modeling. Serology included standard heartworm antigen test and a commonly used heartworm antibody test. Also included were heat-treated heartworm antigen test and two additional heartworm antibody tests previously evaluated on experimentally-infected cats.

RESULTS

None of the cats were heartworm antibody (HW Ab) positive on a commonly used HW Ab test used by many reference laboratories even though 20% of the study cats were heartworm antigen (HW Ag) positive on heat-treated samples. Two additional HW Ab test were positive on 26% and 22% of the study cats. The combination of heat-treated HW Ag, HW Ab tests, and histopathology indicated 34% of the study cats had HARD.

CONCLUSIONS

Utilizing both, the above tests, and thoracic radiographs, enhanced the ability to predict vascular disease, possibly caused by infection with immature and adult heartworms and supported the premise that cats develop heartworm disease at the same rate as dogs.

Human dirofilariasis - Unforeseen lesion in subcutaneous nodules: Case series from a tertiary care hospital, Wayanad

Human dirofilariasis is a type of zoonotic infection caused by the Dirofilarial species. It is a type of roundworm which is commonly seen in dogs, cats and is transmitted to humans by mosquito bite. Microfilaria is rarely produced in humans. Although clinically they can have varied presentations, it usually presents as ocular or subcutaneous nodules. Definitive diagnosis requires histopathological findings of this worm. We hereby report three cases of Dirofilariasis from a tertiary care hospital in Wayanad.

Testicular Dirofilariasis in an Italian 11-Year-old Child

Dirofilariasis is a rare infection caused by a vector-borne nematode that can be accidentally transmitted to humans. We report a case of a 11-year-old child with a painless scrotal cyst caused by Dirofilaria repens , initially suspected by ultrasound scan and then confirmed by histopathologic examination.

First case of ocular dirofilariosis in Bulgaria caused by gravid female Dirofilaria repens

Dirofilariosis caused by Dirofilaria (Nochtiella) repens is recorded sporadically among people in Europe, Asia and Africa. Still a worldwide controversy exist upon human parasite hosting. Herein, the first case of ocular dirofilariosis in Bulgaria caused by gravid female is presented. A single nematode was removed from the eye of the 76- year-old patient in the course of cataract surgery. Microscopic examination of the histological slides revealed microfilariae in the parasite’s uterus, but not in the blood. Knott’s method for detection of microfilariae in the peripheral blood was negative and the rest of laboratory blood and biochemical tests were within reference limits. A comprehensive review of the etiology, pathogenesis and clinical presentation of Dirofilaria repens infection is also highlighted.

A rare clinical presentation of human Dirofilaria repens infection as a pseudo-tumour of the epididymis - Case Report

Introduction. Epididymal dirofilariasis is one of the unusual manifestations of this zoonosis. In Slovakia, this is the third case out of 20 Dirofilaria repens infected patients in whom the worm (the parasite) was identified in the epididymis. The patient felt a painless tumour about 2 cm in size on the left testicle. During ultrasound examination, the radiologist observed a cyst containing a live worm within the epididymis. After mechanical stimulation, the movement characteristic for filarial worms (´filarial dance sign´) appeared. An orchiectomy was performed at the Department of Urology in the University Hospital in Košice. Histopathology confirmed a parasitic cyst with a worm, and based on characteristic morphological features, the parasite was identified as Dirofilaria repens. Objective. The aim of case report is to alert physicians to the possibility dirofilarial infection of the epididymis, where tumors and cystic structures often occur and to present clinical signs of the disease.

The first case of periorbital human dirofilariasis in the Czech Republic

Dirofilaria repens and Dirofilaria immitis are the most common filarial species affecting humans in Europe. Dirofilaria repens causes subcutaneous or ocular infection, whereas D. immitis is responsible mainly for the pulmonary form. In this report, we present the first human case of periorbital dirofilariasis in the Czech Republic. A 58-year-old woman suffered from an eyelid oedema, redness and pain in the left eye. After excising the parasite from her eyelid, all clinical symptoms disappeared. Based on the morphology and cytochrome oxidase I sequencing, the parasite was identified as D. repens. Histology revealed that the excised worm was female with absent microfilariae in uteri. With respect to the length of the incubation period and the sequence identity with a known Czech isolate, we concluded that D. repens was most likely of autochthonous origin.

A case of human Dirofilaria repens infection, causing an asymptomatic subcutaneous nodule

We present a case of subcutaneous dirofilariasis, a vector-borne zoonotic disease, in a young woman from Austria. The diagnosis was confirmed by ultrasound and histology of the excised subcutaneous nodule. The parasite species was identified as Dirofilaria repens by polymerase chain reaction. We expect to see more cases of human dirofilariasis also due to climate change and associated increase of the spectrum of suitable mosquito vectors.

Epididymal Dirofilariasis in a Child: First Case Report from Bulgaria

OBJECTIVE

To present case of a child with epididymal dirofil-ariasis.

CLINICAL PRESENTATION AND INTERVENTION

An 11-year-old boy was admitted to the Clinic of Pediatric Urology for elective surgery treatment of epididymal cyst on the left side. After removal, the cyst was sent for histological examination. Microscopic examination of the histological slides revealed cross-sections of a nematode belonging to Dirofilaria spp., differentiated morphologically as D. repens. After surgery, the patient recovered completely.

CONCLUSIONS

In most parts around the world, dirofilariasis is a rare and neglected infection. Nevertheless, the clinicians and pathologists must be informed about it.

Dirofilaria repens infection as a cause of intensive peripheral microfilariemia in a Polish patient: process description and cases review

Dirofilariasis is a parasitic disease of dogs and other carnivores transmitted mainly by the mosquitoes of the genera Culex, Aedes, Anopheles. Full life cycle of the Dirofilaria nematodes in humans is extremely rarely observed, usually lacking species determination at the molecular level. We report fully documented unusual clinical manifestation of subcutaneous dirofilariasis with intensive microfilariemia in peripheral blood revealed by the Knott's concentration technique. The identification of the Dirofilaria repens nematode was based on typical morphological findings for adult gravid female nematode found in the histopathological preparations. The morphology of microfilariae obtained from patient's peripheral blood was also typical for D. repens. The final identification was confirmed by the molecular analysis of microfilariae collected from the blood.

Heartworm-associated respiratory disease (HARD) induced by immature adult Dirofilaria immitis in cats

BACKGROUND

A controlled, blind research study was conducted to define the initial inflammatory response and lung damage associated with the death of immature adult Dirofilaria immitis in cats as compared with cats developing adult heartworm infections and cats on preventive medication.

METHODS

Three groups of cats were utilized, 10 per group. All cats were infected with 100 third-stage (L3) larvae by subcutaneous injection. Group A cats were treated topically with selamectin (Revolution®; Zoetis) per label directions at 28 days post infection (PI) and once monthly for 8 months. Group B cats were treated orally with ivermectin (Ivomec®; Merial) at 150 μg/kg at 70 days PI, then every 2 weeks for 5 months. Group C cats were untreated PI. At baseline (Day 0) and on Days 70, 110, 168, and 240 PI, peripheral blood, serum, bronchial lavage, and thoracic radiographic images were collected on all cats. Upon completion of the study (Day 245), cats were euthanized and necropsies were conducted.

RESULTS

Results were analyzed statistically between groups by ANOVA and by paired sample T testing for changes within the group over time. The selamectin-treated cats (Group A) did not develop radiographically evident changes throughout the study and were free of adult heartworms or worm fragments at necropsy. The heartworm life cycle was abbreviated with oral doses of ivermectin (Group B), shown by the absence of adult heartworms or worm fragments at necropsy. The early stage of immature adult worm in Group B cats, however, did induce severe pulmonary airway, interstitial, and arterial lung lesions, revealing that the abbreviated infection is a significant cause of respiratory pathology in cats. Cats in Groups B and C could not be differentiated based on radiographic changes, serologic antibody titers, complete blood count, or bronchoalveolar lavage cytology at any time point throughout the study. Eighty percent of cats in Group A and 100% of cats in Groups B and C became heartworm antibody positive at some time point post infection.

CONCLUSIONS

The clinical implications of this study are that cats that become infected with immature adult heartworms may not develop fully mature heartworms and are only transiently heartworm antibody positive, but do develop Heartworm-Associated Respiratory Disease (HARD).

The progression of heartworm associated respiratory disease (HARD) in SPF cats 18 months after Dirofilaria immitis infection

BACKGROUND

Heartworm-associated respiratory disease (HARD) in cats is induced by the arrival and death of immature adult Dirofilaria immitis in the pulmonary system and is indistinguishable from mature adult heartworm infection.

METHODS

A controlled, blind research study investigated the long-term (18 months post infection, PI) consequences of the inflammatory response associated with the death of immature adult heartworms in cats. Three groups of cats, 10 per group, were infected with 100 third-stage (L3) larvae by subcutaneous injection. Group A cats were treated with selamectin (Revolution®; Zoetis) per label directions at 28 days PI and once monthly for 17 months. Group B cats were treated orally with ivermectin (Ivomec®; Merial) at 150 μg/kg) at 70 days PI, then every 2 weeks for 15 months. Group C cats were untreated PI. At baseline (Day 0) and on Days 70, 110, 168, 240, 309, 380, and 505 PI, peripheral blood, serum, bronchial lavage, and thoracic radiographic images were collected.

RESULTS

The selamectin-treated cats (Group A) and ivermectin-treated cats (Group B) were free of heartworms or heartworm fragments at necropsy. All cats became heartworm antibody positive at some time point in the study except for one cat in Group A. Only cats in Group C (all with adult heartworms) were heartworm antigen positive. The heartworm antibody titer for Group B was highest on Days 110 to 168 and then decreased over time and 50% were serologically antibody negative on Day 240. Eosinophilic bronchoalveolar lavage (BAL) cytology and peripheral eosinophilia were most pronounced on Day 110 in all cats. Randomly distributed myofibrocytes in the lungs of some Group A cats suggest that precardiac larval stages were affecting the lungs. Radiographs in Group B cats demonstrated partial resolution of the initial HARD reaction but chronic myofibrocyte proliferation was histologically evident 18 months after infection.

CONCLUSION

HARD was induced by immature adult worm infection with progressive improvement starting 6 to 8 months after infection but histologic lesions were evident in some cats 18 months after infection. The serologic antibody assay was negative in 50% of cats at 8 months and 100% of cats at 18 months post infection. Abnormal radiographic lung patterns continued in a subset of Group B cats for months after heartworm antibody serology and BAL cytology returned to normal.

Aberrant peritoneal localization of Dirofilaria repens in a dog

Subcutaneous dirofilariosis is a widely spread vector-borne zoonotic disease caused by Dirofilaria repens. In the last years, a rise of human and animal cases of infection by D. repens has been reported in different European countries. The disease may be subclinical or characterized by different skin conditions. This report describes an unusual ectopic localization of D. repens in a naturally infected dog. The six-year old Pit Bull mixed breed dog presented dysorexia, exercise intolerance, orchialgia and moderate abdominal effusion. The abdominal ultrasound examination revealed multiple linear tubular structures with writhing and undulating movements within the peritoneal effusion. The microscopic examination of the peritoneal effusion revealed many larvae microscopically and molecularly identified as D. repens. This is the first case of peritoneal localization of D. repens in a dog. Epidemiological implications are discussed.

Evaluation of serum symmetric dimethylarginine in dogs with heartworm infection

This study evaluated the circulating levels of serum symmetric dimethylarginine (SDMA) in 12 dogs with different severities of heartworm disease (HWD) and assessed the biochemical renal markers (blood urea nitrogen, creatinine). Dogs were classified into 2 groups based on the severity of clinical signs. Group A - asymptomatic to mild clinical signs, group B - moderate to severe clinical signs. The serum SDMA levels were higher in dogs in group B. Although the serum SDMA levels in dogs in group A were also higher than those of the control dogs, the difference was not statistically significant. There was a good correlation between renal markers and severity of clinical signs. This study demonstrated that the glomerular filtration rate was significantly decreased in dogs in group A; therefore, earlier detection of renal impairment is required for successful management of dogs with HWD.

[CLINICAL CASE OF DIROFILARIASIS.]

The paper describes a case of the rare localization of a pregnant Dirofilaria female in a man's genitalia. Patient T born in 1973 was infected in the Krasnoyarsk Territory presumably in the summer of 2012. A migratory mass appeared under the skin of the chest at the beginning of 2016. A dense mass was located beneath the skin in the penis by early April. Histological specimens from the removed tumor, entered the specialized Clinical Diagnostic Laboratory for parasitic diseases. The specimens exhibited transverse and oblique sections of Dirofilaria spp. The body cavity contained nematodes - multiple microfilariae. However, routine studies and PCR could not reveal the microfilariae in the blood.

[INFECTION OF BLOOD-SUCKING MOSQUITOES (DIPTERA: CULICIDAE) WITH DIROFILARIAE (SPIRURIDA, ONCHOCERCIDAE) IN THE TULA REGION]

Blood-sucking mosquitoes (n = 2277) collected in Tula and its Region in 2013-2014 were examined using a PCR assay for dirofilariae. A total of 12 species from 4 genera (Culiseta, Aedes, Ochlerotatus [foreign character] Culex) out of 18 found mosquito species were infected with Dirofilaria immitis and D. repens. The proportion of the infected mosquitoes was 2.5% (D. immitis, 1.5%; D.repens, 1%). According to preliminary data, the most efficient Dirofilaria vectors, in the Tula Region may be Ae. vexans, Ae. geniculatus, Och. cantans, and Cx. pipiens.

[CURRENT IDEAS ON OBLIGATE AND FACULTATIVE RELATIONSHIPS BETWEEN MAN AND THE DIROFILARIASIS PATHOGEN DIROFILARIA (N.) REPENS]

The ability of D. repens to complete its ontogenesis in man points to their obligate, rather than facultative rela- tionships. The fact that microfilariae are rarely found in human blood or are absent there may be associated with the removal of developing dirofilariae from humans in earlier than they achieve sexual maturity. Facultative ecological relationships to mosquitoes may be one of the reasons for limitation of human invasion cases. However, in long-standing microfilaremia in man (an obligate host), D.repens may take part in the epidemiological chain of dirofilariasis as a source of invasion.

Aberrant heartworm migration to the abdominal aorta and systemic arteriolitis in a dog presenting with vomiting and hemorrhagic diarrhea

A 2-year-old Dachshund was presented for vomiting and diarrhea. Abdominal ultrasound revealed Dirofilaria immitis in the abdominal aorta and an avascular segment of small intestine. The dog was euthanized. Necropsy revealed D. immitis in the abdominal aorta and widespread necrotizing arteriolitis. This is a unique presentation of aberrant migration of D. immitis.

Morphological and molecular identification of Dirofilaria immitis from Jackal (Canis aureus) in North Khorasan, northeast Iran

BACKGROUND & OBJECTIVES

The heartworm Dirofilaria immitis is an important mosquito-borne zoonotic nematode of domestic and wild mammals throughout the world, causing cardiopulmonary dirofilariasis. This parasite has been reported from carnivores in some provinces of Iran. However, in the present study, the occurrence of this filarial nematode is reported for the first time in wild canids of the North Khorasan Province, located in northeast Iran, based on morphological and molecular characteristics.

METHODS

The carcasses of 45 golden jackals (Canis aureus), 16 foxes (Vulpes vulpes), 15 dogs (Canis familiaris), and one wolf (Canis lupus) were necropsied between 2013 and 2014.

RESULTS

By gross examination, adult filarial nematodes were found in the cardiovascular system of four jackals (8.9%). The morphological characteristics of the recovered heartworms were compatible with D. immitis. DNA sequencing of the cytochrome c oxidase subunit I (cox1) gene of all four isolates was identical, showing 100% homology with several sequences registered in GenBank from other countries. No adult D. immitis was found in any of the other animals examined.

INTERPRETATION & CONCLUSION

D. immitis is circulating in wildlife of the study area, suggesting the relevance of developing control programmes to prevent transmission of the disease to humans and domestic animals.

Dirofilariasis - an emergent human parasitosis in Romania

Changing vector habitats due to climate change increase the risk of less common vector-borne diseases spreading to temperate areas. An example of such a disease is dirofilariasis. The present article is a case presentation of ocular dirofilariasis. The peculiarities of this case and its implications to public health are presented herein, in addition to a literature review of the epidemiological data regarding dirofilariasis in dogs and humans. A16-year-old adolescent, who had never travelled outside Galaţi County, was admitted to the hospital's pediatric department with conjunctival edema, foreign body perception, redness and local pain in the left eye. A parasitological exam identified Dirofilaria repens. The outcome of the condition was favorable. Although canine dirofilariasis is more often encountered by veterinary practices, only few human cases had hither to been reported in Romania, none in Galaţi County. A national Romanian prevalence study on dirofilariasis in animals is called for in order to improve the management of the disease, both in veterinary and human medicine.

Fibrinolysis and proliferative endarteritis: two related processes in chronic infections? The model of the blood-borne pathogen Dirofilaria immitis

The interaction between blood-borne pathogens and fibrinolysis is one of the most important mechanisms that mediate invasion and the establishment of infectious agents in their hosts. However, overproduction of plasmin (final product of the route) has been related in other contexts to proliferation and migration of the arterial wall cells and degradation of the extracellular matrix. We have recently identified fibrinolysis-activating antigens from Dirofilaria immitis, a blood-borne parasite whose key pathological event (proliferative endarteritis) is produced by similar mechanisms to those indicated above. The objective of this work is to study how two of this antigens [actin (ACT) and fructose-bisphosphate aldolase (FBAL)] highly conserved in pathogens, activate fibrinolysis and to establish a relationship between this activation and the development of proliferative endarteritis during cardiopulmonary dirofilariasis. We demonstrate that both proteins bind plasminogen, enhance plasmin generation, stimulate the expression of the fibrinolytic activators tPA and uPA in endothelial cell cultures and are located on the surface of the worm in contact with the host’s blood. ELISA, western blot and immunofluorescence techniques were employed for this purpose. Additionally, the implication of lysine residues in this interaction was analyzed by bioinformatics. The involvement of plasmin generated by the ACT/FBAL and plasminogen binding in cell proliferation and migration, and degradation of the extracellular matrix were shown in an “in vitro” model of endothelial and smooth muscle cells in culture. The obtained results indicate that ACT and FBAL from D. immitis activate fibrinolysis, which could be used by the parasite like a survival mechanism to avoid the clot formation. However, long-term overproduction of plasmin can trigger pathological events similar to those described in the emergence of proliferative endarteritis. Due to the high degree of evolutionary conservation of these antigens, similar processes may occur in other blood-borne pathogens.

[Pulmonary dirofilariasis]

A 70-year-old man was admitted to our department for pulmonary nodule of 15 mm in diameter in the left lower lobe detected by chest computed tomography (CT). A possibility of malignant tumor could not be ruled out, and lung partial resection was performed. Pathological examination during operation revealed a coagulation necrosis and the lesion was finally diagnosed as pulmonary dirofilariasis.

[Results of studies of human dirofilariasis in Russia]

Human dirofilariasis is a pressing health problem in Russia. By 2014, there have been as many as 850 Dirofilaria repens-infested people living in 42 subjects of the Russian Federation. One of the favorable factors for circulation and spread of invasion is a temperature of above +20-24 degrees C; when the latter is maintained during at least 20 days there may be 1.-1.5 circulations of invasion in the carrier and a 2.8-fold increase in transmission intensity. The border ofa dirofilariasis area with a temperate climate is southward to 58 degrees N in European Russia and West Siberia and southward to 50 degrees N in the Far East. The conditions in the human body have been found to be more favorable for the development of Dirofilaria than considered before and allow the helminth to achieve sexual maturity and to propagate. If man has microfilaremia, he may be a source of invasion. It is necessary to examine venous blood by the enrichment method and, if possible, polymerase chain reaction and enzyme immunoassay, which make it possible to establish a diagnosis in occult invasion and to identify a pathogen species.

[Human dirofilariasis: clinical and diagnostic signs and diagnostic methods]

The clinical and diagnostic signs caused by the tissue location and migration of adult Dirofilaria in the human body determine the use of different methods for the diagnosis of dirofilariasis. During their investigations, the authors modified polymerase chain reaction (PCR): they chose and synthesized primers and selected amplification regimens for them and obtained agarose gel bands that corresponded to PCR fragment length nucleotide sequences that were equal to 245 bp for D. (N.) repens and 656 bp for D. immitis. There was 100% agreement in the results of PCR and microscopic examination of sera from 32 dogs and 1 female patient with low parasitemia and in the blood nucleotide sequence characteristic of D. repens.

Case Report of dirofilariasis in grey wolf in Serbia

This paper describes a case of dirofilariasis in a two-year old, female grey wolf (Canis lupus lupus). The autopsy revealed the presence of 42 adult forms of Dirofilaria immitis in the pulmonary artery, right ventricle and right atrium, varying in length from 9.5 to 30 cm. This is, to the best of our knowledge, the second report of D. immitis in grey wolves in Serbia. Our finding confirms that the wolf, as a subspecies distinct from the dog, should also be considered as a very suitable definitive host for dirofilariasis.

Dirofilaria repens infection in a ten-year-old boy from the Istria Peninsula: case report

Dirofilariasis is a zoonotic infection caused by worms belonging to the genus Dirofilaria. The disease is transmitted by mosquitoes and the hosts are usually dogs. Infections in humans are rare and they usually manifest as a subcutaneous nodule or a conjunctival form. We present a 10-year-old boy with a subcutaneous nodule on his left forearm, who was admitted to the hospital. On examination, the only significant findings were high levels of eosinophils. The pediatrician suspected dirofilariasis and the boy was referred to pediatric surgery. The whole lesion was surgically removed and histopathologic examination confirmed parasitic infection by Dirofilaria repens. Although human dirofilariasis is a rare disease, the number of reported cases has recently increased worldwide. The disease mainly occurs in southern European countries, but has also been described in eastern Europe, Central Asia and Sri Lanka. Croatia is one of the endemic areas for dirofilariasis, especially in the region of the Istria Peninsula. The case presented highlights the requirement for further monitoring of endemic areas in order to establish effective preventive measures.

Pseudo-tumor of the scrotum, a rare clinical presentation of dirofilariasis: a report of two autochtonous cases due to Dirofilaria repens

In Europe, human dirofilariasis refers to a group of autochtonous parasitic infections caused by tissue nematodes of the genus Dirofilaria, responsible for two distinct clinical presentations: Dirofilaria immitis usually presenting as pulmonary lesions and Dirofilaria repens as subcutaneous nodules. Rare in humans, genital involvement manifests itself as pseudotumor nodules affecting the scrotum, epididymis, or spermatic cord. We report on two cases of Dirofilaria repens infections, involving the spermatic cord and epididymis.

Human and animal dirofilariasis: the emergence of a zoonotic mosaic

Dirofilariasis represents a zoonotic mosaic, which includes two main filarial species (Dirofilaria immitis and D. repens) that have adapted to canine, feline, and human hosts with distinct biological and clinical implications. At the same time, both D. immitis and D. repens are themselves hosts to symbiotic bacteria of the genus Wolbachia, the study of which has resulted in a profound shift in the understanding of filarial biology, the mechanisms of the pathologies that they produce in their hosts, and issues related to dirofilariasis treatment. Moreover, because dirofilariasis is a vector-borne transmitted disease, their distribution and infection rates have undergone significant modifications influenced by global climate change. Despite advances in our knowledge of D. immitis and D. repens and the pathologies that they inflict on different hosts, there are still many unknown aspects of dirofilariasis. This review is focused on human and animal dirofilariasis, including the basic morphology, biology, protein composition, and metabolism of Dirofilaria species; the climate and human behavioral factors that influence distribution dynamics; the disease pathology; the host-parasite relationship; the mechanisms involved in parasite survival; the immune response and pathogenesis; and the clinical management of human and animal infections.

[Dirofilariasis in the Nizhny Novgorod Region]

The paper describes cases of dirofilariasis in the Nizhny Novgorod Region in 2006-2010. During this period 26 patients with dirofilariasis were registered. Their age was 20 to 68 years; the maximum cases (26.9%) were among those aged 50-59 years. Females constituted most cases (70%). In 73% of patients, the helminth was found in different areas of the head, with the predominant involvement of eye lesion (34.6%), in the temple (11.5%), cheek (8%), and nose (8%). Dirofilaria were randomly detected in 2 patients. Helminth migration occurred in 15.3% of cases. No clear seasonality for this helminthiasis was found. Local dirofilariasis was noted in most cases (92.3%). This infection was observed in 13 of 49 districts of the region and in 3 of 8 districts of Nizhny Novgorod. The Nizhny Novgorod Region is situated in a low infection transmission risk area (latitude 54-58 degrees North). However, among 11 areas located in this zone, the Nizhny Novgorod Region registered the maximum cases of dirofilariasis. Dirofilariasis in the Nizhny Novgorod Region shares the manifestations of this helminthiasis in the Russian Federation.

Human dirofilariosis in Poland: the first cases of autochthonous infections with Dirofilaria repens

Dirofilaria (Nochtiella) repens Railliet et Henry, 1911 (Nematoda: Onchocercidae) is a subcutaneous parasite of dogs and other carnivorous animals, with human acting as incidental hosts. D. repens occurs endemically in warm climates on various continents, in Europe mainly in Mediterranean countries. The aim of this study was to summarize information on human dirofilariosis in Poland, taking into consideration parasitological and epidemiological data. Between April 2009-December 2011, in the parasitological laboratories of Medical University in Warsaw and the National Institute of Public Health/National Institute of Hygiene, fragments of affected human tissues and parasite specimens were examined microscopically. Molecular methods were used to confirm the results from eight microscopic investigations. A literature review to summarize all data on dirofilarial infections in humans in Poland was conducted. In these investigations, autochthonous dirofilariosis was found in humans for the first time in Poland. During the last 3 years, 12 new cases of human D. repens dirofilariosis were recognized. Since 2007, a total of 18 D. repens infection have been found in humans in Poland. Parasitic changes were located in various parts of the body, in the form of subcutaneous nodules containing single nematodes surrounded by granulation tissue (15 cases). In 3 cases, a subconjuctival localization was found. Seventeen of the 18 described cases were noted in central Poland where dirofilariosis occured in dogs. In this area, autochtonous infection was identified in 3 women who had never left Poland in their lives; the others were probably infected outside the country while staying in endemic regions. Data on human and canine infection collected from central Poland during the last 5 years indicates that Dirofilaria repens has been introduced into our country, and that the infection is successfully spreading, with the border of the endemic area currently on 52°N, 21°E. To control the epidemiological situation it is necessary to identify D. repens hosts within local mosquito populations, and to monitor dogs. Because of the increasing number of cases of human infections, whether introduced or local, physicians should take dirofilariosis into consideration in differential diagnosis of skin and eye diseases.

[Case of pulmonary dirofilariasis with cavity formation in a young woman]

A 22-year-old woman was referred to our hospital because of an abnormal shadow in her chest X-ray found on a medical examination. Chest CT showed a 16-mm nodule with cavity formation in the left lung. We did not reach a definitive diagnosis by blood test and bronchoscopy. Because we could not exclude the possibility of a malignancy, lung partial resection was performed by video-assisted thoracoscopic surgery for treatment and diagnosis. We recognized the Dirofilaria immitis by pathological diagnosis and we diagnosed this case as pulmonary dirofilariasis. It seemed to be a valuable case that the patient was young, at 22 years old, and there was, cavity formation, which is comparatively rare in pulmonary dirofilariasis.

Dirofilaria immitis in cats: anatomy of a disease

It is now understood that wherever heartworm infection exists in the local canine population, it will also be found in the feline population. However, this does not mean that the parasite and resulting disease behave the same way in both species. For example, heartworms rarely reach the adult stage in cats, but they can cause respiratory sequelae nonetheless.

First case of cutaneous human dirofilariosis in Slovak Republic

Dirofilariosis is a zoonotic disease caused by several species of the genus of Dirofilaria. The causative agent initiates a dangerous canine disease reported from many parts of the globe. The parasites are transmitted by arthropods, which act either as a vector or intermediate hosts. In humans the parasites do not usually reach the adult stage but microfilaremia is absent because of mating impossibility. Human dirofilariosis is caused by D. immitis or D. repens and has been reported from many parts of the world including European countries, namely Italy, France, Spain and Greece. Sporadically, this parasitosis is detected in Central European countries such as Hungary and Switzerland. The presented paper reports the first case of human cutaneous dirofilariosis in Slovakia. The clinical manifestation was a typical subcutaneous granuloma with the adult worm in the center. The identification of Dirofilaria repens was made based on morphological appearance of the parasite. The patient 60 years old, lives in the area where in 2005 six cases of canine dirofilariosis caused by the same species were reported (Fig. 2, Ref. 16).

Membranoproliferative glomerulonephritis type III in a simultaneous infection of Leishmania infantum and Dirofilaria immitis in a dog

In this report a 9-year-old female German Shepherd dog with a membranoproliferative glomerulonephritis (MPGN) type III associated with concomitant infection of Dirofilaria immitis and Leishmania infantum is presented. Light microscopic evaluation of kidney revealed a diffuse hypercellularity and thickening of glomerular basement membrane. Heavy and coarse granular complement C(3) deposition and a weaker positive reaction to immunoglobulin G were present along peripheral glomerular basement membrane and in the mesangium in the immunofluorescent study. Transmission electron microscopy revealed deposits in the mesangium, subendothelium, and subepithelium. These lesions are compatible with membranoproliferative glomerulonephritis type III in humans.

Allergic inflammatory reaction is involved in necrosis of human pulmonary dirofilariasis

AIMS

To determine whether, in view of the massive inflammatory cell infiltration and the rounded rather than wedge-shaped character of pulmonary lesions in dirofilariasis, the inflammatory response against the worm contributes to the coagulative necrosis, in addition to an ischaemic process.

METHODS AND RESULTS

The histopathological features of 13 resected dirofilariasis cases with well-defined nodules ranged from 10 to 30 mm were analysed. On routine histology and using immunohistochemistry, the peripheral encapsulating wall showed mild to severe infiltration of eosinophils, lymphocytes and plasma cells and a histiocytic reaction in all cases, often with necrotic eosinophils seen within the necrosis (84.6%) and inflammatory changes in the adjacent lung (38.5%). The CD4+ lymphocyte count (80.8 +/- 33.4) was greater than that of CD8+ lymphocytes (24.5 +/- 16.9) in the central necrosis and vice versa in the wall. In the necrotic regions, disruption of the pulmonary artery (61.5%) and extravasation of the torn worm (23.1%) could be seen.

CONCLUSIONS

These findings indicate that an allergic inflammatory reaction, mediated by eosinophils and lymphocytes, is involved in the formation of the dirofilarial necrotizing granuloma rather than infarction caused simply by embolism.

Human dirofilariasis: raccoon heartworm causing a leg nodule

Human dirofilariasis is a rare zoonotic infection caused by various filarial species of the genus Dirofilaria. Dirofilaria tenuis causes heartworm infection in raccoons and infrequently causes human disease. The Dirofilaria organism accidentally is transmitted to humans through the bite of a mosquito and subcutaneous nodules, coin lesions of the lungs, or ophthalmic lesions develop at the inoculation site. We report a rare case of D tenuis infection in a patient that manifested as a subcutaneous nodule.

Dirofilaria immitis infection in dogs: unusually located and unusual findings

Clinical, blood, serum biochemistry, and parasitological assessments were performed on four hospitalized dogs, not in good general condition, in a study carried out to determine the prevalence of general parasitic infections. Hematological and biochemical parameters and electrocardiographic recording of the animals were determined during the general clinical examinations. Four dogs were indicated to have been infected with Dirofilaria immitis by using modified Knott's method, and the microfilarial density was determined. Mild to moderate anemia and decrease in sedimentation velocity were established in dogs. Differences in other hematological and biochemical values between the dogs were determined. Right axis deviation was determined in a dog. D. immitis was encountered in the right ventricle, bronchus, and the pericardial sac at the end of the necropsy. On the other hand, in the histopathological examinations, pulmonary adenocarcinoma deriving from bronchial epithelium was identified in a dog, and microfilaria was encountered in bronchial and bronchiolar lumens, interstitium of the lungs, and bile ducts. D. immitis has not been considered in the diagnosis of dogs with pneumonia and tumors. The requirement of parasitological examination with respect to D. immitis in the diagnosis of dogs with tumor or pneumonia has been considered vital.

Dirofilaria repens diagnosed by the presence of microfilariae in fine needle aspirates: a case report

BACKGROUND

Dirofilariasis due to Dirofilaria repens with viable microfilariae outside the worm have not been reported before.

CASE

A 40-year-old truck driver from rural Shiraz, Iran, had a firm mass, 2.5 x 2.5 cm, at the dorsolateral aspect of the right forearm. Fine needle aspiration (FNA) was performed on 2 occasions. Several microfilariae with blunt heads, pointed posterior ends and empty caudal spaces resembling microfilariae of Wuchereria bancrofti but longer were seen. Since Iran is a nonendemic area for lymphatic filariae and the patient had a history of contact with a dog, with the impression of dirofilariasis, the mass was excised, and the presence of adult worms in tissue sections confirmed the diagnosis.

CONCLUSION

This case ofsubcutaneous dirofilariasis was diagnosed by detecting microfilariae in FNA smears and was confirmed on histopathology.

Human subcutaneous dirofilariasis, Russia

We report 14 cases of human subcutaneous dirofilariasis caused by Dirofilaria repens, diagnosed from February 2003 through July 2004, in patients from Rostovon-Don, Russia. Serologic analysis showed evidence of high risk of exposure to D. repens. Surveillance studies on prevalence and prevention effectiveness of canine infection are needed to control this emerging zoonosis.

Immunopathology of Dirofilaria immitis infection

Heartworm disease caused by Dirofilaria immitis affects canine and feline hosts, with infections occasionally being reported in humans. Studies have shown that both dirofilarial antigens and those derived from its bacterial endosymbiont Wolbachia, interact with the host organism during canine, feline and human infections and participate in the development of the pathology and in the regulation of the host's immune response. Both innate and acquired immune responses are observed and the development of the acquired response may depend on the host and, or on its parasitological status. This review aims at illustrating current research on the role of both D. immitis and Wolbachia, in the immunology and immunopathology of dirofilariosis.