Dirofilaria repens infection in northern Israel

Lymphatic filariasis in Asia: a systematic review and meta-analysis

Lymphatic filariasis (LF) is an important neglected parasitic disease according to the World Health Organization. In this study, we aimed to determine the prevalence of human LF in Asia using a systematic review and meta-analysis approach. Records from 1990 to 2018 in reputable databases including PubMed, Science Direct, Embase, and Cochrane Library were searched using a panel of related keywords. All 48 countries of Asia were searched one by one in combination with the keywords. In all, 41,742 cases identified in this study were included in the analysis. According to our findings, the pooled prevalence of LF in Asia was estimated at 3% (95% CI: [1.7, 5.2]). There was no major trend in the cumulative prevalence of LF over time. Some countries in Asia including China, Japan, Vietnam, and South Korea succeeded in eliminating LF as a public health problem, but others still need to monitor the disease. Based on the initiative of the WHO starting in 2000, some countries in Asia succeeded in eliminating LF as a public health problem. Other countries have taken steps to eliminate the disease with variable degrees of success. These efforts might be affected by issues such as climate change.

Unusual Breast Lumps

Two new Italian cases of breast infection by Dirofilaria Repens are presented. In one case the correct diagnosis was clinically achieved through needle aspiration. This case is documented by a surprising macrophotography.

Marked subcutaneous mast cell and eosinophilic infiltration associated with the presence of multiple Dirofilaria repens microfilariae in 4 dogs

Dirofilaria repens is a parasitic nematode in the subcutaneous tissue of carnivores, including dogs and cats, transmitted by mosquitoes. Human beings may be accidental hosts. Infection of a dog with D repens was first reported in Palestine in 1934, and 2 additional cases were reported in dogs in Israel to date. This report describes D repens infection in 4 dogs in Israel that presented with subcutaneous masses, which were cytologically characterized by marked mast cell and eosinophil infiltration. In 3 cases, multiple microfilariae were present in the lesions; rare microfilariae were present in the 4^th case. In all 4 dogs, PCR of fine-needle aspirates from the lesions were positive for D repens. The mast cells observed in all lesions were uniform and highly granulated, and with the presence of the microfilariae, a mast cell tumor was considered less likely. This report suggests that D repens infection-associated subcutaneous lesions, characterized cytologically by massive mast cell and eosinophil infiltration, should be considered a differential diagnosis for mast cell tumor, especially in geographic locations endemic for this nematode. Notably, all 4 dogs were infected with D repens despite a routine prophylactic doramectin therapy administered every 3 months, probably due to the relatively long time interval between treatments.

Mammary Dirofilariasis

We report a case of a dirofilariasis manifesting as a breast nodule in a 32-year-old Tunisian woman. It appeared as a relatively well-circumscribed and slightly dense nodule on mammography and was hypoechogenic with enhanced through transmission on ultrasonographic examination. The patient was treated by surgical resection. Histopathologic analysis could identify viable female and male worms as Dirofilaria repens. Dirofilaria is rare in Tunisia and this is the second human case reported. The patient lived all her life in Tunisia and had never been abroad.

Molecular analysis of Dirofilaria repens removed from a subcutaneous nodule in a Japanese woman after a tour to Europe

A premature female Dirofilaria species, subsequently identified as Dirofilaria repens by its morphological features and mitochondrial 12S ribosomal RNA (12S rRNA) gene sequence, was removed from a subcutaneous nodule of the right temporal region of the head in a Japanese woman 2 years after she noticed swelling of her left calf following an insect sting during a tour to Europe; headache symptoms were noticed a few months later. The sequences of the mitochondrial 12S rRNA and cytochrome c oxidase subunit I genes from the organism were almost identical to those of sequences AM779772 (100% homology, 337/337) and AM749233 (99.8% homology, 536/537) of D. repens isolated from humans in Italy. However, the phylogenetic position of the 18S rRNA-internal transcribed spacer 1-5.8S rRNA region was in the same cluster as that of sequence JX290195 of Dirofilaria sp. “hongkongensis” (96.7% homology, 348/360), which was recently reported from Hong Kong as a novel Dirofilaria species. Information on regional genetic variation in D. repens isolated from animals and humans remains scarce. We report the detailed genetic features of this filaria as a reference isolate from a specific endemic area, to enrich the genetic database of D. repens.

Subcutaneous dirofilariasis caused by Dirofilaria repens in Greece: a case report

Dirofilaria repens (formerly Dirofilaria conjunctiva) is a natural parasite of the subcutaneous tissues of dogs, cats and wild carnivores in Europe, Africa and Asia. Microfilariae are transmitted to humans by various species of mosquito. An autochthonous case of subcutaneous dirofilariasis is reported in a Greek patient from the island of Corfu. The clinical manifestation of the infection was a palpable, painless, subcutaneous nodule in the region of the groin, which 2 days before the patient consulted the doctor developed symptoms and signs of inflammation (pain, edema and redness). The entire lesion was surgically removed, and the nematode worm D. repens was identified on histological sections of biopsy material. The aim of this report was (a) to describe the microscopic morphological features of D. repens that enable identification of the parasite on histological examination and (b) to emphasize the importance of consideration of subcutaneous dirofilariasis in the differential diagnosis of subcutaneous nodules with inflammatory eosinophilic infiltration in countries where the infection is endemic.

Three new cases of human infection with Dirofilaria repens, one pulmonary and two subcutaneous, in the Egyptian governorate of Assiut

Human dirofilariasis caused by Dirofilaria repens is a parasitic infection, currently considered to be an emerging zoonosis, that has been observed in many areas of the Old World. Dogs are the main 'reservoir' host. In humans, D. repens can cause inflammatory nodules, most commonly in the subcutaneous tissues or in the subconjunctival space. Lung involvement, which is the most common of the non-cutaneous and non-ocular manifestations, is frequently mis-diagnosed as a primary or metastatic lung tumour. Two new subcutaneous cases and one new pulmonary case, all observed in the Egyptian governorate of Assiut, are described here. This represents the first report of human pulmonary dirofilariasis caused by D. repens on the African continent. All the worms collected from the cases, including a living worm from the left lung of the pulmonary case, were identified morphologically, and the identity of the lung parasite was confirmed by PCR.

Detection of Dirofilaria (Nochtiella) repens DNA by polymerase chain reaction in embedded paraffin tissues from two human pulmonary locations

We here report two new cases of human pulmonary dirofilariasis in men aged 62 and 64 from Northern and Central Italy, respectively. Both were asymptomatic and the infections were discovered incidentally when chest radiographs taken for another reason revealed the presence of a coin lesion. The initial clinical diagnosis was oriented towards a lung tumour, and an excisional lung biopsy after thoracotomy was necessary for the final diagnosis. Pathologically, the lesion consisted of a roundish subpleural infarct with a central thrombotic artery containing sections of an immature nematode: Dirofilaria repens was diagnosed histologically in one case, the necrotic condition of the worm allowing only genus identification, Dirofilaria, in the other case. In both samples, PCR analysis amplified a 246 bp product, specific for the IpS insert 11 of D. repens. The authors stress the role of PCR in the diagnosis of this parasite from paraffin samples, also in cases in which identification of the species was not possible by conventional morphology due to poor conservation of the worm. These cases represent the first PCR-based diagnosis of D. repens in a human pulmonary dirofilariasis on samples embedded in paraffin.

Genotypic assignment of infection by Dirofilaria repens

Dirofilariasis is a parasitic disease, which if treated inappropriately due to misdiagnosis, can cause unwanted complications particularly when the infection is located in the breast. The numerous obstacles that can cause misdiagnosis of dirofilariases by standard morphological procedures prompted the development of a Dirofilaria repens-specific direct polymerase chain reaction (PCR)-based diagnostic approach using freshly infected dog blood. Reliable amplification of nematode DNA from formalin-fixed infected human specimens by this method is only possible from relatively fresh biological material, preserved in the fixative for up to 20 days. We report here our first case of dirofilariasis since the development of PCR genotyping, where the pathogen was morphologically unrecognizable and the diagnosis was based exclusively on DNA amplification. We complete our methodological contribution to the clinical laboratory diagnosis of dirofilariasis by presenting two more cases, where the primary genotypic assignment of infection by D. repens was further confirmed by conventional morphological means.

Subcutaneous infection caused by Dirofilaria repens imported to Slovenia

A case of human subcutaneous dirofilariasis is presented. A complete nematode removed from the tumour in the occipital region of a 61-year-old woman was identified, on the basis of its anatomical and histological characteristics, as a nongravid adult female of the species Dirofilaria repens. The patient had probably been infected on the Canary Islands, Spain, 7 months previously. In the future, the clinical and laboratory staff in Slovenia will have to be more alert to the possibility of dirofilariasis in patients with subcutaneous tumours, particularly in individuals who had travelled to endemic areas several months or years before the tumour was detected.

Pitfalls and difficulties in histological diagnosis of human dirofilariasis due to Dirofilaria (Nochtiella) repens

The authors have conducted a histologic study of over 90 cases of Dirofilaria infection in man due to Dirofilaria repens, the most extensive study of its kind in the world. On the basis of their findings, they illustrate the diagnostic difficulties that may arise when regressive phenomena render the parasite's morphologic characteristics largely or completely unrecognizable. These phenomena are due to the death of the filaria inside the inflammatory nodule weeks or months prior to surgical removal, and to the consequent invasion of inflammatory cells. They start at the nematode's natural orifices (mouth, vulva, anus, cloaca) and gradually spread throughout its body. In cases of difficult diagnosis, therefore, it is recommended that the nodule be sectioned at different points comprising caudal, cephalic and middle body aspects, so as to reveal the few morphologic features that are still recognizable and which may afford a correct diagnosis. The authors present examples of histologic sections in color plates in which the nematode was in an excellent state of preservation and others illustrating the full range of regressive phenomena, from slight to total disintegration of the bodily structure.

Ophthalmic dirofilariasis

PURPOSE

To report a rare case of ophthalmic dirofilariasis in a 68-year-old man with sudden, intense pain and itching in the left eye. The nematode was located in the eye and recognized as Dirofilaria repens.

METHODS

Slit-lamp examination disclosed a moving nematelminth under the bulbar conjunctiva of the left eye. The nematode was surgically removed.

RESULTS

The nematelminth surgically removed from the subconjunctival space was identified as D repens on the basis of transverse sections and its macroscopic characteristics.

CONCLUSION

It is important to identify the nematode as D repens, based on both its microscopic and macroscopic characteristics, to avoid treatment with anthelminthic agents. The surgical removal of the worm is the sole recommended treatment.

Extrapulmonary Dirofilaria immitis-like infections in the Western Hemisphere

One worm recovered from the orbit of a patient in Indiana, and two from the peritoneal cavity of another patient in California are described and classified as Dirofilaria. Both patients were elderly men who have lived all their lives in the United States. The main morphologic feature of these three immature worms is the presence of a smooth cuticle devoid of longitudinal ridges, similar to the cuticle of D. immitis. However, because other dirofilariid with similar cuticular characteristics have been found in animals in the Western Hemisphere, and they cannot be conclusively ruled out as the cause of the infection in our patients, a diagnosis of D. immitis-like organism is proposed for these nematodes. The relationship of these worms to other dirofilariid of animals and humans on the American continent is important because of the diagnostic problems these infections posed to practicing pathologists.